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	diff --git a/README.md b/README.md
	index 82a1513..64abe8c 100644
	--- a/README.md
	+++ b/README.md
	@@ -1,499 +1,524 @@
	# Tesla

	[![Build Status](https://github.com/teamon/tesla/workflows/Test/badge.svg)](https://github.com/teamon/tesla/actions)
	[![Hex.pm](https://img.shields.io/hexpm/v/tesla.svg)](http://hex.pm/packages/tesla)
	[![Hex.pm](https://img.shields.io/hexpm/dt/tesla.svg)](https://hex.pm/packages/tesla)
	[![Hex.pm](https://img.shields.io/hexpm/dw/tesla.svg)](https://hex.pm/packages/tesla)
	[![codecov](https://codecov.io/gh/teamon/tesla/branch/master/graph/badge.svg)](https://codecov.io/gh/teamon/tesla)
	[![Inline docs](https://inch-ci.org/github/teamon/tesla.svg)](http://inch-ci.org/github/teamon/tesla)

	Tesla is an HTTP client loosely based on [Faraday](https://github.com/lostisland/faraday).
	It embraces the concept of middleware when processing the request/response cycle.

	> Note that this README refers to the `master` branch of Tesla, not the latest
	released version on Hex. See [the documentation](http://hexdocs.pm/tesla) for
	the documentation of the version you're using.

	-<hr/>
	+---

	## [`0.x` to `1.0` Migration Guide](https://github.com/teamon/tesla/wiki/0.x-to-1.0-Migration-Guide)

	```elixir
	defp deps do
	[{:tesla, "~> 1.3.0"}]
	end
	```

	[Documentation for 0.x branch](https://github.com/teamon/tesla/tree/0.x)

	-<hr/>
	+---

	## HTTP Client example

	Define module with `use Tesla` and choose from a variety of middleware.

	```elixir
	defmodule GitHub do
	use Tesla

	plug Tesla.Middleware.BaseUrl, "https://api.github.com"
	plug Tesla.Middleware.Headers, [{"authorization", "token xyz"}]
	plug Tesla.Middleware.JSON

	def user_repos(login) do
	get("/user/" <> login <> "/repos")
	end
	end
	```

	Then use it like this:

	```elixir
	{:ok, response} = GitHub.user_repos("teamon")
	-response.status # => 200
	-response.body # => [%{…}, …]
	-response.headers # => [{"content-type", "application/json"}, ...]
	+
	+response.status
	+# => 200
	+
	+response.body
	+# => [%{…}, …]
	+
	+response.headers
	+# => [{"content-type", "application/json"}, ...]
	```

	See below for documentation.

	## Installation

	Add `tesla` as dependency in `mix.exs`:

	```elixir
	defp deps do
	[
	{:tesla, "~> 1.3.0"},
	- {:hackney, "~> 1.14.0"}, # optional, but recommended adapter
	- {:jason, ">= 1.0.0"} # optional, required by JSON middleware
	+
	+ # optional, but recommended adapter
	+ {:hackney, "~> 1.14.0"},
	+
	+ # optional, required by JSON middleware
	+ {:jason, ">= 1.0.0"}
	]
	end
	+
	```

	Configure default adapter in `config/config.exs` (optional).

	```elixir
	# config/config.exs

	config :tesla, adapter: Tesla.Adapter.Hackney
	```

	> The default adapter is erlang's built-in `httpc`, but it is not recommended
	to use it in production environment as it does not validate SSL certificates
	[among other issues](https://github.com/teamon/tesla/issues?utf8=%E2%9C%93&q=is%3Aissue+label%3Ahttpc+).

	## Documentation
	+
	- [Middleware](#middleware)
	- [Runtime middleware](#runtime-middleware)
	- [Adapters](#adapters)
	- [Streaming](#streaming)
	- [Multipart](#multipart)
	- [Testing](#testing)
	- [Writing middleware](#writing-middleware)
	- [Direct usage](#direct-usage)
	- [Cheatsheet](#cheatsheet)
	- [Cookbook](https://github.com/teamon/tesla/wiki)
	- [Changelog](https://github.com/teamon/tesla/releases)

	-
	## Middleware
	+
	Tesla is built around the concept of composable middlewares.
	This is very similar to how [Plug Router](https://github.com/elixir-plug/plug#the-plug-router) works.

	-#### Basic
	+### Basic
	+
	- [`Tesla.Middleware.BaseUrl`](https://hexdocs.pm/tesla/Tesla.Middleware.BaseUrl.html) - set base url
	- [`Tesla.Middleware.Headers`](https://hexdocs.pm/tesla/Tesla.Middleware.Headers.html) - set request headers
	- [`Tesla.Middleware.Query`](https://hexdocs.pm/tesla/Tesla.Middleware.Query.html) - set query parameters
	- [`Tesla.Middleware.Opts`](https://hexdocs.pm/tesla/Tesla.Middleware.Opts.html) - set request options
	- [`Tesla.Middleware.FollowRedirects`](https://hexdocs.pm/tesla/Tesla.Middleware.FollowRedirects.html) - follow 3xx redirects
	- [`Tesla.Middleware.MethodOverride`](https://hexdocs.pm/tesla/Tesla.Middleware.MethodOverride.html) - set X-Http-Method-Override
	- [`Tesla.Middleware.Logger`](https://hexdocs.pm/tesla/Tesla.Middleware.Logger.html) - log requests (method, url, status, time)
	- [`Tesla.Middleware.KeepRequest`](https://hexdocs.pm/tesla/Tesla.Middleware.KeepRequest.html) - keep request body & headers
	- [`Tesla.Middleware.PathParams`](https://hexdocs.pm/tesla/Tesla.Middleware.PathParams.html) - use templated URLs

	-#### Formats
	-- [`Tesla.Middleware.FormUrlencoded`](https://hexdocs.pm/tesla/Tesla.Middleware.FormUrlencoded.html) - urlencode POST body parameter, useful for POSTing a map/keyword list
	+### Formats
	+
	+- [`Tesla.Middleware.FormUrlencoded`](https://hexdocs.pm/tesla/Tesla.Middleware.FormUrlencoded.html) - urlencode POST body, useful for POSTing a map/keyword list
	- [`Tesla.Middleware.JSON`](https://hexdocs.pm/tesla/Tesla.Middleware.JSON.html) - JSON request/response body
	- [`Tesla.Middleware.Compression`](https://hexdocs.pm/tesla/Tesla.Middleware.Compression.html) - gzip & deflate
	- [`Tesla.Middleware.DecodeRels`](https://hexdocs.pm/tesla/Tesla.Middleware.DecodeRels.html) - decode `Link` header into `opts[:rels]` field in response

	-#### Auth
	+### Auth
	+
	- [`Tesla.Middleware.BasicAuth`](https://hexdocs.pm/tesla/Tesla.Middleware.BasicAuth.html) - HTTP Basic Auth
	- [`Tesla.Middleware.DigestAuth`](https://hexdocs.pm/tesla/Tesla.Middleware.DigestAuth.html) - Digest access authentication

	-#### Error handling
	+### Error handling
	+
	- [`Tesla.Middleware.Timeout`](https://hexdocs.pm/tesla/Tesla.Middleware.Timeout.html) - timeout request after X milliseconds despite of server response
	- [`Tesla.Middleware.Retry`](https://hexdocs.pm/tesla/Tesla.Middleware.Retry.html) - retry few times in case of connection refused
	- [`Tesla.Middleware.Fuse`](https://hexdocs.pm/tesla/Tesla.Middleware.Fuse.html) - fuse circuit breaker integration

	-
	## Runtime middleware

	-All HTTP functions (`get`, `post`, etc.) can take a dynamic client as the first parameter.
	+All HTTP functions (`get`, `post`, etc.) can take a dynamic client as the first argument.
	This allow to use convenient syntax for modifying the behaviour in runtime.

	Consider the following case: GitHub API can be accessed using OAuth token authorization.

	We can't use `plug Tesla.Middleware.Headers, [{"authorization", "token here"}]`
	since this would be compiled only once and there is no way to insert dynamic user token.

	Instead, we can use `Tesla.client` to create a client with dynamic middleware:

	```elixir
	defmodule GitHub do
	# notice there is no `use Tesla`

	def user_repos(client, login) do
	# pass `client` argument to `Tesla.get` function
	Tesla.get(client, "/user/" <> login <> "/repos")
	end

	def issues(client) do
	Tesla.get(client, "/issues")
	end

	# build dynamic client based on runtime arguments
	def client(token) do
	middleware = [
	{Tesla.Middleware.BaseUrl, "https://api.github.com"},
	Tesla.Middleware.JSON,
	{Tesla.Middleware.Headers, [{"authorization", "token: " <> token }]}
	]

	Tesla.client(middleware)
	end
	end
	```

	and then:

	```elixir
	client = GitHub.client(user_token)
	client \|> GitHub.user_repos("teamon")
	client \|> GitHub.get("/me")
	```

	## Adapters

	Tesla supports multiple HTTP adapter that do the actual HTTP request processing.

	- [`Tesla.Adapter.Httpc`](https://hexdocs.pm/tesla/Tesla.Adapter.Httpc.html) - the default, built-in erlang [httpc](http://erlang.org/doc/man/httpc.html) adapter
	- [`Tesla.Adapter.Hackney`](https://hexdocs.pm/tesla/Tesla.Adapter.Hackney.html) - [hackney](https://github.com/benoitc/hackney), "simple HTTP client in Erlang"
	- [`Tesla.Adapter.Ibrowse`](https://hexdocs.pm/tesla/Tesla.Adapter.Ibrowse.html) - [ibrowse](https://github.com/cmullaparthi/ibrowse), "Erlang HTTP client"
	- [`Tesla.Adapter.Gun`](https://hexdocs.pm/tesla/Tesla.Adapter.Gun.html) - [gun](https://github.com/ninenines/gun), "HTTP/1.1, HTTP/2 and Websocket client for Erlang/OTP"
	- [`Tesla.Adapter.Mint`](https://hexdocs.pm/tesla/Tesla.Adapter.Mint.html) - [mint](https://github.com/elixir-mint/mint), "Functional HTTP client for Elixir with support for HTTP/1 and HTTP/2"

	When using adapter other than httpc remember to add it to the dependencies list in `mix.exs`

	```elixir
	defp deps do
	[{:tesla, "~> 1.3.0"},
	{:jason, ">= 1.0.0"}, # optional, required by JSON middleware
	{:hackney, "~> 1.10"}] # or :gun etc.
	end
	```

	### Adapter options

	In case there is a need to pass specific adapter options you can do it in one of three ways:

	Using `adapter` macro:

	```elixir
	defmodule GitHub do
	use Tesla

	adapter Tesla.Adapter.Hackney, recv_timeout: 30_000, ssl_options: [certfile: "certs/client.crt"]
	end
	```

	Using `Tesla.client/2`:

	```elixir
	def new(...) do
	middleware = [...]
	adapter = {Tesla.Adapter.Hackney, [recv_timeout: 30_000]}
	Tesla.client(middleware, adapter)
	end
	```

	Passing directly to `get`/`post`/etc.

	```elixir
	MyClient.get("/", opts: [adapter: [recv_timeout: 30_000]])
	Tesla.get(client, "/", opts: [adapter: [recv_timeout: 30_000]])
	```

	## Streaming

	If adapter supports it, you can pass a [Stream](http://elixir-lang.org/docs/stable/elixir/Stream.html) as body, e.g.:

	```elixir
	defmodule ElasticSearch do
	use Tesla

	plug Tesla.Middleware.BaseUrl, "http://localhost:9200"
	plug Tesla.Middleware.JSON

	def index(records_stream) do
	stream = records_stream \|> Stream.map(fn record -> %{index: [some, data]} end)
	post("/_bulk", stream)
	end
	end
	```

	Each piece of stream will be encoded as JSON and sent as a new line (conforming to JSON stream format)

	-
	-
	-
	## Multipart

	You can pass a `Tesla.Multipart` struct as the body.

	-
	```elixir
	alias Tesla.Multipart

	mp =
	- Multipart.new
	+ Multipart.new()
	\|> Multipart.add_content_type_param("charset=utf-8")
	\|> Multipart.add_field("field1", "foo")
	- \|> Multipart.add_field("field2", "bar", headers: [{"content-id", "1"}, {"content-type", "text/plain"}])
	+ \|> Multipart.add_field("field2", "bar",
	+ headers: [{"content-id", "1"}, {"content-type", "text/plain"}]
	+ )
	\|> Multipart.add_file("test/tesla/multipart_test_file.sh")
	\|> Multipart.add_file("test/tesla/multipart_test_file.sh", name: "foobar")
	\|> Multipart.add_file_content("sample file content", "sample.txt")

	{:ok, response} = MyApiClient.post("http://httpbin.org/post", mp)
	```

	## Testing

	You can set the adapter to `Tesla.Mock` in tests.

	```elixir
	# config/test.exs
	# Use mock adapter for all clients
	config :tesla, adapter: Tesla.Mock
	# or only for one
	config :tesla, MyApi, adapter: Tesla.Mock
	```

	Then, mock requests before using your client:

	-
	```elixir
	defmodule MyAppTest do
	use ExUnit.Case

	import Tesla.Mock

	setup do
	- mock fn
	+ mock(fn
	%{method: :get, url: "http://example.com/hello"} ->
	%Tesla.Env{status: 200, body: "hello"}
	+
	%{method: :post, url: "http://example.com/world"} ->
	json(%{"my" => "data"})
	- end
	+ end)

	:ok
	end

	test "list things" do
	assert {:ok, %Tesla.Env{} = env} = MyApp.get("/hello")
	assert env.status == 200
	assert env.body == "hello"
	end
	end
	```

	-
	## Writing middleware

	-A Tesla middleware is a module with `call/3` function, that at some point calls `Tesla.run(env, next)` to process
	+A Tesla middleware is a module with `c:Tesla.Middleware.call/3` function, that at some point calls `Tesla.run/2` with `env` and `next` to process
	the rest of stack.

	```elixir
	defmodule MyMiddleware do
	@behaviour Tesla.Middleware

	def call(env, next, options) do
	env
	- \|> do_something_with_request
	+ \|> do_something_with_request()
	\|> Tesla.run(next)
	- \|> do_something_with_response
	+ \|> do_something_with_response()
	end
	end
	```

	The arguments are:
	+
	- `env` - `Tesla.Env` instance
	-- `next` - middleware continuation stack; to be executed with `Tesla.run(env, next)`
	+- `next` - middleware continuation stack; to be executed with `Tesla.run/2` with `env` and `next`
	- `options` - arguments passed during middleware configuration (`plug MyMiddleware, options`)

	There is no distinction between request and response middleware, it's all about executing `Tesla.run/2` function at the correct time.

	For example, a request logger middleware could be implemented like this:

	```elixir
	defmodule Tesla.Middleware.RequestLogger do
	@behaviour Tesla.Middleware

	def call(env, next, _) do
	- IO.inspect env # print request env
	- Tesla.run(env, next)
	+ env
	+ \|> IO.inspect()
	+ \|> Tesla.run(next)
	end
	end
	```

	and response logger middleware like this:

	```elixir
	defmodule Tesla.Middleware.ResponseLogger do
	@behaviour Tesla.Middleware

	def call(env, next, _) do
	- res = Tesla.run(env, next)
	- IO.inspect res # print response env
	- res
	+ env
	+ \|> Tesla.run(next)
	+ \|> IO.inspect()
	end
	end
	```

	See [built-in middlewares](https://github.com/teamon/tesla/tree/master/lib/tesla/middleware) for more examples.

	Middleware should have documentation following this template:

	````elixir
	defmodule Tesla.Middleware.SomeMiddleware do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Short description what it does

	Longer description, including e.g. additional dependencies.


	### Example usage
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.SomeMiddleware, most: :common, options: "here"
	end
	```

	### Options
	+
	- `:list` - all possible options
	- `:with` - their default values
	"""
	+
	+ @behaviour Tesla.Middleware
	end
	````

	-
	## Direct usage

	You can also use Tesla directly, without creating a client module.
	This however won’t include any middleware.

	```elixir
	# Example get request
	{:ok, response} = Tesla.get("http://httpbin.org/ip")
	-response.status # => 200
	-response.body # => "{\n "origin": "87.205.72.203"\n}\n"
	-response.headers # => [{"content-type", "application/json" ...}]

	+response.status
	+# => 200
	+
	+response.body
	+# => "{\n "origin": "87.205.72.203"\n}\n"
	+
	+response.headers
	+# => [{"content-type", "application/json" ...}]

	{:ok, response} = Tesla.get("http://httpbin.org/get", query: [a: 1, b: "foo"])
	-response.url # => "http://httpbin.org/get?a=1&b=foo"

	+response.url
	+# => "http://httpbin.org/get?a=1&b=foo"

	# Example post request
	-{:ok, response} = Tesla.post("http://httpbin.org/post", "data", headers: [{"content-type", "application/json"}])
	+{:ok, response} =
	+ Tesla.post("http://httpbin.org/post", "data", headers: [{"content-type", "application/json"}])
	```

	-
	## Cheatsheet

	+### Making requests 101

	-#### Making requests 101
	```elixir
	# GET /path
	get("/path")

	# GET /path?a=hi&b[]=1&b[]=2&b[]=3
	-get("/path", query: [a: "hi", b: [1,2,3]])
	+get("/path", query: [a: "hi", b: [1, 2, 3]])

	# GET with dynamic client
	get(client, "/path")
	get(client, "/path", query: [page: 3])

	# arguments are the same for GET, HEAD, OPTIONS & TRACE
	head("/path")
	options("/path")
	trace("/path")

	# POST, PUT, PATCH
	post("/path", "some-body-i-used-to-know")
	put("/path", "some-body-i-used-to-know", query: [a: "0"])
	patch("/path", multipart)
	```

	-#### Configuring HTTP functions visibility
	+### Configuring HTTP functions visibility
	+
	```elixir
	# generate only get and post function
	use Tesla, only: ~w(get post)a

	-# generate only delete fuction
	+# generate only delete function
	use Tesla, only: [:delete]

	# generate all functions except delete and options
	use Tesla, except: [:delete, :options]
	```

	-#### Disable docs for HTTP functions
	+### Disable docs for HTTP functions
	+
	```elixir
	use Tesla, docs: false
	```

	-#### Decode only JSON response (do not encode request)
	+### Decode only JSON response (do not encode request)
	+
	```elixir
	plug Tesla.Middleware.DecodeJson
	```

	-#### Use other JSON library
	+### Use other JSON library
	+
	```elixir
	# use JSX
	plug Tesla.Middleware.JSON, engine: JSX, engine_opts: [strict: [:comments]]

