package quic

import (
	"errors"
	"io"
	"runtime"
	"strconv"
	"time"

	"os"

	"github.com/golang/mock/gomock"
	"github.com/lucas-clemente/quic-go/internal/mocks"
	"github.com/lucas-clemente/quic-go/internal/protocol"
	"github.com/lucas-clemente/quic-go/internal/wire"

	. "github.com/onsi/ginkgo"
	. "github.com/onsi/gomega"
	"github.com/onsi/gomega/gbytes"
)

var _ = Describe("Stream", func() {
	const streamID protocol.StreamID = 1337

	var (
		str            *stream
		strWithTimeout io.ReadWriter // str wrapped with gbytes.Timeout{Reader,Writer}
		onDataCalled   bool

		resetCalled          bool
		resetCalledForStream protocol.StreamID
		resetCalledAtOffset  protocol.ByteCount

		mockFC *mocks.MockStreamFlowController
	)

	// in the tests for the stream deadlines we set a deadline
	// and wait to make an assertion when Read / Write was unblocked
	// on the CIs, the timing is a lot less precise, so scale every duration by this factor
	scaleDuration := func(t time.Duration) time.Duration {
		scaleFactor := 1
		if f, err := strconv.Atoi(os.Getenv("TIMESCALE_FACTOR")); err == nil { // parsing "" errors, so this works fine if the env is not set
			scaleFactor = f
		}
		Expect(scaleFactor).ToNot(BeZero())
		return time.Duration(scaleFactor) * t
	}

	onData := func() {
		onDataCalled = true
	}

	onReset := func(id protocol.StreamID, offset protocol.ByteCount) {
		resetCalled = true
		resetCalledForStream = id
		resetCalledAtOffset = offset
	}

	BeforeEach(func() {
		onDataCalled = false
		resetCalled = false
		mockFC = mocks.NewMockStreamFlowController(mockCtrl)
		str = newStream(streamID, onData, onReset, mockFC, protocol.VersionWhatever)

		timeout := scaleDuration(250 * time.Millisecond)
		strWithTimeout = struct {
			io.Reader
			io.Writer
		}{
			gbytes.TimeoutReader(str, timeout),
			gbytes.TimeoutWriter(str, timeout),
		}
	})

	It("gets stream id", func() {
		Expect(str.StreamID()).To(Equal(protocol.StreamID(1337)))
	})

	Context("reading", func() {
		It("reads a single StreamFrame", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(4))
			frame := wire.StreamFrame{
				Offset: 0,
				Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
			}
			err := str.AddStreamFrame(&frame)
			Expect(err).ToNot(HaveOccurred())
			b := make([]byte, 4)
			n, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(4))
			Expect(b).To(Equal([]byte{0xDE, 0xAD, 0xBE, 0xEF}))
		})

		It("reads a single StreamFrame in multiple goes", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2))
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2))
			frame := wire.StreamFrame{
				Offset: 0,
				Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
			}
			err := str.AddStreamFrame(&frame)
			Expect(err).ToNot(HaveOccurred())
			b := make([]byte, 2)
			n, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(2))
			Expect(b).To(Equal([]byte{0xDE, 0xAD}))
			n, err = strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(2))
			Expect(b).To(Equal([]byte{0xBE, 0xEF}))
		})

		It("reads all data available", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(2), false)
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2)).Times(2)
			frame1 := wire.StreamFrame{
				Offset: 0,
				Data:   []byte{0xDE, 0xAD},
			}
			frame2 := wire.StreamFrame{
				Offset: 2,
				Data:   []byte{0xBE, 0xEF},
			}
			err := str.AddStreamFrame(&frame1)
			Expect(err).ToNot(HaveOccurred())
			err = str.AddStreamFrame(&frame2)
			Expect(err).ToNot(HaveOccurred())
			b := make([]byte, 6)
			n, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(4))
			Expect(b).To(Equal([]byte{0xDE, 0xAD, 0xBE, 0xEF, 0x00, 0x00}))
		})

		It("assembles multiple StreamFrames", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(2), false)
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2)).Times(2)
			frame1 := wire.StreamFrame{
				Offset: 0,
				Data:   []byte{0xDE, 0xAD},
			}
			frame2 := wire.StreamFrame{
				Offset: 2,
				Data:   []byte{0xBE, 0xEF},
			}
			err := str.AddStreamFrame(&frame1)
			Expect(err).ToNot(HaveOccurred())
			err = str.AddStreamFrame(&frame2)
			Expect(err).ToNot(HaveOccurred())
			b := make([]byte, 4)
			n, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(4))
			Expect(b).To(Equal([]byte{0xDE, 0xAD, 0xBE, 0xEF}))
		})

