[REF][FIX] mail, im_livechat: various improvements (JS)

This commit makes a lot of small improvements of the JS of mail and
related modules.

	A. Mail Manager
	---------------

		im_support:

		- [REF] Slightly more robust way to determine a support
		        message, so that it more reliably falls back on
		        default kind of message (i.e. support channel UUID
		        should be clearly set).

		mail:

		- [REF] Improved method names for readability purposes.
		        Some examples:

		        - `fetchFromServer` becomes `fetchMailStateFromServer`
		        - `_initialize{*}` becomes `_update{*}FromServer`
		        - `_isModerator` becomes `_isMyselfModerator`

		- [REF] Use 'template' pattern design to make Include on
				Mail Manager much more robust. In particular,
				the flow is always as follow:

					1. Initialize internal state.
					2. Listen on buses.
					3. Fetch mail data from server.

		- [REF] Improved workflow for thread window workflow
		        (Shorter & more readable).

	B. Mail Tests
	-------------

		- [REF] Thread Window Tests crashes with clean message when
		        there are some thread windows open before running the
		        tests.

	C. (Model) Message
	------------------

		- [REF] Improved method names for readability purposes
				(e.g. `isAuthor` becomes `isMyselfAuthor`).

	D. (Model) Thread
	-----------------

		- [REF] Improved `init` parameters on each kind of thread.
		- [REF] 'Thread With Cache' has been renamed to 'Searchable
		        Thread': it embraces all kinds of threads that can
		        be used with the search view.
		- [REF] 'DM' has been renamed to 'DM Chat' (for clarity).
		- [IMP] New Livechat model in the backend.
		- [REF] No more direct instances of the Channel class: public
		        and private channels are now 'Multi-User' channels,
		        while DM Chat and Livechat are 'Two-User' channels:

		        This change has been made so that instances of classes
		        always have direct classes as "leaf" in the Class
		        modeling. It eases making changes to a certain model
		        without being too constrained by another model.

		- [REF] As a consequence of above changed, the method `isChat`
		        has been renamed to `isTwoUserThread`.

		        This is to avoid confusion with the terminology
		        'chat', which is more like a shortcut for 'quick real-
		        time conversation'. In other words, the property of
		        'chat' depends of the way to interact on a thread, not
		        of the intrinsic type of the thread.

		        Still, some parts have kept the terminology 'chat',
		        such as in the systray messagin menu.

		- [IMP] Added `message_added` and `message_posted` hooks,
		        which may be useful to easily hook on those events.

	E. Thread Widget
	----------------

		- [REF] Now uses a `mail.model.AbstractThread` for the
		        rendering of a thread, instead of a list of
		        `{mail.model.AbstractMessage}`.
		- [FIX] Stick thread scroll height to bottom on new rendering,
		        if it was previously at the bottom of the thread.
		- [REF] Option ORDER has its meaning changed: it now refers
		        to the chronological order of messages in the thread,
		        in which DESC means 'from top to bottom', while ASC
		        means 'from bottom to top'.
		- [REF] Improved doc on templates, in particular with the
	            option `ORDER`.

	F. Thread Window
	----------------

		- [REF] Moved more logic to thread windows, which were
		        previously in Mail Window Manager.
		- [REF] Now hides the thread widget attribute. So instead of
		        `threadWindow.threadWidget.isAtBottom()`, it uses
		        `threadWindow.isAtBottom()`.
		- [FIX] New received messages when not having focus on Odoo
		        tab should always make the corresponding thread
		        windows "passive" (i.e. windows that keep threads
		        unread until click on them).
		- [FIX] Blank thread window (i.e. 'New message' TW) correctly
		        opens Discuss with 'Inbox' when clicking on 'Expand'
		        Button in the title
		- [FIX] Do not display the composer for channels with property
		        'mass-mailing' set in thread windows.

	G. (Website) Livechat
	---------------------

		- [REF] Some `trigger` have been turned into `trigger_up`.
		- [REF] Some logic has been moved to models (e.g.
		        `{im_livechat.model.WebsiteLivechat}`), from
		        `{im_livechat.im_livechat.LivechatButton}`.
		- [FIX] New messages should be received in real-time. The
		        longpolling was broken with a recent refactoring on
		        bus service (6448420c5dd160470e465dee7729d19d8d5e7bab).

12 files changed, 474 insertions, 338 deletions

diff --git a/addons/mail/static/src/js/models/messages/abstract_message.js b/addons/mail/static/src/js/models/messages/abstract_message.js
index 420ac2da41b..f5cf55f0ef1 100644
--- a/addons/mail/static/src/js/models/messages/abstract_message.js
+++ b/addons/mail/static/src/js/models/messages/abstract_message.js
@@ -344,7 +344,7 @@ var AbstractMessage =  Class.extend({
      * @return {boolean}
      */
     shouldRedirectToAuthor: function () {
-        return !this._isAuthor();
+        return !this._isMyselfAuthor();
     },
 