	# use custom functions
	plug Tesla.Middleware.JSON, decode: &JSX.decode/1, encode: &JSX.encode/1
	```

	+### Custom middleware

	-#### Custom middleware
	```elixir
	defmodule Tesla.Middleware.MyCustomMiddleware do
	def call(env, next, options) do
	env
	- \|> do_something_with_request
	+ \|> do_something_with_request()
	\|> Tesla.run(next)
	- \|> do_something_with_response
	+ \|> do_something_with_response()
	end
	end
	```

	## Contributing

	1. Fork it (https://github.com/teamon/tesla/fork)
	2. Create your feature branch (`git checkout -b my-new-feature`)
	3. Commit your changes (`git commit -am 'Add some feature'`)
	4. Push to the branch (`git push origin my-new-feature`)
	5. Create new Pull Request

	## License

	This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details

	Copyright (c) 2015-2018 [Tymon Tobolski](http://teamon.eu/about/)
	diff --git a/lib/tesla.ex b/lib/tesla.ex
	index e48e5db..3bd432d 100644
	--- a/lib/tesla.ex
	+++ b/lib/tesla.ex
	@@ -1,512 +1,532 @@
	defmodule Tesla.Error do
	defexception env: nil, stack: [], reason: nil

	def message(%Tesla.Error{env: %{url: url, method: method}, reason: reason}) do
	"#{inspect(reason)} (#{method \|> to_string \|> String.upcase()} #{url})"
	end
	end

	defmodule Tesla.Env do
	@moduledoc """
	This module defines a `t:Tesla.Env.t/0` struct that stores all data related to request/response.

	## Fields

	- * `:method` - method of request. Example: `:get`
	- * `:url` - request url. Example: `"https://www.google.com"`
	- * `:query` - list of query params.
	- Example: `[{"param", "value"}]` will be translated to `?params=value`.
	- Note: query params passed in url (e.g. `"/get?param=value"`) are not parsed to `query` field.
	- * `:headers` - list of request/response headers.
	- Example: `[{"content-type", "application/json"}]`.
	- Note: request headers are overriden by response headers when adapter is called.
	- * `:body` - request/response body.
	- Note: request body is overriden by response body when adapter is called.
	- * `:status` - response status. Example: `200`
	- * `:opts` - list of options. Example: `[adapter: [recv_timeout: 30_000]]`
	+ - `:method` - method of request. Example: `:get`
	+ - `:url` - request url. Example: `"https://www.google.com"`
	+ - `:query` - list of query params.
	+ Example: `[{"param", "value"}]` will be translated to `?params=value`.
	+ Note: query params passed in url (e.g. `"/get?param=value"`) are not parsed to `query` field.
	+ - `:headers` - list of request/response headers.
	+ Example: `[{"content-type", "application/json"}]`.
	+ Note: request headers are overriden by response headers when adapter is called.
	+ - `:body` - request/response body.
	+ Note: request body is overriden by response body when adapter is called.
	+ - `:status` - response status. Example: `200`
	+ - `:opts` - list of options. Example: `[adapter: [recv_timeout: 30_000]]`
	"""

	@type client :: Tesla.Client.t()
	@type method :: :head \| :get \| :delete \| :trace \| :options \| :post \| :put \| :patch
	@type url :: binary
	@type param :: binary \| [{binary \| atom, param}]
	@type query :: [{binary \| atom, param}]
	@type headers :: [{binary, binary}]

	@type body :: any
	@type status :: integer
	@type opts :: [any]

	@type stack :: [{atom, atom, any} \| {atom, atom} \| {:fn, (t -> t)} \| {:fn, (t, stack -> t)}]
	@type result :: {:ok, t()} \| {:error, any}

	@type t :: %__MODULE__{
	method: method,
	query: query,
	url: url,
	headers: headers,
	body: body,
	status: status,
	opts: opts,
	__module__: atom,
	__client__: client
	}

	defstruct method: nil,
	url: "",
	query: [],
	headers: [],
	body: nil,
	status: nil,
	opts: [],
	__module__: nil,
	__client__: nil
	end

	defmodule Tesla.Client do
	@type adapter :: module \| {module, any} \| (Tesla.Env.t() -> Tesla.Env.result())
	@type middleware :: module \| {module, any}

	@type t :: %__MODULE__{
	pre: Tesla.Env.stack(),
	post: Tesla.Env.stack(),
	adapter: adapter \| nil
	}
	defstruct fun: nil,
	pre: [],
	post: [],
	adapter: nil
	end

	defmodule Tesla.Middleware do
	@moduledoc """
	The middleware specification

	Middleware is an extension of basic `Tesla` functionality. It is a module that must
	- export `call/3` function.
	+ implement `c:Tesla.Middleware.call/3`.

	## Middleware options

	Options can be passed to middleware in second param of `Tesla.Builder.plug/2` macro:

	plug Tesla.Middleware.BaseUrl, "https://example.com"

	or inside tuple in case of dynamic middleware (`Tesla.client/1`)

	Tesla.client([{Tesla.Middleware.BaseUrl, "https://example.com"}])

	## Writing custom middleware

	- Writing custom middleware is as simple as creating a module with `call/3` function that:
	- * (optionally) read and/or writes request data
	- * calls `Tesla.run/2`
	- * (optionally) read and/or writes response data
	+ Writing custom middleware is as simple as creating a module implementing `c:Tesla.Middleware.call/3`.

	- `call/3` params:
	- * env - `Tesla.Env` struct that stores request/response data
	- * stack - middlewares that should be called after current one
	- * options - middleware options provided by user
	+ See `c:Tesla.Middleware.call/3` for details.

	- #### Example
	+ ### Example

	defmodule MyProject.InspectHeadersMiddleware do
	@behaviour Tesla.Middleware

	- @impl true
	+ @impl Tesla.Middleware
	def call(env, next, options) do
	env
	\|> inspect_headers(options)
	\|> Tesla.run(next)
	\|> inspect_headers(options)
	end

	defp inspect_headers(env, options) do
	IO.inspect(env.headers, options)
	end
	end

	"""
	+
	+ @doc """
	+ Invoked when a requset runs.
	+
	+ - (optionally) read and/or writes request data
	+ - calls `Tesla.run/2`
	+ - (optionally) read and/or writes response data
	+
	+ ## Arguments
	+
	+ - `env` - `Tesla.Env` struct that stores request/response data
	+ - `next` - middlewares that should be called after current one
	+ - `options` - middleware options provided by user
	+ """
	@callback call(env :: Tesla.Env.t(), next :: Tesla.Env.stack(), options :: any) ::
	Tesla.Env.result()
	end

	defmodule Tesla.Adapter do
	@moduledoc """
	- The adapter specification
	+ The adapter specification.

	Adapter is a module that denormalize request data stored in `Tesla.Env` in order to make
	request with lower level http client (e.g. `:httpc` or `:hackney`) and normalize response data
	- in order to store it back to `Tesla.Env`. It has to export `call/2` function.
	+ in order to store it back to `Tesla.Env`. It has to implement `c:Tesla.Adapter.call/2`.

	## Writing custom adapter

	- `call/2` params:
	- * env - `Tesla.Env` struct that stores request/response data
	- * options - middleware options provided by user
	+ Create a module implementing `c:Tesla.Adapter.call/2`.

	- #### Example
	+ See `c:Tesla.Adapter.call/2` for details.
	+
	+ ### Example

	defmodule MyProject.CustomAdapter do
	alias Tesla.Multipart

	@behaviour Tesla.Adapter

	@override_defaults [follow_redirect: false]

	- @impl true
	+ @impl Tesla.Adapter
	def call(env, opts) do
	opts = Tesla.Adapter.opts(@override_defaults, env, opts)

	with {:ok, {status, headers, body}} <- request(env.method, env.body, env.headers, opts) do
	{:ok, normalize_response(env, status, headers, body)}
	end
	end

	defp request(_method, %Stream{}, _headers, _opts) do
	{:error, "stream not supported by adapter"}
	end

	defp request(_method, %Multipart{}, _headers, _opts) do
	{:error, "multipart not supported by adapter"}
	end

	defp request(method, body, headers, opts) do
	:lower_level_http.request(method, body, denormalize_headers(headers), opts)
	end

	defp denormalize_headers(headers), do: ...
	defp normalize_response(env, status, headers, body), do: %Tesla.Env{env \| ...}
	end

	"""
	+
	+ @doc """
	+ Invoked when a request runs.
	+
	+ ## Arguments
	+
	+ - `env` - `Tesla.Env` struct that stores request/response data
	+ - `options` - middleware options provided by user
	+ """
	@callback call(env :: Tesla.Env.t(), options :: any) :: Tesla.Env.result()

	@doc """
	- Helper function that merges all adapter options
	+ Helper function that merges all adapter options.

	- ## Params:
	- * `defaults` (optional) - useful to override lower level http client default configuration
	- * `env` - `Tesla.Env` struct
	- * `opts` - options provided to `Tesla.Builder.adapter/2` macro
	+ ## Arguments

	- ## Precedence rules:
	- * config from `opts` overrides config from `defaults` when same key is encountered
	- * config from `env` overrides config from both `defaults` and `opts` when same key is encountered
	+ - `defaults` (optional) - useful to override lower level http client default configuration
	+ - `env` - `Tesla.Env` struct
	+ - `opts` - options provided to `Tesla.Builder.adapter/2` macro
	+
	+ ## Precedence rules
	+
	+ - config from `opts` overrides config from `defaults` when same key is encountered
	+ - config from `env` overrides config from both `defaults` and `opts` when same key is encountered
	"""
	@spec opts(Keyword.t(), Tesla.Env.t(), Keyword.t()) :: Keyword.t()
	def opts(defaults \\ [], env, opts) do
	defaults
	\|> Keyword.merge(opts \|\| [])
	\|> Keyword.merge(env.opts[:adapter] \|\| [])
	end
	end

	defmodule Tesla do
	use Tesla.Builder

	alias Tesla.Env

	require Tesla.Adapter.Httpc
	@default_adapter Tesla.Adapter.Httpc

	@moduledoc """
	A HTTP toolkit for building API clients using middlewares

	## Building API client

	`use Tesla` macro will generate basic http functions (e.g. get, post) inside your module.
	It supports following options:
	- * `:only` - builder will generate only functions included in list given in this option
	- * `:except` - builder won't generate functions included in list given in this option
	- * `:docs` - when set to false builder will won't add documentation to generated functions

	- #### Example
	+ - `:only` - builder will generate only functions included in list given in this option
	+ - `:except` - builder won't generate functions included in list given in this option
	+ - `:docs` - when set to false builder will won't add documentation to generated functions
	+
	+ ### Example

	defmodule ExampleApi do
	use Tesla, only: [:get], docs: false

	plug Tesla.Middleware.BaseUrl, "http://api.example.com"
	plug Tesla.Middleware.JSON

	def fetch_data do
	get("/data")
	end
	end

	- In example above `ExampleApi.fetch_data/0` is equivalent of `ExampleApi.get("/data")`
	+ In example above `ExampleApi.fetch_data/0` is equivalent of `ExampleApi.get("/data")`.

	## Direct usage

	It is also possible to do request directly with `Tesla` module.

	Tesla.get("https://example.com")

	- #### Common pitfalls
	+ ### Common pitfalls

	Direct usage won't include any middlewares.

	In following example:

	defmodule ExampleApi do
	use Tesla, only: [:get], docs: false

	plug Tesla.Middleware.BaseUrl, "http://api.example.com"
	plug Tesla.Middleware.JSON

	def fetch_data do
	Tesla.get("/data")
	end
	end

	call to `ExampleApi.fetch_data/0` will fail, because request will be missing base url.

	## Default adapter

	By default `Tesla` is using `Tesla.Adapter.Httpc`, because `:httpc` is included in Erlang/OTP and
	doen not require installation of any additional dependency. It can be changed globally with config

	config :tesla, :adapter, Tesla.Adapter.Hackney

	or by `Tesla.Builder.adapter/2` macro for given API client module

	defmodule ExampleApi do
	use Tesla

	adapter Tesla.Adapter.Hackney

	...
	end

	"""

	defmacro __using__(opts \\ []) do
	quote do
	use Tesla.Builder, unquote(opts)
	end
	end

	@doc false
	def execute(module, client, options) do
	{env, stack} = prepare(module, client, options)
	run(env, stack)
	end

	@doc false
	def execute!(module, client, options) do
	{env, stack} = prepare(module, client, options)

	case run(env, stack) do
	{:ok, env} -> env
	{:error, error} -> raise Tesla.Error, env: env, stack: stack, reason: error
	end
	end

	defp prepare(module, %{pre: pre, post: post} = client, options) do
	env = struct(Env, options ++ [__module__: module, __client__: client])
	stack = pre ++ module.__middleware__ ++ post ++ [effective_adapter(module, client)]
	{env, stack}
	end

	@doc false
	def effective_adapter(module, client \\ %Tesla.Client{}) do
	with nil <- client.adapter,
	nil <- adapter_per_module_from_config(module),
	nil <- adapter_per_module(module),
	nil <- adapter_from_config() do
	adapter_default()
	end
	end

	defp adapter_per_module_from_config(module) do
	case Application.get_env(:tesla, module, [])[:adapter] do
	nil -> nil
	{adapter, opts} -> {adapter, :call, [opts]}
	adapter -> {adapter, :call, [[]]}
	end
	end

	defp adapter_per_module(module) do
	module.__adapter__
	end

	defp adapter_from_config do
	case Application.get_env(:tesla, :adapter) do
	nil -> nil
	{adapter, opts} -> {adapter, :call, [opts]}
	adapter -> {adapter, :call, [[]]}
	end
	end

	defp adapter_default do
	{@default_adapter, :call, [[]]}
	end

	def run_default_adapter(env, opts \\ []) do
	apply(@default_adapter, :call, [env, opts])
	end

	# empty stack case is useful for reusing/testing middlewares (just pass [] as next)
	def run(env, []), do: {:ok, env}

	# last item in stack is adapter - skip passing rest of stack
	def run(env, [{:fn, f}]), do: apply(f, [env])
	def run(env, [{m, f, a}]), do: apply(m, f, [env \| a])

	# for all other elements pass (env, next, opts)
	def run(env, [{:fn, f} \| rest]), do: apply(f, [env, rest])
	def run(env, [{m, f, a} \| rest]), do: apply(m, f, [env, rest \| a])

	@doc """
	- Adds given key/value pair to `:opts` field in `Tesla.Env`
	+ Adds given key/value pair to `:opts` field in `Tesla.Env`.

	Useful when there's need to store additional middleware data in `Tesla.Env`

	## Example

	iex> %Tesla.Env{opts: []} \|> Tesla.put_opt(:option, "value")
	%Tesla.Env{opts: [option: "value"]}

	"""
	@spec put_opt(Tesla.Env.t(), atom, any) :: Tesla.Env.t()
	def put_opt(env, key, value) do
	Map.update!(env, :opts, &Keyword.put(&1, key, value))
	end

	@doc """
	- Returns value of header specified by `key` from `:headers` field in `Tesla.Env`
	+ Returns value of header specified by `key` from `:headers` field in `Tesla.Env`.

	## Examples

	# non existing header
	iex> env = %Tesla.Env{headers: [{"server", "Cowboy"}]}
	iex> Tesla.get_header(env, "some-key")
	nil

	# existing header
	iex> env = %Tesla.Env{headers: [{"server", "Cowboy"}]}
	iex> Tesla.get_header(env, "server")
	"Cowboy"

	# first of multiple headers with the same name
	iex> env = %Tesla.Env{headers: [{"cookie", "chocolate"}, {"cookie", "biscuits"}]}
	iex> Tesla.get_header(env, "cookie")
	"chocolate"

	"""
	@spec get_header(Env.t(), binary) :: binary \| nil
	def get_header(%Env{headers: headers}, key) do
	case List.keyfind(headers, key, 0) do
	{_, value} -> value
	_ -> nil
	end
	end

	@spec get_headers(Env.t(), binary) :: [binary]
	def get_headers(%Env{headers: headers}, key) when is_binary(key) do
	for {k, v} <- headers, k == key, do: v
	end

	@spec put_header(Env.t(), binary, binary) :: Env.t()
	def put_header(%Env{} = env, key, value) when is_binary(key) and is_binary(value) do
	headers = List.keystore(env.headers, key, 0, {key, value})
	%{env \| headers: headers}
	end

	@spec put_headers(Env.t(), [{binary, binary}]) :: Env.t()
	def put_headers(%Env{} = env, list) when is_list(list) do
	%{env \| headers: env.headers ++ list}
	end

	@spec delete_header(Env.t(), binary) :: Env.t()
	def delete_header(%Env{} = env, key) when is_binary(key) do
	headers = for {k, v} <- env.headers, k != key, do: {k, v}
	%{env \| headers: headers}
	end

	@spec put_body(Env.t(), Env.body()) :: Env.t()
	def put_body(%Env{} = env, body), do: %{env \| body: body}

	@doc """
	Dynamically build client from list of middlewares and/or adapter.

	```
	# add dynamic middleware
	client = Tesla.client([{Tesla.Middleware.Headers, [{"authorization", token}]}])
	Tesla.get(client, "/path")

	# configure adapter in runtime
	client = Tesla.client([], Tesla.Adapter.Hackney)
	client = Tesla.client([], {Tesla.Adapter.Hackney, pool: :my_pool})
	Tesla.get(client, "/path")

	# complete module example
	defmodule MyApi do
	# note there is no need for `use Tesla`

	@middleware [
	{Tesla.Middleware.BaseUrl, "https://example.com"},
	Tesla.Middleware.JSON,
	Tesla.Middleware.Logger
	]

	@adapter Tesla.Adapter.Hackney

	def new(opts) do
	# do any middleware manipulation you need
	middleware = [
	{Tesla.Middleware.BasicAuth, username: opts[:username], password: opts[:password]}
	] ++ @middleware

	# allow configuring adapter in runtime
	adapter = opts[:adapter] \|\| @adapter

	# use Tesla.client/2 to put it all together
	Tesla.client(middleware, adapter)
	end

	def get_something(client, id) do
	# pass client directly to Tesla.get/2
	Tesla.get(client, "/something/\#{id}")
	# ...
	end
	end

