# frozen_string_literal: true

RSpec.shared_examples "a connection" do
  let(:conn) { described_class.new }
  let(:f) { Framer.new }

  context "settings synchronization" do
    it "should reflect incoming settings when SETTINGS is received" do
      expect(conn.remote_settings[:settings_header_table_size]).to eq 4096
      settings = settings_frame
      settings[:payload] = [[:settings_header_table_size, 256]]

      conn << f.generate(settings)

      expect(conn.remote_settings[:settings_header_table_size]).to eq 256
    end

    it "should send SETTINGS ACK when SETTINGS is received" do
      settings = settings_frame
      settings[:payload] = [[:settings_header_table_size, 256]]

      # We should expect two frames here (append .twice) - one for the connection setup, and one for the settings ack.
      frames = []
      allow(conn).to receive(:send) do |frame|
        frames << frame
      end

      conn << f.generate(settings)

      frame = frames.last
      expect(frame[:type]).to eq :settings
      expect(frame[:flags]).to eq [:ack]
      expect(frame[:payload]).to eq []
    end
  end

  context "flow control" do
    it "should initialize to default flow window" do
      expect(conn.remote_window).to eq DEFAULT_FLOW_WINDOW
    end

    it "should update connection and stream windows on SETTINGS" do
      settings = settings_frame
      data = data_frame
      settings[:payload] = [[:settings_initial_window_size, 1024]]
      data[:payload] = "x" * 2048

      stream = conn.new_stream

      stream.send headers_frame
      stream.send data
      expect(stream.remote_window).to eq(DEFAULT_FLOW_WINDOW - 2048)
      expect(conn.remote_window).to eq(DEFAULT_FLOW_WINDOW - 2048)

      conn << f.generate(settings)

      # connection window size can only be updated through WINDOW_UPDATE
      expect(conn.remote_window).to eq(DEFAULT_FLOW_WINDOW - 2048)
      expect(stream.remote_window).to eq(-1024)
    end

    it "should initialize streams with window specified by peer" do
      settings = settings_frame
      settings[:payload] = [[:settings_initial_window_size, 1024]]

      conn << f.generate(settings)
      expect(conn.new_stream.remote_window).to eq 1024
    end

    it "should observe connection flow control" do
      settings = settings_frame
      data = data_frame
      settings[:payload] = [[:settings_max_frame_size, 65_535]]

      conn << f.generate(settings)
      s1 = conn.new_stream
      s2 = conn.new_stream

      s1.send headers_frame
      s1.send data.merge(payload: "x" * 65_000)
      expect(conn.remote_window).to eq 535

      s2.send headers_frame
      s2.send data.merge(payload: "x" * 635)
      expect(conn.remote_window).to eq 0
      expect(conn.buffered_amount).to eq 100

      conn << f.generate(window_update_frame.merge(stream: 0, increment: 1000))
      expect(conn.buffered_amount).to eq 0
      expect(conn.remote_window).to eq 900
    end

    it "should update window when data received is over half of the maximum local window size" do
      settings = settings_frame
      data = data_frame
      conn = Client.new(settings_initial_window_size: 500)

      conn.receive f.generate(settings)
      s1 = conn.new_stream
      s2 = conn.new_stream

      s1.send headers_frame
      s2.send headers_frame
      expect(conn).to receive(:send) do |frame|
        expect(frame[:type]).to eq :window_update
        expect(frame[:stream]).to eq 0
        expect(frame[:increment]).to eq 400
      end
      conn.receive f.generate(data.merge(payload: "x" * 200, stream: s1.id))
      conn.receive f.generate(data.merge(payload: "x" * 200, stream: s2.id))
      expect(s1.local_window).to eq 300
      expect(s2.local_window).to eq 300
      expect(conn.local_window).to eq 500
    end
  end

