#!/usr/bin/env python
#
# Copyright (C) 2016 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 aiohttp
from contextlib import contextmanager

from ..notification_queue import NotificationQueue


class Notification:
    """
    Manage notification for the controller
    """

    def __init__(self, controller):
        self._controller = controller
        self._listeners = {}

    @contextmanager
    def queue(self, project):
        """
        Get a queue of notifications

        Use it with Python with
        """
        queue = NotificationQueue()
        self._listeners.setdefault(project.id, set())
        self._listeners[project.id].add(queue)
        yield queue
        self._listeners[project.id].remove(queue)

    def dispatch(self, action, event, compute_id):
        """
        Notification received from compute node. Send it directly
        to clients or process it

        :param action: Action name
        :param event: Event to send
        :param compute_id: Compute id of the sender
        """
        if action == "node.updated":
            try:
                # Update controller node data and send the event node.updated
                project = self._controller.get_project(event["project_id"])
                node = project.get_node(event["node_id"])
                node.parse_node_response(event)

                self.emit("node.updated", node.__json__())
            except aiohttp.web.HTTPNotFound:
                return
        elif action == "ping":
            event["compute_id"] = compute_id
            self.emit(action, event)
        else:
            self.emit(action, event)

    def emit(self, action, event):
        """
        Send a notification to clients scoped by projects

        :param action: Action name
        :param event: Event to send
        """
        if "project_id" in event:
            self._send_event_to_project(event["project_id"], action, event)
        else:
            self._send_event_to_all(action, event)

    def _send_event_to_project(self, project_id, action, event):
        """
        Send an event to all the client listening for notifications for
        this project

        :param project: Project where we need to send the event
        :param action: Action name
        :param event: Event to send
        """
        try:
            project_listeners = self._listeners[project_id]
        except KeyError:
            return
        for listener in project_listeners:
            listener.put_nowait((action, event, {}))

    def _send_event_to_all(self, action, event):
        """
        Send an event to all the client listening for notifications on all
        projects

        :param action: Action name
        :param event: Event to send
        """
        for project_listeners in self._listeners.values():
            for listener in project_listeners:
                listener.put_nowait((action, event, {}))