Page exit prevention refactor (#637)

* Add page exit prevention functionality to SettingsController

* Update dictionary controller to use new page exit prevention system

* Remove page-exit-prevention.js

2 files changed, 42 insertions, 8 deletions

diff --git a/ext/bg/js/settings/dictionaries.js b/ext/bg/js/settings/dictionaries.js
index 94a71233..1e780909 100644
--- a/ext/bg/js/settings/dictionaries.js
+++ b/ext/bg/js/settings/dictionaries.js
@@ -16,7 +16,6 @@
  */
 
 /* global
- * PageExitPrevention
  * api
  * utilBackgroundIsolate
  */
@@ -156,6 +155,11 @@ class SettingsDictionaryListUI extends EventDispatcher {
         // Overwrite
     }
 
+    preventPageExit() {
+        // Overwrite
+        return {end: () => {}};
+    }
+
     onDictionaryConfirmDelete(e) {
         e.preventDefault();
         const n = document.querySelector('#dict-delete-modal');
@@ -286,10 +290,8 @@ class SettingsDictionaryEntryUI {
         const progressBar = this.content.querySelector('.progress-bar');
         this.isDeleting = true;
 
-        const prevention = new PageExitPrevention();
+        const prevention = this.parent.preventPageExit();
         try {
-            prevention.start();
-
             const onProgress = ({processed, count, storeCount, storesProcesed}) => {
                 let percent = 0.0;
                 if (count > 0 && storesProcesed > 0) {
@@ -409,6 +411,7 @@ class DictionaryController {
             document.querySelector('#dict-extra-template')
         );
         this._dictionaryUI.save = () => this._settingsController.save();
+        this._dictionaryUI.preventPageExit = this._preventPageExit.bind(this);
         this._dictionaryUI.on('databaseUpdated', this._onDatabaseUpdated.bind(this));
 
         document.querySelector('#dict-purge-button').addEventListener('click', this._onPurgeButtonClick.bind(this), false);
@@ -610,10 +613,9 @@ class DictionaryController {
         const dictProgress = document.querySelector('#dict-purge');
         dictProgress.hidden = false;
 
-        const prevention = new PageExitPrevention();
+        const prevention = this._preventPageExit();
 
         try {
-            prevention.start();
             this._dictionaryErrorsShow(null);
             this._dictionarySpinnerShow(true);
 
@@ -649,10 +651,9 @@ class DictionaryController {
         const dictProgress = $('#dict-import-progress').show();
         const dictImportInfo = document.querySelector('#dict-import-info');
 
-        const prevention = new PageExitPrevention();
+        const prevention = this._preventPageExit();
 
         try {
-            prevention.start();
             this._dictionaryErrorsShow(null);
             this._dictionarySpinnerShow(true);
 
@@ -718,4 +719,8 @@ class DictionaryController {
         optionsFull.global.database.prefixWildcardsSupported = !!e.target.checked;
         await this._settingsController.save();
     }
+
+    _preventPageExit() {
+        return this.settingsController.preventPageExit();
+    }
 }
diff --git a/ext/bg/js/settings/settings-controller.js b/ext/bg/js/settings/settings-controller.js
index 87dea408..6479714d 100644
--- a/ext/bg/js/settings/settings-controller.js
+++ b/ext/bg/js/settings/settings-controller.js
@@ -26,6 +26,8 @@ class SettingsController extends EventDispatcher {
         super();
         this._profileIndex = profileIndex;
         this._source = yomichan.generateId(16);
+        this._pageExitPreventions = new Set();
+        this._pageExitPreventionEventListeners = new EventListenerCollection();
     }
 
     get source() {
@@ -109,6 +111,16 @@ class SettingsController extends EventDispatcher {
         return {index: this._profileIndex};
     }
 
+    preventPageExit() {
+        const obj = {end: null};
+        obj.end = this._endPreventPageExit.bind(this, obj);
+        if (this._pageExitPreventionEventListeners.size === 0) {
+            this._pageExitPreventionEventListeners.addEventListener(window, 'beforeunload', this._onBeforeUnload.bind(this), false);
+        }
+        this._pageExitPreventions.add(obj);
+        return obj;
+    }
+
     // Private
 
     _setProfileIndex(value) {
@@ -147,4 +159,21 @@ class SettingsController extends EventDispatcher {
         targets = this._setupTargets(targets, extraFields);
         return await api.modifySettings(targets, this._source);
     }
+
+    _onBeforeUnload(e) {
+        if (this._pageExitPreventions.size === 0) {
+            return;
+        }
+
+        e.preventDefault();
+        e.returnValue = '';
+        return '';
+    }
+
+    _endPreventPageExit(obj) {
+        this._pageExitPreventions.delete(obj);
+        if (this._pageExitPreventions.size === 0) {
+            this._pageExitPreventionEventListeners.removeAllEventListeners();
+        }
+    }
 }