	client = MyApi.new(username: "admin", password: "secret")
	MyApi.get_something(client, 42)
	```
	"""
	if Version.match?(System.version(), "~> 1.7"), do: @doc(since: "1.2.0")
	@spec client([Tesla.Client.middleware()], Tesla.Client.adapter()) :: Tesla.Client.t()
	def client(middleware, adapter \\ nil), do: Tesla.Builder.client(middleware, [], adapter)

	@deprecated "Use client/1 or client/2 instead"
	def build_client(pre, post \\ []), do: Tesla.Builder.client(pre, post)

	@deprecated "Use client/1 or client/2 instead"
	def build_adapter(fun), do: Tesla.Builder.client([], [], fun)

	def build_url(url, []), do: url

	def build_url(url, query) do
	join = if String.contains?(url, "?"), do: "&", else: "?"
	url <> join <> encode_query(query)
	end

	defp encode_query(query) do
	query
	\|> Enum.flat_map(&encode_pair/1)
	\|> URI.encode_query()
	end

	@doc false
	def encode_pair({key, value}) when is_list(value) do
	if Keyword.keyword?(value) do
	Enum.flat_map(value, fn {k, v} -> encode_pair({"#{key}[#{k}]", v}) end)
	else
	Enum.map(value, fn e -> {"#{key}[]", e} end)
	end
	end

	@doc false
	def encode_pair({key, value}), do: [{key, value}]
	end
	diff --git a/lib/tesla/adapter/gun.ex b/lib/tesla/adapter/gun.ex
	index 62214f7..5c929f0 100644
	--- a/lib/tesla/adapter/gun.ex
	+++ b/lib/tesla/adapter/gun.ex
	@@ -1,447 +1,456 @@
	if Code.ensure_loaded?(:gun) do
	defmodule Tesla.Adapter.Gun do
	@moduledoc """
	- Adapter for [gun](https://github.com/ninenines/gun)
	+ Adapter for [gun](https://github.com/ninenines/gun).
	+
	Remember to add `{:gun, "~> 1.3"}` to dependencies.
	In version 1.3 gun sends `host` header with port. Fixed in master branch.
	Also, you need to recompile tesla after adding `:gun` dependency:
	+
	```
	mix deps.clean tesla
	mix deps.compile tesla
	```
	- ### Example usage
	+
	+ ## Example usage
	+
	```
	# set globally in config/config.exs
	config :tesla, :adapter, Tesla.Adapter.Gun
	+
	# set per module
	defmodule MyClient do
	use Tesla
	adapter Tesla.Adapter.Gun
	end
	```
	- ### Adapter specific options:
	- * `timeout` - Time, while process, will wait for gun messages.
	- * `body_as` - What will be returned in `%Tesla.Env{}` body key. Possible values - `:plain`, `:stream`, `:chunks`. Defaults to `:plain`.
	- * `:plain` - as binary.
	- * `:stream` - as stream. If you don't want to close connection (because you want to reuse it later) pass `close_conn: false` in adapter opts.
	- * `:chunks` - as chunks. You can get response body in chunks using `Tesla.Adapter.Gun.read_chunk/3` function.
	+
	+ ## Adapter specific options
	+
	+ - `:timeout` - Time, while process, will wait for gun messages.
	+ - `:body_as` - What will be returned in `%Tesla.Env{}` body key. Possible values - `:plain`, `:stream`, `:chunks`. Defaults to `:plain`.
	+ - `:plain` - as binary.
	+ - `:stream` - as stream. If you don't want to close connection (because you want to reuse it later) pass `close_conn: false` in adapter opts.
	+ - `:chunks` - as chunks. You can get response body in chunks using `Tesla.Adapter.Gun.read_chunk/3` function.
	Processing of the chunks and checking body size must be done by yourself. Example of processing function is in `test/tesla/adapter/gun_test.exs` - `Tesla.Adapter.GunTest.read_body/4`. If you don't need connection later don't forget to close it with `Tesla.Adapter.Gun.close/1`.
	- * `max_body` - Max response body size in bytes. Works only with `body_as: :plain`, with other settings you need to check response body size by yourself.
	- * `conn` - Opened connection pid with gun. Is used for reusing gun connections.
	- * `original` - Original host with port, for which reused connection was open. Needed for `Tesla.Middleware.FollowRedirects`. Otherwise adapter will use connection for another open host. Example: `"example.com:80"`.
	- * `close_conn` - Close connection or not after receiving full response body. Is used for reusing gun connections. Defaults to `true`.
	- * `certificates_verification` - Add SSL certificates verification. [erlang-certifi](https://github.com/certifi/erlang-certifi) [ssl_verify_fun.erl](https://github.com/deadtrickster/ssl_verify_fun.erl)
	- * `proxy` - Proxy for requests. Socks proxy are supported only for gun master branch. Examples: `{'localhost', 1234}`, `{{127, 0, 0, 1}, 1234}`, `{:socks5, 'localhost', 1234}`.
	- ### [Gun options](https://ninenines.eu/docs/en/gun/1.3/manual/gun/):
	- * `connect_timeout` - Connection timeout.
	- * `http_opts` - Options specific to the HTTP protocol.
	- * `http2_opts` - Options specific to the HTTP/2 protocol.
	- * `protocols` - Ordered list of preferred protocols. Defaults: [http2, http] - for :tls, [http] - for :tcp.
	- * `trace` - Whether to enable dbg tracing of the connection process. Should only be used during debugging. Default: false.
	- * `transport` - Whether to use TLS or plain TCP. The default varies depending on the port used. Port 443 defaults to tls. All other ports default to tcp.
	- * `transport_opts` - Transport options. They are TCP options or TLS options depending on the selected transport. Default: []. Gun version: 1.3
	- * `tls_opts` - TLS transport options. Default: []. Gun from master branch.
	- * `tcp_opts` - TCP trasnport options. Default: []. Gun from master branch.
	- * `socks_opts` - Options for socks. Default: []. Gun from master branch.
	- * `ws_opts` - Options specific to the Websocket protocol. Default: %{}.
	- * `compress` - Whether to enable permessage-deflate compression. This does not guarantee that compression will be used as it is the server that ultimately decides. Defaults to false.
	- * `protocols` - A non-empty list enables Websocket protocol negotiation. The list of protocols will be sent in the sec-websocket-protocol request header. The handler module interface is currently undocumented and must be set to `gun_ws_h`.
	+ - `:max_body` - Max response body size in bytes. Works only with `body_as: :plain`, with other settings you need to check response body size by yourself.
	+ - `:conn` - Opened connection pid with gun. Is used for reusing gun connections.
	+ - `:original` - Original host with port, for which reused connection was open. Needed for `Tesla.Middleware.FollowRedirects`. Otherwise adapter will use connection for another open host. Example: `"example.com:80"`.
	+ - `:close_conn` - Close connection or not after receiving full response body. Is used for reusing gun connections. Defaults to `true`.
	+ - `:certificates_verification` - Add SSL certificates verification. [erlang-certifi](https://github.com/certifi/erlang-certifi) [ssl_verify_fun.erl](https://github.com/deadtrickster/ssl_verify_fun.erl)
	+ - `:proxy` - Proxy for requests. Socks proxy are supported only for gun master branch. Examples: `{'localhost', 1234}`, `{{127, 0, 0, 1}, 1234}`, `{:socks5, 'localhost', 1234}`.
	+
	+ ## [Gun options](https://ninenines.eu/docs/en/gun/1.3/manual/gun/)
	+
	+ - `:connect_timeout` - Connection timeout.
	+ - `:http_opts` - Options specific to the HTTP protocol.
	+ - `:http2_opts` - Options specific to the HTTP/2 protocol.
	+ - `:protocols` - Ordered list of preferred protocols. Defaults: `[:http2, :http]`- for :tls, `[:http]` - for :tcp.
	+ - `:trace` - Whether to enable dbg tracing of the connection process. Should only be used during debugging. Default: false.
	+ - `:transport` - Whether to use TLS or plain TCP. The default varies depending on the port used. Port 443 defaults to tls. All other ports default to tcp.
	+ - `:transport_opts` - Transport options. They are TCP options or TLS options depending on the selected transport. Default: `[]`. Gun version: 1.3
	+ - `:tls_opts` - TLS transport options. Default: `[]`. Gun from master branch.
	+ - `:tcp_opts` - TCP trasnport options. Default: `[]`. Gun from master branch.
	+ - `:socks_opts` - Options for socks. Default: `[]`. Gun from master branch.
	+ - `:ws_opts` - Options specific to the Websocket protocol. Default: `%{}`.
	+ - `:compress` - Whether to enable permessage-deflate compression. This does not guarantee that compression will be used as it is the server that ultimately decides. Defaults to false.
	+ - `:protocols` - A non-empty list enables Websocket protocol negotiation. The list of protocols will be sent in the sec-websocket-protocol request header. The handler module interface is currently undocumented and must be set to `gun_ws_h`.
	"""
	@behaviour Tesla.Adapter
	alias Tesla.Multipart

	@gun_keys [
	:connect_timeout,
	:http_opts,
	:http2_opts,
	:protocols,
	:retry,
	:retry_timeout,
	:trace,
	:transport,
	:socks_opts,
	:ws_opts
	]

	@adapter_default_timeout 1_000

	- @impl true
	- @doc false
	+ @impl Tesla.Adapter
	def call(env, opts) do
	with {:ok, status, headers, body} <- request(env, opts) do
	{:ok, %{env \| status: status, headers: format_headers(headers), body: body}}
	end
	end

	@doc """
	Reads chunk of the response body.
	+
	Returns `{:fin, binary()}` if all body received, otherwise returns `{:nofin, binary()}`.
	"""
	@spec read_chunk(pid(), reference(), keyword() \| map()) ::
	{:fin, binary()} \| {:nofin, binary()} \| {:error, :timeout}
	def read_chunk(pid, stream, opts) do
	receive do
	{:gun_data, ^pid, ^stream, :fin, body} ->
	if opts[:close_conn], do: close(pid)
	{:fin, body}

	{:gun_data, ^pid, ^stream, :nofin, part} ->
	{:nofin, part}

	{:DOWN, _, _, _, reason} ->
	if opts[:close_conn], do: close(pid)
	{:error, reason}
	after
	opts[:timeout] \|\| @adapter_default_timeout ->
	{:error, :recv_chunk_timeout}
	end
	end

	@doc """
	- Brutally close the `gun` connection
	+ Brutally close the `gun` connection.
	"""
	@spec close(pid()) :: :ok
	defdelegate close(pid), to: :gun

	defp format_headers(headers) do
	for {key, value} <- headers do
	{String.downcase(to_string(key)), to_string(value)}
	end
	end

	defp request(env, opts) do
	request(
	Tesla.Adapter.Shared.format_method(env.method),
	Tesla.build_url(env.url, env.query),
	format_headers(env.headers),
	env.body \|\| "",
	Tesla.Adapter.opts(
	[close_conn: true, body_as: :plain, send_body: :at_once, receive: true],
	env,
	opts
	)
	\|> Enum.into(%{})
	)
	end

	defp request(method, url, headers, %Stream{} = body, opts),
	do: request_stream(method, url, headers, body, Map.put(opts, :send_body, :stream))

	defp request(method, url, headers, body, opts) when is_function(body),
	do: request_stream(method, url, headers, body, Map.put(opts, :send_body, :stream))

	defp request(method, url, headers, %Multipart{} = mp, opts) do
	headers = headers ++ Multipart.headers(mp)
	body = Multipart.body(mp)

	request(method, url, headers, body, opts)
	end

	defp request(method, url, headers, body, opts),
	do: do_request(method, url, headers, body, opts)

	defp request_stream(method, url, headers, body, opts),
	do: do_request(method, url, headers, body, opts)

	defp do_request(method, url, headers, body, opts) do
	with uri <- URI.parse(url),
	path <- Tesla.Adapter.Shared.prepare_path(uri.path, uri.query),
	opts <- check_original(uri, opts),
	{:ok, pid, opts} <- open_conn(uri, opts),
	stream <- open_stream(pid, method, path, headers, body, opts) do
	read_response(pid, stream, opts)
	end
	end

	defp check_original(%URI{host: host, port: port}, %{original: original} = opts) do
	Map.put(opts, :original_matches, original == "#{domain_or_fallback(host)}:#{port}")
	end

	defp check_original(_uri, opts), do: opts

	defp open_conn(_uri, %{conn: conn, original_matches: true} = opts) do
	{:ok, conn, Map.put(opts, :receive, false)}
	end

	defp open_conn(uri, %{conn: conn, original_matches: false} = opts) do
	# current url is different from the original, so we can't use transferred connection
	opts =
	opts
	\|> Map.put_new(:old_conn, conn)
	\|> Map.delete(:conn)

	open_conn(uri, opts)
	end

	defp open_conn(uri, opts) do
	opts =
	if uri.scheme == "https" and uri.port != 443 do
	Map.put(opts, :transport, :tls)
	else
	opts
	end

	tls_opts =
	opts
	\|> Map.get(:tls_opts, [])
	\|> Keyword.merge(Map.get(opts, :transport_opts, []))

	tls_opts =
	with "https" <- uri.scheme,
	false <- opts[:original_matches] do
	# current url is different from the original, so we can't use verify_fun for https requests
	Keyword.delete(tls_opts, :verify_fun)
	else
	_ -> tls_opts
	end

	# Support for gun master branch where transport_opts, were splitted to tls_opts and tcp_opts
	# https://github.com/ninenines/gun/blob/491ddf58c0e14824a741852fdc522b390b306ae2/doc/src/manual/gun.asciidoc#changelog

	tls_opts =
	with "https" <- uri.scheme,
	true <- opts[:certificates_verification] do
	security_opts = [
	verify: :verify_peer,
	cacertfile: CAStore.file_path(),
	depth: 20,
	reuse_sessions: false,
	verify_fun:
	{&:ssl_verify_hostname.verify_fun/3, [check_hostname: domain_or_fallback(uri.host)]}
	]

	Keyword.merge(security_opts, tls_opts)
	else
	_ -> tls_opts
	end

	gun_opts = Map.take(opts, @gun_keys)

	with {:ok, pid} <- do_open_conn(uri, opts, gun_opts, tls_opts) do
	# If there were redirects, and passed `closed_conn: false`, we need to close opened connections to these intermediate hosts.
	{:ok, pid, Map.put(opts, :close_conn, true)}
	end
	end

	defp do_open_conn(uri, %{proxy: {proxy_host, proxy_port}}, gun_opts, tls_opts) do
	connect_opts =
	uri
	\|> tunnel_opts()
	\|> tunnel_tls_opts(uri.scheme, tls_opts)

	with {:ok, pid} <- :gun.open(proxy_host, proxy_port, gun_opts),
	{:ok, _} <- :gun.await_up(pid),
	stream <- :gun.connect(pid, connect_opts),
	{:response, :fin, 200, _} <- :gun.await(pid, stream) do
	{:ok, pid}
	end
	end

	defp do_open_conn(uri, %{proxy: {proxy_type, proxy_host, proxy_port}}, gun_opts, tls_opts) do
	version =
	proxy_type
	\|> to_string()
	\|> String.last()
	\|> case do
	"4" -> 4
	_ -> 5
	end

	socks_opts =
	uri
	\|> tunnel_opts()
	\|> tunnel_tls_opts(uri.scheme, tls_opts)
	\|> Map.put(:version, version)

	gun_opts =
	gun_opts
	\|> Map.put(:protocols, [:socks])
	\|> Map.update(:socks_opts, socks_opts, &Map.merge(socks_opts, &1))

	with {:ok, pid} <- :gun.open(proxy_host, proxy_port, gun_opts),
	{:ok, _} <- :gun.await_up(pid) do
	{:ok, pid}
	else
	{:error, {:options, {:protocols, [:socks]}}} ->
	{:error, "socks protocol is not supported"}

	error ->
	error
	end
	end

	defp do_open_conn(uri, opts, gun_opts, tls_opts) do
	tcp_opts = Map.get(opts, :tcp_opts, [])

	# if gun used from master
	opts_with_master_keys =
	gun_opts
	\|> Map.put(:tls_opts, tls_opts)
	\|> Map.put(:tcp_opts, tcp_opts)

	{_type, host} = domain_or_ip(uri.host)

	with {:ok, pid} <- :gun.open(host, uri.port, opts_with_master_keys) do
	{:ok, pid}
	else
	{:error, {:options, {key, _}}} when key in [:tcp_opts, :tls_opts] ->
	:gun.open(
	host,
	uri.port,
	Map.put(gun_opts, :transport_opts, tls_opts)
	)

	error ->
	error
	end
	end

	defp tunnel_opts(uri) do
	{_type, host} = domain_or_ip(uri.host)
	%{host: host, port: uri.port}
	end

	defp tunnel_tls_opts(opts, "https", tls_opts) do
	http2_opts = %{protocols: [:http2], transport: :tls, tls_opts: tls_opts}
	Map.merge(opts, http2_opts)
	end

	defp tunnel_tls_opts(opts, _, _), do: opts

	defp open_stream(pid, method, path, headers, body, opts) do
	req_opts = %{reply_to: opts[:reply_to] \|\| self()}

	open_stream(pid, method, path, headers, body, req_opts, opts[:send_body])
	end

	defp open_stream(pid, method, path, headers, body, req_opts, :stream) do
	stream = :gun.request(pid, method, path, headers, "", req_opts)
	for data <- body, do: :ok = :gun.data(pid, stream, :nofin, data)
	:gun.data(pid, stream, :fin, "")
	stream
	end

	defp open_stream(pid, method, path, headers, body, req_opts, :at_once),
	do: :gun.request(pid, method, path, headers, body, req_opts)

	defp read_response(pid, stream, opts) do
	receive? = opts[:receive]

	receive do
	{:gun_response, ^pid, ^stream, :fin, status, headers} ->
	if opts[:close_conn], do: close(pid)
	{:ok, status, headers, ""}

	{:gun_response, ^pid, ^stream, :nofin, status, headers} ->
	format_response(pid, stream, opts, status, headers, opts[:body_as])

	{:gun_up, ^pid, _protocol} when receive? ->
	read_response(pid, stream, opts)

	{:gun_error, ^pid, reason} ->
	if opts[:close_conn], do: close(pid)
	{:error, reason}

	{:gun_down, ^pid, _, _, _, _} when receive? ->
	read_response(pid, stream, opts)

	{:DOWN, _, _, _, reason} ->
	if opts[:close_conn], do: close(pid)
	{:error, reason}
	after
	opts[:timeout] \|\| @adapter_default_timeout ->
	if opts[:close_conn], do: :ok = close(pid)
	{:error, :recv_response_timeout}
	end
	end

	defp format_response(pid, stream, opts, status, headers, :plain) do
	case read_body(pid, stream, opts) do
	{:ok, body} ->
	if opts[:close_conn], do: close(pid)
	{:ok, status, headers, body}

	{:error, error} ->
	if opts[:close_conn], do: close(pid)
	{:error, error}
	end
	end

	defp format_response(pid, stream, opts, status, headers, :stream) do
	stream_body =
	Stream.resource(
	fn -> %{pid: pid, stream: stream} end,
	fn
	%{pid: pid, stream: stream} ->
	case read_chunk(pid, stream, opts) do
	{:nofin, part} -> {[part], %{pid: pid, stream: stream}}
	{:fin, body} -> {[body], %{pid: pid, final: :fin}}
	end

	%{pid: pid, final: :fin} ->
	{:halt, %{pid: pid}}
	end,
	fn %{pid: pid} ->
	if opts[:close_conn], do: close(pid)
	end
	)

	{:ok, status, headers, stream_body}
	end

	defp format_response(pid, stream, opts, status, headers, :chunks) do
	{:ok, status, headers, %{pid: pid, stream: stream, opts: Enum.into(opts, [])}}
	end

	defp read_body(pid, stream, opts, acc \\ "") do
	limit = opts[:max_body]

	receive do
	{:gun_data, ^pid, ^stream, :fin, body} ->
	check_body_size(acc, body, limit)

	{:gun_data, ^pid, ^stream, :nofin, part} ->
	with {:ok, acc} <- check_body_size(acc, part, limit) do
	read_body(pid, stream, opts, acc)
	end

	{:DOWN, _, _, _, reason} ->
	{:error, reason}
	after
	opts[:timeout] \|\| @adapter_default_timeout ->
	{:error, :recv_body_timeout}
	end
	end

	defp check_body_size(acc, part, nil), do: {:ok, acc <> part}

	defp check_body_size(acc, part, limit) do
	body = acc <> part

	if limit - byte_size(body) >= 0 do
	{:ok, body}
	else
	{:error, :body_too_large}
	end
	end

	defp domain_or_fallback(host) do
	case domain_or_ip(host) do
	{:domain, domain} -> domain
	{:ip, _ip} -> to_charlist(host)
	end
	end

	defp domain_or_ip(host) do
	charlist = to_charlist(host)

	case :inet.parse_address(charlist) do
	{:error, :einval} ->
	{:domain, :idna.encode(charlist)}

	{:ok, ip} when is_tuple(ip) and tuple_size(ip) in [4, 8] ->
	{:ip, ip}
	end
	end
	end
	end
	diff --git a/lib/tesla/adapter/hackney.ex b/lib/tesla/adapter/hackney.ex
	index 0e53382..ca2a8ec 100644
	--- a/lib/tesla/adapter/hackney.ex
	+++ b/lib/tesla/adapter/hackney.ex
	@@ -1,112 +1,113 @@
	if Code.ensure_loaded?(:hackney) do
	defmodule Tesla.Adapter.Hackney do
	@moduledoc """
	- Adapter for [hackney](https://github.com/benoitc/hackney)
	+ Adapter for [hackney](https://github.com/benoitc/hackney).

	Remember to add `{:hackney, "~> 1.13"}` to dependencies (and `:hackney` to applications in `mix.exs`)
	Also, you need to recompile tesla after adding `:hackney` dependency:

	```
	mix deps.clean tesla
	mix deps.compile tesla
	```

	- ### Example usage
	+ ## Example usage
	+
	```
	# set globally in config/config.exs
	config :tesla, :adapter, Tesla.Adapter.Hackney

