"""Clean file names (snake_case)

Renames every file in one folder to a clean, lowercase, web-safe name:
"My Photo (Final) #2.JPG" becomes "my_photo_final_2.jpg".

Free script from LinearAndLoom Icons: https://linearandloomicons.netlify.app/scripts/
Provided as is. Renaming and zipping cannot be undone, so try it on a copy of your folder first.
"""
import re
import unicodedata
from pathlib import Path


def to_snake_case_filename(filename: str, max_length: int = 180) -> str:
    """
    Convert filename to clean SEO-friendly snake_case.
    Preserves extension and removes invalid characters.
    """
    path = Path(filename)
    stem = path.stem
    suffix = path.suffix.lower()

    # Normalize unicode → ASCII
    stem = unicodedata.normalize("NFKD", stem)
    stem = stem.encode("ascii", "ignore").decode("ascii")

    # Lowercase for snake_case
    stem = stem.lower()

    # Remove invalid filename chars (Windows + cross-platform safe)
    stem = re.sub(r'[<>:"/\\|?*\x00-\x1F]', "", stem)

    # Replace any non-alphanumeric sequence with underscore
    stem = re.sub(r"[^a-z0-9]+", "_", stem)

    # Remove repeated underscores
    stem = re.sub(r"_+", "_", stem)

    # Strip leading/trailing underscores
    stem = stem.strip("_")

    # Prevent empty names
    if not stem:
        stem = "file"

    # Trim total length safely
    max_stem_len = max_length - len(suffix)
    stem = stem[:max_stem_len].rstrip("_")

    return stem + suffix


def normalize_folder_filenames(folder_path: str):
    folder = Path(folder_path)

    if not folder.exists() or not folder.is_dir():
        print("Invalid folder path.")
        return

    used_names = set()
    this_script = Path(__file__).resolve()

    # List the files first, so files renamed along the way are not picked up twice
    for file in sorted(f for f in folder.iterdir() if f.is_file()):
        # Leave hidden system files (.DS_Store, .gitignore) and this script alone
        if file.name.startswith(".") or file.resolve() == this_script:
            continue

        new_name = to_snake_case_filename(file.name)
        new_path = folder / new_name

        # Handle duplicates
        base_stem = Path(new_name).stem
        suffix = Path(new_name).suffix
        counter = 1

        # samefile() keeps "Photo.JPG" -> "photo.jpg" working on Windows and macOS,
        # where both names point to the same file
        while new_name in used_names or (new_path.exists() and not new_path.samefile(file)):
            new_name = f"{base_stem}_{counter}{suffix}"
            new_path = folder / new_name
            counter += 1

        used_names.add(new_name)

        if file.name != new_name:
            file.rename(new_path)
            print(f"Renamed: {file.name} -> {new_name}")


if __name__ == "__main__":
    folder_path = input("Enter folder path: ").strip().strip('"').strip("'")
    normalize_folder_filenames(folder_path)