package h2mux

import (
	"bytes"
	"io"
	"testing"

	"github.com/stretchr/testify/assert"
)

const testWindowSize uint32 = 65535
const testMaxWindowSize uint32 = testWindowSize << 2

// Only sending WINDOW_UPDATE frame, so sendWindow should never change
func TestFlowControlSingleStream(t *testing.T) {
	stream := &MuxedStream{
		responseHeadersReceived: make(chan struct{}),
		readBuffer:              NewSharedBuffer(),
		writeBuffer:             &bytes.Buffer{},
		receiveWindow:           testWindowSize,
		receiveWindowCurrentMax: testWindowSize,
		receiveWindowMax:        testMaxWindowSize,
		sendWindow:              testWindowSize,
		readyList:               NewReadyList(),
	}
	assert.True(t, stream.consumeReceiveWindow(testWindowSize/2))
	dataSent := testWindowSize / 2
	assert.Equal(t, testWindowSize-dataSent, stream.receiveWindow)
	assert.Equal(t, testWindowSize, stream.receiveWindowCurrentMax)
	assert.Equal(t, uint32(0), stream.windowUpdate)
	tempWindowUpdate := stream.windowUpdate

	streamChunk := stream.getChunk()
	assert.Equal(t, tempWindowUpdate, streamChunk.windowUpdate)
	assert.Equal(t, testWindowSize-dataSent, stream.receiveWindow)
	assert.Equal(t, uint32(0), stream.windowUpdate)
	assert.Equal(t, testWindowSize, stream.sendWindow)

	assert.True(t, stream.consumeReceiveWindow(2))
	dataSent += 2
	assert.Equal(t, testWindowSize-dataSent, stream.receiveWindow)
	assert.Equal(t, testWindowSize<<1, stream.receiveWindowCurrentMax)
	assert.Equal(t, (testWindowSize<<1)-stream.receiveWindow, stream.windowUpdate)
	tempWindowUpdate = stream.windowUpdate

	streamChunk = stream.getChunk()
	assert.Equal(t, tempWindowUpdate, streamChunk.windowUpdate)
	assert.Equal(t, testWindowSize<<1, stream.receiveWindow)
	assert.Equal(t, uint32(0), stream.windowUpdate)
	assert.Equal(t, testWindowSize, stream.sendWindow)

	assert.True(t, stream.consumeReceiveWindow(testWindowSize+10))
	dataSent = testWindowSize + 10
	assert.Equal(t, (testWindowSize<<1)-dataSent, stream.receiveWindow)
	assert.Equal(t, testWindowSize<<2, stream.receiveWindowCurrentMax)
	assert.Equal(t, (testWindowSize<<2)-stream.receiveWindow, stream.windowUpdate)
	tempWindowUpdate = stream.windowUpdate

	streamChunk = stream.getChunk()
	assert.Equal(t, tempWindowUpdate, streamChunk.windowUpdate)
	assert.Equal(t, testWindowSize<<2, stream.receiveWindow)
	assert.Equal(t, uint32(0), stream.windowUpdate)
	assert.Equal(t, testWindowSize, stream.sendWindow)

	assert.False(t, stream.consumeReceiveWindow(testMaxWindowSize+1))
	assert.Equal(t, testWindowSize<<2, stream.receiveWindow)
	assert.Equal(t, testMaxWindowSize, stream.receiveWindowCurrentMax)
}

func TestMuxedStreamEOF(t *testing.T) {
	for i := 0; i < 4096; i++ {
		readyList := NewReadyList()
		stream := &MuxedStream{
			streamID:         1,
			readBuffer:       NewSharedBuffer(),
			receiveWindow:    65536,
			receiveWindowMax: 65536,
			sendWindow:       65536,
			readyList:        readyList,
		}

		go func() { stream.Close() }()
		n, err := stream.Read([]byte{0})
		assert.Equal(t, io.EOF, err)
		assert.Equal(t, 0, n)
		// Write comes after read, because write buffers data before it is flushed. It wouldn't know about EOF
		// until some time later. Calling read first forces it to know about EOF now.
		n, err = stream.Write([]byte{1})
		assert.Equal(t, io.EOF, err)
		assert.Equal(t, 0, n)
	}
}