from __future__ import absolute_import

from django.conf import settings
from django.utils.importlib import import_module
from django.utils import timezone
from django.contrib.sessions.models import Session as djSession

import sockjs.tornado
import tornado.ioloop
import ujson
import logging
import time

from zerver.models import UserProfile, get_user_profile_by_id, get_client
from zerver.lib.queue import queue_json_publish
from zerver.lib.actions import check_send_message, extract_recipients
from zerver.decorator import JsonableError
from zerver.lib.utils import statsd
from zerver.lib.event_queue import get_client_descriptor
from zerver.middleware import record_request_start_data, record_request_stop_data, \
    record_request_restart_data, write_log_line, format_timedelta
from zerver.lib.redis_utils import get_redis_client
from zerver.lib.session_user import get_session_user

logger = logging.getLogger('zulip.socket')

djsession_engine = import_module(settings.SESSION_ENGINE)
def get_user_profile(session_id):
    if session_id is None:
        return None

    try:
        djsession = djSession.objects.get(expire_date__gt=timezone.now(),
                                          session_key=session_id)
    except djSession.DoesNotExist:
        return None

    try:
        return UserProfile.objects.get(pk=get_session_user(djsession))
    except (UserProfile.DoesNotExist, KeyError):
        return None

connections = dict()

def get_connection(id):
    return connections.get(id)

def register_connection(id, conn):
    # Kill any old connections if they exist
    if id in connections:
        connections[id].close()

    conn.client_id = id
    connections[conn.client_id] = conn

def deregister_connection(conn):
    del connections[conn.client_id]

redis_client = get_redis_client()

def req_redis_key(req_id):
    return 'socket_req_status:%s' % (req_id,)

class SocketAuthError(Exception):
    def __init__(self, msg):
        self.msg = msg

class CloseErrorInfo(object):
    def __init__(self, status_code, err_msg):
        self.status_code = status_code
        self.err_msg = err_msg

class SocketConnection(sockjs.tornado.SockJSConnection):
    def on_open(self, info):
        log_data = dict(extra='[transport=%s]' % (self.session.transport_name,))
        record_request_start_data(log_data)

        ioloop = tornado.ioloop.IOLoop.instance()

        self.authenticated = False
        self.session.user_profile = None
        self.close_info = None
        self.did_close = False

        try:
            self.browser_session_id = info.get_cookie(settings.SESSION_COOKIE_NAME).value
            self.csrf_token = info.get_cookie(settings.CSRF_COOKIE_NAME).value
        except AttributeError:
            # The request didn't contain the necessary cookie values.  We can't
            # close immediately because sockjs-tornado doesn't expect a close
            # inside on_open(), so do it on the next tick.
            self.close_info = CloseErrorInfo(403, "Initial cookie lacked required values")
            ioloop.add_callback(self.close)
            return

        def auth_timeout():
            self.close_info = CloseErrorInfo(408, "Timeout while waiting for authentication")
            self.close()

        self.timeout_handle = ioloop.add_timeout(time.time() + 10, auth_timeout)
        write_log_line(log_data, path='/socket/open', method='SOCKET',
                       remote_ip=info.ip, email='unknown', client_name='?')

    def authenticate_client(self, msg):
        if self.authenticated:
            self.session.send_message({'req_id': msg['req_id'], 'type': 'response',
                                       'response': {'result': 'error', 'msg': 'Already authenticated'}})
            return

        user_profile = get_user_profile(self.browser_session_id)
        if user_profile is None:
            raise SocketAuthError('Unknown or missing session')
        self.session.user_profile = user_profile

        if msg['request']['csrf_token'] != self.csrf_token:
            raise SocketAuthError('CSRF token does not match that in cookie')

        if not 'queue_id' in msg['request']:
            raise SocketAuthError("Missing 'queue_id' argument")

        queue_id = msg['request']['queue_id']
        client = get_client_descriptor(queue_id)
        if client is None:
            raise SocketAuthError('Bad event queue id: %s' % (queue_id,))

        if user_profile.id != client.user_profile_id:
            raise SocketAuthError("You are not the owner of the queue with id '%s'" % (queue_id,))

        self.authenticated = True
        register_connection(queue_id, self)

        response = {'req_id': msg['req_id'], 'type': 'response',
                    'response': {'result': 'success', 'msg': ''}}

        status_inquiries = msg['request'].get('status_inquiries')
        if status_inquiries is not None:
            results = {}
            for inquiry in status_inquiries:
                status = redis_client.hgetall(req_redis_key(inquiry))
                if len(status) == 0:
                    status['status'] = 'not_received'
                if 'response' in status:
                    status['response'] = ujson.loads(status['response'])
                results[str(inquiry)] = status
            response['response']['status_inquiries'] = results

        self.session.send_message(response)
        ioloop = tornado.ioloop.IOLoop.instance()
        ioloop.remove_timeout(self.timeout_handle)

    def on_message(self, msg):
        log_data = dict(extra='[transport=%s' % (self.session.transport_name,))
        record_request_start_data(log_data)
        msg = ujson.loads(msg)

        if self.did_close:
            logger.info("Received message on already closed socket! transport=%s user=%s client_id=%s"
                        % (self.session.transport_name,
                           self.session.user_profile.email if self.session.user_profile is not None else 'unknown',
                           self.client_id))