     //--------------------------------------------------------------------------
@@ -370,7 +370,7 @@ var AbstractMessage =  Class.extend({
      * @private
      * @return {boolean}
      */
-    _isAuthor: function () {
+    _isMyselfAuthor: function () {
         return this.hasAuthor() && (this.getAuthorID() === session.partner_id);
     },
     /**
diff --git a/addons/mail/static/src/js/models/messages/message.js b/addons/mail/static/src/js/models/messages/message.js
index 0c6480f3264..881a5ae2c97 100644
--- a/addons/mail/static/src/js/models/messages/message.js
+++ b/addons/mail/static/src/js/models/messages/message.js
@@ -358,14 +358,6 @@ var Message =  AbstractMessage.extend(Mixins.EventDispatcherMixin, ServicesMixin
         return !!(this._trackingValueIDs && (this._trackingValueIDs.length > 0));
     },
     /**
-     * State whether the current user is the author of this message
-     *
-     * @return {boolean}
-     */
-    isAuthor: function () {
-        return this._isAuthor();
-    },
-    /**
      * State whether this message is linked to a document thread (not channel)
      *
      * Usually, if this is true, then this message comes from a document thread,
@@ -382,6 +374,14 @@ var Message =  AbstractMessage.extend(Mixins.EventDispatcherMixin, ServicesMixin
         return !!(this._documentModel !== 'mail.channel' && this._documentID);
     },
     /**
+     * State whether the current user is the author of this message
+     *
+     * @return {boolean}
+     */
+    isMyselfAuthor: function () {
+        return this._isMyselfAuthor();
+    },
+    /**
      * States whether the current message needs moderation in general.
      *
      * @override
diff --git a/addons/mail/static/src/js/models/threads/abstract_thread.js b/addons/mail/static/src/js/models/threads/abstract_thread.js
index 67929517ed4..fb6695c6a6c 100644
--- a/addons/mail/static/src/js/models/threads/abstract_thread.js
+++ b/addons/mail/static/src/js/models/threads/abstract_thread.js
@@ -2,6 +2,7 @@ odoo.define('mail.model.AbstractThread', function (require) {
 "use strict";
 
 var Class = require('web.Class');
+var Mixins = require('web.mixins');
 
 /**
  * Abstract thread is the super class of all threads, either backend threads
@@ -9,15 +10,20 @@ var Class = require('web.Class');
  *
  * Abstract threads contain abstract messages
  */
-var AbstractThread = Class.extend({
+var AbstractThread = Class.extend(Mixins.EventDispatcherMixin, {
     /**
      * @param {Object} params
      * @param {Object} params.data
      * @param {integer|string} params.data.id the ID of this thread
      * @param {string} params.data.name the name of this thread
      * @param {string} params.data.status the status of this thread
+     * @param {Object} params.parent Object with the event-dispatcher mixin
+     *   (@see {web.mixins.EventDispatcherMixin})
      */
     init: function (params) {
+        Mixins.EventDispatcherMixin.init.call(this, arguments);
+        this.setParent(params.parent);
+
         this._folded = false; // threads are unfolded by default
         this._id = params.data.id;
         this._name = params.data.name;
@@ -30,6 +36,15 @@ var AbstractThread = Class.extend({
     //--------------------------------------------------------------------------
 
     /**
+     * Add a message to this thread.
+     *
+     * @param {mail.model.AbstractMessage} message
+     */
+    addMessage: function (message) {
+        this._addMessage.apply(this, arguments);
+        this.trigger('message_added', message);
+    },
+    /**
      * Updates the folded state of the thread
      *
      * @param {boolean} folded
@@ -88,12 +103,6 @@ var AbstractThread = Class.extend({
         return !_.isEmpty(this.getMessages());
     },
     /**
-     * Increments the unread counter of this thread by 1 unit.
-     */
-    incrementUnreadCounter: function () {
-        this._unreadCounter++;
-    },
-    /**
      * States whether this thread is folded or not.
      *
      * @return {boolean}
@@ -102,11 +111,76 @@ var AbstractThread = Class.extend({
         return this._folded;
     },
     /**
+     * Mark the thread as read, which resets the unread counter to 0. This is
+     * only performed if the unread counter is not 0.
+     *
+     * @returns {$.Promise}
+     */
+    markAsRead: function () {
+        if (this._unreadCounter > 0) {
+            return this._markAsRead();
+        }
+        return $.when();
+    },
+    /**
+     * Post a message on this thread
+     *
+     * @returns {$.Promise} resolved with the message object to be sent to the
+     *   server
+     */
+    postMessage: function () {
+        return this._postMessage.apply(this, arguments)
+                                .then(this.trigger.bind(this, 'message_posted'));
+    },
+    /**
      * Resets the unread counter of this thread to 0.
      */
     resetUnreadCounter: function () {
         this._unreadCounter = 0;
     },
+
+    //--------------------------------------------------------------------------
+    // Private
+    //--------------------------------------------------------------------------
+
+    /**
+     * Add a message to this thread.
+     *
+     * @abstract
+     * @private
+     * @param {mail.model.AbstractMessage} message
+     */
+    _addMessage: function (message) {},
+    /**
+     * Increments the unread counter of this thread by 1 unit.
+     *
+     * @private
+     */
+    _incrementUnreadCounter: function () {
+        this._unreadCounter++;
+    },
+    /**
+     * Mark the thread as read
+     *
+     * @private
+     * @returns {$.Promise}
+     */
+    _markAsRead: function () {
+        this.resetUnreadCounter();
+        this._warnUpdatedUnreadCounter();
+        return $.when();
+    },
+    /**
+     * Post a message on this thread
+     *
+     * @abstract
+     * @private
+     * @returns {$.Promise} resolved with the message object to be sent to the
+     *   server
+     */
+    _postMessage: function () {
+        return $.when();
+    },
 });
 
 return AbstractThread;
diff --git a/addons/mail/static/src/js/models/threads/channel.js b/addons/mail/static/src/js/models/threads/channel.js
index a33319c7f1f..3f932ccb8ec 100644
--- a/addons/mail/static/src/js/models/threads/channel.js
+++ b/addons/mail/static/src/js/models/threads/channel.js
@@ -1,7 +1,7 @@
 odoo.define('mail.model.Channel', function (require) {
 "use strict";
 
