#!/usr/bin/env python
#
# Copyright 2009 Facebook
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

import logging
import tornado.ioloop
import tornado.options
import tornado.web
import tornado.websocket
import os.path
import uuid
import json
import datetime

from tornado.options import define, options

define("port", default=8888, help="run on the given port", type=int)


class Application(tornado.web.Application):
    def __init__(self):
        handlers = [
            (r"/", MainHandler),
            (r"/chat", WebSocketHandler),
        ]
        settings = dict(
            template_path=os.path.join(os.path.dirname(__file__), "templates"),
            static_path=os.path.join(os.path.dirname(__file__), "static"),
            debug=True
        )
        tornado.web.Application.__init__(self, handlers, **settings)


class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.render("index.html")


class MessageMixin(object):
    subscribers = set()

    def subscribe(self, callback):
        cls = MessageMixin
        cls.subscribers.add(callback)

    def unsubscribe(self, callback):
        cls = MessageMixin
        cls.subscribers.remove(callback)

    def broadcast(self, message):
        cls = MessageMixin
        logging.info("Sending new message to %r listeners", len(cls.subscribers))
        for callback in cls.subscribers:
            try:
                callback(json.dumps({
                    "message" : message,
                    "time"    : str(datetime.datetime.today()),
                    "username" : "Jesse"
                }))
            except:
                logging.error("Error in waiter callback", exc_info=True)


class WebSocketHandler(tornado.websocket.WebSocketHandler, MessageMixin):
    def open(self):
        logging.info("WebSocket opened!")
        self.subscribe(self.send_message)
        
    def send_message(self, message):
        self.write_message(message)

    def on_message(self, message):
        self.broadcast(message)

    def on_close(self):
        logging.info("WebSocket closed!")
        self.unsubscribe(self.send_message)

def main():
    tornado.options.parse_command_line()
    app = Application()
    app.listen(options.port)
    tornado.ioloop.IOLoop.instance().start()


if __name__ == "__main__":
    main()