import sys
from argparse import ArgumentParser

from borgmatic.config import generate, validate

DEFAULT_DESTINATION_CONFIG_FILENAME = '/etc/borgmatic/config.yaml'


def parse_arguments(*arguments):
    '''
    Given command-line arguments with which this script was invoked, parse the arguments and return
    them as an ArgumentParser instance.
    '''
    parser = ArgumentParser(description='Generate a sample borgmatic YAML configuration file.')
    parser.add_argument(
        '-s',
        '--source',
        dest='source_filename',
        help='Optional YAML configuration file to merge into the generated configuration, useful for upgrading your configuration',
    )
    parser.add_argument(
        '-d',
        '--destination',
        dest='destination_filename',
        default=DEFAULT_DESTINATION_CONFIG_FILENAME,
        help=f'Destination YAML configuration file, default: {DEFAULT_DESTINATION_CONFIG_FILENAME}',
    )
    parser.add_argument(
        '--overwrite',
        default=False,
        action='store_true',
        help='Whether to overwrite any existing destination file, defaults to false',
    )

    return parser.parse_args(arguments)


def main():  # pragma: no cover
    try:
        args = parse_arguments(*sys.argv[1:])

        generate.generate_sample_configuration(
            args.source_filename,
            args.destination_filename,
            validate.schema_filename(),
            overwrite=args.overwrite,
        )

        print(f'Generated a sample configuration file at {args.destination_filename}.')
        print()
        if args.source_filename:
            print(f'Merged in the contents of configuration file at {args.source_filename}.')
            print('To review the changes made, run:')
            print()
            print(f'    diff --unified {args.source_filename} {args.destination_filename}')
            print()
        print('This includes all available configuration options with example values. The few')
        print('required options are indicated. Please edit the file to suit your needs.')
        print()
        print('If you ever need help: https://torsion.org/borgmatic/#issues')
    except (ValueError, OSError) as error:
        print(error, file=sys.stderr)
        sys.exit(1)