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lib/tesla/middleware/compression.ex

defmodule Tesla.Middleware.Compression do
@moduledoc """
Compress requests and decompress responses.
Supports "gzip" and "deflate" encodings using Erlang's built-in `:zlib` module.
## Examples
```
defmodule MyClient do
use Tesla
plug Tesla.Middleware.Compression, format: "gzip"
end
```
## Options
- `:format` - request compression format, `"gzip"` (default) or `"deflate"`
"""
@behaviour Tesla.Middleware
@impl Tesla.Middleware
def call(env, next, opts) do
env
|> compress(opts)
|> Tesla.put_headers([{"accept-encoding", "gzip, deflate"}])
|> Tesla.run(next)
|> decompress()
end
defp compressible?(body), do: is_binary(body)
@doc """
Compress request.
It is used by `Tesla.Middleware.CompressRequest`.
"""
def compress(env, opts) do
if compressible?(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.
It is used by `Tesla.Middleware.DecompressResponse`.
"""
def decompress({:ok, env}), do: {:ok, decompress(env)}
def decompress({:error, reason}), do: {:error, reason}
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
@moduledoc """
Only compress request.
See `Tesla.Middleware.Compression` for options.
"""
@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
@moduledoc """
Only decompress response.
See `Tesla.Middleware.Compression` for options.
"""
@behaviour Tesla.Middleware
@impl Tesla.Middleware
def call(env, next, _opts) do
env
|> Tesla.put_headers([{"accept-encoding", "gzip, deflate"}])
|> Tesla.run(next)
|> Tesla.Middleware.Compression.decompress()
end
end