-var ThreadWithCache = require('mail.model.ThreadWithCache');
+var SearchableThread = require('mail.model.SearchableThread');
 var mailUtils = require('mail.utils');
 
 var session = require('web.session');
@@ -15,12 +15,11 @@ var time = require('web.time');
  * Any piece of code in JS that make use of channels must ideally interact with
  * such objects, instead of direct data from the server.
  */
-var Channel = ThreadWithCache.extend({
+var Channel = SearchableThread.extend({
     /**
      * @override
      * @param {Object} params
      * @param {Object} params.data
-     * @param {string} [params.data.anonymous_name]
      * @param {string} params.data.channel_type
      * @param {integer} [params.data.create_uid] the ID of the user that has
      *   created the channel.
@@ -29,9 +28,7 @@ var Channel = ThreadWithCache.extend({
      * @param  {boolean} params.data.is_moderator whether the current user is
      *   moderator of this channel.
      * @param {string} [params.data.last_message_date] date in server-format
-     * @param {boolean} [params.data.mass_mailing]
      * @param {integer} [params.data.message_unread_counter]
-     * @param {string} [params.data.public] either 'public' or 'private'
      * @param {string} params.data.state
      * @param {string} [params.data.uuid]
      * @param {Object} params.options
@@ -48,9 +45,8 @@ var Channel = ThreadWithCache.extend({
 
         // If set, autoswitch channel on joining this channel in discuss
         // the default behaviour is to autoswitch on join.
-        // exception: receiving channel or chat session notifications
+        // exception: receiving channel session notifications
         this._autoswitch = 'autoswitch' in options ? options.autoswitch : true;
-        this._chat = undefined; // FIXME: could be dropped when livechat and DM are moved out of this class
         this._commands = undefined;
         this._creatorUID = data.create_uid;
         this._detached = data.is_minimized;
@@ -58,12 +54,12 @@ var Channel = ThreadWithCache.extend({
         this._folded = data.state === 'folded';
         // if set: hide 'Leave channel' button
         this._groupBasedSubscription = data.group_based_subscription;
-        this._isModerator = data.is_moderator;
+        this._isModerated = data.is_moderation;
+        this._isMyselfModerator = data.is_moderator;
         this._lastMessageDate = undefined;
-        this._massMailing = data.mass_mailing;
+        this._members = [];
         // Deferred that is resolved on fetched members of this channel.
         this._membersDef = undefined;
-        this._moderation = data.is_moderation;
         // number of messages that are 'needaction', which is equivalent to the
         // number of messages in this channel that are in inbox.
         this._needactionCounter = data.message_needaction_counter || 0;
@@ -78,16 +74,9 @@ var Channel = ThreadWithCache.extend({
             return !command.channel_types ||
                     _.contains(command.channel_types, self._serverType);
         });
-        if (this._type === 'channel') {
-            this._type = data.public !== 'private' ? 'public' : 'private';
-        }
-        if ('anonymous_name' in data) {
-            this._name = data.anonymous_name;
-        }
         if (data.last_message_date) {
             this._lastMessageDate = moment(time.str_to_datetime(data.last_message_date));
         }
-        this._chat = !this.getType().match(/^(public|private)$/);
         if (data.message_unread_counter) {
             this._unreadCounter = data.message_unread_counter;
         }
@@ -190,6 +179,7 @@ var Channel = ThreadWithCache.extend({
      * @returns {$.Promise<Object[]>} resolved with list of channel listeners
      */
     getMentionPartnerSuggestions: function () {
+        var self = this;
         if (!this._membersDef) {
             this._membersDef = this._rpc({
                 model: 'mail.channel',
@@ -199,6 +189,7 @@ var Channel = ThreadWithCache.extend({
                 shadow: true
             })
             .then(function (members) {
+                self._members = members;
                 return members;
             });
         }
@@ -215,7 +206,7 @@ var Channel = ThreadWithCache.extend({
      */
     getPreview: function () {
         var result = this._super.apply(this, arguments);
-        if (!this.isChat()) {
+        if (!this.isTwoUserThread()) {
             result.imageSRC = '/web/image/mail.channel/' + this.getID() + '/image_small';
         }
         var lastMessage = this.getLastMessage();
@@ -223,7 +214,7 @@ var Channel = ThreadWithCache.extend({
             author: lastMessage ? lastMessage.getDisplayedAuthor() : '',
             body: lastMessage ? mailUtils.parseAndTransform(lastMessage.getBody(), mailUtils.inline) : '',
             date: lastMessage ? lastMessage.getDate() : moment(),
-            isAuthor: this.hasMessages() && this.getLastMessage().isAuthor(),
+            isMyselfAuthor: this.hasMessages() && this.getLastMessage().isMyselfAuthor(),
         });
     },
     /**
@@ -252,15 +243,6 @@ var Channel = ThreadWithCache.extend({
         this._needactionCounter++;
     },
     /**
-     * Tells whether the current user is administrator of the channel.
-     * Note that there is no administrator for chat channels
-     *
-     * @returns {boolean}
-     */
-    isAdministrator: function () {
-        return session.uid === this._creatorUID && !this.isChat();
-    },
-    /**
      * States whether the channel should be auto-selected on creation
      *
      * Note that this is not of the responsibility of the channel
@@ -282,18 +264,6 @@ var Channel = ThreadWithCache.extend({
         return true;
     },
     /**
-     * States whether this channel is a chat or not.
-     * These types of channels are chat:
-     * - direct messages (DM)
-     * - livechat
-     *
-     * @override
-     * @returns {boolean}
-     */
-    isChat: function () {
-        return this._chat;
-    },
-    /**
      * States whether the channel auto-subscribes some users in a group
      *
      * @returns {boolean}
@@ -308,81 +278,32 @@ var Channel = ThreadWithCache.extend({
      * @returns {boolean}
      */
     isModerated: function () {
-        return this._moderation;
+        return this._isModerated;
     },
     /**
-     * States whether the current user is moderator of this channel.
+     * Tells whether the current user is administrator of the channel.
+     * Note that there is no administrator for two-user channels
      *
      * @returns {boolean}
      */
-    isModerator: function () {
-        return this._isModerator;
-    },
-    /**
-     * Marks this channel as read.
-     * The last seen message will be the last message.
-     * Resolved with the last seen message, only for non-mailbox channels
-     *
-     * @override
-     * @returns {$.Promise<integer|undefined>} resolved with last message ID
-     *   seen in the channel, and when the channel has been marked as seen on
-     *   the server.
-     */
-    markAsRead: function () {
-        if (this._unreadCounter > 0) {
-            this.resetUnreadCounter();
-            return this._throttleFetchSeen();
-        }
-        return this._super.apply(this, arguments);
+    isMyselfAdministrator: function () {
+        return session.uid === this._creatorUID && !this.isTwoUserThread();
     },
     /**
-     * Prepare and send a message to the server on this channel
+     * States whether the current user is moderator of this channel.
      *
-     * @override
-     * @param {Object} data data related to the new message
-     * @returns {$.Promise<Object>} resolved when the message has been sent to
-     *   the server, with the object message that has been sent to the server.
+     * @returns {boolean}
      */
-    postMessage: function (data) {
-        var self = this;
-        return this._super.apply(this, arguments).then(function (messageData) {
-            _.extend(messageData, {
-                message_type: 'comment',
-                subtype: 'mail.mt_comment',
-                command: data.command,
-            });
-            return self._rpc({
-                    model: 'mail.channel',
-                    method: data.command ? 'execute_command' : 'message_post',
-                    args: [self._id],
-                    kwargs: messageData,
-                }).then(function () {
-                    return messageData;
-                });
-        });
+    isMyselfModerator: function () {
+        return this._isMyselfModerator;
     },
     /**
      * Unsubscribes from channel
      *
+     * @abstract
      * @returns {$.Promise} resolve when unsubscribed
      */
-    unsubscribe: function () {
-        if (_.contains(['public', 'private'], this.getType())) {
-            // unfollow channel
-            return this._rpc({
-                model: 'mail.channel',
-                method: 'action_unfollow',
-                args: [[this._id]],
-            });
-        } else {
-            // unpin livechat
-            return this._rpc({
-                model: 'mail.channel',
-                method: 'channel_pin',
-                args: [this.getUUID(), false],
-            });
-        }
-    },
+    unsubscribe: function () {},
     /**
      * Updates the internal state of the channel, and reflects the changes in
      * the UI.
@@ -453,6 +374,47 @@ var Channel = ThreadWithCache.extend({
                 ['need_moderation', '=', true],
                 ['channel_ids', 'in', [this._id]]];
     },
+    /**
+     * Marks this channel as read.
+     * The last seen message will be the last message.
+     * Resolved with the last seen message, only for non-mailbox channels
+     *
+     * @override
+     * @private
+     * @returns {$.Promise} resolved when message has been marked as read
+     */
+    _markAsRead: function () {
+        var superDef = this._super.apply(this, arguments);
+        var seenDef = this._throttleFetchSeen();
+        return $.when(superDef, seenDef);
+    },
+    /**
+     * Prepare and send a message to the server on this channel.
+     *
+     * @override
+     * @private
+     * @param {Object} data data related to the new message
+     * @returns {$.Promise<Object>} resolved when the message has been sent to
+     *   the server, with the object message that has been sent to the server.
+     */
+    _postMessage: function (data) {
+        var self = this;
+        return this._super.apply(this, arguments).then(function (messageData) {
+            _.extend(messageData, {
+                message_type: 'comment',
+                subtype: 'mail.mt_comment',
+                command: data.command,
+            });
+            return self._rpc({
+                    model: 'mail.channel',
+                    method: data.command ? 'execute_command' : 'message_post',
+                    args: [self._id],
+                    kwargs: messageData,
+                }).then(function () {
+                    return messageData;
+                });
+        });
+    },
 });
 
