#!/usr/bin/env python
#
# A library that provides a Python interface to the Telegram Bot API
# Copyright (C) 2015-2018
# Leandro Toledo de Souza <devs@python-telegram-bot.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser 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 Lesser Public License for more details.
#
# You should have received a copy of the GNU Lesser Public License
# along with this program.  If not, see [http://www.gnu.org/licenses/].
import logging
from telegram import Update
from future.utils import bytes_to_native_str
from threading import Lock
try:
    import ujson as json
except ImportError:
    import json
from tornado.httpserver import HTTPServer
from tornado.ioloop import IOLoop
import tornado.web
import tornado.iostream

logging.getLogger(__name__).addHandler(logging.NullHandler())


class WebhookServer(object):

    def __init__(self, listen, port, webhook_app, ssl_ctx):
        self.http_server = HTTPServer(webhook_app, ssl_options=ssl_ctx)
        self.listen = listen
        self.port = port
        self.loop = None
        self.logger = logging.getLogger(__name__)
        self.is_running = False
        self.server_lock = Lock()
        self.shutdown_lock = Lock()

    def serve_forever(self):
        with self.server_lock:
            IOLoop().make_current()
            self.is_running = True
            self.logger.debug('Webhook Server started.')
            self.http_server.listen(self.port, address=self.listen)
            self.loop = IOLoop.current()
            self.loop.start()
            self.logger.debug('Webhook Server stopped.')
            self.is_running = False

    def shutdown(self):
        with self.shutdown_lock:
            if not self.is_running:
                self.logger.warning('Webhook Server already stopped.')
                return
            else:
                self.loop.add_callback(self.loop.stop)

    def handle_error(self, request, client_address):
        """Handle an error gracefully."""
        self.logger.debug('Exception happened during processing of request from %s',
                          client_address, exc_info=True)


class WebhookAppClass(tornado.web.Application):

    def __init__(self, webhook_path, bot, update_queue):
        self.shared_objects = {"bot": bot, "update_queue": update_queue}
        handlers = [
            (r"{0}/?".format(webhook_path), WebhookHandler,
             self.shared_objects)
            ]  # noqa
        tornado.web.Application.__init__(self, handlers)

    def log_request(self, handler):
        pass


# WebhookHandler, process webhook calls
class WebhookHandler(tornado.web.RequestHandler):
    SUPPORTED_METHODS = ["POST"]

    def __init__(self, application, request, **kwargs):
        super(WebhookHandler, self).__init__(application, request, **kwargs)
        self.logger = logging.getLogger(__name__)

    def initialize(self, bot, update_queue):
        self.bot = bot
        self.update_queue = update_queue

    def set_default_headers(self):
        self.set_header("Content-Type", 'application/json; charset="utf-8"')

    def post(self):
        self.logger.debug('Webhook triggered')
        self._validate_post()
        json_string = bytes_to_native_str(self.request.body)
        data = json.loads(json_string)
        self.set_status(200)
        self.logger.debug('Webhook received data: ' + json_string)
        update = Update.de_json(data, self.bot)
        self.logger.debug('Received Update with ID %d on Webhook' % update.update_id)
        self.update_queue.put(update)

    def _validate_post(self):
        ct_header = self.request.headers.get("Content-Type", None)
        if ct_header != 'application/json':
            raise tornado.web.HTTPError(403)

    def write_error(self, status_code, **kwargs):
        """Log an arbitrary message.

        This is used by all other logging functions.

        It overrides ``BaseHTTPRequestHandler.log_message``, which logs to ``sys.stderr``.

        The first argument, FORMAT, is a format string for the message to be logged.  If the format
        string contains any % escapes requiring parameters, they should be specified as subsequent
        arguments (it's just like printf!).

        The client ip is prefixed to every message.

        """
        super(WebhookHandler, self).write_error(status_code, **kwargs)
        self.logger.debug("%s - - %s" % (self.request.remote_ip, "Exception in WebhookHandler"),
                          exc_info=kwargs['exc_info'])