package ll

import (
	"bytes"
	"io"
	"os"
	"sync"
	"testing"
	"time"

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

func TestDecoderNoDataPayload(t *testing.T) {
	buf := bytes.NewBuffer([]byte{0x44, 0x4a, 0x52, 0x40, 0x00, 0x06})
	var msg Msg

	dec := NewDecoder(buf)
	require.Nil(t, dec.Decode(&msg))

	require.Equal(t, msg.Type, MsgTypeTime)
}

func TestDecoderLeadingTrailingSpuriousBytes(t *testing.T) {
	buf := bytes.NewBuffer([]byte{0x00, 0x00, 0x12, 0x13, 0x33, 0x44, 0x4a, 0x52, 0x40, 0x00, 0x06})
	var msg Msg

	dec := NewDecoder(buf)
	require.Nil(t, dec.Decode(&msg))
	require.Equal(t, msg.Type, MsgTypeTime)
}

func TestDecoderChunkedTransfer(t *testing.T) {
	r, w, err := os.Pipe()
	require.Nil(t, err)
	defer func(t *testing.T) {
		require.Nil(t, r.Close())
	}(t)
	defer func(t *testing.T) {
		require.Nil(t, w.Close())
	}(t)

	dec := NewDecoder(r)
	var wg sync.WaitGroup

	errChan := make(chan error, 4)
	wg.Add(1)
	go func() {
		_, werr := w.Write([]byte{0x00, 0x12, 0x34, 0x44})
		errChan <- werr
		time.Sleep(time.Millisecond * 5)
		_, werr = w.Write([]byte{0x4a, 0x52, 0x10})
		errChan <- werr
		time.Sleep(time.Millisecond * 5)
		_, werr = w.Write([]byte{0x00, 0x0A, 0xde})
		errChan <- werr
		time.Sleep(time.Millisecond * 5)
		_, werr = w.Write([]byte{0xad, 0xbe, 0xef})
		errChan <- werr
		close(errChan)
		wg.Done()
	}()

	var msg Msg
	require.Nil(t, dec.Decode(&msg))
	require.Equal(t, msg.Type, MsgTypePlain)
	require.Equal(t, []byte{0xde, 0xad, 0xbe, 0xef}, msg.Data)
	wg.Wait()
	for err := range errChan {
		require.Nil(t, err)
	}
}

func TestDecoderDataPayload(t *testing.T) {
	expectData := []byte{0xde, 0xad, 0xbe, 0xef}

	buf := bytes.NewBuffer([]byte{0x44, 0x4a, 0x52, 0x10, 0x00, 0x0a, 0xde, 0xad, 0xbe, 0xef})
	var msg Msg

	dec := NewDecoder(buf)
	require.Nil(t, dec.Decode(&msg))
	require.Equal(t, msg.Type, MsgTypePlain)
	require.Equal(t, expectData, msg.Data)
}

func TestDecoderDataExceedDecodeChunk(t *testing.T) {
	var msg Msg
	data := make([]byte, 4096)
	buf := bytes.NewBuffer(data)

	dec := NewDecoder(buf)
	require.Equal(t, io.EOF, dec.Decode(&msg))
}