#!/usr/bin/env python
#
# Copyright (C) 2020 GNS3 Technologies Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import asyncio

from fastapi import FastAPI
from contextlib import asynccontextmanager

from gns3server.controller import Controller
from gns3server.config import Config
from gns3server.compute import MODULES
from gns3server.compute.port_manager import PortManager
from gns3server.compute.marker.marker_manager import MarkerManager
from gns3server.utils.http_client import HTTPClient
from gns3server.db.tasks import connect_to_db, get_computes, disconnect_from_db, discover_images_on_filesystem


import logging

log = logging.getLogger(__name__)

auto_discover_images_task_handle = None


@asynccontextmanager
async def lifespan(app: FastAPI):

    await startup(app)
    yield
    await shutdown(app)


async def startup(app: FastAPI) -> None:
    """
    Tasks to be performed when the server is starting.
    """

    loop = asyncio.get_event_loop()
    logger = logging.getLogger("asyncio")
    logger.setLevel(logging.ERROR)

    if log.getEffectiveLevel() == logging.DEBUG:
        # On debug version we enable info that
        # coroutine is not called in a way await/await
        loop.set_debug(True)

    # connect to the database
    await connect_to_db(app)

    # retrieve the computes from the database
    computes = await get_computes(app)

    await Controller.instance().start(computes)

    # Because with a large image collection
    # without md5sum already computed we start the
    # computing with server start
    from gns3server.compute.qemu import Qemu

    if Config.instance().settings.Server.auto_discover_images is True:
        # Start the discovering new images on file system 5 seconds after the server has started
        # to give it a chance to process API requests
        global auto_discover_images_task_handle
        auto_discover_images_task_handle = asyncio.get_event_loop().call_later(
            5,
            lambda: asyncio.create_task(discover_images_on_filesystem(app))
        )

    for module in MODULES:
        log.debug(f"Loading module {module.__name__}")
        m = module.instance()
        m.port_manager = PortManager.instance()

    # Start the marker (traffic-insight) UDP sink. One listener per compute
    # process receives ubridge MARK signals; ubridges are told its host/port at
    # startup (see BaseNode._start_ubridge).
    server_settings = Config.instance().settings.Server
    await MarkerManager.instance().start(
        host=server_settings.marker_listen_host, port=server_settings.marker_listen_port
    )

    # Mark MCP server as ready to accept connections (if MCP is available)
    from gns3server.agent import MCP_AVAILABLE

    if MCP_AVAILABLE:
        from gns3server.api.routes.mcp import set_mcp_server_ready
        set_mcp_server_ready(True)
    log.info("GNS3 server startup completed")


async def shutdown(app: FastAPI) -> None:
    """
    Tasks to be performed when the server is exiting.
    """

    if auto_discover_images_task_handle is not None and not auto_discover_images_task_handle.cancelled():
        auto_discover_images_task_handle.cancel()
    await HTTPClient.close_session()
    await MarkerManager.instance().stop()
    await Controller.instance().stop()

    for module in MODULES:
        log.debug(f"Unloading module {module.__name__}")
        m = module.instance()
        await m.unload()

    if PortManager.instance().tcp_ports:
        log.warning(f"TCP ports are still used {PortManager.instance().tcp_ports}")

    if PortManager.instance().udp_ports:
        log.warning(f"UDP ports are still used {PortManager.instance().udp_ports}")

    await disconnect_from_db(app)
