--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/sat_browser/plugin_xep_0085.py	Sat Aug 25 17:59:48 2018 +0200
@@ -0,0 +1,77 @@
+#!/usr/bin/python
+# -*- coding: utf-8 -*-
+
+# SAT plugin for Chat State Notifications Protocol (xep-0085)
+# Copyright (C) 2013-2016 Adrien Cossa (souliane@mailoo.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero 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 Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from pyjamas.Timer import Timer
+
+
+# Copy of the map from sat/src/plugins/plugin_xep_0085
+TRANSITIONS = {"active": {"next_state": "inactive", "delay": 120},
+               "inactive": {"next_state": "gone", "delay": 480},
+               "gone": {"next_state": "", "delay": 0},
+               "composing": {"next_state": "paused", "delay": 30},
+               "paused": {"next_state": "inactive", "delay": 450}
+               }
+
+
+class ChatStateMachine:
+    """This is an adapted version of the ChatStateMachine from sat/src/plugins/plugin_xep_0085
+    which manage a timer on the web browser and keep it synchronized with the timer that runs
+    on the backend. This is only needed to avoid calling the bridge method chatStateComposing
+    too often ; accuracy is not needed so we can ignore the delay of the communication between
+    the web browser and the backend (the timer on the web browser always starts a bit before).
+    /!\ Keep this file up to date if you modify the one in the sat plugins directory.
+    """
+    def __init__(self, host, target_s):
+
+        self.host = host
+        self.target_s = target_s
+        self.started = False
+        self.state = None
+        self.timer = None
+
+    def _onEvent(self, state):
+        # Pyjamas callback takes no extra argument so we need this trick
+
+        # Here we should check the value of the parameter "Send chat state notifications"
+        # but this costs two messages. It's even better to call chatStateComposing
+        # with a doubt, it will be checked by the back-end anyway before sending
+        # the actual notifications to the other client.
+        if state == "composing" and not self.started:
+            return
+        self.started = True
+        self.next_state = state
+        self.__onEvent(None)
+
+    def __onEvent(self, timer):
+        state = self.next_state
+
+        assert(state in TRANSITIONS)
+        transition = TRANSITIONS[state]
+        assert("next_state" in transition and "delay" in transition)
+
+        if state != self.state and state == "composing":
+            self.host.bridge.call('chatStateComposing', None, self.target_s)
+
+        self.state = state
+        if self.timer is not None:
+            self.timer.cancel()
+
+        if transition["next_state"] and transition["delay"] > 0:
+            self.next_state = transition["next_state"]
+            self.timer = Timer(transition["delay"] * 1000, self.__onEvent)  # pyjamas timer is in milliseconds