Implement offline support for context entries

src/matrix/room/timeline/Timeline.js

@@ -101,6 +101,7 @@ export class Timeline {
                 pe => this._mapPendingEventToEntry(pe),
                 (pee, params) => {
                     // is sending but redacted, who do we detect that here to remove the relation?
+                    this._loadContextEntriesWhereNeeded([pee]);
                     pee.notifyUpdate(params);
                 },
                 pee => this._applyAndEmitLocalRelationChange(pee, target => target.removeLocalRelation(pee))
@@ -124,6 +125,7 @@ export class Timeline {
             pendingEvent: pe, member: this._ownMember,
             clock: this._clock, redactingEntry
         });
+        this._loadContextEntriesWhereNeeded([pee]);
         this._applyAndEmitLocalRelationChange(pee, target => target.addRelation(pee));
         return pee;
     }

src/matrix/room/timeline/entries/BaseEventEntry.js

@@ -27,6 +27,8 @@ export class BaseEventEntry extends BaseEntry {
         super(fragmentIdComparer);
         this._pendingRedactions = null;
         this._pendingAnnotations = null;
+        this._contextEntry = null;
+        this._contextForEntries = null;
     }
 
     get isReply() {
@@ -52,6 +54,26 @@ export class BaseEventEntry extends BaseEntry {
         return null;
     }
 
+    setContextEntry(entry) {
+        this._contextEntry = entry;
+        entry._setAsContextOf(this);
+    }
+
+    _setAsContextOf(entry) {
+        if (!this._contextForEntries) {
+            this._contextForEntries = [];
+        }
+        this._contextForEntries.push(entry);
+    }
+
+    get contextForEntries() {
+        return this._contextForEntries;
+    }
+
+    get contextEntry() {
+        return this._contextEntry;
+    }
+
     /**
         Aggregates relation or redaction of remote relation.  
         Used in two situations:

src/matrix/room/timeline/entries/EventEntry.js

@@ -24,8 +24,6 @@ export class EventEntry extends BaseEventEntry {
         this._eventEntry = eventEntry;
         this._decryptionError = null;
         this._decryptionResult = null;
-        this._contextEntry = null;
-        this._contextForEntries = null;
     }
 
     clone() {
@@ -45,20 +43,8 @@ export class EventEntry extends BaseEventEntry {
         this._contextEntry = other.contextEntry;
     }
 
-    setContextEntry(entry) {
-        this._contextEntry = entry;
-        entry._setAsContextOf(this);
-    }
-
-    _setAsContextOf(entry) {
-        if (!this._contextForEntries) {
-            this._contextForEntries = [];
-        }
-        this._contextForEntries.push(entry);
-    }
-
-    get contextForEntries() {
-        return this._contextForEntries;
+    setRelatedEntry(entry) {
+        this._relatedEntry = entry;
     }
 
     get event() {
@@ -142,18 +128,13 @@ export class EventEntry extends BaseEventEntry {
         return getRelatedEventId(this.event);
     }
 
-    // similar to relatedEventID but only for replies
-    get contextEventId() {
-        if (this.isReply) {
-            return this.relatedEventId;
+    get threadEventId() {
+        if (this.isThread) {
+            return this.relation?.event_id;
         }
         return null;
     }
 
-    get contextEntry() {
-        return this._contextEntry;
-    }
-
     get isRedacted() {
         return super.isRedacted || isRedacted(this._eventEntry.event);
     }
@@ -176,6 +157,15 @@ export class EventEntry extends BaseEventEntry {
         const originalRelation = originalContent && getRelationFromContent(originalContent);
         return originalRelation || getRelationFromContent(this.content);
     }
+
+    // similar to relatedEventID but only for replies
+    get contextEventId() {
+        if (this.isReply) {
+            return this.relatedEventId;
+        }
+        return null;
+    }
+
 }
 
 import {withTextBody, withContent, createEvent} from "../../../../mocks/event.js";

src/matrix/room/timeline/entries/PendingEventEntry.js

@@ -100,4 +100,11 @@ export class PendingEventEntry extends BaseEventEntry {
     get redactingEntry() {
         return this._redactingEntry;
     }
+
+    get contextEventId() {
+        if (this.isReply) {
+            return this._pendingEvent.relatedEventId ?? this._pendingEvent.relatedTxnId;
+        }
+        return null;
+    }
 }