	# set per module
	defmodule MyClient do
	use Tesla

	adapter Tesla.Adapter.Hackney
	end
	```
	"""
	@behaviour Tesla.Adapter
	alias Tesla.Multipart

	- @doc false
	+ @impl Tesla.Adapter
	def call(env, opts) do
	with {:ok, status, headers, body} <- request(env, opts) do
	{:ok, %{env \| status: status, headers: format_headers(headers), body: format_body(body)}}
	end
	end

	defp format_headers(headers) do
	for {key, value} <- headers do
	{String.downcase(to_string(key)), to_string(value)}
	end
	end

	defp format_body(data) when is_list(data), do: IO.iodata_to_binary(data)
	defp format_body(data) when is_binary(data) or is_reference(data), do: data

	defp request(env, opts) do
	request(
	env.method,
	Tesla.build_url(env.url, env.query),
	env.headers,
	env.body,
	Tesla.Adapter.opts(env, opts)
	)
	end

	defp request(method, url, headers, %Stream{} = body, opts),
	do: request_stream(method, url, headers, body, opts)

	defp request(method, url, headers, body, opts) when is_function(body),
	do: request_stream(method, url, headers, body, opts)

	defp request(method, url, headers, %Multipart{} = mp, opts) do
	headers = headers ++ Multipart.headers(mp)
	body = Multipart.body(mp)

	request(method, url, headers, body, opts)
	end

	defp request(method, url, headers, body, opts) do
	handle(:hackney.request(method, url, headers, body \|\| '', opts))
	end

	defp request_stream(method, url, headers, body, opts) do
	with {:ok, ref} <- :hackney.request(method, url, headers, :stream, opts) do
	for data <- body, do: :ok = :hackney.send_body(ref, data)
	handle(:hackney.start_response(ref))
	else
	e -> handle(e)
	end
	end

	defp handle({:error, _} = error), do: error
	defp handle({:ok, status, headers}), do: {:ok, status, headers, []}

	defp handle({:ok, ref}) when is_reference(ref) do
	handle_async_response({ref, %{status: nil, headers: nil}})
	end

	defp handle({:ok, status, headers, ref}) when is_reference(ref) do
	with {:ok, body} <- :hackney.body(ref) do
	{:ok, status, headers, body}
	end
	end

	defp handle({:ok, status, headers, body}), do: {:ok, status, headers, body}

	defp handle_async_response({ref, %{headers: headers, status: status}})
	when not (is_nil(headers) or is_nil(status)) do
	{:ok, status, headers, ref}
	end

	defp handle_async_response({ref, output}) do
	receive do
	{:hackney_response, ^ref, {:status, status, _}} ->
	handle_async_response({ref, %{output \| status: status}})

	{:hackney_response, ^ref, {:headers, headers}} ->
	handle_async_response({ref, %{output \| headers: headers}})
	end
	end
	end
	end
	diff --git a/lib/tesla/adapter/httpc.ex b/lib/tesla/adapter/httpc.ex
	index 083ff9b..5374a02 100644
	--- a/lib/tesla/adapter/httpc.ex
	+++ b/lib/tesla/adapter/httpc.ex
	@@ -1,103 +1,103 @@
	defmodule Tesla.Adapter.Httpc do
	@moduledoc """
	- Adapter for [httpc](http://erlang.org/doc/man/httpc.html)
	+ Adapter for [httpc](http://erlang.org/doc/man/httpc.html).

	This is the default adapter.

	NOTE Tesla overrides default autoredirect value with false to ensure
	consistency between adapters
	"""

	@behaviour Tesla.Adapter
	import Tesla.Adapter.Shared, only: [stream_to_fun: 1, next_chunk: 1]
	alias Tesla.Multipart

	@override_defaults autoredirect: false
	@http_opts ~w(timeout connect_timeout ssl essl autoredirect proxy_auth version relaxed url_encode)a

	- @doc false
	+ @impl Tesla.Adapter
	def call(env, opts) do
	opts = Tesla.Adapter.opts(@override_defaults, env, opts)

	with {:ok, {status, headers, body}} <- request(env, opts) do
	{:ok, format_response(env, status, headers, body)}
	end
	end

	defp format_response(env, {_, status, _}, headers, body) do
	%{env \| status: status, headers: format_headers(headers), body: format_body(body)}
	end

	# from http://erlang.org/doc/man/httpc.html
	# headers() = [header()]
	# header() = {field(), value()}
	# field() = string()
	# value() = string()
	defp format_headers(headers) do
	for {key, value} <- headers do
	{String.downcase(to_string(key)), to_string(value)}
	end
	end

	# from http://erlang.org/doc/man/httpc.html
	# string() = list of ASCII characters
	# Body = string() \| binary()
	defp format_body(data) when is_list(data), do: IO.iodata_to_binary(data)
	defp format_body(data) when is_binary(data), do: data

	defp request(env, opts) do
	content_type = to_charlist(Tesla.get_header(env, "content-type") \|\| "")

	handle(
	request(
	env.method,
	Tesla.build_url(env.url, env.query) \|> to_charlist,
	Enum.map(env.headers, fn {k, v} -> {to_charlist(k), to_charlist(v)} end),
	content_type,
	env.body,
	Keyword.split(opts, @http_opts)
	)
	)
	end

	# fix for # see https://github.com/teamon/tesla/issues/147
	defp request(:delete, url, headers, content_type, nil, {http_opts, opts}) do
	request(:delete, url, headers, content_type, "", {http_opts, opts})
	end

	defp request(method, url, headers, _content_type, nil, {http_opts, opts}) do
	:httpc.request(method, {url, headers}, http_opts, opts)
	end

	defp request(method, url, headers, _content_type, %Multipart{} = mp, opts) do
	headers = headers ++ Multipart.headers(mp)
	headers = for {key, value} <- headers, do: {to_charlist(key), to_charlist(value)}

	{content_type, headers} =
	case List.keytake(headers, 'content-type', 0) do
	nil -> {'text/plain', headers}
	{{_, ct}, headers} -> {ct, headers}
	end

	body = stream_to_fun(Multipart.body(mp))

	request(method, url, headers, to_charlist(content_type), body, opts)
	end

	defp request(method, url, headers, content_type, %Stream{} = body, opts) do
	fun = stream_to_fun(body)
	request(method, url, headers, content_type, fun, opts)
	end

	defp request(method, url, headers, content_type, body, opts) when is_function(body) do
	body = {:chunkify, &next_chunk/1, body}
	request(method, url, headers, content_type, body, opts)
	end

	defp request(method, url, headers, content_type, body, {http_opts, opts}) do
	:httpc.request(method, {url, headers, content_type, body}, http_opts, opts)
	end

	defp handle({:error, {:failed_connect, _}}), do: {:error, :econnrefused}
	defp handle(response), do: response
	end
	diff --git a/lib/tesla/adapter/ibrowse.ex b/lib/tesla/adapter/ibrowse.ex
	index b85f9fb..f637fab 100644
	--- a/lib/tesla/adapter/ibrowse.ex
	+++ b/lib/tesla/adapter/ibrowse.ex
	@@ -1,98 +1,99 @@
	if Code.ensure_loaded?(:ibrowse) do
	defmodule Tesla.Adapter.Ibrowse do
	@moduledoc """
	- Adapter for [ibrowse](https://github.com/cmullaparthi/ibrowse)
	+ Adapter for [ibrowse](https://github.com/cmullaparthi/ibrowse).

	Remember to add `{:ibrowse, "~> 4.2"}` to dependencies (and `:ibrowse` to applications in `mix.exs`)
	Also, you need to recompile tesla after adding `:ibrowse` dependency:

	```
	mix deps.clean tesla
	mix deps.compile tesla
	```

	- ### Example usage
	+ ## Example usage
	+
	```
	# set globally in config/config.exs
	config :tesla, :adapter, Tesla.Adapter.Ibrowse

	# set per module
	defmodule MyClient do
	use Tesla

	adapter Tesla.Adapter.Ibrowse
	end
	```
	"""

	@behaviour Tesla.Adapter
	import Tesla.Adapter.Shared, only: [stream_to_fun: 1, next_chunk: 1]
	alias Tesla.Multipart

	- @doc false
	+ @impl Tesla.Adapter
	def call(env, opts) do
	with {:ok, status, headers, body} <- request(env, opts) do
	{:ok,
	%{
	env
	\| status: format_status(status),
	headers: format_headers(headers),
	body: format_body(body)
	}}
	end
	end

	defp format_status(status) when is_list(status) do
	status \|> to_string() \|> String.to_integer()
	end

	defp format_headers(headers) do
	for {key, value} <- headers do
	{String.downcase(to_string(key)), to_string(value)}
	end
	end

	defp format_body(data) when is_list(data), do: IO.iodata_to_binary(data)
	defp format_body(data) when is_binary(data), do: data

	defp request(env, opts) do
	body = env.body \|\| []

	handle(
	request(
	Tesla.build_url(env.url, env.query) \|> to_charlist,
	env.headers,
	env.method,
	body,
	Tesla.Adapter.opts(env, opts)
	)
	)
	end

	defp request(url, headers, method, %Multipart{} = mp, opts) do
	headers = headers ++ Multipart.headers(mp)
	body = stream_to_fun(Multipart.body(mp))

	request(url, headers, method, body, opts)
	end

	defp request(url, headers, method, %Stream{} = body, opts) do
	fun = stream_to_fun(body)
	request(url, headers, method, fun, opts)
	end

	defp request(url, headers, method, body, opts) when is_function(body) do
	body = {&next_chunk/1, body}
	opts = Keyword.put(opts, :transfer_encoding, :chunked)
	request(url, headers, method, body, opts)
	end

	defp request(url, headers, method, body, opts) do
	{timeout, opts} = opts \|> Keyword.pop(:timeout, 30_000)
	:ibrowse.send_req(url, headers, method, body, opts, timeout)
	end

	defp handle({:error, {:conn_failed, error}}), do: error
	defp handle(response), do: response
	end
	end
	diff --git a/lib/tesla/adapter/mint.ex b/lib/tesla/adapter/mint.ex
	index 551ca73..71893bb 100644
	--- a/lib/tesla/adapter/mint.ex
	+++ b/lib/tesla/adapter/mint.ex
	@@ -1,334 +1,341 @@
	if Code.ensure_loaded?(Mint.HTTP) do
	defmodule Tesla.Adapter.Mint do
	@moduledoc """
	- Adapter for [mint](https://github.com/elixir-mint/mint)
	+ Adapter for [mint](https://github.com/elixir-mint/mint).

	Caution: The minimum supported Elixir version for mint is 1.5.0

	Remember to add `{:mint, "~> 1.0"}` and `{:castore, "~> 0.1"}` to dependencies
	Also, you need to recompile tesla after adding `:mint` dependency:
	+
	```
	mix deps.clean tesla
	mix deps.compile tesla
	```
	- ### Example usage
	+
	+ ## Example usage
	+
	```
	# set globally in config/config.exs
	config :tesla, :adapter, Tesla.Adapter.Mint
	# set per module
	defmodule MyClient do
	use Tesla
	adapter Tesla.Adapter.Mint
	end
	# set global custom cacertfile
	config :tesla, Tesla.Adapter.Mint, cacert: ["path_to_cacert"]
	```
	- ### Adapter specific options:
	- * `timeout` - Time, while process, will wait for mint messages.
	- * `body_as` - What will be returned in `%Tesla.Env{}` body key. Possible values - `:plain`, `:stream`, `:chunks`. Defaults to `:plain`.
	- * `:plain` - as binary.
	- * `:stream` - as stream. If you don't want to close connection (because you want to reuse it later) pass `close_conn: false` in adapter opts.
	- * `:chunks` - as chunks. You can get response body in chunks using `Tesla.Adapter.Mint.read_chunk/3` function.
	+
	+ ## Adapter specific options:
	+
	+ - `:timeout` - Time, while process, will wait for mint messages.
	+ - `:body_as` - What will be returned in `%Tesla.Env{}` body key. Possible values - `:plain`, `:stream`, `:chunks`. Defaults to `:plain`.
	+ - `:plain` - as binary.
	+ - `:stream` - as stream. If you don't want to close connection (because you want to reuse it later) pass `close_conn: false` in adapter opts.
	+ - `:chunks` - as chunks. You can get response body in chunks using `Tesla.Adapter.Mint.read_chunk/3` function.
	Processing of the chunks and checking body size must be done by yourself. Example of processing function is in `test/tesla/adapter/mint_test.exs` - `Tesla.Adapter.MintTest.read_body/4`. If you don't need connection later don't forget to close it with `Tesla.Adapter.Mint.close/1`.
	- * `max_body` - Max response body size in bytes. Works only with `body_as: :plain`, with other settings you need to check response body size by yourself.
	- * `conn` - Opened connection with mint. Is used for reusing mint connections.
	- * `original` - Original host with port, for which reused connection was open. Needed for `Tesla.Middleware.FollowRedirects`. Otherwise adapter will use connection for another open host.
	- * `close_conn` - Close connection or not after receiving full response body. Is used for reusing mint connections. Defaults to `true`.
	- * `proxy` - Proxy settings. E.g.: `{:http, "localhost", 8888, []}`, `{:http, "127.0.0.1", 8888, []}`
	+ - `:max_body` - Max response body size in bytes. Works only with `body_as: :plain`, with other settings you need to check response body size by yourself.
	+ - `:conn` - Opened connection with mint. Is used for reusing mint connections.
	+ - `:original` - Original host with port, for which reused connection was open. Needed for `Tesla.Middleware.FollowRedirects`. Otherwise adapter will use connection for another open host.
	+ - `:close_conn` - Close connection or not after receiving full response body. Is used for reusing mint connections. Defaults to `true`.
	+ - `:proxy` - Proxy settings. E.g.: `{:http, "localhost", 8888, []}`, `{:http, "127.0.0.1", 8888, []}`
	"""
	+
	@behaviour Tesla.Adapter
	+
	import Tesla.Adapter.Shared
	alias Tesla.Multipart
	alias Mint.HTTP

	@default timeout: 2_000, body_as: :plain, close_conn: true, mode: :active

	- @impl true
	+ @impl Tesla.Adapter
	def call(env, opts) do
	opts = Tesla.Adapter.opts(@default, env, opts)

	with {:ok, status, headers, body} <- request(env, opts) do
	{:ok, %{env \| status: status, headers: headers, body: body}}
	end
	end

	@doc """
	Reads chunk of the response body.
	Returns `{:fin, HTTP.t(), binary()}` if all body received, otherwise returns `{:nofin, HTTP.t(), binary()}`.
	"""

	@spec read_chunk(HTTP.t(), reference(), keyword()) ::
	{:fin, HTTP.t(), binary()} \| {:nofin, HTTP.t(), binary()}
	def read_chunk(conn, ref, opts) do
	with {:ok, conn, acc} <- receive_packet(conn, ref, opts),
	{state, data} <- response_state(acc) do
	{:ok, conn} =
	if state == :fin and opts[:close_conn] do
	close(conn)
	else
	{:ok, conn}
	end

	{state, conn, data}
	end
	end

	@doc """
	Closes mint connection.
	"""
	@spec close(HTTP.t()) :: {:ok, HTTP.t()}
	defdelegate close(conn), to: HTTP

	defp request(env, opts) do
	request(
	format_method(env.method),
	Tesla.build_url(env.url, env.query),
	env.headers,
	env.body,
	Enum.into(opts, %{})
	)
	end

	defp request(method, url, headers, %Stream{} = body, opts) do
	fun = stream_to_fun(body)
	request(method, url, headers, fun, opts)
	end

	defp request(method, url, headers, %Multipart{} = body, opts) do
	headers = headers ++ Multipart.headers(body)
	fun = stream_to_fun(Multipart.body(body))
	request(method, url, headers, fun, opts)
	end

	defp request(method, url, headers, body, opts),
	do: do_request(method, url, headers, body, opts)

	defp do_request(method, url, headers, body, opts) do
	with uri <- URI.parse(url),
	path <- prepare_path(uri.path, uri.query),
	opts <- check_original(uri, opts),
	{:ok, conn, opts} <- open_conn(uri, opts),
	{:ok, conn, ref} <- make_request(conn, method, path, headers, body) do
	format_response(conn, ref, opts)
	end
	end

	defp check_original(uri, %{original: original} = opts) do
	Map.put(opts, :original_matches, original == "#{uri.host}:#{uri.port}")
	end

	defp check_original(_uri, opts), do: opts

	defp open_conn(_uri, %{conn: conn, original_matches: true} = opts) do
	{:ok, conn, opts}
	end

	defp open_conn(uri, %{conn: conn, original_matches: false} = opts) do
	opts =
	opts
	\|> Map.put_new(:old_conn, conn)
	\|> Map.delete(:conn)

	open_conn(uri, opts)
	end

	defp open_conn(uri, opts) do
	opts =
	with "https" <- uri.scheme,
	global_cacertfile when not is_nil(global_cacertfile) <-
	Application.get_env(:tesla, Tesla.Adapter.Mint)[:cacert] do
	Map.update(opts, :transport_opts, [cacertfile: global_cacertfile], fn tr_opts ->
	Keyword.put_new(tr_opts, :cacertfile, global_cacertfile)
	end)
	else
	_ -> opts
	end

	with {:ok, conn} <-
	HTTP.connect(String.to_atom(uri.scheme), uri.host, uri.port, Enum.into(opts, [])) do
	# If there were redirects, and passed `closed_conn: false`, we need to close opened connections to these intermediate hosts.
	{:ok, conn, Map.put(opts, :close_conn, true)}
	end
	end

	defp make_request(conn, method, path, headers, body) when is_function(body) do
	with {:ok, conn, ref} <-
	HTTP.request(
	conn,
	method,
	path,
	headers,
	:stream
	),
	{:ok, conn} <- stream_request(conn, ref, body) do
	{:ok, conn, ref}
	end
	end

	defp make_request(conn, method, path, headers, body),
	do: HTTP.request(conn, method, path, headers, body)

	defp stream_request(conn, ref, fun) do
	case next_chunk(fun) do
	{:ok, item, fun} when is_list(item) ->
	chunk = List.to_string(item)
	{:ok, conn} = HTTP.stream_request_body(conn, ref, chunk)
	stream_request(conn, ref, fun)

	{:ok, item, fun} ->
	{:ok, conn} = HTTP.stream_request_body(conn, ref, item)
	stream_request(conn, ref, fun)

	:eof ->
	HTTP.stream_request_body(conn, ref, :eof)
	end
	end

	defp format_response(conn, ref, %{body_as: :plain} = opts) do
	with {:ok, response} <- receive_responses(conn, ref, opts) do
	{:ok, response[:status], response[:headers], response[:data]}
	end
	end

	defp format_response(conn, ref, %{body_as: :chunks} = opts) do
	with {:ok, conn, %{status: status, headers: headers} = acc} <-
	receive_headers_and_status(conn, ref, opts),
	{state, data} <-
	response_state(acc) do
	{:ok, conn} =
	if state == :fin and opts[:close_conn] do
	close(conn)
	else
	{:ok, conn}
	end

	{:ok, status, headers, %{conn: conn, ref: ref, opts: opts, body: {state, data}}}
	end
	end

	defp format_response(conn, ref, %{body_as: :stream} = opts) do
	# there can be some data already
	with {:ok, conn, %{status: status, headers: headers} = acc} <-
	receive_headers_and_status(conn, ref, opts) do
	body_as_stream =
	Stream.resource(
	fn -> %{conn: conn, data: acc[:data], done: acc[:done]} end,
	fn
	%{conn: conn, data: data, done: true} ->
	{[data], %{conn: conn, is_fin: true}}

	%{conn: conn, data: data} when is_binary(data) ->
	{[data], %{conn: conn}}

	%{conn: conn, is_fin: true} ->
	{:halt, %{conn: conn}}

	%{conn: conn} ->
	case receive_packet(conn, ref, opts) do
	{:ok, conn, %{done: true, data: data}} ->
	{[data], %{conn: conn, is_fin: true}}

	{:ok, conn, %{done: true}} ->
	{[], %{conn: conn, is_fin: true}}

	{:ok, conn, %{data: data}} ->
	{[data], %{conn: conn}}

	{:ok, conn, _} ->
	{[], %{conn: conn}}
	end
	end,
	fn %{conn: conn} -> if opts[:close_conn], do: {:ok, _conn} = close(conn) end
	)

	{:ok, status, headers, body_as_stream}
	end
	end

	defp receive_responses(conn, ref, opts, acc \\ %{}) do
	with {:ok, conn, acc} <- receive_packet(conn, ref, opts, acc),
	:ok <- check_data_size(acc, conn, opts) do
	if acc[:done] do
	if opts[:close_conn], do: {:ok, _conn} = close(conn)
	{:ok, acc}
	else
	receive_responses(conn, ref, opts, acc)
	end
	end
	end

	defp check_data_size(%{data: data}, conn, %{max_body: max_body} = opts)
	when is_binary(data) do
	if max_body - byte_size(data) >= 0 do
	:ok
	else
	if opts[:close_conn], do: {:ok, _conn} = close(conn)
	{:error, :body_too_large}
	end
	end

	defp check_data_size(_, _, _), do: :ok

	defp receive_headers_and_status(conn, ref, opts, acc \\ %{}) do
	with {:ok, conn, acc} <- receive_packet(conn, ref, opts, acc) do
	case acc do
	%{status: _status, headers: _headers} -> {:ok, conn, acc}
	# if we don't have status or headers we try to get them in next packet
	_ -> receive_headers_and_status(conn, ref, opts, acc)
	end
	end
	end

	defp response_state(%{done: true, data: data}), do: {:fin, data}
	defp response_state(%{data: data}), do: {:nofin, data}
	defp response_state(%{done: true}), do: {:fin, ""}
	defp response_state(_), do: {:nofin, ""}

	defp receive_packet(conn, ref, opts, acc \\ %{}) do
	with {:ok, conn, responses} <- receive_message(conn, opts),
	acc <- reduce_responses(responses, ref, acc) do
	{:ok, conn, acc}
	else
	{:error, error} ->
	if opts[:close_conn], do: {:ok, _conn} = close(conn)
	{:error, error}

	{:error, _conn, error, _res} ->
	if opts[:close_conn], do: {:ok, _conn} = close(conn)
	{:error, "Encounter Mint error #{inspect(error)}"}

	:unknown ->
	if opts[:close_conn], do: {:ok, _conn} = close(conn)
	{:error, :unknown}
	end
	end

	defp receive_message(conn, %{mode: :active} = opts) do
	receive do
	message ->
	HTTP.stream(conn, message)
	after
	opts[:timeout] -> {:error, :timeout}
	end
	end

	defp receive_message(conn, %{mode: :passive} = opts),
	do: HTTP.recv(conn, 0, opts[:timeout])

	defp reduce_responses(responses, ref, acc) do
	Enum.reduce(responses, acc, fn
	{:status, ^ref, code}, acc ->
	Map.put(acc, :status, code)

	{:headers, ^ref, headers}, acc ->
	Map.update(acc, :headers, headers, &(&1 ++ headers))

	{:data, ^ref, data}, acc ->
	Map.update(acc, :data, data, &(&1 <> data))

	{:done, ^ref}, acc ->
	Map.put(acc, :done, true)
	end)
	end
	end
	end
	diff --git a/lib/tesla/builder.ex b/lib/tesla/builder.ex
	index cfe81c3..c1dc4ff 100644
	--- a/lib/tesla/builder.ex
	+++ b/lib/tesla/builder.ex
	@@ -1,314 +1,311 @@
	defmodule Tesla.Builder do
	@http_verbs ~w(head get delete trace options post put patch)a
	@body ~w(post put patch)a

	defmacro __using__(opts \\ []) do
	opts = Macro.prewalk(opts, &Macro.expand(&1, __CALLER__))
	docs = Keyword.get(opts, :docs, true)

	quote do
	Module.register_attribute(__MODULE__, :__middleware__, accumulate: true)
	Module.register_attribute(__MODULE__, :__adapter__, [])

	@type option ::
	{:method, Tesla.Env.method()}
	\| {:url, Tesla.Env.url()}
	\| {:query, Tesla.Env.query()}
	\| {:headers, Tesla.Env.headers()}
	\| {:body, Tesla.Env.body()}
	\| {:opts, Tesla.Env.opts()}

	if unquote(docs) do
	@doc """
	- Perform a request
	-
	- Options:
	- - `:method` - the request method, one of [:head, :get, :delete, :trace, :options, :post, :put, :patch]
	- - `:url` - either full url e.g. "http://example.com/some/path" or just "/some/path" if using `Tesla.Middleware.BaseUrl`
	- - `:query` - a keyword list of query params, e.g. `[page: 1, per_page: 100]`
	- - `:headers` - a keyworld list of headers, e.g. `[{"content-type", "text/plain"}]`
	- - `:body` - depends on used middleware:
	+ Perform a request.
	+
	+ ## Options
	+
	+ - `:method` - the request method, one of [:head, :get, :delete, :trace, :options, :post, :put, :patch]
	+ - `:url` - either full url e.g. "http://example.com/some/path" or just "/some/path" if using `Tesla.Middleware.BaseUrl`
	+ - `:query` - a keyword list of query params, e.g. `[page: 1, per_page: 100]`
	+ - `:headers` - a keyworld list of headers, e.g. `[{"content-type", "text/plain"}]`
	+ - `:body` - depends on used middleware:
	- by default it can be a binary
	- if using e.g. JSON encoding middleware it can be a nested map
	- if adapter supports it it can be a Stream with any of the above
	- - `:opts` - custom, per-request middleware or adapter options
	+ - `:opts` - custom, per-request middleware or adapter options

	- Examples:
	+ ## Examples

	ExampleApi.request(method: :get, url: "/users/path")

	- You can also use shortcut methods like:
	-
	+ # use shortcut methods
	ExampleApi.get("/users/1")
	-
	- or
	-
	ExampleApi.post(client, "/users", %{name: "Jon"})
	"""
	else
	@doc false
	end

	@spec request(Tesla.Env.client(), [option]) :: Tesla.Env.result()
	def request(%Tesla.Client{} = client \\ %Tesla.Client{}, options) do
	Tesla.execute(__MODULE__, client, options)
	end

	if unquote(docs) do
	@doc """
	Perform request and raise in case of error.

	This is similar to `request/2` behaviour from Tesla 0.x

	See `request/2` for list of available options.
	"""
	else
	@doc false
	end

	@spec request!(Tesla.Env.client(), [option]) :: Tesla.Env.t() \| no_return
	def request!(%Tesla.Client{} = client \\ %Tesla.Client{}, options) do
	Tesla.execute!(__MODULE__, client, options)
	end

	unquote(generate_http_verbs(opts))

	import Tesla.Builder, only: [plug: 1, plug: 2, adapter: 1, adapter: 2]
	@before_compile Tesla.Builder
	end
	end

	@doc """
	- Attach middleware to your API client
	+ Attach middleware to your API client.

