package filetrans

import (
	"encoding/binary"
	"testing"
)

func wavHeader(channels uint16) []byte {
	b := make([]byte, 44)
	copy(b[0:4], "RIFF")
	binary.LittleEndian.PutUint32(b[4:8], 36)
	copy(b[8:12], "WAVE")
	copy(b[12:16], "fmt ")
	binary.LittleEndian.PutUint32(b[16:20], 16)
	binary.LittleEndian.PutUint16(b[20:22], 1)
	binary.LittleEndian.PutUint16(b[22:24], channels)
	binary.LittleEndian.PutUint32(b[24:28], 16000)
	copy(b[36:40], "data")
	return b
}

func TestWavChannelsFromHeader(t *testing.T) {
	if got := wavChannelsFromHeader(wavHeader(2)); got != 2 {
		t.Fatalf("stereo: got %d", got)
	}
	if got := wavChannelsFromHeader(wavHeader(1)); got != 1 {
		t.Fatalf("mono: got %d", got)
	}
	// 客户端 WavWriter 的头只有 44 字节，但取 64 字节的 Range 会带上 data 的前 20 字节
	if got := wavChannelsFromHeader(append(wavHeader(2), make([]byte, 20)...)); got != 2 {
		t.Fatalf("stereo+data: got %d", got)
	}
	if got := wavChannelsFromHeader([]byte("OggS\x00\x02")); got != 0 {
		t.Fatalf("ogg: got %d", got)
	}
	if got := wavChannelsFromHeader(wavHeader(2)[:20]); got != 0 {
		t.Fatalf("truncated: got %d", got)
	}
}