package output

import (
	"bytes"
	"errors"
	"testing"

	"mxl-player/internal/playback"
)

func validAudioFrame() playback.AudioFrame {
	return playback.AudioFrame{
		Index:                 42,
		SampleCount:           2,
		Channels:              2,
		SampleRateNumerator:   48000,
		SampleRateDenominator: 1,
		Samples: [][]byte{
			{1, 2, 3, 4, 5, 6, 7, 8},
			{9, 10, 11, 12, 13, 14, 15, 16},
		},
	}
}

func TestInterleaveF32OrdersSamplesByFrameThenChannel(t *testing.T) {
	frame := validAudioFrame()
	want := []byte{
		1, 2, 3, 4,
		9, 10, 11, 12,
		5, 6, 7, 8,
		13, 14, 15, 16,
	}

	got, err := InterleaveF32(frame)
	if err != nil {
		t.Fatalf("InterleaveF32() error = %v", err)
	}
	if !bytes.Equal(got, want) {
		t.Fatalf("InterleaveF32() = %v, want %v", got, want)
	}
}

func TestInterleaveF32IgnoresBytesAfterSampleCount(t *testing.T) {
	frame := validAudioFrame()
	frame.SampleCount = 1

	got, err := InterleaveF32(frame)
	if err != nil {
		t.Fatalf("InterleaveF32() error = %v", err)
	}
	want := []byte{1, 2, 3, 4, 9, 10, 11, 12}
	if !bytes.Equal(got, want) {
		t.Fatalf("InterleaveF32() = %v, want %v", got, want)
	}
}

func TestInterleaveF32RejectsInvalidMetadata(t *testing.T) {
	tests := []struct {
		name   string
		mutate func(*playback.AudioFrame)
	}{
		{name: "zero samples", mutate: func(f *playback.AudioFrame) { f.SampleCount = 0 }},
		{name: "zero channels", mutate: func(f *playback.AudioFrame) { f.Channels = 0 }},
		{name: "zero rate numerator", mutate: func(f *playback.AudioFrame) { f.SampleRateNumerator = 0 }},
		{name: "negative rate numerator", mutate: func(f *playback.AudioFrame) { f.SampleRateNumerator = -1 }},
		{name: "zero rate denominator", mutate: func(f *playback.AudioFrame) { f.SampleRateDenominator = 0 }},
		{name: "wrong channel count", mutate: func(f *playback.AudioFrame) { f.Channels = 3 }},
		{name: "sample size overflow", mutate: func(f *playback.AudioFrame) { f.SampleCount = ^uint64(0) }},
		{
			name: "allocation size overflow",
			mutate: func(f *playback.AudioFrame) {
				f.SampleCount = uint64(^uint(0)>>1) / 4
			},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			frame := validAudioFrame()
			tt.mutate(&frame)
			result, err := InterleaveF32(frame)
			if result != nil {
				t.Fatalf("InterleaveF32() result = %v, want nil", result)
			}
			if !errors.Is(err, ErrInvalidAudioFrame) {
				t.Fatalf("InterleaveF32() error = %v, want %v", err, ErrInvalidAudioFrame)
			}
		})
	}
}

func TestInterleaveF32RejectsShortChannel(t *testing.T) {
	frame := validAudioFrame()
	frame.Samples[1] = frame.Samples[1][:7]

	result, err := InterleaveF32(frame)
	if result != nil {
		t.Fatalf("InterleaveF32() result = %v, want nil", result)
	}
	if !errors.Is(err, ErrAudioPayloadTooSmall) {
		t.Fatalf("InterleaveF32() error = %v, want %v", err, ErrAudioPayloadTooSmall)
	}
}

func TestInterleaveF32ReturnsIndependentOutput(t *testing.T) {
	frame := validAudioFrame()
	result, err := InterleaveF32(frame)
	if err != nil {
		t.Fatalf("InterleaveF32() error = %v", err)
	}

	frame.Samples[0][0] = 99
	if result[0] != 1 {
		t.Fatalf("output changed with borrowed input: first byte = %d, want 1", result[0])
	}
}