import argparse
import sys
import unittest

from tap.loader import Loader
from tap.runner import TAPTestRunner


def main(argv=sys.argv, stream=sys.stderr):
    """Entry point for ``tappy`` command."""
    args = parse_args(argv)
    suite = build_suite(args)
    runner = unittest.TextTestRunner(verbosity=args.verbose, stream=stream)
    result = runner.run(suite)

    return get_status(result)


def build_suite(args):
    """Build a test suite by loading TAP files or a TAP stream."""
    loader = Loader()
    if len(args.files) == 0 or args.files[0] == "-":
        suite = loader.load_suite_from_stdin()
    else:
        suite = loader.load(args.files)
    return suite


def parse_args(argv):
    description = "A TAP consumer for Python"
    epilog = (
        "When no files are given or a dash (-) is used for the file name, "
        "tappy will read a TAP stream from STDIN."
    )
    parser = argparse.ArgumentParser(description=description, epilog=epilog)
    parser.add_argument(
        "files",
        metavar="FILE",
        nargs="*",
        help=(
            "A file containing TAP output. Any directories listed will be "
            "scanned for files to include as TAP files."
        ),
    )
    parser.add_argument(
        "-v",
        "--verbose",
        action="store_const",
        default=1,
        const=2,
        help="use verbose messages",
    )

    # argparse expects the executable to be removed from argv.
    args = parser.parse_args(argv[1:])

    # When no files are provided, the user wants to use a TAP stream on STDIN.
    # But they probably didn't mean it if there is no pipe connected.
    # In that case, print the help and exit.
    if not args.files and sys.stdin.isatty():
        sys.exit(parser.print_help())

    return args


def get_status(result):
    """Get a return status from the result."""
    if result.wasSuccessful():
        return 0
    else:
        return 1


def main_module():
    """Entry point for running as ``python -m tap``."""
    runner = TAPTestRunner()
    runner.set_stream(True)
    unittest.main(module=None, testRunner=runner)