 return Channel;
diff --git a/addons/mail/static/src/js/models/threads/dm.js b/addons/mail/static/src/js/models/threads/dm_chat.js
index fba63830a55..767a6e32edd 100644
--- a/addons/mail/static/src/js/models/threads/dm.js
+++ b/addons/mail/static/src/js/models/threads/dm_chat.js
@@ -1,19 +1,18 @@
-odoo.define('mail.model.DM', function (require) {
+odoo.define('mail.model.DMChat', function (require) {
 "use strict";
 
-var Channel = require('mail.model.Channel');
+var TwoUserChannel = require('mail.model.TwoUserChannel');
 
 /**
- *
  * Any piece of code in JS that make use of DMs must ideally interact with
  * such objects, instead of direct data from the server.
  */
-var DM = Channel.extend({
+var DMChat = TwoUserChannel.extend({
     /**
      * @override
      * @param {Object} params
      * @param {Object} params.data
-     * @param {Object} params.data.direct_partner
+     * @param {Object[]} params.data.direct_partner
      * @param {integer} params.data.direct_partner[0].id
      * @param {string} params.data.direct_partner[0].im_status
      * @param {string} params.data.direct_partner[0].name
@@ -23,10 +22,10 @@ var DM = Channel.extend({
 
         var data = params.data;
 
-        this._type = 'dm';
-        this._name = data.direct_partner[0].name;
         this._directPartnerID = data.direct_partner[0].id;
+        this._name = data.direct_partner[0].name;
         this._status = data.direct_partner[0].im_status;
+        this._type = 'dm_chat';
     },
 
     //--------------------------------------------------------------------------
@@ -35,8 +34,8 @@ var DM = Channel.extend({
 
