package ffmpeg

import (
	"encoding/binary"
	"testing"
)

func TestEncodeWAV(t *testing.T) {
	pcm := []float32{0, 1, -1, 2, -2} // last two exercise clamping
	sampleRate := 22050

	data := encodeWAV(pcm, sampleRate)

	if string(data[0:4]) != "RIFF" || string(data[8:12]) != "WAVE" {
		t.Fatalf("encodeWAV() missing RIFF/WAVE header: %q", data[:12])
	}
	if string(data[12:16]) != "fmt " || string(data[36:40]) != "data" {
		t.Fatalf("encodeWAV() missing fmt/data chunk headers")
	}

	gotSampleRate := binary.LittleEndian.Uint32(data[24:28])
	if gotSampleRate != uint32(sampleRate) {
		t.Fatalf("encodeWAV() sample rate = %d, want %d", gotSampleRate, sampleRate)
	}

	dataSize := binary.LittleEndian.Uint32(data[40:44])
	if int(dataSize) != len(pcm)*2 {
		t.Fatalf("encodeWAV() data size = %d, want %d", dataSize, len(pcm)*2)
	}

	samples := data[44:]
	want := []int16{0, 32767, -32767, 32767, -32767} // clamped to [-1, 1] before scaling
	for i, w := range want {
		got := int16(binary.LittleEndian.Uint16(samples[i*2 : i*2+2]))
		if got != w {
			t.Errorf("sample %d = %d, want %d", i, got, w)
		}
	}
}