		It("waits until data is available", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(2), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2))
			go func() {
				defer GinkgoRecover()
				frame := wire.StreamFrame{Data: []byte{0xDE, 0xAD}}
				time.Sleep(10 * time.Millisecond)
				err := str.AddStreamFrame(&frame)
				Expect(err).ToNot(HaveOccurred())
			}()
			b := make([]byte, 2)
			n, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(2))
		})

		It("handles StreamFrames in wrong order", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(2), false)
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2)).Times(2)
			frame1 := wire.StreamFrame{
				Offset: 2,
				Data:   []byte{0xBE, 0xEF},
			}
			frame2 := wire.StreamFrame{
				Offset: 0,
				Data:   []byte{0xDE, 0xAD},
			}
			err := str.AddStreamFrame(&frame1)
			Expect(err).ToNot(HaveOccurred())
			err = str.AddStreamFrame(&frame2)
			Expect(err).ToNot(HaveOccurred())
			b := make([]byte, 4)
			n, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(4))
			Expect(b).To(Equal([]byte{0xDE, 0xAD, 0xBE, 0xEF}))
		})

		It("ignores duplicate StreamFrames", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(2), false)
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(2), false)
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2)).Times(2)
			frame1 := wire.StreamFrame{
				Offset: 0,
				Data:   []byte{0xDE, 0xAD},
			}
			frame2 := wire.StreamFrame{
				Offset: 0,
				Data:   []byte{0x13, 0x37},
			}
			frame3 := wire.StreamFrame{
				Offset: 2,
				Data:   []byte{0xBE, 0xEF},
			}
			err := str.AddStreamFrame(&frame1)
			Expect(err).ToNot(HaveOccurred())
			err = str.AddStreamFrame(&frame2)
			Expect(err).ToNot(HaveOccurred())
			err = str.AddStreamFrame(&frame3)
			Expect(err).ToNot(HaveOccurred())
			b := make([]byte, 4)
			n, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(4))
			Expect(b).To(Equal([]byte{0xDE, 0xAD, 0xBE, 0xEF}))
		})

		It("doesn't rejects a StreamFrames with an overlapping data range", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(6), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2))
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(4))
			frame1 := wire.StreamFrame{
				Offset: 0,
				Data:   []byte("foob"),
			}
			frame2 := wire.StreamFrame{
				Offset: 2,
				Data:   []byte("obar"),
			}
			err := str.AddStreamFrame(&frame1)
			Expect(err).ToNot(HaveOccurred())
			err = str.AddStreamFrame(&frame2)
			Expect(err).ToNot(HaveOccurred())
			b := make([]byte, 6)
			n, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(n).To(Equal(6))
			Expect(b).To(Equal([]byte("foobar")))
		})

		It("calls onData", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(4))
			frame := wire.StreamFrame{
				Offset: 0,
				Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
			}
			str.AddStreamFrame(&frame)
			b := make([]byte, 4)
			_, err := strWithTimeout.Read(b)
			Expect(err).ToNot(HaveOccurred())
			Expect(onDataCalled).To(BeTrue())
		})

		It("sets the read offset", func() {
			str.SetReadOffset(0x42)
			Expect(str.readOffset).To(Equal(protocol.ByteCount(0x42)))
			Expect(str.frameQueue.readPosition).To(Equal(protocol.ByteCount(0x42)))
		})

		Context("deadlines", func() {
			It("the deadline error has the right net.Error properties", func() {
				Expect(errDeadline.Temporary()).To(BeTrue())
				Expect(errDeadline.Timeout()).To(BeTrue())
			})

			It("returns an error when Read is called after the deadline", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(6), false).AnyTimes()
				f := &wire.StreamFrame{Data: []byte("foobar")}
				err := str.AddStreamFrame(f)
				Expect(err).ToNot(HaveOccurred())
				str.SetReadDeadline(time.Now().Add(-time.Second))
				b := make([]byte, 6)
				n, err := strWithTimeout.Read(b)
				Expect(err).To(MatchError(errDeadline))
				Expect(n).To(BeZero())
			})

			It("unblocks after the deadline", func() {
				deadline := time.Now().Add(scaleDuration(50 * time.Millisecond))
				str.SetReadDeadline(deadline)
				b := make([]byte, 6)
				n, err := strWithTimeout.Read(b)
				Expect(err).To(MatchError(errDeadline))
				Expect(n).To(BeZero())
				Expect(time.Now()).To(BeTemporally("~", deadline, scaleDuration(10*time.Millisecond)))
			})

			It("doesn't unblock if the deadline is changed before the first one expires", func() {
				deadline1 := time.Now().Add(scaleDuration(50 * time.Millisecond))
				deadline2 := time.Now().Add(scaleDuration(100 * time.Millisecond))
				str.SetReadDeadline(deadline1)
				go func() {
					defer GinkgoRecover()
					time.Sleep(scaleDuration(20 * time.Millisecond))
					str.SetReadDeadline(deadline2)
					// make sure that this was actually execute before the deadline expires
					Expect(time.Now()).To(BeTemporally("<", deadline1))
				}()
				runtime.Gosched()
				b := make([]byte, 10)
				n, err := strWithTimeout.Read(b)
				Expect(err).To(MatchError(errDeadline))
				Expect(n).To(BeZero())
				Expect(time.Now()).To(BeTemporally("~", deadline2, scaleDuration(20*time.Millisecond)))
			})

