import argparse
import os
import re
import pathlib


def build_argument_parser(description: str) -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(description=description)
    parser.add_argument(
        "--data-dir",
        "-d",
        type=valid_directory,
        required=True,
        help="Data directory from 5etools",
    )
    parser.add_argument(
        "--source-code",
        "-s",
        action="append",
        metavar="CODE",
        type=valid_source_code,
        help="Filter data to just the given sources, may be provided multiple times",
    )
    return parser


def valid_directory(path: str) -> pathlib.Path:
    if os.path.isdir(path):
        return pathlib.Path(os.path.realpath(path))
    raise argparse.ArgumentTypeError(f"{path} is not a directory")


def valid_source_code(code: str) -> str:
    if re.match(r"^[A-Z]+$", code) is None:
        raise argparse.ArgumentTypeError(f"{code} is not a valid data source code")
    return code