feat(chat): on web, group messages by sender

css/_chat.scss

     border-radius:0;
     box-shadow: none;
     color: white;
-    font-size: 10pt;
+    font-size: 15px;
     line-height: 30px;
     padding: 5px;
     max-height:150px;
     }
 
     .display-name {
-        float: left;
-        padding-left: 5px;
+        font-size: 13px;
         font-weight: bold;
         white-space: nowrap;
         text-overflow: ellipsis;
-        width: 95%;
         overflow: hidden;
     }
-
-    .timestamp {
-        float: right;
-        padding-right: 5px;
-        font-size: 11px;
-    }
-}
-
-.usermessage {
-    padding-top: 20px;
-    padding-left: 5px;
 }
 
 .chatmessage {
 #usermsg::-webkit-scrollbar-track-piece {
     background: #3a3a3a;
 }
+
+.chat-message-group {
+    display: flex;
+    flex-direction: column;
+
+    &.local {
+        align-items: flex-end;
+
+        .display-name {
+            display: none;
+        }
+
+        .chatmessage {
+            background-color: $chatLocalMessageBackgroundColor;
+            border-radius: 6px 0px 6px 6px;
+        }
+    }
+
+    &.error {
+        .chatmessage {
+            border-radius: 0px;
+            color: red;
+        }
+
+        .display-name {
+            display: none;
+        }
+    }
+
+    .chatmessage {
+        background-color: $chatRemoteMessageBackgroundColor;
+        border-radius: 0px 6px 6px 6px;
+        display: inline-block;
+        margin-top: 3px;
+        color: white;
+        padding: 8px;
+    }
+}

react/features/chat/components/AbstractChatMessage.js

      */
     message: Object,
 
+    /**
+     * Whether or not the name of the participant which sent the message should
+     * be displayed.
+     */
+    showDisplayName: boolean,
+
     /**
      * Invoked to receive translated strings.
      */
 /**
  * Abstract component to display a chat message.
  */
-export default class AbstractChatMessage<P: Props> extends PureComponent<P> {}
+export default class AbstractChatMessage<P: Props> extends PureComponent<P> {
+    static defaultProps = {
+        showDisplayName: true
+    };
+}
 
 /**
  * Maps part of the Redux state to the props of this component.

react/features/chat/components/web/Chat.js

     type Props
 } from '../AbstractChat';
 import ChatInput from './ChatInput';
-import ChatMessage from './ChatMessage';
+import ChatMessageGroup from './ChatMessageGroup';
 import DisplayNameForm from './DisplayNameForm';
 
 /**
         this._messagesListEnd = null;
 
         // Bind event handlers so they are only bound once for every instance.
-        this._renderMessage = this._renderMessage.bind(this);
         this._renderPanelContent = this._renderPanelContent.bind(this);
         this._setMessageListEndRef = this._setMessageListEndRef.bind(this);
     }
         );
     }
 
+    /**
+     * Iterates over all the messages and creates nested arrays which hold
+     * consecutive messages sent be the same participant.
+     *
+     * @private
+     * @returns {Array<Array<Object>>}
+     */
+    _getMessagesGroupedBySender() {
+        const messagesCount = this.props._messages.length;
+        const groups = [];
+        let currentGrouping = [];
+        let currentGroupParticipantId;
+
+        for (let i = 0; i < messagesCount; i++) {
+            const message = this.props._messages[i];
+
+            if (message.id === currentGroupParticipantId) {
+                currentGrouping.push(message);
+            } else {
+                groups.push(currentGrouping);
+
+                currentGrouping = [ message ];
+                currentGroupParticipantId = message.id;
+            }
+        }
+
+        groups.push(currentGrouping);
+
+        return groups;
+    }
+
     /**
      * Returns a React Element for showing chat messages and a form to send new
      * chat messages.
      * @returns {ReactElement}
      */
     _renderChat() {
-        const messages = this.props._messages.map(this._renderMessage);
+        const groupedMessages = this._getMessagesGroupedBySender();
+
+        const messages = groupedMessages.map((group, index) => {
+            const messageType = group[0] && group[0].messageType;
+            let className = 'remote';
+
+            if (messageType === 'local') {
+                className = 'local';
+            } else if (messageType === 'error') {
+                className = 'error';
+            }
+
+            return (
+                <ChatMessageGroup
+                    className = { className }
+                    key = { index }
+                    messages = { group } />
+            );
+        });
 
         messages.push(<div
             key = 'end-marker'
         );
     }
 
-    _renderMessage: (Object) => void;
-
-    /**
-     * Called by {@code _onSubmitMessage} to create the chat div.
-     *
-     * @param {string} message - The chat message to display.
-     * @param {string} id - The chat message ID to use as a unique key.
-     * @returns {Array<ReactElement>}
-     */
-    _renderMessage(message: Object, id: string) {
-        return (
-            <ChatMessage
-                key = { id }
-                message = { message } />
-        );
-    }
-
     _renderPanelContent: (string) => React$Node | null;
 
