#!/usr/bin/env python3
"""Set a video file's filesystem modification time to match its embedded
creation-time metadata.

Some tools (e.g. Synology Photos, for videos) sort/date by filesystem mtime
instead of parsing embedded video metadata, so a video with correct
metadata but a wrong mtime (common after copying, downloading, or exporting
a file) can show up filed under the wrong date. This resets mtime (and
atime) to match the video's own embedded creation time.

Usage:
    ./set_mtime_from_metadata.py video1.mov video2.mp4 ...
    ./set_mtime_from_metadata.py --dry-run *.mov

Requirements:
    - ffprobe on PATH
"""
import argparse
import os
import subprocess
import sys
from datetime import datetime
from pathlib import Path

# Preference order: the Apple tag is local time (matches what Photos/Finder
# display); the generic tag is whatever the encoder wrote, usually UTC.
TAG_PRIORITY = ["com.apple.quicktime.creationdate", "creation_time"]


def parse_timestamp(raw):
    raw = raw.strip().replace("Z", "+0000")
    for fmt in ("%Y-%m-%dT%H:%M:%S%z", "%Y-%m-%dT%H:%M:%S.%f%z"):
        try:
            return datetime.strptime(raw, fmt)
        except ValueError:
            continue
    return None


def fetch_creation_time(path):
    """Best-effort embedded creation time for a video, checking
    container-level tags first and falling back to the first video
    stream's tags. Returns None if nothing usable is found."""
    tag_list = ",".join(TAG_PRIORITY)
    for scope, extra_args in (("format_tags", []), ("stream_tags", ["-select_streams", "v:0"])):
        try:
            out = subprocess.run(
                ["ffprobe", "-v", "error", *extra_args,
                 "-show_entries", f"{scope}={tag_list}",
                 "-of", "default=noprint_wrappers=1:nokey=0", str(path)],
                check=True, capture_output=True, text=True,
            ).stdout
        except subprocess.CalledProcessError as e:
            raise RuntimeError(e.stderr.strip() or str(e)) from e
        tags = dict(line.split("=", 1) for line in out.strip().splitlines() if "=" in line)
        for tag in TAG_PRIORITY:
            raw = tags.get(f"TAG:{tag}")
            if raw:
                dt = parse_timestamp(raw)
                if dt:
                    return dt
    return None


def main():
    parser = argparse.ArgumentParser(description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
    parser.add_argument("files", nargs="+", type=Path, help="Video files to fix")
    parser.add_argument("--dry-run", action="store_true", help="Show what would change without modifying anything")
    args = parser.parse_args()

    exit_code = 0
    for f in args.files:
        if not f.is_file():
            print(f"skip: {f}: not found", file=sys.stderr)
            exit_code = 1
            continue
        try:
            dt = fetch_creation_time(f)
        except RuntimeError as e:
            print(f"skip: {f}: ffprobe failed ({e})", file=sys.stderr)
            exit_code = 1
            continue
        if dt is None:
            print(f"skip: {f}: no creation-time metadata found", file=sys.stderr)
            exit_code = 1
            continue

        if args.dry_run:
            current = datetime.fromtimestamp(f.stat().st_mtime, tz=dt.tzinfo)
            print(f"would set: {f}: {current.isoformat()} -> {dt.isoformat()}", file=sys.stderr)
        else:
            ts = dt.timestamp()
            os.utime(f, (ts, ts))
            print(f"set: {f}: mtime -> {dt.isoformat()}", file=sys.stderr)

    sys.exit(exit_code)


if __name__ == "__main__":
    main()