			It("unblocks earlier, when a new deadline is set", func() {
				deadline1 := time.Now().Add(scaleDuration(200 * time.Millisecond))
				deadline2 := time.Now().Add(scaleDuration(50 * time.Millisecond))
				go func() {
					defer GinkgoRecover()
					time.Sleep(scaleDuration(10 * time.Millisecond))
					str.SetReadDeadline(deadline2)
					// make sure that this was actually execute before the deadline expires
					Expect(time.Now()).To(BeTemporally("<", deadline2))
				}()
				str.SetReadDeadline(deadline1)
				runtime.Gosched()
				b := make([]byte, 10)
				_, err := strWithTimeout.Read(b)
				Expect(err).To(MatchError(errDeadline))
				Expect(time.Now()).To(BeTemporally("~", deadline2, scaleDuration(25*time.Millisecond)))
			})

			It("sets a read deadline, when SetDeadline is called", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(6), false).AnyTimes()
				f := &wire.StreamFrame{Data: []byte("foobar")}
				err := str.AddStreamFrame(f)
				Expect(err).ToNot(HaveOccurred())
				str.SetDeadline(time.Now().Add(-time.Second))
				b := make([]byte, 6)
				n, err := strWithTimeout.Read(b)
				Expect(err).To(MatchError(errDeadline))
				Expect(n).To(BeZero())
			})
		})

		Context("closing", func() {
			Context("with FIN bit", func() {
				It("returns EOFs", func() {
					mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), true)
					mockFC.EXPECT().AddBytesRead(protocol.ByteCount(4))
					frame := wire.StreamFrame{
						Offset: 0,
						Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
						FinBit: true,
					}
					str.AddStreamFrame(&frame)
					b := make([]byte, 4)
					n, err := strWithTimeout.Read(b)
					Expect(err).To(MatchError(io.EOF))
					Expect(n).To(Equal(4))
					Expect(b).To(Equal([]byte{0xDE, 0xAD, 0xBE, 0xEF}))
					n, err = strWithTimeout.Read(b)
					Expect(n).To(BeZero())
					Expect(err).To(MatchError(io.EOF))
				})

				It("handles out-of-order frames", func() {
					mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(2), false)
					mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), true)
					mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2)).Times(2)
					frame1 := wire.StreamFrame{
						Offset: 2,
						Data:   []byte{0xBE, 0xEF},
						FinBit: true,
					}
					frame2 := wire.StreamFrame{
						Offset: 0,
						Data:   []byte{0xDE, 0xAD},
					}
					err := str.AddStreamFrame(&frame1)
					Expect(err).ToNot(HaveOccurred())
					err = str.AddStreamFrame(&frame2)
					Expect(err).ToNot(HaveOccurred())
					b := make([]byte, 4)
					n, err := strWithTimeout.Read(b)
					Expect(err).To(MatchError(io.EOF))
					Expect(n).To(Equal(4))
					Expect(b).To(Equal([]byte{0xDE, 0xAD, 0xBE, 0xEF}))
					n, err = strWithTimeout.Read(b)
					Expect(n).To(BeZero())
					Expect(err).To(MatchError(io.EOF))
				})

				It("returns EOFs with partial read", func() {
					mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(2), true)
					mockFC.EXPECT().AddBytesRead(protocol.ByteCount(2))
					frame := wire.StreamFrame{
						Offset: 0,
						Data:   []byte{0xDE, 0xAD},
						FinBit: true,
					}
					err := str.AddStreamFrame(&frame)
					Expect(err).ToNot(HaveOccurred())
					b := make([]byte, 4)
					n, err := strWithTimeout.Read(b)
					Expect(err).To(MatchError(io.EOF))
					Expect(n).To(Equal(2))
					Expect(b[:n]).To(Equal([]byte{0xDE, 0xAD}))
				})

				It("handles immediate FINs", func() {
					mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
					mockFC.EXPECT().AddBytesRead(protocol.ByteCount(0))
					frame := wire.StreamFrame{
						Offset: 0,
						Data:   []byte{},
						FinBit: true,
					}
					err := str.AddStreamFrame(&frame)
					Expect(err).ToNot(HaveOccurred())
					b := make([]byte, 4)
					n, err := strWithTimeout.Read(b)
					Expect(n).To(BeZero())
					Expect(err).To(MatchError(io.EOF))
				})
			})

