lostisland · mislav · Mar 9, 2014 · Feb 25, 2014
diff --git a/lib/faraday_middleware.rb b/lib/faraday_middleware.rb
@@ -17,6 +17,7 @@ module FaradayMiddleware
   autoload :RackCompatible,  'faraday_middleware/rack_compatible'
   autoload :FollowRedirects, 'faraday_middleware/response/follow_redirects'
   autoload :Instrumentation, 'faraday_middleware/instrumentation'
+  autoload :Gzip, 'faraday_middleware/gzip'
 
   if Faraday.respond_to? :register_middleware
     Faraday.register_middleware :request,
@@ -39,7 +40,8 @@ module FaradayMiddleware
       :chunked => lambda { Chunked }
 
     Faraday.register_middleware \
-      :instrumentation  => lambda { Instrumentation }
+      :instrumentation  => lambda { Instrumentation },
+      :gzip => lambda { Gzip }
   end
 end
 

diff --git a/lib/faraday_middleware/gzip.rb b/lib/faraday_middleware/gzip.rb
@@ -0,0 +1,45 @@
+require 'faraday'
+
+module FaradayMiddleware
+  # A middleware that ensures that the client requests are sent with the
+  # headers that encourage servers to send compressed data, and then uncompresses it.
+  # The Content-Length will reflect the actual body length.
+  class Gzip < Faraday::Middleware
+    dependency 'zlib'
+
+    ACCEPT_ENCODING = 'Accept-Encoding'.freeze
+    ENCODINGS = 'gzip,deflate'.freeze
+
+    def initialize(app, options = nil)
+      @app = app
+    end
+
+    def call(env)
+      (env[:request_headers] ||= {})[ACCEPT_ENCODING] = ENCODINGS
+      @app.call(env).on_complete do |env|
+        encoding = env[:response_headers]['content-encoding'].to_s.downcase
+        if %w[gzip deflate].include?(encoding)
+          case encoding
+          when 'gzip'
+            env[:body] = uncompress_gzip(env[:body])
+          when 'deflate'
+            env[:body] = Zlib::Inflate.inflate(env[:body])
+          end
+          env[:response_headers].delete('content-encoding')
+          env[:response_headers]['content-length'] = env[:body].length
+        end
+      end
+    end
+
+    private
+    def uncompress_gzip(body)
+      io = StringIO.new(body)
+      gzip_reader = if '1.9'.respond_to?(:force_encoding)
+        Zlib::GzipReader.new(io, :encoding => 'ASCII-8BIT')
+      else
+        Zlib::GzipReader.new(io)
+      end
+      gzip_reader.read
+    end
+  end
+end
diff --git a/spec/gzip_spec.rb b/spec/gzip_spec.rb
@@ -0,0 +1,67 @@
+require 'helper'
+require 'faraday_middleware/gzip'
+
+describe FaradayMiddleware::Gzip do
+
+  context 'request' do
+    let(:middleware) { described_class.new(lambda {|env| Faraday::Response.new(env)}) }
+
+    it 'sets the Accept-Encoding header' do
+      headers = Faraday::Utils::Headers.new
+      env = {:body => nil, :request_headers => headers, :response_headers => Faraday::Utils::Headers.new}
+      expect { middleware.call(env) }.to change {
+        headers['Accept-Encoding']
+      }.to('gzip,deflate')
+    end
+  end
+
+  context 'response', :type => :response do
+    let(:uncompressed_body) {
+      "<html><head><title>Rspec</title></head><body>Hello, spec!</body></html>"
+    }
+
+    shared_examples 'compressed response' do
+      it 'uncompresses the body' do
+        expect(process(body).body).to eq(uncompressed_body)
+      end
+
+      it 'sets the Content-Length' do
+        expect(process(body).headers['Content-Length']).to eq(uncompressed_body.length)
+      end
+
+      it 'removes the Content-Encoding' do
+        expect(process(body).headers['Content-Encoding']).to be_nil
+      end
+    end
+
+    context 'gzipped response' do
+      let(:body) do
+        f = StringIO.new
+        gz = Zlib::GzipWriter.new(f)
+        gz.write(uncompressed_body)
+        gz.close
+        res = f.string
+        res.force_encoding('BINARY') if res.respond_to?(:force_encoding)
+        res
+      end
+      let(:headers) { {'Content-Encoding' => 'gzip', 'Content-Length' => body.length} }
+
+      it_behaves_like 'compressed response'
+    end
+
+    context 'deflated response' do
+      let(:body) { Zlib::Deflate.deflate(uncompressed_body) }
+      let(:headers) { {'Content-Encoding' => 'deflate', 'Content-Length' => body.length} }
+
+      it_behaves_like 'compressed response'
+    end
+
+    context 'identity response' do
+      let(:body) { uncompressed_body }
+
+      it 'does not modify the body' do
+        expect(process(body).body).to eq(uncompressed_body)
+      end
+    end
+  end
+end