        self.session.send_message({'req_id': msg['req_id'], 'type': 'ack'})

        if msg['type'] == 'auth':
            log_data['extra'] += ']'
            try:
                self.authenticate_client(msg)
                # TODO: Fill in the correct client
                write_log_line(log_data, path='/socket/auth', method='SOCKET',
                               remote_ip=self.session.conn_info.ip,
                               email=self.session.user_profile.email,
                               client_name='?')
            except SocketAuthError as e:
                response = {'result': 'error', 'msg': e.msg}
                self.session.send_message({'req_id': msg['req_id'], 'type': 'response',
                                           'response': response})
                write_log_line(log_data, path='/socket/auth', method='SOCKET',
                               remote_ip=self.session.conn_info.ip,
                               email='unknown', client_name='?',
                               status_code=403, error_content=ujson.dumps(response))
            return
        else:
            if not self.authenticated:
                response = {'result': 'error', 'msg': "Not yet authenticated"}
                self.session.send_message({'req_id': msg['req_id'], 'type': 'response',
                                           'response': response})
                write_log_line(log_data, path='/socket/service_request', method='SOCKET',
                               remote_ip=self.session.conn_info.ip,
                               email='unknown', client_name='?',
                               status_code=403, error_content=ujson.dumps(response))
                return

        redis_key = req_redis_key(msg['req_id'])
        with redis_client.pipeline() as pipeline:
            pipeline.hmset(redis_key, {'status': 'received'})
            pipeline.expire(redis_key, 60 * 60 * 24)
            pipeline.execute()

        record_request_stop_data(log_data)
        queue_json_publish("message_sender",
                           dict(request=msg['request'],
                                req_id=msg['req_id'],
                                server_meta=dict(user_id=self.session.user_profile.id,
                                                 client_id=self.client_id,
                                                 return_queue="tornado_return",
                                                 log_data=log_data,
                                                 request_environ=dict(REMOTE_ADDR=self.session.conn_info.ip))),
                           fake_message_sender)

    def on_close(self):
        log_data = dict(extra='[transport=%s]' % (self.session.transport_name,))
        record_request_start_data(log_data)
        if self.close_info is not None:
            write_log_line(log_data, path='/socket/close', method='SOCKET',
                           remote_ip=self.session.conn_info.ip, email='unknown',
                           client_name='?', status_code=self.close_info.status_code,
                           error_content=self.close_info.err_msg)
        else:
            deregister_connection(self)
            email = self.session.user_profile.email \
                if self.session.user_profile is not None else 'unknown'
            write_log_line(log_data, path='/socket/close', method='SOCKET',
                           remote_ip=self.session.conn_info.ip, email=email,
                           client_name='?')

        self.did_close = True

def fake_message_sender(event):
    log_data = dict()
    record_request_start_data(log_data)

    req = event['request']
    try:
        sender = get_user_profile_by_id(event['server_meta']['user_id'])
        client = get_client(req['client'])

        msg_id = check_send_message(sender, client, req['type'],
                                    extract_recipients(req['to']),
                                    req['subject'], req['content'],
                                    local_id=req.get('local_id', None),
                                    sender_queue_id=req.get('queue_id', None))
        resp = {"result": "success", "msg": "", "id": msg_id}
    except JsonableError as e:
        resp = {"result": "error", "msg": str(e)}

    server_meta = event['server_meta']
    server_meta.update({'worker_log_data': log_data,
                        'time_request_finished': time.time()})
    result = {'response': resp, 'req_id': event['req_id'],
              'server_meta': server_meta}
    respond_send_message(result)

def respond_send_message(data):
    log_data = data['server_meta']['log_data']
    record_request_restart_data(log_data)

    worker_log_data = data['server_meta']['worker_log_data']
    forward_queue_delay = worker_log_data['time_started'] - log_data['time_stopped']
    return_queue_delay = log_data['time_restarted'] - data['server_meta']['time_request_finished']
    service_time = data['server_meta']['time_request_finished'] - worker_log_data['time_started']
    log_data['extra'] += ', queue_delay: %s/%s, service_time: %s]' % (
        format_timedelta(forward_queue_delay), format_timedelta(return_queue_delay),
        format_timedelta(service_time))

    client_id = data['server_meta']['client_id']
    connection = get_connection(client_id)
    if connection is None:
        logger.info("Could not find connection to send response to! client_id=%s" % (client_id,))
    else:
        connection.session.send_message({'req_id': data['req_id'], 'type': 'response',
                                         'response': data['response']})

        # TODO: Fill in client name
        # TODO: Maybe fill in the status code correctly
        write_log_line(log_data, path='/socket/service_request', method='SOCKET',
                       remote_ip=connection.session.conn_info.ip,
                       email=connection.session.user_profile.email, client_name='?')

# We disable the eventsource and htmlfile transports because they cannot
# securely send us the zulip.com cookie, which we use as part of our
# authentication scheme.
sockjs_router = sockjs.tornado.SockJSRouter(SocketConnection, "/sockjs",
                                            {'sockjs_url': 'https://%s/static/third/sockjs/sockjs-0.3.4.js' % (settings.EXTERNAL_HOST,),
                                             'disabled_transports': ['eventsource', 'htmlfile']})
def get_sockjs_router():
    return sockjs_router