	```
	defmodule ExampleApi do
	use Tesla

	# plug middleware module with options
	plug Tesla.Middleware.BaseUrl, "http://api.example.com"

	# or without options
	plug Tesla.Middleware.JSON

	# or a custom middleware
	plug MyProject.CustomMiddleware
	end
	"""

	defmacro plug(middleware, opts) do
	quote do
	@__middleware__ {
	{unquote(Macro.escape(middleware)), unquote(Macro.escape(opts))},
	{:middleware, unquote(Macro.escape(__CALLER__))}
	}
	end
	end

	defmacro plug(middleware) do
	quote do
	@__middleware__ {
	unquote(Macro.escape(middleware)),
	{:middleware, unquote(Macro.escape(__CALLER__))}
	}
	end
	end

	@doc """
	- Choose adapter for your API client
	+ Choose adapter for your API client.

	```
	defmodule ExampleApi do
	use Tesla

	# set adapter as module
	adapter Tesla.Adapter.Hackney

	# set adapter as anonymous function
	adapter fn env ->
	...
	env
	end
	end
	"""
	defmacro adapter(name, opts) do
	quote do
	@__adapter__ {
	{unquote(Macro.escape(name)), unquote(Macro.escape(opts))},
	{:adapter, unquote(Macro.escape(__CALLER__))}
	}
	end
	end

	defmacro adapter(name) do
	quote do
	@__adapter__ {
	unquote(Macro.escape(name)),
	{:adapter, unquote(Macro.escape(__CALLER__))}
	}
	end
	end

	defmacro __before_compile__(env) do
	adapter =
	env.module
	\|> Module.get_attribute(:__adapter__)
	\|> compile()

	middleware =
	env.module
	\|> Module.get_attribute(:__middleware__)
	\|> Enum.reverse()
	\|> compile()

	quote location: :keep do
	def __middleware__, do: unquote(middleware)
	def __adapter__, do: unquote(adapter)
	end
	end

	def client(pre, post, adapter \\ nil)

	def client(pre, post, nil) do
	%Tesla.Client{pre: runtime(pre), post: runtime(post)}
	end

	def client(pre, post, adapter) do
	%Tesla.Client{pre: runtime(pre), post: runtime(post), adapter: runtime(adapter)}
	end

	@default_opts []

	defp compile(nil), do: nil
	defp compile(list) when is_list(list), do: Enum.map(list, &compile/1)

	# {Tesla.Middleware.Something, opts}
	defp compile({{{:__aliases__, _, _} = ast_mod, ast_opts}, {_kind, _caller}}) do
	quote do: {unquote(ast_mod), :call, [unquote(ast_opts)]}
	end

	# Tesla.Middleware.Something
	defp compile({{:__aliases__, _, _} = ast_mod, {_kind, _caller}}) do
	quote do: {unquote(ast_mod), :call, [unquote(@default_opts)]}
	end

	# fn env -> ... end
	defp compile({{:fn, _, _} = ast_fun, {_kind, _caller}}) do
	quote do: {:fn, unquote(ast_fun)}
	end

	defp runtime(list) when is_list(list), do: Enum.map(list, &runtime/1)
	defp runtime({module, opts}) when is_atom(module), do: {module, :call, [opts]}
	defp runtime(fun) when is_function(fun), do: {:fn, fun}
	defp runtime(module) when is_atom(module), do: {module, :call, [@default_opts]}

	defp generate_http_verbs(opts) do
	only = Keyword.get(opts, :only, @http_verbs)
	except = Keyword.get(opts, :except, [])
	docs = Keyword.get(opts, :docs, true)

	for method <- @http_verbs do
	for bang <- [:safe, :bang],
	client <- [:client, :noclient],
	opts <- [:opts, :noopts],
	method in only && not (method in except) do
	gen(method, bang, client, opts, docs)
	end
	end
	end

	defp gen(method, safe, client, opts, docs) do
	quote location: :keep do
	unquote(gen_doc(method, safe, client, opts, docs))
	unquote(gen_spec(method, safe, client, opts))
	unquote(gen_fun(method, safe, client, opts))
	end
	end

	defp gen_doc(method, safe, :client, :opts, true) do
	request = to_string(req(safe))
	name = name(method, safe)
	body = if method in @body, do: ~s\|, %{name: "Jon"}\|, else: ""

	quote location: :keep do
	@doc """
	Perform a #{unquote(method \|> to_string \|> String.upcase())} request.

	See `#{unquote(request)}/1` or `#{unquote(request)}/2` for options definition.

	#{unquote(name)}("/users"#{unquote(body)})
	#{unquote(name)}("/users"#{unquote(body)}, query: [scope: "admin"])
	#{unquote(name)}(client, "/users"#{unquote(body)})
	#{unquote(name)}(client, "/users"#{unquote(body)}, query: [scope: "admin"])
	"""
	end
	end

	defp gen_doc(_method, _bang, _client, _opts, _) do
	quote location: :keep do
	@doc false
	end
	end

	defp gen_spec(method, safe, client, opts) do
	quote location: :keep do
	@spec unquote(name(method, safe))(unquote_splicing(types(method, client, opts))) ::
	unquote(type(safe))
	end
	end

	defp gen_fun(method, safe, client, opts) do
	quote location: :keep do
	def unquote(name(method, safe))(unquote_splicing(inputs(method, client, opts))) do
	unquote(req(safe))(unquote_splicing(outputs(method, client, opts)))
	end
	end
	\|> gen_guards(opts)
	end

	defp gen_guards({:def, _, [head, [do: body]]}, :opts) do
	quote do
	def unquote(head) when is_list(opts), do: unquote(body)
	end
	end

	defp gen_guards(def, _opts), do: def

	defp name(method, :safe), do: method
	defp name(method, :bang), do: String.to_atom("#{method}!")

	defp req(:safe), do: :request
	defp req(:bang), do: :request!

	defp types(method, client, opts), do: type(client) ++ type(:url) ++ type(method) ++ type(opts)

	defp type(:safe), do: quote(do: Tesla.Env.result())
	defp type(:bang), do: quote(do: Tesla.Env.t() \| no_return)

	defp type(:client), do: [quote(do: Tesla.Env.client())]
	defp type(:noclient), do: []
	defp type(:opts), do: [quote(do: [option])]
	defp type(:noopts), do: []
	defp type(:url), do: [quote(do: Tesla.Env.url())]
	defp type(method) when method in @body, do: [quote(do: Tesla.Env.body())]
	defp type(_method), do: []

	defp inputs(method, client, opts),
	do: input(client) ++ input(:url) ++ input(method) ++ input(opts)

	defp input(:client), do: [quote(do: %Tesla.Client{} = client)]
	defp input(:noclient), do: []
	defp input(:opts), do: [quote(do: opts)]
	defp input(:noopts), do: []
	defp input(:url), do: [quote(do: url)]
	defp input(method) when method in @body, do: [quote(do: body)]
	defp input(_method), do: []

	defp outputs(method, client, opts), do: output(client) ++ [output(output(method), opts)]
	defp output(:client), do: [quote(do: client)]
	defp output(:noclient), do: []
	defp output(m) when m in @body, do: quote(do: [method: unquote(m), url: url, body: body])
	defp output(m), do: quote(do: [method: unquote(m), url: url])
	defp output(prev, :opts), do: quote(do: unquote(prev) ++ opts)
	defp output(prev, :noopts), do: prev
	end
	diff --git a/lib/tesla/middleware/basic_auth.ex b/lib/tesla/middleware/basic_auth.ex
	index 8e6c92c..8623069 100644
	--- a/lib/tesla/middleware/basic_auth.ex
	+++ b/lib/tesla/middleware/basic_auth.ex
	@@ -1,61 +1,63 @@
	defmodule Tesla.Middleware.BasicAuth do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	- Basic authentication middleware
	+ Basic authentication middleware.

	[Wiki on the topic](https://en.wikipedia.org/wiki/Basic_access_authentication)

	- ### Example
	+ ## Example
	+
	```
	defmodule MyClient do
	use Tesla

	# static configuration
	plug Tesla.Middleware.BasicAuth, username: "user", password: "pass"

	# dynamic user & pass
	def new(username, password, opts \\\\ %{}) do
	Tesla.client [
	{Tesla.Middleware.BasicAuth, Map.merge(%{username: username, password: password}, opts)}
	]
	end
	end
	```

	- ### Options
	- - `:username` - username (defaults to `""`)
	- - `:password` - password (defaults to `""`)
	+ ## Options
	+
	+ - `:username` - username (defaults to `""`)
	+ - `:password` - password (defaults to `""`)
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	opts = opts \|\| %{}

	env
	\|> Tesla.put_headers(authorization_header(opts))
	\|> Tesla.run(next)
	end

	defp authorization_header(opts) do
	opts
	\|> authorization_vars()
	\|> encode()
	\|> create_header()
	end

	defp authorization_vars(opts) do
	%{
	username: opts[:username] \|\| "",
	password: opts[:password] \|\| ""
	}
	end

	defp create_header(auth) do
	[{"authorization", "Basic #{auth}"}]
	end

	defp encode(%{username: username, password: password}) do
	Base.encode64("#{username}:#{password}")
	end
	end
	diff --git a/lib/tesla/middleware/compression.ex b/lib/tesla/middleware/compression.ex
	index 9cdc4e7..b9bb204 100644
	--- a/lib/tesla/middleware/compression.ex
	+++ b/lib/tesla/middleware/compression.ex
	@@ -1,98 +1,104 @@
	defmodule Tesla.Middleware.Compression do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Compress requests and decompress responses.

	Supports "gzip" and "deflate" encodings using erlang's built-in `:zlib` module.

	- ### Example usage
	+ ## Example usage
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.Compression, format: "gzip"
	end
	```

	- ### Options
	+ ## Options
	+
	- `:format` - request compression format, `"gzip"` (default) or `"deflate"`
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	env
	\|> compress(opts)
	\|> Tesla.run(next)
	\|> decompress()
	end

	defp compressable?(body), do: is_binary(body)

	@doc """
	- Compress request, used by `Tesla.Middleware.CompressRequest`
	+ Compress request.
	+
	+ It is used by `Tesla.Middleware.CompressRequest`.
	"""
	def compress(env, opts) do
	if compressable?(env.body) do
	format = Keyword.get(opts \|\| [], :format, "gzip")

	env
	\|> Tesla.put_body(compress_body(env.body, format))
	\|> Tesla.put_headers([{"content-encoding", format}])
	else
	env
	end
	end

	defp compress_body(body, "gzip"), do: :zlib.gzip(body)
	defp compress_body(body, "deflate"), do: :zlib.zip(body)

	@doc """
	- Decompress response, used by `Tesla.Middleware.DecompressResponse`
	+ Decompress response.
	+
	+ It is used by `Tesla.Middleware.DecompressResponse`.
	"""
	def decompress({:ok, env}), do: {:ok, decompress(env)}
	def decompress({:error, reasonn}), do: {:error, reasonn}

	def decompress(env) do
	env
	\|> Tesla.put_body(decompress_body(env.body, Tesla.get_header(env, "content-encoding")))
	end

	defp decompress_body(<<31, 139, 8, _::binary>> = body, "gzip"), do: :zlib.gunzip(body)
	defp decompress_body(body, "deflate"), do: :zlib.unzip(body)
	defp decompress_body(body, _content_encoding), do: body
	end

	defmodule Tesla.Middleware.CompressRequest do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Only compress request.

	See `Tesla.Middleware.Compression` for options.
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	env
	\|> Tesla.Middleware.Compression.compress(opts)
	\|> Tesla.run(next)
	end
	end

	defmodule Tesla.Middleware.DecompressResponse do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Only decompress response.

	See `Tesla.Middleware.Compression` for options.
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, _opts) do
	env
	\|> Tesla.run(next)
	\|> Tesla.Middleware.Compression.decompress()
	end
	end
	diff --git a/lib/tesla/middleware/core.ex b/lib/tesla/middleware/core.ex
	index 3ae8519..bae9069 100644
	--- a/lib/tesla/middleware/core.ex
	+++ b/lib/tesla/middleware/core.ex
	@@ -1,124 +1,131 @@
	defmodule Tesla.Middleware.BaseUrl do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Set base URL for all requests.

	The base URL will be prepended to request path/url only
	if it does not include http(s).

