revert solution with cached last header date

DevExpress · Oct 15, 2024 · 8c78826 · 8c78826
1 parent 64eaa6b
commit 8c78826
Showing 1 changed file with 7 additions and 46 deletions.
diff --git a/packages/devextreme/js/__internal/ui/chat/messagelist.ts b/packages/devextreme/js/__internal/ui/chat/messagelist.ts
@@ -38,6 +38,8 @@ export interface Properties extends WidgetOptions<MessageList> {
 class MessageList extends Widget<Properties> {
   private _messageGroups?: MessageGroup[];
 
+  private _lastMessageDate?: null | string | number | Date;
+
   private _containerClientHeight!: number;
 
   private _scrollable!: Scrollable<unknown>;
@@ -55,6 +57,7 @@ class MessageList extends Widget<Properties> {
     super._init();
 
     this._messageGroups = [];
+    this._lastMessageDate = null;
   }
 
   _initMarkup(): void {
@@ -173,10 +176,7 @@ class MessageList extends Widget<Properties> {
     });
   }
 
-  _shouldAddDayHeader(
-    timestamp: undefined | string | number | Date,
-    currentMessageGroupItems: Message[] = [],
-  ): boolean {
+  _shouldAddDayHeader(timestamp: undefined | string | number | Date): boolean {
     const { showDayHeaders } = this.option();
 
     if (!showDayHeaders) {
@@ -189,52 +189,14 @@ class MessageList extends Widget<Properties> {
       return false;
     }
 
-    const lastDayHeaderDate = this._getLastDayHeaderDate(currentMessageGroupItems);
-
-    return !dateUtils.sameDate(lastDayHeaderDate, deserializedDate);
-  }
-
-  _getLastDayHeaderDate(currentMessageGroupItems: Message[] = []): Date | null {
-    let lastDayHeaderDate = null;
-    const messageGroups = this._messageGroups ?? [];
-
-    let index = currentMessageGroupItems.length - 1;
-
-    while (index >= 0 && lastDayHeaderDate === null) {
-      const messageTimestamp = currentMessageGroupItems[index].timestamp;
-
-      if (messageTimestamp) {
-        lastDayHeaderDate = dateSerialization.deserializeDate(messageTimestamp);
-      }
-      index -= 1;
-    }
-
-    index = messageGroups.length - 1;
-
-    while (index >= 0 && lastDayHeaderDate === null) {
-      const { items } = messageGroups[index].option();
-
-      const messageGroupTimestampList: (Date | string | number)[] = [];
-      items.forEach((item: Message) => {
-        if (item.timestamp) {
-          messageGroupTimestampList.push(item.timestamp);
-        }
-      });
-
-      if (messageGroupTimestampList.length > 0) {
-        lastDayHeaderDate = dateSerialization.deserializeDate(messageGroupTimestampList.at(-1));
-      }
-
-      index -= 1;
-    }
-
-    return lastDayHeaderDate;
+    return !dateUtils.sameDate(this._lastMessageDate, deserializedDate);
   }
 
   _createDayHeader(timestamp: string | number | Date | undefined): void {
     const deserializedDate = dateSerialization.deserializeDate(timestamp);
     const today = new Date();
     const yesterday = new Date(new Date().setDate(today.getDate() - 1));
+    this._lastMessageDate = deserializedDate;
 
     let headerDate = deserializedDate.toLocaleDateString(undefined, {
       day: '2-digit',
@@ -270,9 +232,8 @@ class MessageList extends Widget<Properties> {
 
     items.forEach((item, index) => {
       const newMessageGroupItem = item ?? {};
-      const { timestamp } = newMessageGroupItem;
       const id = newMessageGroupItem.author?.id;
-      const shouldCreateDayHeader = this._shouldAddDayHeader(timestamp, currentMessageGroupItems);
+      const shouldCreateDayHeader = this._shouldAddDayHeader(newMessageGroupItem.timestamp);
       const isTimeoutExceeded = this._isTimeoutExceeded(
         currentMessageGroupItems[currentMessageGroupItems.length - 1] ?? {},
         item,