package audio

import (
	"math"
	"testing"
)

// 20ms interleaved stereo sine; both channels identical
func makeSineStereo(freqHz float64) []int16 {
	pcm := make([]int16, SamplesPerOpusFrame*Channels)
	for i := 0; i < SamplesPerOpusFrame; i++ {
		v := int16(math.Sin(2*math.Pi*freqHz*float64(i)/SampleRate) * 16000)
		pcm[i*2] = v
		pcm[i*2+1] = v
	}
	return pcm
}

func TestEncodeDecodeRoundtrip(t *testing.T) {
	enc, err := NewEncoder()
	if err != nil {
		t.Fatalf("NewEncoder: %v", err)
	}
	dec, err := NewDecoder()
	if err != nil {
		t.Fatalf("NewDecoder: %v", err)
	}

	in := makeSineStereo(440)
	pkt := make([]byte, MaxOpusPacketBytes)
	n, err := enc.Encode(in, pkt)
	if err != nil {
		t.Fatalf("Encode: %v", err)
	}
	if n <= 0 || n > MaxOpusPacketBytes {
		t.Fatalf("Encode returned %d bytes", n)
	}

	out := make([]int16, MaxDecodeSamplesPerChannel*Channels)
	samplesPerCh, err := dec.Decode(pkt[:n], out)
	if err != nil {
		t.Fatalf("Decode: %v", err)
	}
	if samplesPerCh != SamplesPerOpusFrame {
		t.Errorf("Decode produced %d samples/ch, want %d", samplesPerCh, SamplesPerOpusFrame)
	}
}