			Context("when CloseRemote is called", func() {
				It("closes", func() {
					mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
					mockFC.EXPECT().AddBytesRead(protocol.ByteCount(0))
					str.CloseRemote(0)
					b := make([]byte, 8)
					n, err := strWithTimeout.Read(b)
					Expect(n).To(BeZero())
					Expect(err).To(MatchError(io.EOF))
				})

				It("doesn't cancel the context", func() {
					mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
					str.CloseRemote(0)
					Expect(str.Context().Done()).ToNot(BeClosed())
				})
			})
		})

		Context("cancelling the stream", func() {
			testErr := errors.New("test error")

			It("immediately returns all reads", func() {
				done := make(chan struct{})
				b := make([]byte, 4)
				go func() {
					defer GinkgoRecover()
					n, err := strWithTimeout.Read(b)
					Expect(n).To(BeZero())
					Expect(err).To(MatchError(testErr))
					close(done)
				}()
				Consistently(done).ShouldNot(BeClosed())
				str.Cancel(testErr)
				Eventually(done).Should(BeClosed())
			})

			It("errors for all following reads", func() {
				str.Cancel(testErr)
				b := make([]byte, 1)
				n, err := strWithTimeout.Read(b)
				Expect(n).To(BeZero())
				Expect(err).To(MatchError(testErr))
			})

			It("cancels the context", func() {
				Expect(str.Context().Done()).ToNot(BeClosed())
				str.Cancel(testErr)
				Expect(str.Context().Done()).To(BeClosed())
			})
		})
	})

	Context("resetting", func() {
		testErr := errors.New("testErr")

		Context("reset by the peer", func() {
			It("continues reading after receiving a remote error", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(10), true)
				frame := wire.StreamFrame{
					Offset: 0,
					Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
				}
				str.AddStreamFrame(&frame)
				str.RegisterRemoteError(testErr, 10)
				b := make([]byte, 4)
				n, err := strWithTimeout.Read(b)
				Expect(err).ToNot(HaveOccurred())
				Expect(n).To(Equal(4))
			})

			It("reads a delayed StreamFrame that arrives after receiving a remote error", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), true)
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
				str.RegisterRemoteError(testErr, 4)
				frame := wire.StreamFrame{
					Offset: 0,
					Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
				}
				err := str.AddStreamFrame(&frame)
				Expect(err).ToNot(HaveOccurred())
				b := make([]byte, 4)
				n, err := strWithTimeout.Read(b)
				Expect(err).ToNot(HaveOccurred())
				Expect(n).To(Equal(4))
			})

			It("returns the error if reading past the offset of the frame received", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(8), true)
				frame := wire.StreamFrame{
					Offset: 0,
					Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
				}
				str.AddStreamFrame(&frame)
				str.RegisterRemoteError(testErr, 8)
				b := make([]byte, 10)
				n, err := strWithTimeout.Read(b)
				Expect(b[0:4]).To(Equal(frame.Data))
				Expect(err).To(MatchError(testErr))
				Expect(n).To(Equal(4))
			})

			It("returns an EOF when reading past the offset, if the stream received a finbit", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), true)
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(8), true)
				frame := wire.StreamFrame{
					Offset: 0,
					Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
					FinBit: true,
				}
				str.AddStreamFrame(&frame)
				str.RegisterRemoteError(testErr, 8)
				b := make([]byte, 10)
				n, err := strWithTimeout.Read(b)
				Expect(b[:4]).To(Equal(frame.Data))
				Expect(err).To(MatchError(io.EOF))
				Expect(n).To(Equal(4))
			})

			It("continues reading in small chunks after receiving a remote error", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), true)
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), true)
				frame := wire.StreamFrame{
					Offset: 0,
					Data:   []byte{0xDE, 0xAD, 0xBE, 0xEF},
					FinBit: true,
				}
				str.AddStreamFrame(&frame)
				str.RegisterRemoteError(testErr, 4)
				b := make([]byte, 3)
				_, err := strWithTimeout.Read(b)
				Expect(err).ToNot(HaveOccurred())
				Expect(b).To(Equal([]byte{0xde, 0xad, 0xbe}))
				b = make([]byte, 3)
				n, err := strWithTimeout.Read(b)
				Expect(err).To(MatchError(io.EOF))
				Expect(b[:1]).To(Equal([]byte{0xef}))
				Expect(n).To(Equal(1))
			})

			It("doesn't inform the flow controller about bytes read after receiving the remote error", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(4), false)
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(10), true)
				// No AddBytesRead()
				frame := wire.StreamFrame{
					Offset:   0,
					StreamID: 5,
					Data:     []byte{0xDE, 0xAD, 0xBE, 0xEF},
				}
				str.AddStreamFrame(&frame)
				str.RegisterRemoteError(testErr, 10)
				b := make([]byte, 3)
				_, err := strWithTimeout.Read(b)
				Expect(err).ToNot(HaveOccurred())
			})