     /**

react/features/chat/components/web/ChatMessage.js

      */
     render() {
         const { message } = this.props;
-        let messageTypeClassname = '';
-        let messageToDisplay = message.message;
-
-        switch (message.messageType) {
-        case 'local':
-            messageTypeClassname = 'localuser';
-
-            break;
-        case 'error':
-            messageTypeClassname = 'error';
-            messageToDisplay = this.props.t('chat.error', {
+        const messageToDisplay = message.messageType === 'error'
+            ? this.props.t('chat.error', {
                 error: message.error,
-                originalText: messageToDisplay
-            });
-            break;
-        default:
-            messageTypeClassname = 'remoteuser';
-        }
+                originalText: message.message
+            })
+            : message.message;
 
         // replace links and smileys
         // Strophe already escapes special symbols on sending,
         });
 
         return (
-            <div className = { `chatmessage ${messageTypeClassname}` }>
-                <div className = 'display-name'>
+            <div className = 'chatmessage'>
+                { this.props.showDisplayName && <div className = 'display-name'>
                     { message.displayName }
-                </div>
-                <div className = { 'timestamp' }>
-                    { ChatMessage.formatTimestamp(message.timestamp) }
-                </div>
+                </div> }
                 <div className = 'usermessage'>
                     { processedMessage }
                 </div>
             </div>
         );
     }
-
-    /**
-     * Returns a timestamp formatted for display.
-     *
-     * @param {number} timestamp - The timestamp for the chat message.
-     * @private
-     * @returns {string}
-     */
-    static formatTimestamp(timestamp) {
-        const now = new Date(timestamp);
-        let hour = now.getHours();
-        let minute = now.getMinutes();
-        let second = now.getSeconds();
-
-        if (hour.toString().length === 1) {
-            hour = `0${hour}`;
-        }
-
-        if (minute.toString().length === 1) {
-            minute = `0${minute}`;
-        }
-
-        if (second.toString().length === 1) {
-            second = `0${second}`;
-        }
-
-        return `${hour}:${minute}:${second}`;
-    }
 }
 
 export default translate(ChatMessage, { wait: false });

react/features/chat/components/web/ChatMessageGroup.js

+// @flow
+
+import React, { Component } from 'react';
+import ChatMessage from './ChatMessage';
+
+import { getLocalizedDateFormatter } from '../../../base/i18n';
+
+type Props = {
+
+    /**
+     * Additional CSS classes to apply to the root element.
+     */
+    className: string,
+
+    /**
+     * The messages to display as a group.
+     */
+    messages: Array<Object>,
+};
+
+/**
+ * Displays a list of chat messages. Will show only the display name for the
+ * first chat message and the timestamp for the last chat message.
+ *
+ * @extends React.Component
+ */
+class ChatMessageGroup extends Component<Props> {
+    static defaultProps = {
+        className: ''
+    };
+
+    /**
+     * Implements React's {@link Component#render()}.
+     *
+     * @inheritdoc
+     */
+    render() {
+        const { className, messages } = this.props;
+
+        const messagesLength = messages.length;
+
+        if (!messagesLength) {
+            return null;
+        }
+
+        const { timestamp } = messages[messagesLength - 1];
+
+        return (
+            <div className = { `chat-message-group ${className}` }>
+                {
+                    messages.map((message, i) => (
+                        <div key = { i }>
+                            <ChatMessage
+                                key = { i }
+                                message = { message }
+                                showDisplayName = { i === 0 } />
+                        </div>))
+                }
+                <div className = 'chat-message-group-footer'>
+                    { getLocalizedDateFormatter(
+                        new Date(timestamp)).format('H:mm') }
+                </div>
+            </div>
+        );
+    }
+}
+
+export default ChatMessageGroup;