Remove Frontend inheritance (#486)

* Make Frontend use composition instead of inheritance for TextScanner

* Use push instead of concat

* Update setOptions and setEnabled APIs

* Update how onWindowMessage event listener is added/removed

* Rename options to _options

* Use bind instead of arrow function

* Fix selection being cleared due to settings changes

4 files changed, 77 insertions, 49 deletions

diff --git a/ext/bg/js/search-query-parser.js b/ext/bg/js/search-query-parser.js
index 3215f8e4..137234e8 100644
--- a/ext/bg/js/search-query-parser.js
+++ b/ext/bg/js/search-query-parser.js
@@ -86,6 +86,7 @@ class QueryParser extends TextScanner {
 
     setOptions(options) {
         super.setOptions(options);
+        super.setEnabled(true);
         this.queryParser.dataset.termSpacing = `${options.parsing.termSpacing}`;
     }
 
diff --git a/ext/bg/js/settings/popup-preview-frame.js b/ext/bg/js/settings/popup-preview-frame.js
index e73c04a0..cb548ed7 100644
--- a/ext/bg/js/settings/popup-preview-frame.js
+++ b/ext/bg/js/settings/popup-preview-frame.js
@@ -66,12 +66,10 @@ class SettingsPopupPreview {
         this.popup.setCustomOuterCss = this.popupSetCustomOuterCss.bind(this);
 
         this.frontend = new Frontend(this.popup);
-
         this.frontend.getOptionsContext = async () => this.optionsContext;
-        this.frontend.setEnabled = () => {};
-        this.frontend.clearSelection = () => {};
-
         await this.frontend.prepare();
+        this.frontend.setDisabledOverride(true);
+        this.frontend.canClearSelection = false;
 
         // Update search
         this.updateSearch();
@@ -169,8 +167,7 @@ class SettingsPopupPreview {
         const source = new TextSourceRange(range, range.toString(), null, null);
 
         try {
-            await this.frontend.onSearchSource(source, 'script');
-            this.frontend.setCurrentTextSource(source);
+            await this.frontend.setTextSource(source);
         } finally {
             source.cleanup();
         }
diff --git a/ext/fg/js/frontend.js b/ext/fg/js/frontend.js
index 50f52724..76ad27e0 100644
--- a/ext/fg/js/frontend.js
+++ b/ext/fg/js/frontend.js
@@ -25,14 +25,8 @@
  * docSentenceExtract
  */
 
-class Frontend extends TextScanner {
+class Frontend {
     constructor(popup, getUrl=null) {
-        super(
-            window,
-            () => this.popup.isProxy() ? [] : [this.popup.getContainer()],
-            [(x, y) => this.popup.containsPoint(x, y)]
-        );
-
         this._id = yomichan.generateId(16);
 
         this.popup = popup;
@@ -41,15 +35,23 @@ class Frontend extends TextScanner {
 
         this._disabledOverride = false;
 
-        this.options = null;
+        this._options = null;
 
         this._pageZoomFactor = 1.0;
         this._contentScale = 1.0;
         this._orphaned = false;
         this._lastShowPromise = Promise.resolve();
 
+        this._enabledEventListeners = new EventListenerCollection();
+        this._textScanner = new TextScanner(
+            window,
+            () => this.popup.isProxy() ? [] : [this.popup.getContainer()],
+            [(x, y) => this.popup.containsPoint(x, y)]
+        );
+        this._textScanner.onSearchSource = this.onSearchSource.bind(this);
+
         this._windowMessageHandlers = new Map([
-            ['popupClose', () => this.clearSelection(false)],
+            ['popupClose', () => this._textScanner.clearSelection(false)],
             ['selectionCopy', () => document.execCommand('copy')]
         ]);
 
@@ -60,6 +62,14 @@ class Frontend extends TextScanner {
         ]);
     }
 
+    get canClearSelection() {
+        return this._textScanner.canClearSelection;
+    }
+
+    set canClearSelection(value) {
+        this._textScanner.canClearSelection = value;
+    }
+
     async prepare() {
         try {
             await this.updateOptions();
@@ -79,7 +89,7 @@ class Frontend extends TextScanner {
             yomichan.on('zoomChanged', this.onZoomChanged.bind(this));
             chrome.runtime.onMessage.addListener(this.onRuntimeMessage.bind(this));
 
-            this.on('clearSelection', this.onClearSelection.bind(this));
+            this._textScanner.on('clearSelection', this.onClearSelection.bind(this));
 
             this._updateContentScale();
             this._broadcastRootPopupInformation();
@@ -129,44 +139,45 @@ class Frontend extends TextScanner {
         this._updateContentScale();
     }
 