			It("stops writing after receiving a remote error", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(10), true)
				done := make(chan struct{})
				go func() {
					defer GinkgoRecover()
					n, err := strWithTimeout.Write([]byte("foobar"))
					Expect(n).To(BeZero())
					Expect(err).To(MatchError(testErr))
					close(done)
				}()
				str.RegisterRemoteError(testErr, 10)
				Eventually(done).Should(BeClosed())
			})

			It("returns how much was written when recieving a remote error", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(10), true)
				mockFC.EXPECT().SendWindowSize().Return(protocol.ByteCount(9999))
				mockFC.EXPECT().AddBytesSent(protocol.ByteCount(4))
				done := make(chan struct{})
				go func() {
					defer GinkgoRecover()
					n, err := strWithTimeout.Write([]byte("foobar"))
					Expect(err).To(MatchError(testErr))
					Expect(n).To(Equal(4))
					close(done)
				}()

				Eventually(func() []byte { data, _ := str.GetDataForWriting(4); return data }).ShouldNot(BeEmpty())
				str.RegisterRemoteError(testErr, 10)
				Eventually(done).Should(BeClosed())
			})

			It("calls onReset when receiving a remote error", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
				done := make(chan struct{})
				str.writeOffset = 0x1000
				go func() {
					_, _ = strWithTimeout.Write([]byte("foobar"))
					close(done)
				}()
				str.RegisterRemoteError(testErr, 0)
				Expect(resetCalled).To(BeTrue())
				Expect(resetCalledForStream).To(Equal(protocol.StreamID(1337)))
				Expect(resetCalledAtOffset).To(Equal(protocol.ByteCount(0x1000)))
				Eventually(done).Should(BeClosed())
			})

			It("doesn't call onReset if it already sent a FIN", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
				str.Close()
				_, sentFin := str.GetDataForWriting(1000)
				Expect(sentFin).To(BeTrue())
				str.RegisterRemoteError(testErr, 0)
				Expect(resetCalled).To(BeFalse())
			})

			It("doesn't call onReset if the stream was reset locally before", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
				str.Reset(testErr)
				Expect(resetCalled).To(BeTrue())
				resetCalled = false
				str.RegisterRemoteError(testErr, 0)
				Expect(resetCalled).To(BeFalse())
			})

			It("doesn't call onReset twice, when it gets two remote errors", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
				str.RegisterRemoteError(testErr, 0)
				Expect(resetCalled).To(BeTrue())
				resetCalled = false
				str.RegisterRemoteError(testErr, 0)
				Expect(resetCalled).To(BeFalse())
			})
		})

		Context("reset locally", func() {
			It("stops writing", func() {
				done := make(chan struct{})
				go func() {
					defer GinkgoRecover()
					n, err := strWithTimeout.Write([]byte("foobar"))
					Expect(n).To(BeZero())
					Expect(err).To(MatchError(testErr))
					close(done)
				}()
				Consistently(done).ShouldNot(BeClosed())
				str.Reset(testErr)
				Expect(str.GetDataForWriting(6)).To(BeNil())
				Eventually(done).Should(BeClosed())
			})

			It("doesn't allow further writes", func() {
				str.Reset(testErr)
				n, err := strWithTimeout.Write([]byte("foobar"))
				Expect(n).To(BeZero())
				Expect(err).To(MatchError(testErr))
				Expect(str.GetDataForWriting(6)).To(BeNil())
			})

			It("stops reading", func() {
				done := make(chan struct{})
				go func() {
					defer GinkgoRecover()
					b := make([]byte, 4)
					n, err := strWithTimeout.Read(b)
					Expect(n).To(BeZero())
					Expect(err).To(MatchError(testErr))
					close(done)
				}()
				Consistently(done).ShouldNot(BeClosed())
				str.Reset(testErr)
				Eventually(done).Should(BeClosed())
			})

			It("doesn't allow further reads", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(6), false)
				str.AddStreamFrame(&wire.StreamFrame{
					Data: []byte("foobar"),
				})
				str.Reset(testErr)
				b := make([]byte, 6)
				n, err := strWithTimeout.Read(b)
				Expect(n).To(BeZero())
				Expect(err).To(MatchError(testErr))
			})

			It("calls onReset", func() {
				str.writeOffset = 0x1000
				str.Reset(testErr)
				Expect(resetCalled).To(BeTrue())
				Expect(resetCalledForStream).To(Equal(protocol.StreamID(1337)))
				Expect(resetCalledAtOffset).To(Equal(protocol.ByteCount(0x1000)))
			})

			It("doesn't call onReset if it already sent a FIN", func() {
				str.Close()
				_, sentFin := str.GetDataForWriting(1000)
				Expect(sentFin).To(BeTrue())
				str.Reset(testErr)
				Expect(resetCalled).To(BeFalse())
			})

