"""Implementation of the "poller" IPC component"""

import argparse
import os
import sys
import time

import systemd.daemon

import gitubuntu.importer_service as importer_service
import gitubuntu.scriptutils as scriptutils
from gitubuntu.source_information import launchpad_login

def main_loop(
    lp,
    service_state,
    poll_interval,
    filter_func=None,
):
    """Main loop for the importer service poller process

    :param importer_service.State service_state: the state object of the
        importer service.
    :param int poll_interval: how often to poll, in seconds.
    :param filter_func: a function that when called with a sole parameter
        string providing a package name, returns a bool that specifies whether
        or not that package should be imported.
    """
    while True:
        # Notify systemd that we're still alive
        systemd.daemon.notify('WATCHDOG=1')

        importer_service.request_new_imports(
            lp=lp,
            num_days_ago=1,
            service_state=service_state,
            filter_func=filter_func,
        )
        time.sleep(poll_interval)


def main(
    data_directory,
    denylist_path,
    poll_interval,
):
    """Entry point for the importer service poller process

    :param str data_directory: the path where persistent data on the status of
        the import may be stored
    :param str denylist_path: filesystem path to a text file of packages
        to never import
    :param int poll_interval: how often to poll, in seconds.
    """
    service_state = importer_service.State(os.path.join(data_directory, 'db'))
    denylist = frozenset(importer_service.read_package_list(denylist_path))

    # Initialize system notification
    systemd.daemon.notify('READY=1')

    print("Monitoring packages", file=sys.stderr)
    sys.stderr.flush()  # systemd-run services buffer stderr by default

    lp = launchpad_login()

    main_loop(
        lp=lp,
        service_state=service_state,
        poll_interval=poll_interval,
        filter_func=lambda package: package not in denylist,
    )  # never returns

def parse_args(subparsers=None, base_subparsers=None):
    kwargs = {
        'description': (
            "Monitor Launchpad for new publications and request imports "
            "accordingly"
        ),
        'formatter_class': argparse.ArgumentDefaultsHelpFormatter,
    }
    if base_subparsers:
        kwargs['parents'] = base_subparsers
    if subparsers:
        parser = subparsers.add_parser('importer-service-poller', **kwargs)
        parser.set_defaults(func=cli_main)
    else:
        parser = argparse.ArgumentParser(**kwargs)

    parser.add_argument(
        '--data-directory',
        help="Directory to store persistent data",
        default='/var/local/git-ubuntu',
    )
    parser.add_argument(
        '--denylist',
        type=str,
        help="Path to denylist file",
        default=scriptutils.DEFAULTS.denylist,
    )
    parser.add_argument(
        '--poll-interval',
        type=int,
        help=(
            "Polling interval in seconds to examine Launchpad for new "
            "publications"
        ),
        default=600,
    )
    if not subparsers:
        return parser.parse_args()
    return 'import-service-poller - %s' % kwargs['description']

def cli_main(args):
    """CLI entry point for the importer service poller process"""
    main(
        data_directory=args.data_directory,
        denylist_path=args.denylist,
        poll_interval=args.poll_interval,
    )