"""Normalize image names in clouds_1/ to sequential numbers.

Files already named as a plain number (e.g. 42.jpg, 105.JPG) are left
untouched. All other images get numbers continuing after the current
maximum, ordered by date: EXIF DateTimeOriginal when present, file
mtime otherwise — so an earlier date always gets a smaller number.

Usage:
    python3 normalize_names.py          # dry run, prints the plan
    python3 normalize_names.py --apply  # actually rename
"""

import argparse
import json
import os
import re
import sys
from datetime import datetime

from PIL import Image

FOLDER = os.path.join(os.path.dirname(os.path.abspath(__file__)), "clouds_1")
IMAGE_EXTS = {".jpg", ".jpeg", ".png"}
VALID_NAME = re.compile(r"^\d+$")

EXIF_DATETIME_ORIGINAAL = 36867
EXIF_DATETIME_DIGITIZED = 36868
EXIF_DATETIME = 306


def get_date(path):
    """EXIF capture date if available, otherwise file mtime."""
    try:
        with Image.open(path) as img:
            exif = img.getexif()
            raw = (
                exif.get_ifd(0x8769).get(EXIF_DATETIME_ORIGINAAL)
                or exif.get_ifd(0x8769).get(EXIF_DATETIME_DIGITIZED)
                or exif.get(EXIF_DATETIME)
            )
        if raw:
            return datetime.strptime(str(raw), "%Y:%m:%d %H:%M:%S")
    except Exception:
        pass
    return datetime.fromtimestamp(os.path.getmtime(path))


def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--apply", action="store_true", help="perform the renames")
    args = parser.parse_args()

    max_num = -1
    to_rename = []
    for name in sorted(os.listdir(FOLDER)):
        stem, ext = os.path.splitext(name)
        if ext.lower() not in IMAGE_EXTS:
            continue
        if VALID_NAME.match(stem):
            max_num = max(max_num, int(stem))
        else:
            path = os.path.join(FOLDER, name)
            to_rename.append((get_date(path), name, ext))

    if not to_rename:
        print("Nothing to rename: all image names are already numeric.")
        return

    to_rename.sort()  # by date, then name for stable ties

    mapping = {}
    next_num = max_num + 1
    for date, name, ext in to_rename:
        new_name = f"{next_num}{ext}"
        mapping[name] = new_name
        print(f"{date}  {name:30s} -> {new_name}")
        next_num += 1

    if not args.apply:
        print(f"\nDry run: {len(mapping)} files would be renamed "
              f"({max_num + 1}..{next_num - 1}). Re-run with --apply.")
        return

    for old, new in mapping.items():
        os.rename(os.path.join(FOLDER, old), os.path.join(FOLDER, new))

    map_path = os.path.join(FOLDER, "rename_map.json")
    with open(map_path, "w") as f:
        json.dump(mapping, f, indent=2, ensure_ascii=False)
    print(f"\nRenamed {len(mapping)} files; mapping saved to {map_path}")


if __name__ == "__main__":
    sys.exit(main())