From 6edc29dce213c83425b6c645583a1dfbb50f3482 Mon Sep 17 00:00:00 2001
From: Elena Torro <elenatorro@gmail.com>
Date: Tue, 28 Oct 2025 10:59:49 +0100
Subject: [PATCH] :bug: Fix text selection

---
 frontend/text-editor/package.json             |  1 +
 .../editor/controllers/SelectionController.js | 74 +++++++++++++++++--
 2 files changed, 67 insertions(+), 8 deletions(-)

diff --git a/frontend/text-editor/package.json b/frontend/text-editor/package.json
index b31fc91b7f..40ffaf6472 100644
--- a/frontend/text-editor/package.json
+++ b/frontend/text-editor/package.json
@@ -9,6 +9,7 @@
     "coverage": "vitest run --coverage",
     "wasm:update": "cp ../resources/public/js/render_wasm.wasm ./src/wasm/render_wasm.wasm && cp ../resources/public/js/render_wasm.js ./src/wasm/render_wasm.js",
     "test": "vitest --run",
+    "fmt:js": "yarn run prettier -c src/**/*.js",
     "test:watch": "vitest",
     "test:watch:ui": "vitest --ui",
     "test:watch:e2e": "vitest --browser"
diff --git a/frontend/text-editor/src/editor/controllers/SelectionController.js b/frontend/text-editor/src/editor/controllers/SelectionController.js
index 7c2ff0edd8..4dc8979542 100644
--- a/frontend/text-editor/src/editor/controllers/SelectionController.js
+++ b/frontend/text-editor/src/editor/controllers/SelectionController.js
@@ -1263,6 +1263,7 @@ export class SelectionController extends EventTarget {
   replaceText(newText) {
     const startOffset = Math.min(this.anchorOffset, this.focusOffset);
     const endOffset = Math.max(this.anchorOffset, this.focusOffset);
+
     if (this.isTextFocus) {
       this.focusNode.nodeValue = replaceWith(
         this.focusNode.nodeValue,
@@ -1279,7 +1280,11 @@ export class SelectionController extends EventTarget {
       this.focusNode.replaceChildren(newParagraph);
       return this.collapse(newTextNode, newText.length + 1);
     } else {
-      throw new Error("Unknown node type");
+      const newTextNode = new Text(newText);
+      const newTextSpan = createTextSpan(newTextNode, this.#currentStyle);
+      const newParagraph = createParagraph([newTextSpan], this.#currentStyle);
+      this.#textEditor.root.replaceChildren(newParagraph);
+      return this.collapse(newTextNode, newText.length + 1);
     }
     this.#mutations.update(this.focusTextSpan);
     return this.collapse(this.focusNode, startOffset + newText.length);
@@ -1538,15 +1543,15 @@ export class SelectionController extends EventTarget {
     const affectedTextSpans = new Set();
     const affectedParagraphs = new Set();
 
-    const startNode = getClosestTextNode(this.#range.startContainer);
-    const endNode = getClosestTextNode(this.#range.endContainer);
-
-    const startOffset = this.#range.startOffset;
-    const endOffset = this.#range.endOffset;
-
     let previousNode = null;
     let nextNode = null;
 
+    let { startNode, endNode, startOffset, endOffset } = this.getRanges();
+
+    if (this.shouldHandleCompleteDeletion(startNode, endNode)) {
+      return this.handleCompleteContentDeletion();
+    }
+
     // This is the simplest case, when the startNode and
     // the endNode are the same and they're textNodes.
     if (startNode === endNode) {
@@ -1612,7 +1617,8 @@ export class SelectionController extends EventTarget {
       } else if (currentNode === endNode) {
         if (
           isLineBreak(endNode) ||
-          (isTextNode(endNode) && endOffset === (endNode.nodeValue?.length || 0))
+          (isTextNode(endNode) &&
+            endOffset === (endNode.nodeValue?.length || 0))
         ) {
           // We should remove this node completely.
           shouldRemoveNodeCompletely = true;
@@ -1694,6 +1700,58 @@ export class SelectionController extends EventTarget {
     return this.collapse(startNode, startOffset);
   }
 
+  getRanges() {
+    let startNode = getClosestTextNode(this.#range.startContainer);
+    let endNode = getClosestTextNode(this.#range.endContainer);
+
+    let startOffset = this.#range.startOffset;
+    let endOffset = this.#range.startOffset + this.#range.toString().length;
+
+    return { startNode, endNode, startOffset, endOffset };
+  }
+
+  shouldHandleCompleteDeletion(startNode, endNode) {
+    const root = this.#textEditor.root;
+    return (
+      (startNode &&
+        endNode &&
+        this.#range.toString() === (root.textContent || "") &&
+        root.textContent.length > 0) ||
+      !startNode ||
+      !endNode
+    );
+  }
+
+  /**
+   * Handles complete content deletion when all content is selected.
+   * @returns {SelectionController}
+   */
+  handleCompleteContentDeletion() {
+    const root = this.#textEditor.root;
+    const firstParagraph = root.firstElementChild;
+
+    const newTextSpan = createEmptyTextSpan(this.#currentStyle);
+    if (!newTextSpan.firstChild) {
+      newTextSpan.appendChild(new Text(""));
+    }
+
+    if (firstParagraph) {
+      firstParagraph.replaceChildren(newTextSpan);
+      let currentParagraph = firstParagraph.nextElementSibling;
+      while (currentParagraph) {
+        const nextParagraph = currentParagraph.nextElementSibling;
+        currentParagraph.remove();
+        currentParagraph = nextParagraph;
+      }
+    } else {
+      const newParagraph = createEmptyParagraph();
+      newParagraph.appendChild(newTextSpan);
+      root.replaceChildren(newParagraph);
+    }
+
+    return this.collapse(newTextSpan.firstChild, 0);
+  }
+
   /**
    * Applies styles from the startNode to the endNode.
    *