#!/usr/bin/env python3
from datetime import datetime, timezone
from pathlib import Path
from typing import Optional
import argparse
import logging
import os
import pwd

logging.basicConfig(
    level=logging.INFO,
    format='%(levelname)s: %(message)s',
)
logger = logging.getLogger(__name__)


def _get_username():
    return pwd.getpwuid(os.getuid()).pw_name


# The recfile descriptor for package requests.
# Used if Breadpack generates the file from scratch.
REQUEST_DESCRIPTOR = """
%rec: PackageRequest
%type: Date date
%type: Processed bool
%type: User line
%type: Package line
%mandatory: Package
%allowed: Date User Processed Package Comment
%sort: Processed Date
%doc: Package requests made via breadpack
""".strip()


def request_subcommand(
        requestsfile: Path,
        package_name: str,
        comment: Optional[str] = None,
        **kwargs):
    if not requestsfile.exists():
        logger.warning(f'Creating file {requestsfile}')
        with requestsfile.open('w') as f:
            f.write(REQUEST_DESCRIPTOR)

    data = {
        'Date': datetime.now(timezone.utc).isoformat(),
        'User': _get_username(),
        'Processed': 'no',
        'Package': package_name,
    }
    if comment:
        data['Comment'] = comment

    with requestsfile.open('a') as f:
        f.write('\n\n' + '\n'.join([f'{k}: {v}' for k, v in data.items()]))

    logger.info(f'Your request for {package_name!r} has been sent!')


def list_subcommand(json: bool = False, upgradable: bool = False, **kwargs):
    raise NotImplementedError


def lint_subcommand(file, **kwargs):
    raise NotImplementedError


def check_subcommand(json: bool = False, save: bool = True, **kwargs):
    raise NotImplementedError


def lock_subcommand(**kwargs):
    raise NotImplementedError


def main():
    parser = argparse.ArgumentParser(
        description='Breadpunk.club meta-package manager'
    )
    parser.add_argument(
        '--file',
        type=Path,
        help='Path to the breadpack.json file.',
        default=Path('/bread/breadpack.json'),
    )
    parser.add_argument(
        '--lockfile',
        type=Path,
        help='Path to the breadpack-lock.json file.',
        default=Path('/bread/breadpack-lock.json'),
    )
    parser.add_argument(
        '--requestsfile',
        type=Path,
        help='Path to the breadpack-requests.rec file.',
        default=Path('/bread/breadpack-requests.rec'),
    )

    def nocommand(**kwargs):
        parser.error('A subcommand is required.')

    parser.set_defaults(func=nocommand)
    subparsers = parser.add_subparsers(
        title='subcommands',
    )

    request_parser = subparsers.add_parser(
        'request',
        help='Request for a new package to be installed.',
    )
    request_parser.add_argument(
        'package_name',
        help='Name of the requested package.',
    )
    request_parser.add_argument(
        '-c', '--comment',
        help='Optional comment to add notes '
             'for the admin processing your request.',
        default=None,
    )
    request_parser.set_defaults(func=request_subcommand)

    list_parser = subparsers.add_parser(
        'list',
        help='List installed packages.',
    )
    list_parser.add_argument(
        '--json',
        help='Use JSON output.',
        action='store_true',
        default=False,
    )
    list_parser.add_argument(
        '--upgradable',
        help='Only list packages with available updates.',
        action='store_true',
        default=False,
    )
    list_parser.set_defaults(func=list_subcommand)

    lint_parser = subparsers.add_parser(
        'lint',
        help='Check the syntax of the packages file and lockfile.',
    )
    lint_parser.set_defaults(func=lint_subcommand)

    lock_parser = subparsers.add_parser(
        'lock',
        help='Regenerate the lockfile from scratch.',
    )
    lock_parser.set_defaults(func=lock_subcommand)

    check_parser = subparsers.add_parser(
        'check',
        help='Check for available updates.',
    )
    check_parser.add_argument(
        '--json',
        help='Use JSON output.',
        action='store_true',
        default=False,
    )
    check_parser.add_argument(
        '--save',
        help='Update the lockfile. This is the default.',
        action='store_true',
        default=True,
    )
    check_parser.add_argument(
        '--no-save',
        help='Do not update the lockfile.',
        action='store_false',
        dest='save',
    )

    args = vars(parser.parse_args())
    args.pop('func', nocommand)(**args)


if __name__ == '__main__':
    main()