from string import ascii_letters as s

import click


@click.command()
@click.option('--dec', is_flag=True)
@click.argument('filename', nargs=1)
@click.argument('key', nargs=1)
def cli(dec, filename, key):
    with open(filename, 'r') as text:
        table = str.maketrans(key, s) if dec else str.maketrans(s, key)
        click.echo(text.read().translate(table))


if __name__ == "__main__":
    cli()