  context "connection management" do
    it "should respond to PING frames" do
      conn << f.generate(settings_frame)
      expect(conn).to receive(:send) do |frame|
        expect(frame[:type]).to eq :ping
        expect(frame[:flags]).to eq [:ack]
        expect(frame[:payload]).to eq "12345678"
      end

      conn << f.generate(ping_frame)
    end

    it "should fire callback on PONG" do
      conn << f.generate(settings_frame)

      pong = nil
      conn.ping("12345678") { |d| pong = d }
      conn << f.generate(pong_frame)
      expect(pong).to eq "12345678"
    end

    it "should fire callback on receipt of GOAWAY" do
      last_stream, payload, error = nil
      conn << f.generate(settings_frame)
      conn.on(:goaway) do |s, e, p|
        last_stream = s
        error = e
        payload = p
      end
      conn << f.generate(goaway_frame.merge(last_stream: 17, payload: "test"))

      expect(last_stream).to eq 17
      expect(error).to eq :no_error
      expect(payload).to eq "test"

      expect(conn).to be_closed
    end

    it "should raise error when opening new stream after sending GOAWAY" do
      conn.goaway
      expect(conn).to be_closed

      expect { conn.new_stream }.to raise_error(ConnectionClosed)
    end

    it "should raise error when opening new stream after receiving GOAWAY" do
      conn << f.generate(settings_frame)
      conn << f.generate(goaway_frame)
      expect { conn.new_stream }.to raise_error(ConnectionClosed)
    end

    it "should not raise error when receiving connection management frames immediately after emitting goaway" do
      conn.goaway
      expect(conn).to be_closed

      expect { conn << f.generate(settings_frame) }.not_to raise_error(ProtocolError)
      expect { conn << f.generate(ping_frame) }.not_to raise_error(ProtocolError)
    end

    it "should respond with protocol error when receiving goaway" do
      conn.goaway
      expect(conn).to be_closed

      expect { conn << f.generate(goaway_frame) }.to raise_error(ProtocolError)
    end

    it "should raise error on frame for invalid stream ID" do
      conn << f.generate(settings_frame)

      expect do
        conn << f.generate(data_frame.merge(stream: 31))
      end.to raise_error(ProtocolError)
    end

    it "should allow to change the frame size" do
      buffer = []
      conn.on(:frame) do |bytes|
        buffer << bytes
      end
      stream1 = conn.new_stream
      stream1.send headers_frame

      # splits big data
      expect { stream1.data("a" * 16_385) }.to change { buffer.size }.by(2)

      conn << f.generate(settings_frame.merge(payload: [[:settings_max_frame_size, 65_536]]))

      stream2 = conn.new_stream
      stream2.send headers_frame
      expect { stream2.data("a" * 16_385, end_stream: false) }.to change { buffer.size }.by(1)
    end
  end

  context "stream management" do
    it "should initialize to default stream limit (100)" do
      expect(conn.local_settings[:settings_max_concurrent_streams]).to eq 100
    end

    it "should change stream limit to received SETTINGS value" do
      conn << f.generate(settings_frame)
      expect(conn.remote_settings[:settings_max_concurrent_streams]).to eq 10
    end

    it "should count open streams against stream limit" do
      s = conn.new_stream
      expect(conn.active_stream_count).to eq 0
      s.receive headers_frame
      expect(conn.active_stream_count).to eq 1
    end

    it "should not count reserved streams against stream limit" do
      s1 = conn.new_stream
      s1.receive push_promise_frame
      expect(conn.active_stream_count).to eq 0

      s2 = conn.new_stream
      s2.send push_promise_frame
      expect(conn.active_stream_count).to eq 0

      s3 = conn.new_stream
      s3.send push_promise_frame
      expect(conn.active_stream_count).to eq 0

      # transition to half closed
      s1.receive headers_frame
      s2.send headers_frame
      s3.send rst_stream_frame
      expect(conn.active_stream_count).to eq 2

