Merge pull request #3393 from matrix-org/bwindels/cider-fix-lastcaret

New composer: fix needing to push arrow-up twice after sending first message after switching to a room

src/editor/model.js

@@ -149,6 +149,9 @@ export default class EditorModel {
 
     reset(serializedParts, caret, inputType) {
         this._parts = serializedParts.map(p => this._partCreator.deserializePart(p));
+        if (!caret) {
+            caret = this.getPositionAtEnd();
+        }
         // close auto complete if open
         // this would happen when clearing the composer after sending
         // a message with the autocomplete still open

src/editor/position.js

@@ -120,4 +120,17 @@ export default class DocumentPosition {
         const atEnd = offset >= lastPart.text.length;
         return new DocumentOffset(offset, atEnd);
     }
+
+    isAtEnd(model) {
+        if (model.parts.length === 0) {
+            return true;
+        }
+        const lastPartIdx = model.parts.length - 1;
+        const lastPart = model.parts[lastPartIdx];
+        return this.index === lastPartIdx && this.offset === lastPart.text.length;
+    }
+
+    isAtStart() {
+        return this.index === 0 && this.offset === 0;
+    }
 }