#!/usr/bin/python3

# Copyright (C) 2017 Internet Systems Consortium, Inc. ("ISC")
#
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

"""
Text client for Control Agent process
"""

# First, let's import the right kea_connector.
# We have two versions: one for python 2.x and another for python 3.x.
# Sadly, there's no unified way to handle http connections. The recommended
# way is to use Requests (http://docs.python-requests.org/en/master/), but
# that's a stand alone package that requires separate installation. One of
# the design requirements was to not require any additional packages, so
# the code uses standard libraries available in python. Hence two versions.
import os
import sys
import signal
import argparse

sys.path.append('/usr/lib/python3.7/site-packages/kea')

from kea_conn import CARequest # CAResponse

if sys.version_info[0] == 2:
    # This is Python 2.x
    import kea_connector2 as kea_connector
elif sys.version_info[0] == 3:
    # This is Python 3.x
    import kea_connector3 as kea_connector
else:
    # This is... have no idea what it is.
    raise SystemExit("Unknown python version:" + str(sys.version_info[0]))

def timeout_handler(signum, frame):
    """Connection timeout handler"""
    del signum, frame
    print("Connection timeout")
    sys.exit(1)

VERSION = "1.5.0"

def shell_body():
    """
    Second step: Need to parse command line parameters. We will use
    argparse for that purpose. It does great job with having default
    values, taking care of the help and sanity checking input
    parameters.
    """
    parser = argparse.ArgumentParser(description='kea-shell is a simple text '
                                     'client that uses REST interface to '
                                     'connect to Kea Control Agent.')
    parser.add_argument('--host', type=str, default='127.0.0.1',
                        help='hostname of the CA to connect to '
                        '(default:; 127.0.0.1)')
    parser.add_argument('--port', type=int, default=8000,
                        help='TCP port of the CA to connect to '
                        '(default: 8000)')
    parser.add_argument('--path', type=str, default='',
                        help='Path of the URL to connect to '
                        '(default: "")')
    parser.add_argument('--timeout', type=int, default='10',
                        help='Timeout (in seconds) when attempting to '
                        'connect to CA (default: 10)')
    parser.add_argument('--service', nargs="?", action="append",
                        help='target spcified service. If not specified,'
                        'control agent will receive command.')
    parser.add_argument('command', type=str, nargs="?",
                        default='list-commands',
                        help='command to be executed. If not specified, '
                        '"list-commands" is used')
    parser.add_argument('-v', action="store_true", help="Prints version")
    cmd_args = parser.parse_args()

    if cmd_args.v:
        print(VERSION)
        exit(0)

    # Ok, now it's time to put the parameters parsed into the structure to be
    # used by the connection.
    params = CARequest()
    params.command = cmd_args.command
    params.service = cmd_args.service
    params.http_host = cmd_args.host
    params.http_port = cmd_args.port
    params.path += cmd_args.path
    params.timeout = cmd_args.timeout
    params.version = VERSION

    # Load command processor
    # @todo - command specific processing will be added as part of
    # future work (either #5138 or #5139, whichever is implemented
    # first)

    # Read arguments from stdin (they're optional for some commands)
    for line in sys.stdin:
        params.args += line

    # Now we have the arguments so we can build the request
    params.generate_body()
    params.generate_headers()

    # Set the timeout timer. If the connection takes too long,
    # it will send a signal to us.
    signal.signal(signal.SIGALRM, timeout_handler)
    signal.alarm(params.timeout)

    # Ok, everything is ready. Let's send the command and get a response.
    try:
        resp = kea_connector.send_to_control_agent(params)
    except Exception as exc:
        print("Failed to run: " + str(exc))
        sys.exit(1)

    resp.print_response()

    sys.exit(0)

if __name__ == "__main__":
    shell_body()
