# https://github.com/lostisland/faraday_middleware/blob/master/lib/faraday_middleware/gzip.rb

require 'faraday'

# Middleware to automatically decompress response bodies. If the
# "Accept-Encoding" header wasn't set in the request, this sets it to
# "gzip,deflate" and appropriately handles the compressed response from the
# server. This resembles what Ruby 1.9+ does internally in Net::HTTP#get.
#
# This middleware is NOT necessary when these adapters are used:
# - net_http on Ruby 1.9+
# - net_http_persistent on Ruby 2.0+
# - em_http
class Gzip < Faraday::Middleware
  dependency 'zlib'

  ACCEPT_ENCODING = 'Accept-Encoding'.freeze
  CONTENT_ENCODING = 'Content-Encoding'.freeze
  CONTENT_LENGTH = 'Content-Length'.freeze
  SUPPORTED_ENCODINGS = 'gzip,deflate,br'.freeze
  RUBY_ENCODING = '1.9'.respond_to?(:force_encoding)

  def call(env)
    env[:request_headers][ACCEPT_ENCODING] ||= SUPPORTED_ENCODINGS
    @app.call(env).on_complete do |response_env|
      case response_env[:response_headers][CONTENT_ENCODING]
      when 'gzip'
        reset_body(response_env, &method(:uncompress_gzip))
      when 'deflate'
        reset_body(response_env, &method(:inflate))
      when 'br'
        reset_body(response_env, &method(:brotli_inflate))
      end
    end
  end

  def reset_body(env)
    env[:body] = yield(env[:body])
    env[:response_headers].delete(CONTENT_ENCODING)
    env[:response_headers][CONTENT_LENGTH] = env[:body].length
  end

  def uncompress_gzip(body)
    io = StringIO.new(body)
    gzip_reader = if RUBY_ENCODING
      Zlib::GzipReader.new(io, :encoding => 'ASCII-8BIT')
    else
      Zlib::GzipReader.new(io)
    end
    gzip_reader.read
  end

  def inflate(body)
    # Inflate as a DEFLATE (RFC 1950+RFC 1951) stream
    Zlib::Inflate.inflate(body)
  rescue Zlib::DataError
    # Fall back to inflating as a "raw" deflate stream which
    # Microsoft servers return
    inflate = Zlib::Inflate.new(-Zlib::MAX_WBITS)
    begin
      inflate.inflate(body)
    ensure
      inflate.close
    end
  end

  def brotli_inflate(body)
    self.class.dependency 'brotli'

    Brotli.inflate(body)
  end
end