     /**
      * Get the direct partner ID linked to the DM, i.e. the partner ID of the
-     * user at the other end of the DM conversation. All DM do have a direct
-     * partner iD.
+     * user at the other end of the DM conversation. All DM chats do have a
+     * direct partner iD.
      *
      * @returns {integer}
      */
@@ -52,35 +51,13 @@ var DM = Channel.extend({
         return result;
     },
     /**
-     * DM are chat
-     *
-     * @override
-     * @returns {boolean}
-     */
-    isChat: function () {
-        return true;
-    },
-    /**
      * @param {string} newStatus
      */
     setStatus: function (newStatus) {
         this._status = newStatus;
     },
-    /**
-     * Unpin this DM
-     *
-     * @override
-     * @return {$.Promise} resolve when unpinned
-     */
-    unsubscribe: function () {
-        return this._rpc({
-            model: 'mail.channel',
-            method: 'channel_pin',
-            args: [this.getUUID(), false],
-        });
-    },
 });
 
-return DM;
+return DMChat;
 
 });
diff --git a/addons/mail/static/src/js/models/threads/document_thread.js b/addons/mail/static/src/js/models/threads/document_thread.js
index 831c46939a8..283bcf3ca66 100644
--- a/addons/mail/static/src/js/models/threads/document_thread.js
+++ b/addons/mail/static/src/js/models/threads/document_thread.js
@@ -58,28 +58,6 @@ var DocumentThread = Thread.extend({
     //--------------------------------------------------------------------------
 
     /**
-     * Add this message to this document thread.
-     *
-     * This is ignored if the message is already linked to this document thread.
-     *
-     * @override
-     * @param {mail.model.Message} message
-     */
-    addMessage: function (message) {
-        if (_.contains(this._messages, message)) {
-            return;
-        }
-        // update internal list of messages
-        this._messages.push(message);
-        this._messages = _.sortBy(this._messages, function (msg) {
-            return msg.getID();
-        });
-        // update message ids associated to this document thread
-        if (!_.contains(this._messageIDs, message.getID())) {
-            this._messageIDs.push(message.getID());
-        }
-    },
-    /**
      * Overrides to store the thread's state in the LocalStorage, so that it is
      * shared between tabs, and restored on F5.
      *
@@ -179,59 +157,6 @@ var DocumentThread = Thread.extend({
         return true;
     },
     /**
-     * Overrides this method so that all the messages of this document thread
-     * are marked as read on the server.
-     *
-     * @override
-     * @returns {$.Promise} resolved when messages have been marked as read on
-     *   the server.
-     */
-    markAsRead: function () {
-        this._super.apply(this, arguments);
-        return this.call('mail_service', 'markMessagesAsRead', this._messageIDs);
-    },
-    /**
-     * Post message for document thread
-     *
-     * @override
-     * @param {Object} data data related to the new message
-     * @return {$.Promise<Object>} resolved when the message has been sent to
-     *   the server, with the object message that has been sent to the server.
-     */
-    postMessage: function (data) {
-        var self = this;
-        var resModel = this.getDocumentModel();
-        var resID = this.getDocumentID();
-        return this._super.apply(this, arguments)
-            .then(function (messageData) {
-                _.extend(messageData, {
-                    context: data.context,
-                    message_type: data.message_type,
-                    subtype: data.subtype || "mail.mt_comment",
-                    subtype_id: data.subtype_id,
-                });
-                return self._rpc({
-                        model: resModel,
-                        method: 'message_post',
-                        args: [resID],
-                        kwargs: messageData,
-                    })
-                    .then(function (messageID) {
-                        return self._rpc({
-                                model: 'mail.message',
-                                method: 'message_format',
-                                args: [[messageID]],
-                            })
-                            .then(function (messages) {
-                                messages[0].model = resModel;
-                                messages[0].res_id = resID;
-                                self.call('mail_service', 'addMessage', messages[0]);
-                                return messages[0];
-                            });
-                    });
-        });
-    },
-    /**
      * Set list of message IDs of this document thread
      *
      * Useful in order to handle message history of the document thread,
@@ -260,6 +185,30 @@ var DocumentThread = Thread.extend({
     //--------------------------------------------------------------------------
 
     /**
+     * Add this message to this document thread.
+     *
+     * This is ignored if the message is already linked to this document thread.
+     *
+     * @override
+     * @private
+     * @param {mail.model.Message} message
+     */
+    _addMessage: function (message) {
+        this._super.apply(this, arguments);
+        if (_.contains(this._messages, message)) {
+            return;
+        }
+        // update internal list of messages
+        this._messages.push(message);
+        this._messages = _.sortBy(this._messages, function (msg) {
+            return msg.getID();
+        });
+        // update message ids associated to this document thread
+        if (!_.contains(this._messageIDs, message.getID())) {
+            this._messageIDs.push(message.getID());
+        }
+    },
+    /**
      * Get most up to date messageIDs
      *
      * @private
@@ -324,6 +273,63 @@ var DocumentThread = Thread.extend({
 
         });
     },
+    /**
+     * Overrides this method so that all the messages of this document thread
+     * are marked as read on the server.
+     *
+     * @override
+     * @private
+     * @returns {$.Promise} resolved when messages have been marked as read on
+     *   the server.
+     */
+    _markAsRead: function () {
+        var self = this;
+        return this._super.apply(this, arguments).then(function () {
+            self.call('mail_service', 'markMessagesAsRead', self._messageIDs);
+        });
+    },
+    /**
+     * Post message for document thread
+     *
+     * @override
+     * @private
+     * @param {Object} data data related to the new message
+     * @return {$.Promise<Object>} resolved when the message has been sent to
+     *   the server, with the object message that has been sent to the server.
+     */
+    _postMessage: function (data) {
+        var self = this;
+        var resModel = this.getDocumentModel();
+        var resID = this.getDocumentID();
+        return this._super.apply(this, arguments)
+            .then(function (messageData) {
+                _.extend(messageData, {
+                    context: data.context,
+                    message_type: data.message_type,
+                    subtype: data.subtype || "mail.mt_comment",
+                    subtype_id: data.subtype_id,
+                });
+                return self._rpc({
+                        model: resModel,
+                        method: 'message_post',
+                        args: [resID],
+                        kwargs: messageData,
+                    })
+                    .then(function (messageID) {
+                        return self._rpc({
+                                model: 'mail.message',
+                                method: 'message_format',
+                                args: [[messageID]],
+                            })
+                            .then(function (messages) {
+                                messages[0].model = resModel;
+                                messages[0].res_id = resID;
+                                self.call('mail_service', 'addMessage', messages[0]);
+                                return messages[0];
+                            });
+                    });
+        });
+    },
 });
 