	- ### Example usage
	+ ## Example usage
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.BaseUrl, "https://example.com/foo"
	end

	MyClient.get("/path") # equals to GET https://example.com/foo/path
	MyClient.get("path") # equals to GET https://example.com/foo/path
	MyClient.get("") # equals to GET https://example.com/foo
	MyClient.get("http://example.com/bar") # equals to GET http://example.com/bar
	```
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, base) do
	env
	\|> apply_base(base)
	\|> Tesla.run(next)
	end

	defp apply_base(env, base) do
	if Regex.match?(~r/^https?:\/\//i, env.url) do
	# skip if url is already with scheme
	env
	else
	%{env \| url: join(base, env.url)}
	end
	end

	defp join(base, url) do
	case {String.last(to_string(base)), url} do
	{nil, url} -> url
	{"/", "/" <> rest} -> base <> rest
	{"/", rest} -> base <> rest
	{_, ""} -> base
	{_, "/" <> rest} -> base <> "/" <> rest
	{_, rest} -> base <> "/" <> rest
	end
	end
	end

	defmodule Tesla.Middleware.Headers do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Set default headers for all requests

	- ### Example usage
	+ ## Example usage
	+
	```
	defmodule Myclient do
	use Tesla

	plug Tesla.Middleware.Headers, [{"user-agent", "Tesla"}]
	end
	```
	"""
	- @doc false
	+
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, headers) do
	env
	\|> Tesla.put_headers(headers)
	\|> Tesla.run(next)
	end
	end

	defmodule Tesla.Middleware.Query do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Set default query params for all requests

	- ### Example usage
	+ ## Example usage
	+
	```
	defmodule Myclient do
	use Tesla

	plug Tesla.Middleware.Query, [token: "some-token"]
	end
	```
	"""
	- @doc false
	+
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, query) do
	env
	\|> merge(query)
	\|> Tesla.run(next)
	end

	defp merge(env, nil), do: env

	defp merge(env, query) do
	Map.update!(env, :query, &(&1 ++ query))
	end
	end

	defmodule Tesla.Middleware.Opts do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	- Set default opts for all requests
	+ Set default opts for all requests.
	+
	+ ## Example usage

	- ### Example usage
	```
	defmodule Myclient do
	use Tesla

	plug Tesla.Middleware.Opts, [some: "option"]
	end
	```
	"""
	- @doc false
	+
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	Tesla.run(%{env \| opts: env.opts ++ opts}, next)
	end
	end
	diff --git a/lib/tesla/middleware/decode_rels.ex b/lib/tesla/middleware/decode_rels.ex
	index 9490df0..8c7c43c 100644
	--- a/lib/tesla/middleware/decode_rels.ex
	+++ b/lib/tesla/middleware/decode_rels.ex
	@@ -1,53 +1,54 @@
	defmodule Tesla.Middleware.DecodeRels do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Decode `Link` Hypermedia HTTP header into `opts[:rels]` field in response.

	+ ## Example usage

	- ### Example usage
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.DecodeRels
	end

	env = MyClient.get("/...")
	- env.opts[:rels] # => %{"Next" => "http://...", "Prev" => "..."}
	- ```

	+ env.opts[:rels]
	+ # => %{"Next" => "http://...", "Prev" => "..."}
	+ ```
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, _opts) do
	env
	\|> Tesla.run(next)
	\|> parse_rels
	end

	defp parse_rels({:ok, env}), do: {:ok, parse_rels(env)}
	defp parse_rels({:error, reason}), do: {:error, reason}

	defp parse_rels(env) do
	if link = Tesla.get_header(env, "link") do
	Tesla.put_opt(env, :rels, rels(link))
	else
	env
	end
	end

	defp rels(link) do
	link
	\|> String.split(",")
	\|> Enum.map(&String.trim/1)
	\|> Enum.map(&rel/1)
	\|> Enum.into(%{})
	end

	defp rel(item) do
	Regex.run(~r/\A<(.+)>; rel="(.+)"\z/, item, capture: :all_but_first)
	\|> Enum.reverse()
	\|> List.to_tuple()
	end
	end
	diff --git a/lib/tesla/middleware/digest_auth.ex b/lib/tesla/middleware/digest_auth.ex
	index 63085a0..241819a 100644
	--- a/lib/tesla/middleware/digest_auth.ex
	+++ b/lib/tesla/middleware/digest_auth.ex
	@@ -1,132 +1,133 @@
	defmodule Tesla.Middleware.DigestAuth do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Digest access authentication middleware

	[Wiki on the topic](https://en.wikipedia.org/wiki/Digest_access_authentication)

	NOTE: Currently the implementation is incomplete and works only for MD5 algorithm
	and auth qop.

	- ### Example
	+ ## Example
	+
	```
	defmodule MyClient do
	use Tesla

	def client(username, password, opts \\ %{}) do
	- Tesla.client [
	+ Tesla.client([
	{Tesla.Middleware.DigestAuth, Map.merge(%{username: username, password: password}, opts)}
	- ]
	+ ])
	end
	end
	```

	- ### Options
	- - `:username` - username (defaults to `""`)
	- - `:password` - password (defaults to `""`)
	+ ## Options
	+ - `:username` - username (defaults to `""`)
	+ - `:password` - password (defaults to `""`)
	- `:cnonce_fn` - custom function generating client nonce (defaults to `&Tesla.Middleware.DigestAuth.cnonce/0`)
	- - `:nc` - nonce counter (defaults to `"00000000"`)
	+ - `:nc` - nonce counter (defaults to `"00000000"`)
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	if env.opts && Keyword.get(env.opts, :digest_auth_handshake) do
	Tesla.run(env, next)
	else
	opts = opts \|\| %{}

	with {:ok, headers} <- authorization_header(env, opts) do
	env
	\|> Tesla.put_headers(headers)
	\|> Tesla.run(next)
	end
	end
	end

	defp authorization_header(env, opts) do
	with {:ok, vars} <- authorization_vars(env, opts) do
	{:ok,
	vars
	\|> calculated_authorization_values
	\|> create_header}
	end
	end

	defp authorization_vars(env, opts) do
	with {:ok, unauthorized_response} <-
	env.__module__.get(
	env.__client__,
	env.url,
	opts: Keyword.put(env.opts \|\| [], :digest_auth_handshake, true)
	) do
	{:ok,
	%{
	username: opts[:username] \|\| "",
	password: opts[:password] \|\| "",
	path: URI.parse(env.url).path,
	auth:
	Tesla.get_header(unauthorized_response, "www-authenticate")
	\|> parse_www_authenticate_header,
	method: env.method \|> to_string \|> String.upcase(),
	client_nonce: (opts[:cnonce_fn] \|\| (&cnonce/0)).(),
	nc: opts[:nc] \|\| "00000000"
	}}
	end
	end

	defp calculated_authorization_values(%{auth: auth}) when auth == %{}, do: []

	defp calculated_authorization_values(auth_vars) do
	[
	{"username", auth_vars.username},
	{"realm", auth_vars.auth["realm"]},
	{"uri", auth_vars[:path]},
	{"nonce", auth_vars.auth["nonce"]},
	{"nc", auth_vars.nc},
	{"cnonce", auth_vars.client_nonce},
	{"response", response(auth_vars)},
	# hard-coded, will not work for MD5-sess
	{"algorithm", "MD5"},
	# hard-coded, will not work for auth-int or unspecified
	{"qop", "auth"}
	]
	end

	defp single_header_val({k, v}) when k in ~w(nc qop algorithm), do: "#{k}=#{v}"
	defp single_header_val({k, v}), do: "#{k}=\"#{v}\""

	defp create_header([]), do: []

	defp create_header(calculated_authorization_values) do
	vals =
	calculated_authorization_values
	\|> Enum.reduce([], fn val, acc -> [single_header_val(val) \| acc] end)
	\|> Enum.join(", ")

	[{"authorization", "Digest #{vals}"}]
	end

	defp ha1(%{username: username, auth: %{"realm" => realm}, password: password}) do
	md5("#{username}:#{realm}:#{password}")
	end

	defp ha2(%{method: method, path: path}) do
	md5("#{method}:#{path}")
	end

	defp response(%{auth: %{"nonce" => nonce}, nc: nc, client_nonce: client_nonce} = auth_vars) do
	md5("#{ha1(auth_vars)}:#{nonce}:#{nc}:#{client_nonce}:auth:#{ha2(auth_vars)}")
	end

	defp parse_www_authenticate_header(nil), do: %{}

	defp parse_www_authenticate_header(header) do
	Regex.scan(~r/(\w+?)="(.+?)"/, header)
	\|> Enum.reduce(%{}, fn [_, key, val], acc -> Map.merge(acc, %{key => val}) end)
	end

	defp md5(data), do: Base.encode16(:erlang.md5(data), case: :lower)

	defp cnonce, do: :crypto.strong_rand_bytes(4) \|> Base.encode16(case: :lower)
	end
	diff --git a/lib/tesla/middleware/follow_redirects.ex b/lib/tesla/middleware/follow_redirects.ex
	index 4da015c..13e5562 100644
	--- a/lib/tesla/middleware/follow_redirects.ex
	+++ b/lib/tesla/middleware/follow_redirects.ex
	@@ -1,87 +1,88 @@
	defmodule Tesla.Middleware.FollowRedirects do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Follow 3xx redirects

	- ### Example
	+ ## Example
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.FollowRedirects, max_redirects: 3 # defaults to 5
	end
	```

	- ### Options
	- - `:max_redirects` - limit number of redirects (default: `5`)
	+ ## Options

	+ - `:max_redirects` - limit number of redirects (default: `5`)
	"""

	+ @behaviour Tesla.Middleware
	+
	@max_redirects 5
	@redirect_statuses [301, 302, 303, 307, 308]

	- @doc false
	+ @impl Tesla.Middleware
	def call(env, next, opts \\ []) do
	max = Keyword.get(opts \|\| [], :max_redirects, @max_redirects)

	redirect(env, next, max)
	end

	defp redirect(env, next, left) when left == 0 do
	case Tesla.run(env, next) do
	{:ok, %{status: status} = env} when not (status in @redirect_statuses) ->
	{:ok, env}

	{:ok, _env} ->
	{:error, {__MODULE__, :too_many_redirects}}

	error ->
	error
	end
	end

	defp redirect(env, next, left) do
	case Tesla.run(env, next) do
	{:ok, %{status: status} = res} when status in @redirect_statuses ->
	case Tesla.get_header(res, "location") do
	nil ->
	{:ok, res}

	location ->
	location = parse_location(location, res)

	env
	\|> new_request(res.status, location)
	\|> redirect(next, left - 1)
	end

	other ->
	other
	end
	end

	# The 303 (See Other) redirect was added in HTTP/1.1 to indicate that the originally
	# requested resource is not available, however a related resource (or another redirect)
	# available via GET is available at the specified location.
	# https://tools.ietf.org/html/rfc7231#section-6.4.4
	defp new_request(env, 303, location), do: %{env \| url: location, method: :get, query: []}

	# The 307 (Temporary Redirect) status code indicates that the target
	# resource resides temporarily under a different URI and the user agent
	# MUST NOT change the request method (...)
	# https://tools.ietf.org/html/rfc7231#section-6.4.7
	defp new_request(env, 307, location), do: %{env \| url: location}

	defp new_request(env, _, location), do: %{env \| url: location, query: []}

	defp parse_location("https://" <> _rest = location, _env), do: location
	defp parse_location("http://" <> _rest = location, _env), do: location

	defp parse_location(location, env) do
	env.url
	\|> URI.parse()
	\|> URI.merge(location)
	\|> URI.to_string()
	end
	end
	diff --git a/lib/tesla/middleware/form_urlencoded.ex b/lib/tesla/middleware/form_urlencoded.ex
	index da1419f..5bbf346 100644
	--- a/lib/tesla/middleware/form_urlencoded.ex
	+++ b/lib/tesla/middleware/form_urlencoded.ex
	@@ -1,109 +1,114 @@
	defmodule Tesla.Middleware.FormUrlencoded do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Send request body as `application/x-www-form-urlencoded`.
	+
	Performs encoding of `body` from a `Map` such as `%{"foo" => "bar"}` into
	url encoded data.
	+
	Performs decoding of the response into a map when urlencoded and content-type
	is `application/x-www-form-urlencoded`, so `"foo=bar"` becomes
	`%{"foo" => "bar"}`.

	+ ## Example usage

	- ### Example usage
	```
	defmodule Myclient do
	use Tesla

	plug Tesla.Middleware.FormUrlencoded
	end

	Myclient.post("/url", %{key: :value})
	```

	- ### Options
	+ ## Options
	+
	- `:decode` - decoding function, defaults to `URI.decode_query/1`
	- `:encode` - encoding function, defaults to `URI.encode_query/1`

	- ### Nested Maps
	+ ## Nested Maps
	+
	Natively, nested maps are not supported in the body, so
	`%{"foo" => %{"bar" => "baz"}}` won't be encoded and raise an error.
	Support for this specific case is obtained by configuring the middleware to
	encode (and decode) with `Plug.Conn.Query`

	```
	defmodule Myclient do
	use Tesla

	plug Tesla.Middleware.FormUrlencoded,
	encode: &Plug.Conn.Query.encode/1,
	decode: &Plug.Conn.Query.decode/1
	end

	Myclient.post("/url", %{key: %{nested: "value"}})
	+ ```
	"""

	+ @behaviour Tesla.Middleware
	+
	@content_type "application/x-www-form-urlencoded"

	- @doc false
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	env
	\|> encode(opts)
	\|> Tesla.run(next)
	\|> case do
	{:ok, env} -> {:ok, decode(env, opts)}
	error -> error
	end
	end

	defp encode(env, opts) do
	if encodable?(env) do
	env
	\|> Map.update!(:body, &encode_body(&1, opts))
	\|> Tesla.put_headers([{"content-type", @content_type}])
	else
	env
	end
	end

	defp encodable?(%{body: nil}), do: false
	defp encodable?(%{body: %Tesla.Multipart{}}), do: false
	defp encodable?(_), do: true

	defp encode_body(body, _opts) when is_binary(body), do: body
	defp encode_body(body, opts), do: do_encode(body, opts)

	defp decode(env, opts) do
	if decodable?(env) do
	env
	\|> Map.update!(:body, &decode_body(&1, opts))
	else
	env
	end
	end

	defp decodable?(env), do: decodable_body?(env) && decodable_content_type?(env)

	defp decodable_body?(env) do
	(is_binary(env.body) && env.body != "") \|\| (is_list(env.body) && env.body != [])
	end

	defp decodable_content_type?(env) do
	case Tesla.get_header(env, "content-type") do
	nil -> false
	content_type -> String.starts_with?(content_type, @content_type)
	end
	end

	defp decode_body(body, opts), do: do_decode(body, opts)

	defp do_encode(data, opts) do
	encoder = Keyword.get(opts, :encode, &URI.encode_query/1)
	encoder.(data)
	end

	defp do_decode(data, opts) do
	decoder = Keyword.get(opts, :decode, &URI.decode_query/1)
	decoder.(data)
	end
	end
	diff --git a/lib/tesla/middleware/fuse.ex b/lib/tesla/middleware/fuse.ex
	index 42ba0ca..83a17d9 100644
	--- a/lib/tesla/middleware/fuse.ex
	+++ b/lib/tesla/middleware/fuse.ex
	@@ -1,75 +1,77 @@
	if Code.ensure_loaded?(:fuse) do
	defmodule Tesla.Middleware.Fuse do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Circuit Breaker middleware using [fuse](https://github.com/jlouis/fuse)

	Remember to add `{:fuse, "~> 2.4"}` to dependencies (and `:fuse` to applications in `mix.exs`)
	Also, you need to recompile tesla after adding `:fuse` dependency:

	```
	mix deps.clean tesla
	mix deps.compile tesla
	```

	- ### Example usage
	+ ## Example usage
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.Fuse, opts: {{:standard, 2, 10_000}, {:reset, 60_000}}
	end
	```

	- ### Options
	+ ## Options
	+
	- `:name` - fuse name (defaults to module name)
	- `:opts` - fuse options (see fuse docs for reference)

	- ### SASL logger
	+ ## SASL logger

	fuse library uses [SASL (System Architecture Support Libraries)](http://erlang.org/doc/man/sasl_app.html).

	You can disable its logger output using:

	```
	config :sasl, sasl_error_logger: :false
	```

	Read more at [jlouis/fuse#32](https://github.com/jlouis/fuse/issues/32) and [jlouis/fuse#19](https://github.com/jlouis/fuse/issues/19).
	"""

	+ @behaviour Tesla.Middleware
	+
	# options borrowed from http://blog.rokkincat.com/circuit-breakers-in-elixir/
	# most probably not valid for your use case
	@defaults {{:standard, 2, 10_000}, {:reset, 60_000}}

	- @doc false
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	opts = opts \|\| []
	name = Keyword.get(opts, :name, env.__module__)

	case :fuse.ask(name, :sync) do
	:ok ->
	run(env, next, name)

	:blown ->
	{:error, :unavailable}

	{:error, :not_found} ->
	:fuse.install(name, Keyword.get(opts, :opts, @defaults))
	run(env, next, name)
	end
	end

	defp run(env, next, name) do
	case Tesla.run(env, next) do
	{:ok, env} ->
	{:ok, env}

	{:error, _reason} ->
	:fuse.melt(name)
	{:error, :unavailable}
	end
	end
	end
	end
	diff --git a/lib/tesla/middleware/json.ex b/lib/tesla/middleware/json.ex
	index 92777f1..fa7b109 100644
	--- a/lib/tesla/middleware/json.ex
	+++ b/lib/tesla/middleware/json.ex
	@@ -1,168 +1,173 @@
	defmodule Tesla.Middleware.JSON do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Encode requests and decode responses as JSON.

	This middleware requires [jason](https://hex.pm/packages/jason) (or other engine) as dependency.

	Remember to add `{:jason, ">= 1.0"}` to dependencies
	Also, you need to recompile tesla after adding `:jason` dependency:

	```
	mix deps.clean tesla
	mix deps.compile tesla
	```

	+ ## Example usage

	- ### Example usage
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.JSON # use jason engine
	# or
	plug Tesla.Middleware.JSON, engine: JSX, engine_opts: [strict: [:comments]]
	# or
	plug Tesla.Middleware.JSON, engine: Poison, engine_opts: [keys: :atoms]
	# or
	plug Tesla.Middleware.JSON, decode: &JSX.decode/1, encode: &JSX.encode/1
	end
	```

	- ### Options
	+ ## Options
	+
	- `:decode` - decoding function
	- `:encode` - encoding function
	- `:encode_content_type` - content-type to be used in request header
	- `:engine` - encode/decode engine, e.g `Jason`, `Poison` or `JSX` (defaults to Jason)
	- `:engine_opts` - optional engine options
	- `:decode_content_types` - list of additional decodable content-types
	"""

	+ @behaviour Tesla.Middleware
	+
	# NOTE: text/javascript added to support Facebook Graph API.
	# see https://github.com/teamon/tesla/pull/13
	@default_content_types ["application/json", "text/javascript"]
	@default_encode_content_type "application/json"
	@default_engine Jason

	- @doc false
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	opts = opts \|\| []

	with {:ok, env} <- encode(env, opts),
	{:ok, env} <- Tesla.run(env, next) do
	decode(env, opts)
	end
	end

	@doc """
	- Encode request body as JSON. Used by `Tesla.Middleware.EncodeJson`
	+ Encode request body as JSON.
	+
	+ It is used by `Tesla.Middleware.EncodeJson`.
	"""
	def encode(env, opts) do
	with true <- encodable?(env),
	{:ok, body} <- encode_body(env.body, opts) do
	{:ok,
	env
	\|> Tesla.put_body(body)
	\|> Tesla.put_headers([{"content-type", encode_content_type(opts)}])}
	else
	false -> {:ok, env}
	error -> error
	end
	end

	defp encode_body(%Stream{} = body, opts), do: {:ok, encode_stream(body, opts)}
	defp encode_body(body, opts) when is_function(body), do: {:ok, encode_stream(body, opts)}
	defp encode_body(body, opts), do: process(body, :encode, opts)

	defp encode_content_type(opts),
	do: Keyword.get(opts, :encode_content_type, @default_encode_content_type)

	defp encode_stream(body, opts) do
	Stream.map(body, fn item ->
	{:ok, body} = encode_body(item, opts)
	body <> "\n"
	end)
	end

	defp encodable?(%{body: nil}), do: false
	defp encodable?(%{body: body}) when is_binary(body), do: false
	defp encodable?(%{body: %Tesla.Multipart{}}), do: false
	defp encodable?(_), do: true

	@doc """
	- Decode response body as JSON. Used by `Tesla.Middleware.DecodeJson`
	+ Decode response body as JSON.
	+
	+ It is used by `Tesla.Middleware.DecodeJson`.
	"""
	def decode(env, opts) do
	with true <- decodable?(env, opts),
	{:ok, body} <- decode_body(env.body, opts) do
	{:ok, %{env \| body: body}}
	else
	false -> {:ok, env}
	error -> error
	end
	end

	defp decode_body(body, opts), do: process(body, :decode, opts)

	defp decodable?(env, opts), do: decodable_body?(env) && decodable_content_type?(env, opts)

	defp decodable_body?(env) do
	(is_binary(env.body) && env.body != "") \|\| (is_list(env.body) && env.body != [])
	end

	defp decodable_content_type?(env, opts) do
	case Tesla.get_header(env, "content-type") do
	nil -> false
	content_type -> Enum.any?(content_types(opts), &String.starts_with?(content_type, &1))
	end
	end

	defp content_types(opts),
	do: @default_content_types ++ Keyword.get(opts, :decode_content_types, [])

	defp process(data, op, opts) do
	case do_process(data, op, opts) do
	{:ok, data} -> {:ok, data}
	{:error, reason} -> {:error, {__MODULE__, op, reason}}
	{:error, reason, _pos} -> {:error, {__MODULE__, op, reason}}
	end
	rescue
	ex in Protocol.UndefinedError ->
	{:error, {__MODULE__, op, ex}}
	end

	defp do_process(data, op, opts) do
	# :encode/:decode
	if fun = opts[op] do
	fun.(data)
	else
	engine = Keyword.get(opts, :engine, @default_engine)
	opts = Keyword.get(opts, :engine_opts, [])

	apply(engine, op, [data, opts])
	end
	end
	end

	defmodule Tesla.Middleware.DecodeJson do
	@moduledoc false
	def call(env, next, opts) do
	opts = opts \|\| []

	with {:ok, env} <- Tesla.run(env, next) do
	Tesla.Middleware.JSON.decode(env, opts)
	end
	end
	end

	defmodule Tesla.Middleware.EncodeJson do
	@moduledoc false
	def call(env, next, opts) do
	opts = opts \|\| []

	with {:ok, env} <- Tesla.Middleware.JSON.encode(env, opts) do
	Tesla.run(env, next)
	end
	end
	end
	diff --git a/lib/tesla/middleware/keep_request.ex b/lib/tesla/middleware/keep_request.ex
	index 828531f..60b9b77 100644
	--- a/lib/tesla/middleware/keep_request.ex
	+++ b/lib/tesla/middleware/keep_request.ex
	@@ -1,28 +1,36 @@
	defmodule Tesla.Middleware.KeepRequest do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Store request body & headers into opts.

