def choose_random_song() -> Optional[str]:
    try:
        if not SONGS_DIR.exists():
            return None

        songs = [
            song
            for song in SONGS_DIR.iterdir()
            if song.is_file() and song.suffix.lower() == ".mp3"
        ]

        if not songs:
            return None

        song = random.choice(songs)
        logger.info(colored(f"Chose song: {song}", "green"))
        return str(song)
    except Exception as e:
        logger.error(
            colored(f"Error occurred while choosing random song: {str(e)}", "red")
        )

if use_music:
    song_path = choose_random_song()
    
    if not song_path:
        emit(
            "[-] Could not find songs in Songs/. Continuing without background music.",
            "warning",
        )
        use_music = False

    if use_music:
        video_clip = VideoFileClip(rendered_video_path)
        song_clip = AudioFileClip(song_path).with_fps(44100)
        
        # Loop song to match video duration
        original_duration = video_clip.duration
        song_clip = song_clip.with_effects(
            [afx.AudioLoop(duration=original_duration)]
        )
        
        # Reduce volume to 10%
        song_clip = song_clip.with_volume_scaled(0.1).with_fps(44100)
        
        # Mix audio tracks
        original_audio = video_clip.audio
        mixed_audio = CompositeAudioClip(
            [original_audio, song_clip]
        ).with_duration(original_duration)

@app.route("/api/upload-songs", methods=["POST"])
def upload_songs():
    try:
        files = request.files.getlist("songs")
        if not files:
            return jsonify({"status": "error", "message": "No files uploaded."}), 400

        clean_dir(str(SONGS_DIR))  # Remove existing songs
        saved = 0
        for file_item in files:
            if file_item.filename and file_item.filename.lower().endswith(".mp3"):
                safe_name = os.path.basename(file_item.filename)
                file_item.save(str(SONGS_DIR / safe_name))
                saved += 1

        if saved == 0:
            return jsonify({"status": "error", "message": "No MP3 files found."}), 400

        log(f"[+] Uploaded {saved} song(s) to {SONGS_DIR}", "success")
        return jsonify({"status": "success", "message": f"Uploaded {saved} song(s)."})
    except Exception as err:
        log(f"[-] Error uploading songs: {str(err)}", "error")
        return jsonify({"status": "error", "message": str(err)}), 500

subprocess.run(
    [
        "ffmpeg",
        "-y",
        "-i", rendered_video_path,
        "-i", mixed_audio_path,
        "-map", "0:v:0",  # Video stream from first input
        "-map", "1:a:0",  # Audio stream from second input
        "-c:v", "copy",   # Copy video codec (no re-encode)
        "-c:a", "aac",    # AAC audio codec
        "-b:a", "192k",   # Audio bitrate
        "-shortest",      # Match shortest stream
        final_output_path,
    ],
    check=True,
    capture_output=True,
    text=True,
)

except Exception:
    emit(
        "[!] ffmpeg remux failed. Falling back to MoviePy render for music mix.",
        "warning",
    )
    video_clip = VideoFileClip(rendered_video_path)
    song_clip = AudioFileClip(song_path).with_fps(44100)
    
    # Mix audio
    comp_audio = CompositeAudioClip([video_clip.audio, song_clip])
    video_clip = video_clip.with_audio(comp_audio)
    
    # Re-encode entire video
    video_clip.write_videofile(
        final_output_path,
        threads=render_threads,
        fps=30,
        codec="libx264",
        audio_codec="aac",
        preset="medium",
    )

# Instead of random selection:
song_path = str(SONGS_DIR / "my_favorite_track.mp3")
if not Path(song_path).exists():
    emit("Specific song not found. Using random.", "warning")
    song_path = choose_random_song()