adding lastReadTimestamp property

ts/models/conversation.ts

@@ -92,6 +92,7 @@ export interface ConversationAttributes {
   triggerNotificationsFor: ConversationNotificationSettingType;
   isTrustedForAttachmentDownload: boolean;
   isPinned: boolean;
+  lastReadTimestamp: number;
 }
 
 export interface ConversationAttributesOptionals {
@@ -160,6 +161,7 @@ export const fillConvoAttributesWithDefaults = (
     triggerNotificationsFor: 'all', // if the settings is not set in the db, this is the default
     isTrustedForAttachmentDownload: false, // we don't trust a contact until we say so
     isPinned: false,
+    lastReadTimestamp: 0,
   });
 };
 
@@ -188,7 +190,13 @@ export class ConversationModel extends Backbone.Model<ConversationAttributes> {
     this.updateLastMessage = _.throttle(this.bouncyUpdateLastMessage.bind(this), 1000);
     this.throttledNotify = _.debounce(this.notify, 500, { maxWait: 1000 });
     //start right away the function is called, and wait 1sec before calling it again
-    this.markRead = _.debounce(this.markReadBouncy, 1000, { leading: true });
+    this.markRead = (readAt: number) => {
+      const lastReadTimestamp = this.get('lastReadTimestamp');
+      if (readAt > lastReadTimestamp) {
+        this.set('lastReadTimestamp', readAt);
+      }
+      _.debounce(this.markReadBouncy, 1000, { leading: true });
+    }
     // Listening for out-of-band data updates
 
     this.typingRefreshTimer = null;
@@ -902,6 +910,10 @@ export class ConversationModel extends Backbone.Model<ConversationAttributes> {
   }
 
   public async markReadBouncy(newestUnreadDate: number, providedOptions: any = {}) {
+    if (this.get('lastReadTimestamp') >= 0) {
+      return;
+    }
+
     const options = providedOptions || {};
     _.defaults(options, { sendReadReceipts: true });