      # transition to closed
      s1.receive data_frame
      s2.send data_frame
      expect(conn.active_stream_count).to eq 0

      expect(s1).to be_closed
      expect(s2).to be_closed
      expect(s3).to be_closed
    end

    it "should not exceed stream limit set by peer" do
      conn << f.generate(settings_frame)

      expect do
        10.times do
          s = conn.new_stream
          s.send headers_frame
        end
      end.to_not raise_error

      expect { conn.new_stream }.to raise_error(StreamLimitExceeded)
    end

    it "should initialize idle stream on PRIORITY frame" do
      conn << f.generate(settings_frame)

      stream = nil
      conn.on(:stream) { |s| stream = s }
      conn << f.generate(priority_frame)

      expect(stream.state).to eq :idle
    end
  end

  context "framing" do
    let(:conn) { connected_conn }

    it "should chain continuation frames" do
      headers = headers_frame
      headers[:flags] = []
      continuation = continuation_frame
      continuation[:stream] = headers[:stream]
      continuation[:flags] = []

      conn << f.generate(headers)
      conn << f.generate(continuation)
      expect(conn.active_stream_count).to be_zero # stream not open yet
    end

    it "should refuse continuation frames which overflow the max frame size" do
      max_frame_size = connected_conn.local_settings[:settings_max_frame_size]

      headers = headers_frame
      headers[:flags] = []

      conn << f.generate(headers)
      expect do
        max_frame_size.times do
          continuation = continuation_frame
          continuation[:stream] = headers[:stream]
          continuation[:flags] = []
          conn << f.generate(continuation)
        end
      end.to raise_error(ProtocolError)
    end

    it "should require that split header blocks are a contiguous sequence" do
      headers = headers_frame
      headers[:flags] = []

      conn << f.generate(headers)
      (frame_types - [continuation_frame]).each do |frame|
        expect { conn << f.generate(frame) }.to raise_error(ProtocolError)
      end
    end

    it "should require that split promise blocks are a contiguous sequence" do
      headers = push_promise_frame
      headers[:flags] = []

      conn << f.generate(headers)
      (frame_types - [continuation_frame]).each do |frame|
        expect { conn << f.generate(frame) }.to raise_error(ProtocolError)
      end
    end

    it "should raise connection error on decode of invalid frame" do
      frame = f.generate(data_frame) # Receiving DATA on unopened stream 1 is an error.
      # Connection errors emit protocol error frames
      expect { conn << frame }.to raise_error(ProtocolError)
    end

    it "should emit encoded frames via on(:frame)" do
      bytes = nil
      conn.on(:frame) { |d| bytes = d }
      conn.settings(settings_max_concurrent_streams: 10,
                    settings_initial_window_size: 0x7fffffff)

      expect(bytes).to eq f.generate(settings_frame)
    end

    it "should compress stream headers" do
      conn.on(:frame) do |bytes|
        expect(bytes).not_to include("get")
        expect(bytes).not_to include("http")
        expect(bytes).not_to include("www.example.org") # should be huffman encoded
      end

      stream = conn.new_stream
      stream.headers({
                       ":method" => "get",
                       ":scheme" => "http",
                       ":authority" => "www.example.org",
                       ":path" => "/resource"
                     })
    end

    it "should generate CONTINUATION if HEADERS is too long" do
      headers = []
      conn.on(:frame) do |bytes|
        # bytes[3]: frame's type field
        headers << f.parse(bytes) if [1, 5, 9].include?(bytes[3].ord)
      end

      stream = conn.new_stream
      stream.headers({
                       ":method" => "get",
                       ":scheme" => "http",
                       ":authority" => "www.example.org",
                       ":path" => "/resource",
                       "custom" => "q" * 44_000
                     }, end_stream: true)
      expect(headers.size).to eq 3
      expect(headers[0][:type]).to eq :headers
      expect(headers[1][:type]).to eq :continuation
      expect(headers[2][:type]).to eq :continuation
      expect(headers[0][:flags]).to eq [:end_stream]
      expect(headers[1][:flags]).to eq []
      expect(headers[2][:flags]).to eq [:end_headers]
    end