			It("doesn't call onReset if the stream was reset remotely before", func() {
				mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
				str.RegisterRemoteError(testErr, 0)
				Expect(resetCalled).To(BeTrue())
				resetCalled = false
				str.Reset(testErr)
				Expect(resetCalled).To(BeFalse())
			})

			It("doesn't call onReset twice", func() {
				str.Reset(testErr)
				Expect(resetCalled).To(BeTrue())
				resetCalled = false
				str.Reset(testErr)
				Expect(resetCalled).To(BeFalse())
			})

			It("cancels the context", func() {
				Expect(str.Context().Done()).ToNot(BeClosed())
				str.Reset(testErr)
				Expect(str.Context().Done()).To(BeClosed())
			})
		})
	})

	Context("writing", func() {
		It("writes and gets all data at once", func() {
			mockFC.EXPECT().SendWindowSize().Return(protocol.ByteCount(9999))
			mockFC.EXPECT().AddBytesSent(protocol.ByteCount(6))
			done := make(chan struct{})
			go func() {
				defer GinkgoRecover()
				n, err := strWithTimeout.Write([]byte("foobar"))
				Expect(err).ToNot(HaveOccurred())
				Expect(n).To(Equal(6))
				close(done)
			}()
			Eventually(func() []byte {
				str.mutex.Lock()
				defer str.mutex.Unlock()
				return str.dataForWriting
			}).Should(Equal([]byte("foobar")))
			Consistently(done).ShouldNot(BeClosed())
			Expect(onDataCalled).To(BeTrue())
			Expect(str.HasDataForWriting()).To(BeTrue())
			data, sendFin := str.GetDataForWriting(1000)
			Expect(data).To(Equal([]byte("foobar")))
			Expect(sendFin).To(BeFalse())
			Expect(str.writeOffset).To(Equal(protocol.ByteCount(6)))
			Expect(str.dataForWriting).To(BeNil())
			Eventually(done).Should(BeClosed())
		})

		It("writes and gets data in two turns", func() {
			mockFC.EXPECT().SendWindowSize().Return(protocol.ByteCount(9999)).Times(2)
			mockFC.EXPECT().AddBytesSent(protocol.ByteCount(3)).Times(2)
			done := make(chan struct{})
			go func() {
				defer GinkgoRecover()
				n, err := strWithTimeout.Write([]byte("foobar"))
				Expect(err).ToNot(HaveOccurred())
				Expect(n).To(Equal(6))
				close(done)
			}()
			Eventually(func() []byte {
				str.mutex.Lock()
				defer str.mutex.Unlock()
				return str.dataForWriting
			}).Should(Equal([]byte("foobar")))
			Consistently(done).ShouldNot(BeClosed())
			Expect(str.HasDataForWriting()).To(BeTrue())
			data, sendFin := str.GetDataForWriting(3)
			Expect(data).To(Equal([]byte("foo")))
			Expect(sendFin).To(BeFalse())
			Expect(str.writeOffset).To(Equal(protocol.ByteCount(3)))
			Expect(str.dataForWriting).ToNot(BeNil())
			Expect(str.HasDataForWriting()).To(BeTrue())
			data, sendFin = str.GetDataForWriting(3)
			Expect(data).To(Equal([]byte("bar")))
			Expect(sendFin).To(BeFalse())
			Expect(str.writeOffset).To(Equal(protocol.ByteCount(6)))
			Expect(str.dataForWriting).To(BeNil())
			Expect(str.HasDataForWriting()).To(BeFalse())
			Eventually(done).Should(BeClosed())
		})

		It("getDataForWriting returns nil if no data is available", func() {
			Expect(str.GetDataForWriting(1000)).To(BeNil())
		})

		It("copies the slice while writing", func() {
			mockFC.EXPECT().SendWindowSize().Return(protocol.ByteCount(9999))
			mockFC.EXPECT().AddBytesSent(protocol.ByteCount(3))
			s := []byte("foo")
			go func() {
				defer GinkgoRecover()
				n, err := strWithTimeout.Write(s)
				Expect(err).ToNot(HaveOccurred())
				Expect(n).To(Equal(3))
			}()
			Eventually(func() bool { return str.HasDataForWriting() }).Should(BeTrue())
			s[0] = 'v'
			Expect(str.GetDataForWriting(3)).To(Equal([]byte("foo")))
		})

		It("returns when given a nil input", func() {
			n, err := strWithTimeout.Write(nil)
			Expect(n).To(BeZero())
			Expect(err).ToNot(HaveOccurred())
		})

		It("returns when given an empty slice", func() {
			n, err := strWithTimeout.Write([]byte(""))
			Expect(n).To(BeZero())
			Expect(err).ToNot(HaveOccurred())
		})

