#!/usr/bin/env python3
"""Small typed CLI example with a few local tests."""

from __future__ import annotations

import argparse
import sys
import unittest
from dataclasses import dataclass
from typing import Sequence


@dataclass(frozen=True)
class Options:
    name: str
    times: int
    shout: bool
    run_tests: bool


def positive_int(value: str) -> int:
    """argparse type callback that accepts only positive integers."""
    try:
        parsed = int(value)
    except ValueError as exc:
        raise argparse.ArgumentTypeError(f"{value!r} is not an integer") from exc

    if parsed < 1:
        raise argparse.ArgumentTypeError("value must be at least 1")
    return parsed


def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(description="Print a greeting.")
    parser.add_argument("name", nargs="?", default="world", help="name to greet")
    parser.add_argument("-n", "--times", type=positive_int, default=1, help="number of greetings")
    parser.add_argument("--shout", action="store_true", help="uppercase the greeting")
    parser.add_argument("--run-tests", action="store_true", help="run this file's tests")
    return parser


def parse_args(argv: Sequence[str]) -> Options:
    namespace = build_parser().parse_args(argv)
    return Options(
        name=namespace.name,
        times=namespace.times,
        shout=namespace.shout,
        run_tests=namespace.run_tests,
    )


def make_greeting(name: str, shout: bool = False) -> str:
    message = f"Hello, {name}!"
    return message.upper() if shout else message


def main(argv: Sequence[str] | None = None) -> int:
    options = parse_args(sys.argv[1:] if argv is None else argv)

    if options.run_tests:
        suite = unittest.defaultTestLoader.loadTestsFromTestCase(CliTests)
        result = unittest.TextTestRunner(verbosity=2).run(suite)
        return 0 if result.wasSuccessful() else 1

    for _ in range(options.times):
        print(make_greeting(options.name, options.shout))
    return 0


class CliTests(unittest.TestCase):
    def test_make_greeting_default_case(self) -> None:
        self.assertEqual(make_greeting("Ada"), "Hello, Ada!")

    def test_parse_args_with_options(self) -> None:
        options = parse_args(["Ada", "--times", "2", "--shout"])
        self.assertEqual(options, Options(name="Ada", times=2, shout=True, run_tests=False))


if __name__ == "__main__":
    raise SystemExit(main())