    it "should not generate CONTINUATION if HEADERS fits exactly in a frame" do
      headers = []
      conn.on(:frame) do |bytes|
        # bytes[3]: frame's type field
        headers << f.parse(bytes) if [1, 5, 9].include?(bytes[3].ord)
      end

      stream = conn.new_stream
      stream.headers({
                       ":method" => "get",
                       ":scheme" => "http",
                       ":authority" => "www.example.org",
                       ":path" => "/resource",
                       "custom" => "q" * 18_682 # this number should be updated when Huffman table is changed
                     }, end_stream: true)
      expect(headers[0][:length]).to eq conn.remote_settings[:settings_max_frame_size]
      expect(headers.size).to eq 1
      expect(headers[0][:type]).to eq :headers
      expect(headers[0][:flags]).to include(:end_headers)
      expect(headers[0][:flags]).to include(:end_stream)
    end

    it "should not generate CONTINUATION if HEADERS fits exactly in a frame" do
      headers = []
      conn.on(:frame) do |bytes|
        # bytes[3]: frame's type field
        headers << f.parse(bytes) if [1, 5, 9].include?(bytes[3].ord)
      end

      stream = conn.new_stream
      stream.headers({
                       ":method" => "get",
                       ":scheme" => "http",
                       ":authority" => "www.example.org",
                       ":path" => "/resource",
                       "custom" => "q" * 18_682 # this number should be updated when Huffman table is changed
                     }, end_stream: true)
      expect(headers[0][:length]).to eq conn.remote_settings[:settings_max_frame_size]
      expect(headers.size).to eq 1
      expect(headers[0][:type]).to eq :headers
      expect(headers[0][:flags]).to include(:end_headers)
      expect(headers[0][:flags]).to include(:end_stream)
    end

    it "should generate CONTINUATION if HEADERS exceed the max payload by one byte" do
      headers = []
      conn.on(:frame) do |bytes|
        headers << f.parse(bytes) if [1, 5, 9].include?(bytes[3].ord)
      end

      stream = conn.new_stream
      stream.headers({
                       ":method" => "get",
                       ":scheme" => "http",
                       ":authority" => "www.example.org",
                       ":path" => "/resource",
                       "custom" => "q" * 18_683 # this number should be updated when Huffman table is changed
                     }, end_stream: true)
      expect(headers[0][:length]).to eq conn.remote_settings[:settings_max_frame_size]
      expect(headers[1][:length]).to eq 1
      expect(headers.size).to eq 2
      expect(headers[0][:type]).to eq :headers
      expect(headers[1][:type]).to eq :continuation
      expect(headers[0][:flags]).to eq [:end_stream]
      expect(headers[1][:flags]).to eq [:end_headers]
    end
  end
  context "API" do
    it ".settings should emit SETTINGS frames" do
      expect(conn).to receive(:send) do |frame|
        expect(frame[:type]).to eq :settings
        expect(frame[:payload].to_a).to eq([
                                             [:settings_max_concurrent_streams, 10],
                                             [:settings_initial_window_size, 0x7fffffff]
                                           ])
        expect(frame[:stream]).to eq 0
      end

      conn.settings(settings_max_concurrent_streams: 10,
                    settings_initial_window_size: 0x7fffffff)
    end

    it ".ping should generate PING frames" do
      expect(conn).to receive(:send) do |frame|
        expect(frame[:type]).to eq :ping
        expect(frame[:payload]).to eq "somedata"
      end

      conn.ping("somedata")
    end

    it ".window_update should emit WINDOW_UPDATE frames" do
      expect(conn).to receive(:send) do |frame|
        expect(frame[:type]).to eq :window_update
        expect(frame[:increment]).to eq 20
        expect(frame[:stream]).to eq 0
      end
      conn.window_update(20)
    end
  end
end