	- ### Example
	+ ## Example
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.KeepRequest
	end

	{:ok, env} = MyClient.post("/", "request-data")
	- env.body # => "response-data"
	- env.opts[:req_body] # => "request-data"
	- env.opts[:req_headers] # => [{"request-headers", "are-safe"}, ...]
	+
	+ env.body
	+ # => "response-data"
	+
	+ env.opts[:req_body]
	+ # => "request-data"
	+
	+ env.opts[:req_headers]
	+ # => [{"request-headers", "are-safe"}, ...]
	```
	"""
	- @doc false
	+
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, _opts) do
	env
	\|> Tesla.put_opt(:req_body, env.body)
	\|> Tesla.put_opt(:req_headers, env.headers)
	\|> Tesla.run(next)
	end
	end
	diff --git a/lib/tesla/middleware/logger.ex b/lib/tesla/middleware/logger.ex
	index e94944d..4e05af7 100644
	--- a/lib/tesla/middleware/logger.ex
	+++ b/lib/tesla/middleware/logger.ex
	@@ -1,247 +1,247 @@
	defmodule Tesla.Middleware.Logger.Formatter do
	@moduledoc false

	# Heavily based on Elixir's Logger.Formatter
	# https://github.com/elixir-lang/elixir/blob/v1.6.4/lib/logger/lib/logger/formatter.ex

	@default_format "$method $url -> $status ($time ms)"
	@keys ~w(method url status time)

	@type format :: [atom \| binary]

	@spec compile(binary \| nil) :: format
	def compile(nil), do: compile(@default_format)

	def compile(binary) do
	~r/(?<h>)\$[a-z]+(?<t>)/
	\|> Regex.split(binary, on: [:h, :t], trim: true)
	\|> Enum.map(&compile_key/1)
	end

	defp compile_key("$" <> key) when key in @keys, do: String.to_atom(key)
	defp compile_key("$" <> key), do: raise(ArgumentError, "$#{key} is an invalid format pattern.")
	defp compile_key(part), do: part

	@spec format(Tesla.Env.t(), Tesla.Env.result(), integer, format) :: IO.chardata()
	def format(request, response, time, format) do
	Enum.map(format, &output(&1, request, response, time))
	end

	defp output(:method, env, _, _), do: env.method \|> to_string() \|> String.upcase()
	defp output(:url, env, _, _), do: env.url
	defp output(:status, _, {:ok, env}, _), do: to_string(env.status)
	defp output(:status, _, {:error, reason}, _), do: "error: " <> inspect(reason)
	defp output(:time, _, _, time), do: :io_lib.format("~.3f", [time / 1000])
	defp output(binary, _, _, _), do: binary
	end

	defmodule Tesla.Middleware.Logger do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Log requests using Elixir's Logger.

	With the default settings it logs request method, url, response status and time taken in milliseconds.

	- ### Example usage
	+ ## Example usage
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.Logger
	end
	```

	- ### Options
	+ ## Options
	- `:log_level` - custom function for calculating log level (see below)
	- `:filter_headers` - sanitizes sensitive headers before logging in debug mode (see below)

	## Custom log format

	The default log format is `"$method $url -> $status ($time ms)"`
	which shows in logs like:

	```
	2018-03-25 18:32:40.397 [info] GET https://bitebot.io -> 200 (88.074 ms)
	```

	Because log format is processed during compile time it needs to be set in config:

	```
	config :tesla, Tesla.Middleware.Logger, format: "$method $url ====> $status / time=$time"
	```

	## Custom log levels

	By default, the following log levels will be used:
	- `:error` - for errors, 5xx and 4xx responses
	- `:warn` - for 3xx responses
	- `:info` - for 2xx responses

	You can customize this setting by providing your own `log_level/1` function:

	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.Logger, log_level: &my_log_level/1

	def my_log_level(env) do
	case env.status do
	404 -> :info
	_ -> :default
	end
	end
	end
	```

	- ### Logger Debug output
	+ ## Logger Debug output

	When the Elixir Logger log level is set to `:debug`
	Tesla Logger will show full request & response.

	If you want to disable detailed request/response logging
	but keep the `:debug` log level (i.e. in development)
	you can set `debug: false` in your config:

	```
	# config/dev.local.exs
	config :tesla, Tesla.Middleware.Logger, debug: false
	```
	- #### Filter headers
	+ ### Filter headers

	To sanitize sensitive headers such as `authorization` in
	debug logs, add them to the `:filter_headers` option.
	`:filter_headers` expects a list of header names as strings.

	```
	# config/dev.local.exs
	config :tesla, Tesla.Middleware.Logger,
	filter_headers: ["authorization"]
	```
	"""

	+ @behaviour Tesla.Middleware
	+
	alias Tesla.Middleware.Logger.Formatter

	@config Application.get_env(:tesla, __MODULE__, [])
	@format Formatter.compile(@config[:format])

	@type log_level :: :info \| :warn \| :error

	require Logger

	- @doc false
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	{time, response} = :timer.tc(Tesla, :run, [env, next])
	level = log_level(response, opts)
	Logger.log(level, fn -> Formatter.format(env, response, time, @format) end)

	if Keyword.get(@config, :debug, true) do
	Logger.debug(fn -> debug(env, response, opts) end)
	end

	response
	end

	defp log_level({:error, _}, _), do: :error

	defp log_level({:ok, env}, opts) do
	case Keyword.get(opts, :log_level) do
	nil ->
	default_log_level(env)

	fun when is_function(fun) ->
	case fun.(env) do
	:default -> default_log_level(env)
	level -> level
	end

	atom when is_atom(atom) ->
	atom
	end
	end

	@spec default_log_level(Tesla.Env.t()) :: log_level
	def default_log_level(env) do
	cond do
	env.status >= 400 -> :error
	env.status >= 300 -> :warn
	true -> :info
	end
	end

	@debug_no_query "(no query)"
	@debug_no_headers "(no headers)"
	@debug_no_body "(no body)"
	@debug_stream "[Elixir.Stream]"

	defp debug(request, {:ok, response}, opts) do
	[
	"\n>>> REQUEST >>>\n",
	debug_query(request.query),
	?\n,
	debug_headers(request.headers, opts),
	?\n,
	debug_body(request.body),
	?\n,
	"\n<<< RESPONSE <<<\n",
	debug_headers(response.headers, opts),
	?\n,
	debug_body(response.body)
	]
	end

	defp debug(request, {:error, error}, opts) do
	[
	"\n>>> REQUEST >>>\n",
	debug_query(request.query),
	?\n,
	debug_headers(request.headers, opts),
	?\n,
	debug_body(request.body),
	?\n,
	"\n<<< RESPONSE ERROR <<<\n",
	inspect(error)
	]
	end

	defp debug_query([]), do: @debug_no_query

	defp debug_query(query) do
	query
	\|> Enum.flat_map(&Tesla.encode_pair/1)
	\|> Enum.map(fn {k, v} -> ["Query: ", to_string(k), ": ", to_string(v), ?\n] end)
	end

	defp debug_headers([], _opts), do: @debug_no_headers

	defp debug_headers(headers, opts) do
	filtered = Keyword.get(opts, :filter_headers, [])

	Enum.map(headers, fn {k, v} ->
	v = if k in filtered, do: "[FILTERED]", else: v
	[k, ": ", v, ?\n]
	end)
	end

	defp debug_body(nil), do: @debug_no_body
	defp debug_body([]), do: @debug_no_body
	defp debug_body(%Stream{}), do: @debug_stream
	defp debug_body(stream) when is_function(stream), do: @debug_stream

	defp debug_body(%Tesla.Multipart{} = mp) do
	[
	"[Tesla.Multipart]\n",
	"boundary: ",
	mp.boundary,
	?\n,
	"content_type_params: ",
	inspect(mp.content_type_params),
	?\n
	\| Enum.map(mp.parts, &[inspect(&1), ?\n])
	]
	end

	defp debug_body(data) when is_binary(data) or is_list(data), do: data
	defp debug_body(term), do: inspect(term)
	end
	diff --git a/lib/tesla/middleware/method_override.ex b/lib/tesla/middleware/method_override.ex
	index 40039f9..e351b4e 100644
	--- a/lib/tesla/middleware/method_override.ex
	+++ b/lib/tesla/middleware/method_override.ex
	@@ -1,49 +1,51 @@
	defmodule Tesla.Middleware.MethodOverride do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Middleware that adds X-Http-Method-Override header with original request
	method and sends the request as post.

	Useful when there's an issue with sending non-post request.

	- ### Example
	+ ## Example
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.MethodOverride
	end
	```

	- ### Options
	+ ## Options
	+
	- `:override` - list of http methods that should be overriden,
	everything except `:get` and `:post` if not specified
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	if overridable?(env, opts) do
	env
	\|> override
	\|> Tesla.run(next)
	else
	env
	\|> Tesla.run(next)
	end
	end

	defp override(env) do
	env
	\|> Tesla.put_headers([{"x-http-method-override", "#{env.method}"}])
	\|> Map.put(:method, :post)
	end

	defp overridable?(env, opts) do
	if opts[:override] do
	env.method in opts[:override]
	else
	not (env.method in [:get, :post])
	end
	end
	end
	diff --git a/lib/tesla/middleware/path_params.ex b/lib/tesla/middleware/path_params.ex
	index 5a78db9..60d012f 100644
	--- a/lib/tesla/middleware/path_params.ex
	+++ b/lib/tesla/middleware/path_params.ex
	@@ -1,43 +1,42 @@
	defmodule Tesla.Middleware.PathParams do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Use templated URLs with separate params.

	Useful when logging or reporting metric per URL.

	+ ## Example usage

	- ### Example usage
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.BaseURl, "https://api.example.com"
	plug Tesla.Middleware.Logger # or some monitoring middleware
	plug Tesla.Middleware.PathParams

	def user(id) do
	params = [id: id]
	get("/users/:id", opts: [path_params: params])
	end
	end
	```
	"""

	+ @behaviour Tesla.Middleware
	+
	@rx ~r/:([\w_]+)/

	- @doc false
	- @impl true
	+ @impl Tesla.Middleware
	def call(env, next, _) do
	url = build_url(env.url, env.opts[:path_params])
	Tesla.run(%{env \| url: url}, next)
	end

	defp build_url(url, nil), do: url

	defp build_url(url, params) do
	Regex.replace(@rx, url, fn match, key ->
	to_string(params[String.to_existing_atom(key)] \|\| match)
	end)
	end
	end
	diff --git a/lib/tesla/middleware/retry.ex b/lib/tesla/middleware/retry.ex
	index e6fc744..392324b 100644
	--- a/lib/tesla/middleware/retry.ex
	+++ b/lib/tesla/middleware/retry.ex
	@@ -1,98 +1,100 @@
	defmodule Tesla.Middleware.Retry do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Retry using exponential backoff and full jitter. This middleware only retries in the
	case of connection errors (`nxdomain`, `connrefused` etc). Application error
	checking for retry can be customized through `:should_retry` option by
	providing a function in returning a boolean.

	## Backoff algorithm

	The backoff algorithm optimizes for tight bounds on completing a request successfully.
	It does this by first calculating an exponential backoff factor based on the
	number of retries that have been performed. It then multiplies this factor against the
	base delay. The total maximum delay is found by taking the minimum of either the calculated delay
	or the maximum delay specified. This creates an upper bound on the maximum delay
	we can see.

	In order to find the actual delay value we take a random number between 0 and
	the maximum delay based on a uniform distribution. This randomness ensures that
	our retried requests don't "harmonize" making it harder for the downstream
	service to heal.

	- ### Example
	+ ## Example
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.Retry,
	delay: 500,
	max_retries: 10,
	max_delay: 4_000,
	should_retry: fn
	{:ok, %{status: status}} when status in [400, 500] -> true
	{:ok, _} -> false
	{:error, _} -> true
	end
	end
	```

	- ### Options
	- - `:delay` - The base delay in milliseconds (defaults to 50)
	- - `:max_retries` - maximum number of retries (defaults to 5)
	- - `:max_delay` - maximum delay in milliseconds (defaults to 5000)
	+ ## Options
	+
	+ - `:delay` - The base delay in milliseconds (defaults to 50)
	+ - `:max_retries` - maximum number of retries (defaults to 5)
	+ - `:max_delay` - maximum delay in milliseconds (defaults to 5000)
	- `:should_retry` - function to determine if request should be retried
	"""

	+ @behaviour Tesla.Middleware
	+
	@defaults [
	delay: 50,
	max_retries: 5,
	max_delay: 5_000
	]

	- @doc false
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	opts = opts \|\| []

	context = %{
	retries: 0,
	delay: Keyword.get(opts, :delay, @defaults[:delay]),
	max_retries: Keyword.get(opts, :max_retries, @defaults[:max_retries]),
	max_delay: Keyword.get(opts, :max_delay, @defaults[:max_delay]),
	should_retry: Keyword.get(opts, :should_retry, &match?({:error, _}, &1))
	}

	retry(env, next, context)
	end

	# If we have max retries set to 0 don't retry
	defp retry(env, next, %{max_retries: 0}), do: Tesla.run(env, next)

	# If we're on our last retry then just run and don't handle the error
	defp retry(env, next, %{max_retries: max, retries: max}) do
	Tesla.run(env, next)
	end

	# Otherwise we retry if we get a retriable error
	defp retry(env, next, context) do
	res = Tesla.run(env, next)

	if context.should_retry.(res) do
	backoff(context.max_delay, context.delay, context.retries)
	context = update_in(context, [:retries], &(&1 + 1))
	retry(env, next, context)
	else
	res
	end
	end

	# Exponential backoff with jitter
	defp backoff(cap, base, attempt) do
	factor = :math.pow(2, attempt)
	max_sleep = trunc(min(cap, base * factor))
	delay = :rand.uniform(max_sleep)

	:timer.sleep(delay)
	end
	end
	diff --git a/lib/tesla/middleware/telemetry.ex b/lib/tesla/middleware/telemetry.ex
	index 9ffac7a..e3dc643 100644
	--- a/lib/tesla/middleware/telemetry.ex
	+++ b/lib/tesla/middleware/telemetry.ex
	@@ -1,32 +1,33 @@
	if Code.ensure_loaded?(:telemetry) do
	defmodule Tesla.Middleware.Telemetry do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Send the request time and meta-information through telemetry.

	- ### Example usage
	+ ## Example usage
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.Telemetry

	end

	:telemetry.attach("my-tesla-telemetry", [:tesla, :request], fn event, time, meta, config ->
	# Do something with the event
	end)
	```

	Please check the [telemetry](https://hexdocs.pm/telemetry/) for the further usage.
	"""

	- @doc false
	+ @behaviour Tesla.Middleware
	+
	+ @impl Tesla.Middleware
	def call(env, next, _opts) do
	{time, res} = :timer.tc(Tesla, :run, [env, next])
	:telemetry.execute([:tesla, :request], %{request_time: time}, %{result: res})
	res
	end
	end
	end
	diff --git a/lib/tesla/middleware/timeout.ex b/lib/tesla/middleware/timeout.ex
	index bb4be11..80d7c08 100644
	--- a/lib/tesla/middleware/timeout.ex
	+++ b/lib/tesla/middleware/timeout.ex
	@@ -1,61 +1,63 @@
	defmodule Tesla.Middleware.Timeout do
	- @behaviour Tesla.Middleware
	-
	@moduledoc """
	Timeout http request after X seconds.

	- ### Example
	+ ## Example
	+
	```
	defmodule MyClient do
	use Tesla

	plug Tesla.Middleware.Timeout, timeout: 2_000
	end
	```

	- ### Options
	+ ## Options
	+
	- `:timeout` - number of milliseconds a request is allowed to take (defaults to 1000)
	"""

	+ @behaviour Tesla.Middleware
	+
	@default_timeout 1_000

	- @doc false
	+ @impl Tesla.Middleware
	def call(env, next, opts) do
	opts = opts \|\| []
	timeout = Keyword.get(opts, :timeout, @default_timeout)

	task = safe_async(fn -> Tesla.run(env, next) end)

	try do
	task
	\|> Task.await(timeout)
	\|> repass_error
	catch
	:exit, {:timeout, _} ->
	Task.shutdown(task, 0)
	{:error, :timeout}
	end
	end

	defp safe_async(func) do
	Task.async(fn ->
	try do
	{:ok, func.()}
	rescue
	e in _ ->
	{:exception, e}
	catch
	type, value ->
	{type, value}
	end
	end)
	end

	defp repass_error({:exception, error}), do: raise(error)

	defp repass_error({:throw, value}), do: throw(value)

	defp repass_error({:exit, value}), do: exit(value)

	defp repass_error({:ok, result}), do: result
	end
	diff --git a/lib/tesla/mock.ex b/lib/tesla/mock.ex
	index aef6e50..61b38d7 100644
	--- a/lib/tesla/mock.ex
	+++ b/lib/tesla/mock.ex
	@@ -1,233 +1,239 @@
	defmodule Tesla.Mock do
	@moduledoc """
	Mock adapter for better testing.

	- ### Setup
	+ ## Setup

	```
	# config/test.exs
	config :tesla, adapter: Tesla.Mock

	# in case MyClient defines specific adapter with `adapter SpecificAdapter`
	config :tesla, MyClient, adapter: Tesla.Mock
	```

	- ### Example test
	+ ## Example test
	+
	```
	defmodule MyAppTest do
	use ExUnit.Case

	setup do
	- Tesla.Mock.mock fn
	+ Tesla.Mock.mock(fn
	%{method: :get} ->
	%Tesla.Env{status: 200, body: "hello"}
	- end
	+ end)

	:ok
	end

	test "list things" do
	assert {:ok, env} = MyApp.get("...")
	assert env.status == 200
	assert env.body == "hello"
	end
	end
	```

	- ### Setting up mocks
	+ ## Setting up mocks
	+
	```
	# Match on method & url and return whole Tesla.Env
	- Tesla.Mock.mock fn
	- %{method: :get, url: "http://example.com/list"} ->
	+ Tesla.Mock.mock(fn
	+ %{method: :get, url: "http://example.com/list"} ->
	%Tesla.Env{status: 200, body: "hello"}
	- end
	+ end)

	# You can use any logic required
	- Tesla.Mock.mock fn env ->
	+ Tesla.Mock.mock(fn env ->
	case env.url do
	"http://example.com/list" ->
	%Tesla.Env{status: 200, body: "ok!"}
	+
	_ ->
	%Tesla.Env{status: 404, body: "NotFound"}
	- end
	+ end
	+ end)
	+

	# mock will also accept short version of response
	# in the form of {status, headers, body}
	- Tesla.Mock.mock fn
	+ Tesla.Mock.mock(fn
	%{method: :post} -> {201, %{}, %{id: 42}}
	- end
	+ end)
	```

	- ### Global mocks
	+ ## Global mocks
	+
	By default, mocks are bound to the current process,
	i.e. the process running a single test case.
	This design allows proper isolation between test cases
	and make testing in parallel (`async: true`) possible.

	While this style is recommended, there is one drawback:
	if Tesla client is called from different process
	it will not use the setup mock.

	To solve this issue it is possible to setup a global mock
	using `mock_global/1` function.

