import argparse
from pathlib import Path
import os
from PIL import Image

def writable_dir(target_path):
    """ Check if a path is a valid directory and that it can be written to. """
    path = Path(target_path)
    if path.is_dir():
        if os.access(path, os.W_OK):
            return path
        else:
            raise argparse.ArgumentTypeError(f"Directory '{path}' is not writable.")
    else:
        raise argparse.ArgumentTypeError(f"Directory '{path}' does not exist.")
    
def main():
    # Define the command-line arguments
    parser = argparse.ArgumentParser()
    parser.add_argument("directory", type=writable_dir,
                        help="the directory containing the images to be converted")
    parser.add_argument("--in_ext", type=str, default="webp",
                        help="the input file extension")
    parser.add_argument("--out_ext", type=str, default="webp",
                        help="the output file extension")
    parser.add_argument("--delete_originals", action="store_true",
                        help="whether to delete the original files after conversion")

    # Parse the command-line arguments
    args = parser.parse_args()
    directory = Path(args.directory)
    in_ext = args.in_ext
    delete_originals = args.delete_originals

    # Create the file pattern string using the input file extension
    file_pattern = f"*.{in_ext}"

    # Get the list of files in the directory that match the file pattern
    files = list(directory.glob(file_pattern))

    # Iterate over the list of files
    for file in files:
        try:
            # Open the image file
            img = Image.open(file)

            # Create a new file path with the output file extension
            new_path = file.with_suffix(f".{args.out_ext}")
            print(new_path)

            # Check if the output file already exists
            if new_path.exists():
                # Skip the conversion if the output file already exists
                print(f"Skipping {file} because {new_path} already exists")
                continue

            # Save the image to the new file as lossless
            img.save(new_path, lossless=True)

            # Close the image file
            img.close()

            # Optionally, delete the original file
            if delete_originals:
                file.unlink()
        except Exception as e:
            print(f"Error processing {file}: {e}")


if __name__ == "__main__":
    main()