"""
Command-line utility to start a stub service.
"""
from __future__ import print_function
import logging
import sys
import time

from .catalog import StubCatalogService
from .comments import StubCommentsService
from .ecommerce import StubEcommerceService
from .edxnotes import StubEdxNotesService
from .lti import StubLtiService
from .video_source import VideoSourceHttpService
from .xqueue import StubXQueueService
from .youtube import StubYouTubeService

USAGE = "USAGE: python -m stubs.start SERVICE_NAME PORT_NUM [CONFIG_KEY=CONFIG_VAL, ...]"

SERVICES = {
    'xqueue': StubXQueueService,
    'youtube': StubYouTubeService,
    'comments': StubCommentsService,
    'lti': StubLtiService,
    'video': VideoSourceHttpService,
    'edxnotes': StubEdxNotesService,
    'ecommerce': StubEcommerceService,
    'catalog': StubCatalogService,
}

# Log to stdout, including debug messages
logging.basicConfig(level=logging.DEBUG, format="%(levelname)s %(message)s")


def get_args():
    """
    Parse arguments, returning tuple of `(service_name, port_num, config_dict)`.
    Exits with a message if arguments are invalid.
    """
    if len(sys.argv) < 3:
        print(USAGE)
        sys.exit(1)

    service_name = sys.argv[1]
    port_num = sys.argv[2]
    config_dict = _parse_config_args(sys.argv[3:])

    if service_name not in SERVICES:
        print("Unrecognized service '{0}'.  Valid choices are: {1}".format(
            service_name, ", ".join(SERVICES.keys())))
        sys.exit(1)

    try:
        port_num = int(port_num)
        if port_num < 0:
            raise ValueError

    except ValueError:
        print("Port '{0}' must be a positive integer".format(port_num))
        sys.exit(1)

    return service_name, port_num, config_dict


def _parse_config_args(args):
    """
    Parse stub configuration arguments, which are strings of the form "KEY=VAL".
    `args` is a list of arguments from the command line.
    Any argument that does not match the "KEY=VAL" format will be logged and skipped.

    Returns a dictionary with the configuration keys and values.
    """
    config_dict = dict()
    for config_str in args:
        try:
            components = config_str.split('=')
            if len(components) >= 2:
                config_dict[components[0]] = "=".join(components[1:])

        except:
            print("Warning: could not interpret config value '{0}'".format(config_str))

    return config_dict


def main():
    """
    Start a server; shut down on keyboard interrupt signal.
    """
    service_name, port_num, config_dict = get_args()
    print("Starting stub service '{0}' on port {1}...".format(service_name, port_num))

    server = SERVICES[service_name](port_num=port_num)
    server.config.update(config_dict)

    try:
        while True:
            time.sleep(1)

    except KeyboardInterrupt:
        print("Stopping stub service...")

    finally:
        server.shutdown()


if __name__ == "__main__":
    main()