		Context("deadlines", func() {
			It("returns an error when Write is called after the deadline", func() {
				str.SetWriteDeadline(time.Now().Add(-time.Second))
				n, err := strWithTimeout.Write([]byte("foobar"))
				Expect(err).To(MatchError(errDeadline))
				Expect(n).To(BeZero())
			})

			It("unblocks after the deadline", func() {
				deadline := time.Now().Add(scaleDuration(50 * time.Millisecond))
				str.SetWriteDeadline(deadline)
				n, err := strWithTimeout.Write([]byte("foobar"))
				Expect(err).To(MatchError(errDeadline))
				Expect(n).To(BeZero())
				Expect(time.Now()).To(BeTemporally("~", deadline, scaleDuration(20*time.Millisecond)))
			})

			It("doesn't unblock if the deadline is changed before the first one expires", func() {
				deadline1 := time.Now().Add(scaleDuration(50 * time.Millisecond))
				deadline2 := time.Now().Add(scaleDuration(100 * time.Millisecond))
				str.SetWriteDeadline(deadline1)
				go func() {
					defer GinkgoRecover()
					time.Sleep(scaleDuration(20 * time.Millisecond))
					str.SetWriteDeadline(deadline2)
					// make sure that this was actually execute before the deadline expires
					Expect(time.Now()).To(BeTemporally("<", deadline1))
				}()
				runtime.Gosched()
				n, err := strWithTimeout.Write([]byte("foobar"))
				Expect(err).To(MatchError(errDeadline))
				Expect(n).To(BeZero())
				Expect(time.Now()).To(BeTemporally("~", deadline2, scaleDuration(20*time.Millisecond)))
			})

			It("unblocks earlier, when a new deadline is set", func() {
				deadline1 := time.Now().Add(scaleDuration(200 * time.Millisecond))
				deadline2 := time.Now().Add(scaleDuration(50 * time.Millisecond))
				go func() {
					defer GinkgoRecover()
					time.Sleep(scaleDuration(10 * time.Millisecond))
					str.SetWriteDeadline(deadline2)
					// make sure that this was actually execute before the deadline expires
					Expect(time.Now()).To(BeTemporally("<", deadline2))
				}()
				str.SetWriteDeadline(deadline1)
				runtime.Gosched()
				_, err := strWithTimeout.Write([]byte("foobar"))
				Expect(err).To(MatchError(errDeadline))
				Expect(time.Now()).To(BeTemporally("~", deadline2, scaleDuration(20*time.Millisecond)))
			})

			It("sets a read deadline, when SetDeadline is called", func() {
				str.SetDeadline(time.Now().Add(-time.Second))
				n, err := strWithTimeout.Write([]byte("foobar"))
				Expect(err).To(MatchError(errDeadline))
				Expect(n).To(BeZero())
			})
		})

		Context("closing", func() {
			It("doesn't allow writes after it has been closed", func() {
				str.Close()
				_, err := strWithTimeout.Write([]byte("foobar"))
				Expect(err).To(MatchError("write on closed stream 1337"))
			})

			It("allows FIN", func() {
				str.Close()
				Expect(str.HasDataForWriting()).To(BeTrue())
				data, sendFin := str.GetDataForWriting(1000)
				Expect(data).To(BeEmpty())
				Expect(sendFin).To(BeTrue())
			})

			It("does not allow FIN when there's still data", func() {
				mockFC.EXPECT().SendWindowSize().Return(protocol.ByteCount(9999)).Times(2)
				mockFC.EXPECT().AddBytesSent(gomock.Any()).Times(2)
				str.dataForWriting = []byte("foobar")
				str.Close()
				Expect(str.HasDataForWriting()).To(BeTrue())
				data, sendFin := str.GetDataForWriting(3)
				Expect(data).To(Equal([]byte("foo")))
				Expect(sendFin).To(BeFalse())
				data, sendFin = str.GetDataForWriting(3)
				Expect(data).To(Equal([]byte("bar")))
				Expect(sendFin).To(BeTrue())
			})

			It("does not allow FIN when the stream is not closed", func() {
				Expect(str.HasDataForWriting()).To(BeFalse())
				_, sendFin := str.GetDataForWriting(3)
				Expect(sendFin).To(BeFalse())
			})

			It("does not allow FIN after an error", func() {
				str.Cancel(errors.New("test"))
				Expect(str.HasDataForWriting()).To(BeFalse())
				data, sendFin := str.GetDataForWriting(1000)
				Expect(data).To(BeEmpty())
				Expect(sendFin).To(BeFalse())
			})

			It("does not allow FIN twice", func() {
				str.Close()
				Expect(str.HasDataForWriting()).To(BeTrue())
				data, sendFin := str.GetDataForWriting(1000)
				Expect(data).To(BeEmpty())
				Expect(sendFin).To(BeTrue())
				Expect(str.HasDataForWriting()).To(BeFalse())
				data, sendFin = str.GetDataForWriting(1000)
				Expect(data).To(BeEmpty())
				Expect(sendFin).To(BeFalse())
			})
		})