 return DocumentThread;
diff --git a/addons/mail/static/src/js/models/threads/livechat.js b/addons/mail/static/src/js/models/threads/livechat.js
new file mode 100644
index 00000000000..d2aa04f926a
--- /dev/null
+++ b/addons/mail/static/src/js/models/threads/livechat.js
@@ -0,0 +1,57 @@
+odoo.define('mail.model.Livechat', function (require) {
+"use strict";
+
+var TwoUserChannel = require('mail.model.TwoUserChannel');
+
+/**
+ * backend-side of the livechat.
+ *
+ * Any piece of code in JS that make use of Livechats must ideally interact with
+ * such objects, instead of direct data from the server.
+ */
+var Livechat = TwoUserChannel.extend({
+    _WEBSITE_USER_ID: '_websiteUser',
+    _WEBSITE_USER_NAME: 'Website user',
+
+    /**
+     * @override
+     * @param {Object} params
+     * @param {Object} params.data
+     * @param {string} params.data.anonymous_name name of the website user
+     */
+    init: function (params) {
+        this._super.apply(this, arguments);
+
+        this._name = params.data.anonymous_name;
+
+        this._WEBSITE_USER_NAME = this._name;
+    },
+
+    //--------------------------------------------------------------------------
+    // Public
+    //--------------------------------------------------------------------------
+
+    /**
+     * For the livechat,
+     *
+     * @override
+     * @returns {$.Promise<Object[]>} resolved with list of livechat members
+     */
+    getMentionPartnerSuggestions: function () {
+        var self = this;
+        return this._super.apply(this, arguments).then(function () {
+            var websiteUser = _.findWhere(self._members, { id: self._WEBSITE_USER_ID });
+            if (!websiteUser) {
+                self._members.push({
+                    id: self._WEBSITE_USER_ID,
+                    name: self._WEBSITE_USER_NAME,
+                });
+            }
+            return self._members;
+        });
+    },
+});
+
+return Livechat;
+
+});
diff --git a/addons/mail/static/src/js/models/threads/mailbox.js b/addons/mail/static/src/js/models/threads/mailbox.js
index 4ba7c4e8d1f..172b5af9e3b 100644
--- a/addons/mail/static/src/js/models/threads/mailbox.js
+++ b/addons/mail/static/src/js/models/threads/mailbox.js
@@ -1,7 +1,7 @@
 odoo.define('mail.model.Mailbox', function (require) {
 "use strict";
 
-var ThreadWithCache = require('mail.model.ThreadWithCache');
+var SearchableThread = require('mail.model.SearchableThread');
 
 var core = require('web.core');
 
@@ -14,7 +14,7 @@ var _t = core._t;
  * list of messages, but the inbox does not represent a conversation: Inbox is
  * modeled as a mailbox.
  */
-var Mailbox = ThreadWithCache.extend({
+var Mailbox = SearchableThread.extend({
 
     /**
      * @override
diff --git a/addons/mail/static/src/js/models/threads/multi_user_channel.js b/addons/mail/static/src/js/models/threads/multi_user_channel.js
new file mode 100644
index 00000000000..c1681744127
--- /dev/null
+++ b/addons/mail/static/src/js/models/threads/multi_user_channel.js
@@ -0,0 +1,56 @@
+odoo.define('mail.model.MultiUserChannel', function (require) {
+"use strict";
+
+var Channel = require('mail.model.Channel');
+
+var MultiUserChannel = Channel.extend({
+    /**
+     * @override
+     * @param {Object} params
+     * @param {Object} params.data
+     * @param {boolean} [params.data.mass_mailing=false]
+     * @param {string} [params.data.public='public'] either 'public' or
+     *   'private'
+     */
+    init: function (params) {
+        this._super.apply(this, arguments);
+
+        var data = params.data;
+
+        this._isMassMailing = data.mass_mailing || false;
+        this._type = data.public !== 'private' ? 'public' : 'private';
+    },
+
+    //--------------------------------------------------------------------------
+    // Public
+    //--------------------------------------------------------------------------
+
+    /**
+     * States whether this thread has the mass mailing setting active or not.
+     * This is a server-side setting, that determine the type of composer that
+     * is used (basic or extended composer).
+     *
+     * @return {boolean}
+     */
+    isMassMailing: function () {
+        return this._isMassMailing;
+    },
+    /**
+     * Unsubscribes from channel
+     *
+     * @override
+     * @returns {$.Promise} resolve when unsubscribed
+     */
+    unsubscribe: function () {
+        return this._rpc({
+            model: 'mail.channel',
+            method: 'action_unfollow',
+            args: [[this.getID()]],
+        });
+    },
+
+});
+
+return MultiUserChannel;
+
+});
diff --git a/addons/mail/static/src/js/models/threads/thread_with_cache.js b/addons/mail/static/src/js/models/threads/searchable_thread.js
index c82432c64d7..fef42c3ffc4 100644
--- a/addons/mail/static/src/js/models/threads/thread_with_cache.js
+++ b/addons/mail/static/src/js/models/threads/searchable_thread.js
@@ -1,4 +1,4 @@
-odoo.define('mail.model.ThreadWithCache', function (require) {
+odoo.define('mail.model.SearchableThread', function (require) {
 "use strict";
 
 var Thread = require('mail.model.Thread');
@@ -13,7 +13,7 @@ var session = require('web.session');
  * Any threads that are instances of this Class can be used with a search view,
  * in order to make searches on messages in a thread.
  */
-var ThreadWithCache = Thread.extend({
+var SearchableThread = Thread.extend({
 
