From ad4b7ba60cf3ee8b862dfc1c37a7a1f9e5e652f3 Mon Sep 17 00:00:00 2001
From: George Berezhnoy <gohabereg@gmail.com>
Date: Mon, 2 Sep 2024 23:52:43 +0100
Subject: [PATCH] Send event if selection is lost for the input

---
 .../dom-adapters/src/CaretAdapter/index.ts    |  4 ++-
 .../src/utils/useSelectionChange.ts           | 25 +++++++++++++++++++
 .../model/src/CaretManagement/Caret/Caret.ts  |  4 +--
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/packages/dom-adapters/src/CaretAdapter/index.ts b/packages/dom-adapters/src/CaretAdapter/index.ts
index ba866c7b..327694e6 100644
--- a/packages/dom-adapters/src/CaretAdapter/index.ts
+++ b/packages/dom-adapters/src/CaretAdapter/index.ts
@@ -82,7 +82,7 @@ export class CaretAdapter extends EventTarget {
    *
    * @param index - new caret index
    */
-  public updateIndex(index: Index): void {
+  public updateIndex(index: Index | null): void {
     this.#userCaret.update(index);
   }
 
@@ -119,6 +119,8 @@ export class CaretAdapter extends EventTarget {
    */
   #onSelectionChange(selection: Selection | null): void {
     if (!selection) {
+      this.updateIndex(null);
+
       return;
     }
 
diff --git a/packages/dom-adapters/src/utils/useSelectionChange.ts b/packages/dom-adapters/src/utils/useSelectionChange.ts
index d0a8fdc7..cc18907e 100644
--- a/packages/dom-adapters/src/utils/useSelectionChange.ts
+++ b/packages/dom-adapters/src/utils/useSelectionChange.ts
@@ -31,6 +31,12 @@ export type InputWithCaret = HTMLElement;
  * Utility composable that watches for document "selection change" event and delegates the provided callbacks to subscribers.
  */
 export const useSelectionChange = createSingleton(() => {
+  /**
+   * Stores the last input that was related to the selection. 
+   * We need that to send update when selection is moved to another input.
+   */
+  let lastRelatedInput: HTMLElement | null  = null;
+
   /**
    * Used to iterate over all inputs and check if selection is related to them.
    */
@@ -72,9 +78,28 @@ export const useSelectionChange = createSingleton(() => {
     inputsWatched.forEach((input) => {
       const subscriber = subscribers.get(input);
 
+      let isRelatedInputFound = false;
+
       if (subscriber && isSelectionRelatedToInput(selection, input)) {
+        lastRelatedInput = input;
+        isRelatedInputFound = true;
+
         subscriber.callback.call(subscriber.context, selection);
       }
+
+      /**
+       * If no related input found or input is changed, we need to notify subscriber selection is out of it's input
+       */
+      if (!isRelatedInputFound || input !== lastRelatedInput) {
+        subscriber?.callback.call(subscriber.context, null);
+      }
+
+      /**
+       * If no related input found, we need to reset last related input
+       */
+      if (!isRelatedInputFound) {
+        lastRelatedInput = null;
+      }
     });
   }
 
diff --git a/packages/model/src/CaretManagement/Caret/Caret.ts b/packages/model/src/CaretManagement/Caret/Caret.ts
index b8a47824..fa6b8dd7 100644
--- a/packages/model/src/CaretManagement/Caret/Caret.ts
+++ b/packages/model/src/CaretManagement/Caret/Caret.ts
@@ -70,7 +70,7 @@ export class Caret extends EventBus {
    *
    * @param index - new caret index
    */
-  public update(index: Index): void {
+  public update(index: Index | null): void {
     this.#index = index;
 
     this.dispatchEvent(new CaretUpdatedEvent(this));
@@ -82,7 +82,7 @@ export class Caret extends EventBus {
   public toJSON(): CaretSerialized {
     return {
       id: this.id,
-      index: this.index?.serialize(),
+      index: this.index !== null ? this.index.serialize() : null,
     } as CaretSerialized;
   }
 }