		Context("cancelling", func() {
			testErr := errors.New("test")

			It("returns errors when the stream is cancelled", func() {
				str.Cancel(testErr)
				n, err := strWithTimeout.Write([]byte("foo"))
				Expect(n).To(BeZero())
				Expect(err).To(MatchError(testErr))
			})

			It("doesn't get data for writing if an error occurred", func() {
				go func() {
					defer GinkgoRecover()
					_, err := strWithTimeout.Write([]byte("foobar"))
					Expect(err).To(MatchError(testErr))
				}()
				Eventually(func() []byte { return str.dataForWriting }).ShouldNot(BeNil())
				Expect(str.HasDataForWriting()).To(BeTrue())
				str.Cancel(testErr)
				data, sendFin := str.GetDataForWriting(6)
				Expect(data).To(BeNil())
				Expect(sendFin).To(BeFalse())
				Expect(str.HasDataForWriting()).To(BeFalse())
			})
		})
	})

	It("errors when a StreamFrames causes a flow control violation", func() {
		testErr := errors.New("flow control violation")
		mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(8), false).Return(testErr)
		frame := wire.StreamFrame{
			Offset: 2,
			Data:   []byte("foobar"),
		}
		err := str.AddStreamFrame(&frame)
		Expect(err).To(MatchError(testErr))
	})

	Context("closing", func() {
		testErr := errors.New("testErr")

		finishReading := func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
			err := str.AddStreamFrame(&wire.StreamFrame{FinBit: true})
			Expect(err).ToNot(HaveOccurred())
			b := make([]byte, 100)
			_, err = strWithTimeout.Read(b)
			Expect(err).To(MatchError(io.EOF))
		}

		It("is finished after it is canceled", func() {
			str.Cancel(testErr)
			Expect(str.Finished()).To(BeTrue())
		})

		It("is not finished if it is only closed for writing", func() {
			str.Close()
			_, sentFin := str.GetDataForWriting(1000)
			Expect(sentFin).To(BeTrue())
			Expect(str.Finished()).To(BeFalse())
		})

		It("cancels the context after it is closed", func() {
			Expect(str.Context().Done()).ToNot(BeClosed())
			str.Close()
			Expect(str.Context().Done()).To(BeClosed())
		})

		It("is not finished if it is only closed for reading", func() {
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(0))
			finishReading()
			Expect(str.Finished()).To(BeFalse())
		})

		It("is finished after receiving a RST and sending one", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
			// this directly sends a rst
			str.RegisterRemoteError(testErr, 0)
			Expect(str.rstSent.Get()).To(BeTrue())
			Expect(str.Finished()).To(BeTrue())
		})

		It("cancels the context after receiving a RST", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(0), true)
			Expect(str.Context().Done()).ToNot(BeClosed())
			str.RegisterRemoteError(testErr, 0)
			Expect(str.Context().Done()).To(BeClosed())
		})

		It("is finished after being locally reset and receiving a RST in response", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(13), true)
			str.Reset(testErr)
			Expect(str.Finished()).To(BeFalse())
			str.RegisterRemoteError(testErr, 13)
			Expect(str.Finished()).To(BeTrue())
		})

		It("is finished after finishing writing and receiving a RST", func() {
			mockFC.EXPECT().UpdateHighestReceived(protocol.ByteCount(13), true)
			str.Close()
			_, sentFin := str.GetDataForWriting(1000)
			Expect(sentFin).To(BeTrue())
			str.RegisterRemoteError(testErr, 13)
			Expect(str.Finished()).To(BeTrue())
		})

		It("is finished after finishing reading and being locally reset", func() {
			mockFC.EXPECT().AddBytesRead(protocol.ByteCount(0))
			finishReading()
			Expect(str.Finished()).To(BeFalse())
			str.Reset(testErr)
			Expect(str.Finished()).To(BeTrue())
		})
	})

	Context("flow control", func() {
		It("says when it's flow control blocked", func() {
			mockFC.EXPECT().IsBlocked().Return(false)
			Expect(str.IsFlowControlBlocked()).To(BeFalse())
			mockFC.EXPECT().IsBlocked().Return(true)
			Expect(str.IsFlowControlBlocked()).To(BeTrue())
		})

		It("updates the flow control window", func() {
			mockFC.EXPECT().UpdateSendWindow(protocol.ByteCount(0x42))
			str.UpdateSendWindow(0x42)
		})

		It("gets a window update", func() {
			mockFC.EXPECT().GetWindowUpdate().Return(protocol.ByteCount(0x100))
			Expect(str.GetWindowUpdate()).To(Equal(protocol.ByteCount(0x100)))
		})
	})
})