	```
	defmodule MyTest do
	use ExUnit.Case, async: false # must be false!

	setup_all do
	Tesla.Mock.mock_global fn
	env -> # ...
	end

	:ok
	end

	# ...
	end
	```

	WARNING: Using global mocks may affect tests with local mock
	(because of fallback to global mock in case local one is not found)
	"""

	defmodule Error do
	defexception env: nil, ex: nil, stacktrace: []

	def message(%__MODULE__{ex: nil}) do
	"""
	There is no mock set for process #{inspect(self())}.
	Use Tesla.Mock.mock/1 to mock HTTP requests.

	See https://github.com/teamon/tesla#testing
	"""
	end

	def message(%__MODULE__{env: env, ex: %FunctionClauseError{} = ex, stacktrace: stacktrace}) do
	"""
	Request not mocked

	The following request was not mocked:

	#{inspect(env, pretty: true)}

	#{Exception.format(:error, ex, stacktrace)}
	"""
	end
	end

	## PUBLIC API

	@doc """
	Setup mocks for current test.

	This mock will only be available to the current process.
	"""
	@spec mock((Tesla.Env.t() -> Tesla.Env.t() \| {integer, map, any})) :: no_return
	def mock(fun) when is_function(fun), do: pdict_set(fun)

	@doc """
	Setup global mocks.

	WARNING: This mock will be available to ALL processes.
	It might cause conflicts when running tests in parallel!
	"""
	@spec mock_global((Tesla.Env.t() -> Tesla.Env.t() \| {integer, map, any})) :: no_return
	def mock_global(fun) when is_function(fun), do: agent_set(fun)

	## HELPERS

	@type response_opt :: :headers \| :status
	@type response_opts :: [{response_opt, any}]

	@doc """
	Return json response.

	Example

	import Tesla.Mock

	mock fn
	%{url: "/ok"} -> json(%{"some" => "data"})
	%{url: "/404"} -> json(%{"some" => "data"}, status: 404)
	end
	"""
	@spec json(body :: term, opts :: [response_opts]) :: Tesla.Env.t()
	def json(body, opts \\ []), do: response(json_encode(body), "application/json", opts)

	defp json_encode(body) do
	engine = Keyword.get(Application.get_env(:tesla, Tesla.Mock, []), :json_engine, Jason)
	engine.encode!(body)
	end

	@doc """
	Return text response.

	Example

	import Tesla.Mock

	mock fn
	%{url: "/ok"} -> text(%{"some" => "data"})
	%{url: "/404"} -> text(%{"some" => "data"}, status: 404)
	end
	"""
	@spec text(body :: term, opts :: [response_opts]) :: Tesla.Env.t()
	def text(body, opts \\ []), do: response(body, "text/plain", opts)

	defp response(body, content_type, opts) do
	defaults = [status: 200, headers: [{"content-type", content_type}]]
	struct(Tesla.Env, Keyword.merge(defaults, [{:body, body} \| opts]))
	end

	## ADAPTER IMPLEMENTATION

	def call(env, _opts) do
	case pdict_get() \|\| agent_get() do
	nil ->
	raise Tesla.Mock.Error, env: env

	fun ->
	case rescue_call(fun, env) do
	{status, headers, body} ->
	{:ok, %{env \| status: status, headers: headers, body: body}}

	%Tesla.Env{} = env ->
	{:ok, env}

	{:ok, %Tesla.Env{} = env} ->
	{:ok, env}

	{:error, reason} ->
	{:error, reason}

	error ->
	{:error, error}
	end
	end
	end

	defp pdict_set(fun), do: Process.put(__MODULE__, fun)
	defp pdict_get, do: Process.get(__MODULE__)

	defp agent_set(fun) do
	case Process.whereis(__MODULE__) do
	nil -> Agent.start_link(fn -> fun end, name: __MODULE__)
	pid -> Agent.update(pid, fn _ -> fun end)
	end
	end

	defp agent_get do
	case Process.whereis(__MODULE__) do
	nil -> nil
	pid -> Agent.get(pid, fn f -> f end)
	end
	end

	defp rescue_call(fun, env) do
	fun.(env)
	rescue
	ex in FunctionClauseError ->
	raise Tesla.Mock.Error, env: env, ex: ex, stacktrace: System.stacktrace()
	end
	end
	diff --git a/lib/tesla/multipart.ex b/lib/tesla/multipart.ex
	index 8560a33..a444a79 100644
	--- a/lib/tesla/multipart.ex
	+++ b/lib/tesla/multipart.ex
	@@ -1,195 +1,201 @@
	defmodule Tesla.Multipart do
	@moduledoc """
	Multipart functionality.

	- ### Example
	+ ## Example
	+
	```
	mp =
	- Multipart.new
	+ Multipart.new()
	\|> Multipart.add_content_type_param("charset=utf-8")
	\|> Multipart.add_field("field1", "foo")
	- \|> Multipart.add_field("field2", "bar", headers: [{"content-id", "1"}, {"content-type", "text/plain"}])
	+ \|> Multipart.add_field("field2", "bar",
	+ headers: [{"content-id", "1"}, {"content-type", "text/plain"}]
	+ )
	\|> Multipart.add_file("test/tesla/multipart_test_file.sh")
	\|> Multipart.add_file("test/tesla/multipart_test_file.sh", name: "foobar")
	\|> Multipart.add_file_content("sample file content", "sample.txt")

	- response = client.post(url, mp)
	+ response = client.post(url, mp)
	```
	"""

	defmodule Part do
	@moduledoc false

	defstruct body: nil,
	dispositions: [],
	headers: []

	@type t :: %__MODULE__{
	body: String.t(),
	headers: Tesla.Env.headers(),
	dispositions: Keyword.t()
	}
	end

	@boundary_chars "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
	\|> String.split("")

	@type part_stream :: Enum.t()
	@type part_value :: iodata \| part_stream

	defstruct parts: [],
	boundary: nil,
	content_type_params: []

	@type t :: %__MODULE__{
	parts: list(Tesla.Multipart.Part.t()),
	boundary: String.t(),
	content_type_params: [String.t()]
	}

	@doc """
	Create a new Multipart struct to be used for a request body.
	"""
	@spec new() :: t
	def new do
	%__MODULE__{boundary: unique_string(32)}
	end

	@doc """
	Add a parameter to the multipart content-type.
	"""
	@spec add_content_type_param(t, String.t()) :: t
	def add_content_type_param(%__MODULE__{} = mp, param) do
	%{mp \| content_type_params: mp.content_type_params ++ [param]}
	end

	@doc """
	Add a field part.
	"""
	@spec add_field(t, String.t(), part_value, Keyword.t()) :: t
	def add_field(%__MODULE__{} = mp, name, value, opts \\ []) do
	:ok = assert_part_value!(value)
	{headers, opts} = Keyword.pop_first(opts, :headers, [])

	part = %Part{
	body: value,
	headers: headers,
	dispositions: [{:name, name}] ++ opts
	}

	%{mp \| parts: mp.parts ++ [part]}
	end

	@doc """
	Add a file part. The file will be streamed.

	- Options:
	+ ## Options
	+
	- `:name` - name of form param
	- `:filename` - filename (defaults to path basename)
	- `:headers` - additional headers
	- `:detect_content_type` - auto-detect file content-type (defaults to false)
	"""
	@spec add_file(t, String.t(), Keyword.t()) :: t
	def add_file(%__MODULE__{} = mp, path, opts \\ []) do
	{filename, opts} = Keyword.pop_first(opts, :filename, Path.basename(path))
	{headers, opts} = Keyword.pop_first(opts, :headers, [])
	{detect_content_type, opts} = Keyword.pop_first(opts, :detect_content_type, false)

	# add in detected content-type if necessary
	headers =
	case detect_content_type do
	true -> List.keystore(headers, "content-type", 0, {"content-type", MIME.from_path(path)})
	false -> headers
	end

	data = File.stream!(path, [:read], 2048)
	add_file_content(mp, data, filename, opts ++ [headers: headers])
	end

	@doc """
	- Add a file part. Same of `add_file/3` but the file content is read from `data` input parameter.
	+ Add a file part with value.
	+
	+ Same of `add_file/3` but the file content is read from `data` input argument.
	+
	+ ## Options

	- Options:
	- `:name` - name of form param
	- `:headers` - additional headers
	"""
	@spec add_file_content(t, part_value, String.t(), Keyword.t()) :: t
	def add_file_content(%__MODULE__{} = mp, data, filename, opts \\ []) do
	{name, opts} = Keyword.pop_first(opts, :name, "file")
	add_field(mp, name, data, opts ++ [filename: filename])
	end

	@doc false
	@spec headers(t) :: Tesla.Env.headers()
	def headers(%__MODULE__{boundary: boundary, content_type_params: params}) do
	ct_params = (["boundary=#{boundary}"] ++ params) \|> Enum.join("; ")
	[{"content-type", "multipart/form-data; #{ct_params}"}]
	end

	@doc false
	@spec body(t) :: part_stream
	def body(%__MODULE__{boundary: boundary, parts: parts}) do
	part_streams = Enum.map(parts, &part_as_stream(&1, boundary))
	Stream.concat(part_streams ++ [["--#{boundary}--\r\n"]])
	end

	@doc false
	@spec part_as_stream(Part.t(), String.t()) :: part_stream
	def part_as_stream(
	%Part{body: body, dispositions: dispositions, headers: part_headers},
	boundary
	) do
	part_headers = Enum.map(part_headers, fn {k, v} -> "#{k}: #{v}\r\n" end)
	part_headers = part_headers ++ [part_headers_for_disposition(dispositions)]

	enum_body =
	case body do
	b when is_binary(b) -> [b]
	b -> b
	end

	Stream.concat([
	["--#{boundary}\r\n"],
	part_headers,
	["\r\n"],
	enum_body,
	["\r\n"]
	])
	end

	@doc false
	@spec part_headers_for_disposition(Keyword.t()) :: [String.t()]
	def part_headers_for_disposition([]), do: []

	def part_headers_for_disposition(kvs) do
	ds =
	kvs
	\|> Enum.map(fn {k, v} -> "#{k}=\"#{v}\"" end)
	\|> Enum.join("; ")

	["content-disposition: form-data; #{ds}\r\n"]
	end

	- @doc false
	@spec unique_string(pos_integer) :: String.t()
	defp unique_string(length) do
	Enum.reduce(1..length, [], fn _i, acc ->
	[Enum.random(@boundary_chars) \| acc]
	end)
	\|> Enum.join("")
	end

	@spec assert_part_value!(any) :: :ok \| no_return
	defp assert_part_value!(%maybe_stream{})
	when maybe_stream in [IO.Stream, File.Stream, Stream],
	do: :ok

	defp assert_part_value!(value)
	when is_list(value)
	when is_binary(value),
	do: :ok

	defp assert_part_value!(val) do
	raise(ArgumentError, "#{inspect(val)} is not a supported multipart value.")
	end
	end
	diff --git a/mix.lock b/mix.lock
	index 530c972..3b0c814 100644
	--- a/mix.lock
	+++ b/mix.lock
	@@ -1,37 +1,37 @@
	%{
	"castore": {:hex, :castore, "0.1.4", "e7fd082c0e755716826a20b95c479f5dd42f536f9d12b8da8f47c92f1d4aed58", [:mix], [], "hexpm"},
	"certifi": {:hex, :certifi, "2.5.1", "867ce347f7c7d78563450a18a6a28a8090331e77fa02380b4a21962a65d36ee5", [:rebar3], [{:parse_trans, "~>3.3", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
	"con_cache": {:hex, :con_cache, "0.13.1", "047e097ab2a8c6876e12d0c29e29a86d487b592df97b98e3e2abedad574e215d", [:mix], [], "hexpm"},
	"cowboy": {:hex, :cowboy, "2.5.0", "4ef3ae066ee10fe01ea3272edc8f024347a0d3eb95f6fbb9aed556dacbfc1337", [:rebar3], [{:cowlib, "~> 2.6.0", [hex: :cowlib, repo: "hexpm", optional: false]}, {:ranch, "~> 1.6.2", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm"},
	"cowlib": {:hex, :cowlib, "2.6.0", "8aa629f81a0fc189f261dc98a42243fa842625feea3c7ec56c48f4ccdb55490f", [:rebar3], [], "hexpm"},
	"dialyxir": {:hex, :dialyxir, "1.0.0-rc.7", "6287f8f2cb45df8584317a4be1075b8c9b8a69de8eeb82b4d9e6c761cf2664cd", [:mix], [{:erlex, ">= 0.2.5", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm"},
	- "earmark": {:hex, :earmark, "1.4.2", "3aa0bd23bc4c61cf2f1e5d752d1bb470560a6f8539974f767a38923bb20e1d7f", [:mix], [], "hexpm"},
	+ "earmark": {:hex, :earmark, "1.4.3", "364ca2e9710f6bff494117dbbd53880d84bebb692dafc3a78eb50aa3183f2bfd", [:mix], [], "hexpm"},
	"erlex": {:hex, :erlex, "0.2.5", "e51132f2f472e13d606d808f0574508eeea2030d487fc002b46ad97e738b0510", [:mix], [], "hexpm"},
	"ex_doc": {:hex, :ex_doc, "0.21.2", "caca5bc28ed7b3bdc0b662f8afe2bee1eedb5c3cf7b322feeeb7c6ebbde089d6", [:mix], [{:earmark, "~> 1.3.3 or ~> 1.4", [hex: :earmark, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm"},
	"excoveralls": {:hex, :excoveralls, "0.12.0", "50e17a1b116fdb7facc2fe127a94db246169f38d7627b391376a0bc418413ce1", [:mix], [{:hackney, "~> 1.0", [hex: :hackney, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm"},
	"exjsx": {:hex, :exjsx, "4.0.0", "60548841e0212df401e38e63c0078ec57b33e7ea49b032c796ccad8cde794b5c", [:mix], [{:jsx, "~> 2.8.0", [hex: :jsx, repo: "hexpm", optional: false]}], "hexpm"},
	"file_system": {:hex, :file_system, "0.2.7", "e6f7f155970975789f26e77b8b8d8ab084c59844d8ecfaf58cbda31c494d14aa", [:mix], [], "hexpm"},
	"fuse": {:hex, :fuse, "2.4.2", "9106b08db8793a34cc156177d7e24c41bd638ee1b28463cb76562fde213e8ced", [:rebar3], [], "hexpm"},
	"gun": {:hex, :gun, "1.3.1", "1489fd96018431b89f401041a9ce0b02b45265247f0fdcf71273bf087c64ea4f", [:rebar3], [{:cowlib, "~> 2.6.0", [hex: :cowlib, repo: "hexpm", optional: false]}], "hexpm"},
	"hackney": {:hex, :hackney, "1.15.2", "07e33c794f8f8964ee86cebec1a8ed88db5070e52e904b8f12209773c1036085", [:rebar3], [{:certifi, "2.5.1", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "6.0.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~>1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.5", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
	"httparrot": {:hex, :httparrot, "1.2.0", "5ca2cb7aa936e8f418051b615fb8ec419ec7f29e792ae9fb698393e82513457b", [:mix], [{:con_cache, "~> 0.13.0", [hex: :con_cache, repo: "hexpm", optional: false]}, {:cowboy, "~> 2.5.0", [hex: :cowboy, repo: "hexpm", optional: false]}, {:exjsx, "~> 3.0 or ~> 4.0", [hex: :exjsx, repo: "hexpm", optional: false]}], "hexpm"},
	"ibrowse": {:hex, :ibrowse, "4.4.1", "2b7d0637b0f8b9b4182de4bd0f2e826a4da2c9b04898b6e15659ba921a8d6ec2", [:rebar3], [], "hexpm"},
	"idna": {:hex, :idna, "6.0.0", "689c46cbcdf3524c44d5f3dde8001f364cd7608a99556d8fbd8239a5798d4c10", [:rebar3], [{:unicode_util_compat, "0.4.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
	"inch_ex": {:hex, :inch_ex, "0.5.6", "418357418a553baa6d04eccd1b44171936817db61f4c0840112b420b8e378e67", [:mix], [{:poison, "~> 1.5 or ~> 2.0 or ~> 3.0", [hex: :poison, repo: "hexpm", optional: false]}], "hexpm"},
	"jason": {:hex, :jason, "1.1.2", "b03dedea67a99223a2eaf9f1264ce37154564de899fd3d8b9a21b1a6fd64afe7", [:mix], [{:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm"},
	"jsx": {:hex, :jsx, "2.8.3", "a05252d381885240744d955fbe3cf810504eb2567164824e19303ea59eef62cf", [:mix, :rebar3], [], "hexpm"},
	"makeup": {:hex, :makeup, "1.0.0", "671df94cf5a594b739ce03b0d0316aa64312cee2574b6a44becb83cd90fb05dc", [:mix], [{:nimble_parsec, "~> 0.5.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm"},
	"makeup_elixir": {:hex, :makeup_elixir, "0.14.0", "cf8b7c66ad1cff4c14679698d532f0b5d45a3968ffbcbfd590339cb57742f1ae", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm"},
	"metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm"},
	"mime": {:hex, :mime, "1.3.1", "30ce04ab3175b6ad0bdce0035cba77bba68b813d523d1aac73d9781b4d193cf8", [:mix], [], "hexpm"},
	"mimerl": {:hex, :mimerl, "1.2.0", "67e2d3f571088d5cfd3e550c383094b47159f3eee8ffa08e64106cdf5e981be3", [:rebar3], [], "hexpm"},
	"mint": {:hex, :mint, "1.0.0", "ca5ab33497ba2bdcc42f6cdd3927420a6159116be87c8173658e93c8746703da", [:mix], [{:castore, "~> 0.1.0", [hex: :castore, repo: "hexpm", optional: true]}], "hexpm"},
	"mix_test_watch": {:hex, :mix_test_watch, "1.0.1", "ae6fc45bbc80b826046fb84208df4b06035e10fae6d44d0cb48c5a2f92ee2e1d", [:mix], [{:file_system, "~> 0.2.1 or ~> 0.3", [hex: :file_system, repo: "hexpm", optional: false]}], "hexpm"},
	"nimble_parsec": {:hex, :nimble_parsec, "0.5.1", "c90796ecee0289dbb5ad16d3ad06f957b0cd1199769641c961cfe0b97db190e0", [:mix], [], "hexpm"},
	"parse_trans": {:hex, :parse_trans, "3.3.0", "09765507a3c7590a784615cfd421d101aec25098d50b89d7aa1d66646bc571c1", [:rebar3], [], "hexpm"},
	"poison": {:hex, :poison, "3.1.0", "d9eb636610e096f86f25d9a46f35a9facac35609a7591b3be3326e99a0484665", [:mix], [], "hexpm"},
	"ranch": {:hex, :ranch, "1.6.2", "6db93c78f411ee033dbb18ba8234c5574883acb9a75af0fb90a9b82ea46afa00", [:rebar3], [], "hexpm"},
	"ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.5", "6eaf7ad16cb568bb01753dbbd7a95ff8b91c7979482b95f38443fe2c8852a79b", [:make, :mix, :rebar3], [], "hexpm"},
	"telemetry": {:hex, :telemetry, "0.4.0", "8339bee3fa8b91cb84d14c2935f8ecf399ccd87301ad6da6b71c09553834b2ab", [:rebar3], [], "hexpm"},
	"unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm"},
	}
	diff --git a/test/support/docs.ex b/test/support/docs.ex
	index 0300367..6c3ef88 100644
	--- a/test/support/docs.ex
	+++ b/test/support/docs.ex
	@@ -1,14 +1,14 @@
	defmodule TeslaDocsTest do
	defmodule Default do
	use Tesla
	end

	defmodule NoDocs do
	use Tesla, docs: false

	@doc """
	- Something something
	+ Something something.
	"""
	def custom(url), do: get(url)
	end
	end

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