import os
import subprocess


def prepend_intro(
    intro_video,
    main_video,
    output_video
):
    """
    Intro boleh:
    - tanpa audio
    - dengan audio
    - codec apa saja
    - resolusi apa saja

    Akan dinormalisasi dulu lalu digabung
    dengan video Quran utama.
    """

    if not intro_video:
        return main_video

    os.makedirs("temp", exist_ok=True)

    normalized_intro = "temp/intro_normalized.mp4"

    print("=" * 60)
    print("NORMALIZING INTRO")
    print("=" * 60)

    subprocess.run(
        [
            "ffmpeg",
            "-y",

            "-i",
            intro_video,

            # tambahkan audio silent
            "-f",
            "lavfi",

            "-i",
            "anullsrc=r=48000:cl=stereo",

            "-shortest",

            "-vf",
            (
                "scale=1920:1080:"
                "force_original_aspect_ratio=decrease,"
                "pad=1920:1080:(ow-iw)/2:(oh-ih)/2"
            ),

            "-r",
            "30",

            "-c:v",
            "libx264",

            "-preset",
            "veryfast",

            "-crf",
            "22",

            "-c:a",
            "aac",

            "-ar",
            "48000",

            "-ac",
            "2",

            "-b:a",
            "192k",

            normalized_intro
        ],
        check=True
    )

    print("=" * 60)
    print("CONCAT INTRO + MAIN")
    print("=" * 60)

    subprocess.run(
        [
            "ffmpeg",
            "-y",

            "-i",
            normalized_intro,

            "-i",
            main_video,

            "-filter_complex",
            "[0:v][0:a][1:v][1:a]concat=n=2:v=1:a=1[v][a]",

            "-map",
            "[v]",

            "-map",
            "[a]",

            "-c:v",
            "libx264",

            "-preset",
            "veryfast",

            "-crf",
            "22",

            "-c:a",
            "aac",

            "-b:a",
            "192k",

            output_video
        ],
        check=True
    )

    print("=" * 60)
    print("INTRO CONCAT SUCCESS")
    print("=" * 60)

    return output_video