     /**
      * @override
@@ -39,23 +39,6 @@ var ThreadWithCache = Thread.extend({
     //--------------------------------------------------------------------------
 
     /**
-     * Add the message to this thread
-     *
-     * @override
-     * @private
-     * @param {mail.model.Message} message
-     * @param {Array} domain
-     */
-    addMessage: function (message, domain) {
-        var cache = this._getCache(domain);
-        var index = _.sortedIndex(cache.messages, message, function (msg) {
-            return msg.getID();
-        });
-        if (cache.messages[index] !== message) {
-            cache.messages.splice(index, 0, message);
-        }
-    },
-    /**
      * @override
      * @param {Array} [domain]
      * @param {boolean} [loadMore=false]
@@ -129,6 +112,24 @@ var ThreadWithCache = Thread.extend({
     //--------------------------------------------------------------------------
 
     /**
+     * Add the message to this thread
+     *
+     * @override
+     * @private
+     * @param {mail.model.Message} message
+     * @param {Array} domain
+     */
+    _addMessage: function (message, domain) {
+        this._super.apply(this, arguments);
+        var cache = this._getCache(domain);
+        var index = _.sortedIndex(cache.messages, message, function (msg) {
+            return msg.getID();
+        });
+        if (cache.messages[index] !== message) {
+            cache.messages.splice(index, 0, message);
+        }
+    },
+    /**
      * Gets messages from thread
      *
      * @override
@@ -202,6 +203,6 @@ var ThreadWithCache = Thread.extend({
     _getThreadDomain: function () {},
 });
 
-return ThreadWithCache;
+return SearchableThread;
 
 });
diff --git a/addons/mail/static/src/js/models/threads/thread.js b/addons/mail/static/src/js/models/threads/thread.js
index 5fcd0285a82..c9dda28dd93 100644
--- a/addons/mail/static/src/js/models/threads/thread.js
+++ b/addons/mail/static/src/js/models/threads/thread.js
@@ -5,7 +5,6 @@ var emojis = require('mail.emojis');
 var AbstractThread = require('mail.model.AbstractThread');
 var mailUtils = require('mail.utils');
 
-var Mixins = require('web.mixins');
 var ServicesMixin = require('web.ServicesMixin');
 
 /**
@@ -15,7 +14,7 @@ var ServicesMixin = require('web.ServicesMixin');
  *
  * In particular, channels and mailboxes are two different kinds of threads.
  */
-var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
+var Thread = AbstractThread.extend(ServicesMixin, {
 
     /**
      * @override
@@ -27,15 +26,9 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
      * @param {string} [params.data.type]
      */
     init: function (params) {
-        Mixins.EventDispatcherMixin.init.call(this, arguments);
-        this.setParent(params.parent);
         this._super.apply(this, arguments);
         // threads are not detached by default
         this._detached = false;
-        // if this._massMailing is set, display subject on messages, use
-        // extended composer and show "Send by messages by email" on discuss
-        // sidebar
-        this._massMailing = false;
         // on 1st request to getPreview, fetch data if incomplete. Otherwise it
         // means that there is no message in this channel.
         this._previewed = false;
@@ -49,13 +42,6 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
     //--------------------------------------------------------------------------
 
     /**
-     * Add a message to this thread.
-     *
-     * @abstract
-     * @param {mail.model.Message} message
-     */
-    addMessage: function (message) {},
-    /**
      * Updates the _detached state of the thread. Must be overriden to reflect
      * the new state in the interface.
      */
@@ -140,7 +126,7 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
         return {
             id: this.getID(),
             imageSRC: '/mail/static/src/img/smiley/avatar.jpg',
-            isChat: this.isChat(),
+            isTwoUserThread: this.isTwoUserThread(),
             status: this.getStatus(),
             title: this.getName(),
             unreadCounter: this.getUnreadCounter(),
@@ -189,16 +175,6 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
      */
     incrementNeedactionCounter: function () {},
     /**
-     * Increment the unread counter of this thread by 1 unit, and warn that the
-     * counter has been changed.
-     *
-     * @override
-     */
-    incrementUnreadCounter: function () {
-        this._super.apply(this, arguments);
-        this._warnUpdatedUnreadCounter();
-    },
-    /**
      * States whether the thread should be auto-selected on creation
      *
      * Note that this is not of the responsibility of the thread: it only
@@ -223,17 +199,6 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
         return false;
     },
     /**
-     * States whether this thread is a chat or not. In particular, public and
-     * private channels are not chat, but DMs and Livechats are chats. Chats
-     * are threads used for communication between two users.
-     * By default, any thread is not a chat
-     *
-     * @returns {boolean}
-     */
-    isChat: function () {
-        return false;
-    },
-    /**
      * States whether this thread is detached or not.
      * A thread that is detached must have a thread window linked to itself.
      *
@@ -256,10 +221,12 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
      * This is a server-side setting, that determine the type of composer that
      * is used (basic or extended composer).
      *
+     * By default, thread have not mass-mailings feature set.
+     *
      * @return {boolean}
      */
     isMassMailing: function () {
-        return this._massMailing;
+        return false;
     },
     /**
 
