rename photos by EXIF / file creation date

renamer.py

import os
import re
from datetime import datetime
from pathlib import Path
from PIL import Image

# Tag IDs for EXIF data
# 36867: DateTimeOriginal (Shutter click)
# 306:   DateTime (Last metadata change)
EXIF_DATE_TAGS = (36867, 306)


def get_best_date(entry: os.DirEntry) -> str:
  """Retrieves the most accurate date available for a file.

  Checks EXIF metadata first, then falls back to the file system creation time.
  Returns a string in YYYYMMDD format.
  """
  # Attempts to read EXIF data
  try:
    with Image.open(entry.path) as img:
      exif = img.getexif()
      if exif:
        for tag in EXIF_DATE_TAGS:
          val = exif.get(tag)
          if val:
            # Cleans EXIF format 'YYYY:MM:DD HH:MM:SS'
            date_str = str(val)[:10].replace(':', '')
            if len(date_str) == 8 and date_str.isdigit():
              return date_str
  except Exception:
    # Fail silently to allow fallback to file system stats
    pass

  # Falls back to file system creation time (st_ctime)
  # Uses the DirEntry stat to avoid an extra syscall
  timestamp = entry.stat().st_ctime
  return datetime.fromtimestamp(timestamp).strftime('%Y%m%d')


def rename_files():
  """Scans the current directory and renames images with a date prefix."""
  valid_extensions = {'.jpg', '.jpeg', '.png'}
  # Matches 8 digits at the start of a string
  date_prefix_regex = re.compile(r"^\d{8}_")

  cwd = Path('.')
  rename_count = 0

  # Uses scandir for better performance on large directories
  with os.scandir(cwd) as entries:
    for entry in entries:
      if not entry.is_file():
        continue

      path = Path(entry.name)
      if path.suffix.lower() not in valid_extensions:
        continue

      # Skips files that already have the YYYYMMDD_ format
      if date_prefix_regex.match(entry.name):
        continue

      date_prefix = get_best_date(entry)
      new_name = f"{date_prefix}_{entry.name}"
      target_path = cwd / new_name

      # Handles naming collisions (e.g., 20251229_photo.jpg already exists)
      counter = 1
      while target_path.exists():
        stem = Path(new_name).stem
        ext = Path(new_name).suffix
        target_path = cwd / f"{stem}_{counter}{ext}"
        counter += 1

      try:
        os.rename(entry.path, target_path)
        print(f"Renamed: {entry.name} -> {target_path.name}")
        rename_count += 1
      except OSError as e:
        print(f"Failed to rename {entry.name}: {e}")

  print(f"\nProcessing complete. {rename_count} files updated.")


if __name__ == "__main__":
  rename_files()