package transcoding

import (
	"bytes"
	"context"
	"os/exec"
	"path/filepath"
	"testing"
	"time"
)

func genTestFile(t *testing.T, dir string) string {
	t.Helper()
	if _, err := exec.LookPath("ffmpeg"); err != nil {
		t.Skip("ffmpeg not installed")
	}
	out := filepath.Join(dir, "src.mp3")
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	cmd := exec.CommandContext(ctx, "ffmpeg", "-f", "lavfi", "-i", "sine=frequency=440:duration=2", "-codec:a", "libmp3lame", out)
	if combined, err := cmd.CombinedOutput(); err != nil {
		t.Fatalf("ffmpeg: %v\n%s", err, combined)
	}
	return out
}

func TestStreamProducesOutput(t *testing.T) {
	dir := t.TempDir()
	src := genTestFile(t, dir)

	m := NewManager("")
	var buf bytes.Buffer
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	if err := m.Stream(ctx, &buf, src, Options{Format: FormatMP3, MaxBitRateKbps: 64}); err != nil {
		t.Fatalf("Stream: %v", err)
	}
	if buf.Len() == 0 {
		t.Fatal("transcoded output is empty")
	}
}

func TestStreamRespectsContextCancellation(t *testing.T) {
	dir := t.TempDir()
	src := genTestFile(t, dir)

	m := NewManager("")
	ctx, cancel := context.WithCancel(context.Background())
	cancel() // already cancelled before starting

	var buf bytes.Buffer
	err := m.Stream(ctx, &buf, src, Options{Format: FormatMP3})
	if err == nil {
		t.Fatal("expected an error when the context is already cancelled")
	}
}

func TestParseFormat(t *testing.T) {
	cases := map[string]Format{
		"mp3":     FormatMP3,
		"opus":    FormatOpus,
		"aac":     FormatAAC,
		"unknown": FormatMP3,
		"":        FormatMP3,
	}
	for in, want := range cases {
		if got := ParseFormat(in); got != want {
			t.Errorf("ParseFormat(%q) = %q, want %q", in, got, want)
		}
	}
}

func TestBuildHLS(t *testing.T) {
	dir := t.TempDir()
	src := genTestFile(t, dir)

	m := NewManager("")
	ctx, cancel := context.WithTimeout(context.Background(), 60*time.Second)
	defer cancel()
	session, err := m.BuildHLS(ctx, src, filepath.Join(dir, "cache"), Options{Format: FormatAAC, MaxBitRateKbps: 96})
	if err != nil {
		t.Fatalf("BuildHLS: %v", err)
	}
	if session.SegmentCount == 0 {
		t.Fatal("expected at least one HLS segment")
	}
	playlist := session.Playlist(func(i int) string { return "seg" + string(rune('0'+i)) })
	if playlist == "" {
		t.Fatal("empty playlist")
	}
	if session.SegmentPath(0) == "" {
		t.Fatal("SegmentPath(0) should resolve")
	}
	if session.SegmentPath(9999) != "" {
		t.Fatal("SegmentPath out of range should return empty")
	}
}