@@ -277,7 +244,18 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
      *
      * @returns {boolean}
      */
-    isModerator: function () {
+    isMyselfModerator: function () {
+        return false;
+    },
+    /**
+     * States whether this is a two-user thread or not. In particular, public
+     * and private channels are not two-user threads, but DMs and Livechats are
+     * two-user threads. Two-user threads are used for communication between
+     * two users. By default, any thread is not two-user thread.
+     *
+     * @returns {boolean}
+     */
+    isTwoUserThread: function () {
         return false;
     },
     /**
@@ -294,29 +272,61 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
     markAsPreviewed: function () {
         this._previewed = true;
     },
+
+    //--------------------------------------------------------------------------
+    // Private
+    //--------------------------------------------------------------------------
+
     /**
-     * Mark the thread as read, which resets the unread counter to 0.
-     *
-     * @returns {$.Promise} resolved
+     * @abstract
+     * @private
+     * @return {$.Promise}
      */
-    markAsRead: function () {
-        if (this._unreadCounter > 0) {
-            this.resetUnreadCounter();
-        }
+    _fetchMessages: function () {
         return $.when();
     },
     /**
+     * Replace character representations of emojis by their unicode
+     * representation in the provided HTML string. Note that the provided html
+     * string is altered by this function.
+     *
+     * @param {string} htmlString
+     * @returns {string}
+     */
+    _generateEmojis: function (htmlString) {
+        _.each(emojis, function (emoji) {
+            _.each(emoji.sources, function (source) {
+                var escapedSource = String(source).replace(/([.*+?=^!:${}()|[\]/\\])/g, '\\$1');
+                var regexp = new RegExp("(\\s|^)(" + escapedSource + ")(?=\\s|$)", 'g');
+                htmlString = htmlString.replace(regexp, '$1' + emoji.unicode);
+            });
+        });
+        return htmlString;
+    },
+    /**
+     * Increment the unread counter of this thread by 1 unit, and warn that the
+     * counter has been changed.
+     *
+     * @override
+     * @private
+     */
+    _incrementUnreadCounter: function () {
+        this._super.apply(this, arguments);
+        this._warnUpdatedUnreadCounter();
+    },
+    /**
      * Post a message on the thread.
      *
      * This method must be completed by concrete threads,
      * As it currently only pre-process the messages at the moment.
      *
      * @abstract
+     * @private
      * @param {Object} data
      * @returns {$.Promise<Object>} resolved with the message object to be sent
      *   to the server
      */
-    postMessage: function (data) {
+    _postMessage: function (data) {
         // This message will be received from the mail composer as html content
         // subtype but the urls will not be linkified. If the mail composer
         // takes the responsibility to linkify the urls we end up with double
@@ -334,58 +344,18 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
         if ('subject' in data) {
             messageData.subject = data.subject;
         }
-        return $.when(messageData);
-    },
-    /**
-     * Overrides the method so that it also warns that the counter has been
-     * changed on this thread.
-     *
-     * @override
-     * @private
-     */
-    resetUnreadCounter: function () {
-        this._super.apply(this, arguments);
-        this._warnUpdatedUnreadCounter();
-    },
-
-    //--------------------------------------------------------------------------
-    // Private
-    //--------------------------------------------------------------------------
-
-    /**
-     * @abstract
-     * @private
-     * @return {$.Promise}
-     */
-    _fetchMessages: function () {
-        return $.when();
-    },
-    /**
-     * Replace character representations of emojis by their unicode
-     * representation in the provided HTML string. Note that the provided html
-     * string is altered by this function.
-     *
-     * @param {string} htmlString
-     * @returns {string}
-     */
-    _generateEmojis: function (htmlString) {
-        _.each(emojis, function (emoji) {
-            _.each(emoji.sources, function (source) {
-                var escapedSource = String(source).replace(/([.*+?=^!:${}()|[\]/\\])/g, '\\$1');
-                var regexp = new RegExp("(\\s|^)(" + escapedSource + ")(?=\\s|$)", 'g');
-                htmlString = htmlString.replace(regexp, '$1' + emoji.unicode);
-            });
+        return this._super.apply(this, arguments).then(function () {
+            return $.when(messageData);
         });
-        return htmlString;
     },
     /**
-     * Warn on the chat bus that the unread counter has been updated
+     * Warn on the mail bus that the unread counter has been updated
      *
+     * @override
      * @private
      */
     _warnUpdatedUnreadCounter: function () {
-        this.call('mail_service', 'getMailBus')
-            .trigger('update_thread_unread_counter', this);
+        this.call('mail_service', 'getMailBus').trigger('update_thread_unread_counter', this);
     },
     /**
      * Warn other mail components that the window state of this thread has
@@ -393,6 +363,7 @@ var Thread = AbstractThread.extend(Mixins.EventDispatcherMixin, ServicesMixin, {
      *
      * @private
      * @param {Object} [options={}]
+     * @param {boolean} [options.passively=false]
      */
     _warnUpdatedWindowState: function (options) {
         options = options || {};
diff --git a/addons/mail/static/src/js/models/threads/two_user_channel.js b/addons/mail/static/src/js/models/threads/two_user_channel.js
new file mode 100644
index 00000000000..204fd95eb82
--- /dev/null
+++ b/addons/mail/static/src/js/models/threads/two_user_channel.js
@@ -0,0 +1,32 @@
+odoo.define('mail.model.TwoUserChannel', function (require) {
+"use strict";
+
+var Channel = require('mail.model.Channel');
+
+var TwoUserChannel = Channel.extend({
+    /**
+     * @override
+     * @returns {boolean}
+     */
+    isTwoUserThread: function () {
+        return true;
+    },
+    /**
+     * Unpin from two-user thread
+     *
+     * @override
+     * @returns {$.Promise} resolve when unsubscribed
+     */
+    unsubscribe: function () {
+        return this._rpc({
+            model: 'mail.channel',
+            method: 'channel_pin',
+            args: [this.getUUID(), false],
+        });
+    },
+
+});
+
+return TwoUserChannel;
+
+});