#!/usr/bin/env python3
import argparse
import os
import subprocess
from pathlib import Path


VIDEO_EXTS = {".mp4", ".mov", ".mkv", ".avi", ".webm", ".m4v"}


def run_cmd(cmd):
    return subprocess.run(cmd, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)


def get_duration_seconds(video_path: Path) -> float:
    cmd = [
        "ffprobe",
        "-v",
        "error",
        "-show_entries",
        "format=duration",
        "-of",
        "default=noprint_wrappers=1:nokey=1",
        str(video_path),
    ]
    out = run_cmd(cmd).stdout.strip()
    return float(out)


def has_audio_stream(video_path: Path) -> bool:
    cmd = [
        "ffprobe",
        "-v",
        "error",
        "-select_streams",
        "a:0",
        "-show_entries",
        "stream=index",
        "-of",
        "csv=p=0",
        str(video_path),
    ]
    out = run_cmd(cmd).stdout.strip()
    return bool(out)


def make_delay_plus_2s(src: Path, dst: Path, duration: float):
    # Delay audio by 2s; keep final duration unchanged.
    cmd = [
        "ffmpeg",
        "-y",
        "-i",
        str(src),
        "-map",
        "0:v:0",
        "-map",
        "0:a:0",
        "-c:v",
        "copy",
        "-af",
        f"adelay=2000:all=1,atrim=0:{duration}",
        "-c:a",
        "aac",
        str(dst),
    ]
    run_cmd(cmd)


def make_advance_minus_2s(src: Path, dst: Path, duration: float):
    # Advance audio by 2s; the last 2s become silence.
    cmd = [
        "ffmpeg",
        "-y",
        "-i",
        str(src),
        "-map",
        "0:v:0",
        "-map",
        "0:a:0",
        "-c:v",
        "copy",
        "-af",
        f"atrim=start=2,asetpts=PTS-STARTPTS,apad=pad_dur=2,atrim=0:{duration}",
        "-c:a",
        "aac",
        str(dst),
    ]
    run_cmd(cmd)


def iter_videos(root: Path):
    for dirpath, _, filenames in os.walk(root):
        for name in filenames:
            p = Path(dirpath) / name
            if p.suffix.lower() in VIDEO_EXTS:
                yield p


def purge_directory(root: Path):
    if not root.exists():
        return
    for dirpath, _, filenames in os.walk(root):
        for name in filenames:
            (Path(dirpath) / name).unlink()


def main():
    parser = argparse.ArgumentParser(
        description="Generate +2s delay and -2s advance audio versions for all videos."
    )
    parser.add_argument(
        "--input-dir",
        default="/home/ubuntu/uag_oops_data/uag_oops",
        help="Source video directory.",
    )
    parser.add_argument(
        "--out-delay-dir",
        default="/home/ubuntu/uag_oops_data/delay",
        help="Output directory for +2s delay versions.",
    )
    parser.add_argument(
        "--out-advance-dir",
        default="/home/ubuntu/uag_oops_data/early",
        help="Output directory for -2s advance versions.",
    )
    parser.add_argument(
        "--overwrite",
        action="store_true",
        help="Overwrite output if file exists.",
    )
    parser.add_argument(
        "--no-purge-output",
        action="store_true",
        help="Do not purge output directories before generation.",
    )
    args = parser.parse_args()

    input_dir = Path(args.input_dir)
    out_delay_dir = Path(args.out_delay_dir)
    out_advance_dir = Path(args.out_advance_dir)

    if not input_dir.exists():
        raise FileNotFoundError(f"Input directory not found: {input_dir}")

    videos = sorted(iter_videos(input_dir))
    if not videos:
        print(f"No videos found in: {input_dir}")
        return

    out_delay_dir.mkdir(parents=True, exist_ok=True)
    out_advance_dir.mkdir(parents=True, exist_ok=True)
    purge_output = not args.no_purge_output
    if purge_output:
        print("Purging output directories first...")
        purge_directory(out_delay_dir)
        purge_directory(out_advance_dir)

    print(f"Found {len(videos)} videos.")
    skipped_no_audio = 0
    processed = 0

    for idx, src in enumerate(videos, start=1):
        rel = src.relative_to(input_dir)
        delay_name = f"{rel.stem}_delay2s{rel.suffix}"
        advance_name = f"{rel.stem}_early2s{rel.suffix}"
        dst_delay = out_delay_dir / rel.parent / delay_name
        dst_advance = out_advance_dir / rel.parent / advance_name
        dst_delay.parent.mkdir(parents=True, exist_ok=True)
        dst_advance.parent.mkdir(parents=True, exist_ok=True)

        if (not args.overwrite) and dst_delay.exists() and dst_advance.exists():
            print(f"[{idx}/{len(videos)}] Skip existing: {rel}")
            continue

        if not has_audio_stream(src):
            skipped_no_audio += 1
            print(f"[{idx}/{len(videos)}] Skip no-audio: {rel}")
            continue

        duration = get_duration_seconds(src)
        print(f"[{idx}/{len(videos)}] Processing: {rel}")
        try:
            if args.overwrite or not dst_delay.exists():
                make_delay_plus_2s(src, dst_delay, duration)
            if args.overwrite or not dst_advance.exists():
                make_advance_minus_2s(src, dst_advance, duration)
            processed += 1
        except subprocess.CalledProcessError as exc:
            print(f"  Failed: {rel}")
            print(exc.stderr[-500:])

    print("\nDone.")
    print(f"Processed videos: {processed}")
    print(f"Skipped no-audio: {skipped_no_audio}")
    print(f"Delay output dir: {out_delay_dir}")
    print(f"Advance output dir: {out_advance_dir}")


if __name__ == "__main__":
    main()