-    getMouseEventListeners() {
-        return [
-            ...super.getMouseEventListeners(),
-            [window, 'message', this.onWindowMessage.bind(this)]
-        ];
-    }
-
     setDisabledOverride(disabled) {
         this._disabledOverride = disabled;
-        this.setEnabled(this.options.general.enable, this._canEnable());
+        this._updateTextScannerEnabled();
     }
 
     async setPopup(popup) {
-        this.clearSelection(true);
+        this._textScanner.clearSelection(true);
         this.popup = popup;
         await popup.setOptionsContext(await this.getOptionsContext(), this._id);
     }
 
     async updateOptions() {
         const optionsContext = await this.getOptionsContext();
-        this.options = await apiOptionsGet(optionsContext);
-        this.setOptions(this.options, this._canEnable());
+        this._options = await apiOptionsGet(optionsContext);
+        this._textScanner.setOptions(this._options);
+        this._updateTextScannerEnabled();
 
         const ignoreNodes = ['.scan-disable', '.scan-disable *'];
-        if (!this.options.scanning.enableOnPopupExpressions) {
+        if (!this._options.scanning.enableOnPopupExpressions) {
             ignoreNodes.push('.source-text', '.source-text *');
         }
-        this.ignoreNodes = ignoreNodes.join(',');
+        this._textScanner.ignoreNodes = ignoreNodes.join(',');
 
         await this.popup.setOptionsContext(optionsContext, this._id);
 
         this._updateContentScale();
 
-        if (this.textSourceCurrent !== null && this.causeCurrent !== null) {
-            await this.onSearchSource(this.textSourceCurrent, this.causeCurrent);
+        const textSourceCurrent = this._textScanner.getCurrentTextSource();
+        const causeCurrent = this._textScanner.causeCurrent;
+        if (textSourceCurrent !== null && causeCurrent !== null) {
+            await this.onSearchSource(textSourceCurrent, causeCurrent);
         }
     }
 
+    async setTextSource(textSource) {
+        await this.onSearchSource(textSource, 'script');
+        this._textScanner.setCurrentTextSource(textSource);
+    }
+
     async onSearchSource(textSource, cause) {
         let results = null;
 
@@ -184,15 +195,15 @@ class Frontend extends TextScanner {
             }
         } catch (e) {
             if (this._orphaned) {
-                if (textSource !== null && this.options.scanning.modifier !== 'none') {
+                if (textSource !== null && this._options.scanning.modifier !== 'none') {
                     this._showPopupContent(textSource, await this.getOptionsContext(), 'orphaned');
                 }
             } else {
                 yomichan.logError(e);
             }
         } finally {
-            if (results === null && this.options.scanning.autoHideResults) {
-                this.clearSelection(false);
+            if (results === null && this._options.scanning.autoHideResults) {
+                this._textScanner.clearSelection(false);
             }
         }
 
@@ -201,7 +212,7 @@ class Frontend extends TextScanner {
 
     showContent(textSource, focus, definitions, type, optionsContext) {
         const {url} = optionsContext;
-        const sentence = docSentenceExtract(textSource, this.options.anki.sentenceExt);
+        const sentence = docSentenceExtract(textSource, this._options.anki.sentenceExt);
         this._showPopupContent(
             textSource,
             optionsContext,
@@ -215,7 +226,7 @@ class Frontend extends TextScanner {
     }
 
     async findTerms(textSource, optionsContext) {
-        this.setTextSourceScanLength(textSource, this.options.scanning.length);
+        this._textScanner.setTextSourceScanLength(textSource, this._options.scanning.length);
 
         const searchText = textSource.text();
         if (searchText.length === 0) { return null; }
@@ -229,7 +240,7 @@ class Frontend extends TextScanner {
     }
 
     async findKanji(textSource, optionsContext) {
-        this.setTextSourceScanLength(textSource, 1);
+        this._textScanner.setTextSourceScanLength(textSource, 1);
 
         const searchText = textSource.text();
         if (searchText.length === 0) { return null; }
@@ -263,8 +274,21 @@ class Frontend extends TextScanner {
         return this._lastShowPromise;
     }
 
+    _updateTextScannerEnabled() {
+        const enabled = (
+            this._options.general.enable &&
+            this.popup.depth <= this._options.scanning.popupNestingMaxDepth &&
+            !this._disabledOverride
+        );
+        this._enabledEventListeners.removeAllEventListeners();
+        this._textScanner.setEnabled(enabled);
+        if (enabled) {
+            this._enabledEventListeners.addEventListener(window, 'message', this.onWindowMessage.bind(this));
+        }
+    }
+
     _updateContentScale() {
-        const {popupScalingFactor, popupScaleRelativeToPageZoom, popupScaleRelativeToVisualViewport} = this.options.general;
+        const {popupScalingFactor, popupScaleRelativeToPageZoom, popupScaleRelativeToVisualViewport} = this._options.general;
         let contentScale = popupScalingFactor;
         if (popupScaleRelativeToPageZoom) {
             contentScale /= this._pageZoomFactor;
@@ -295,12 +319,8 @@ class Frontend extends TextScanner {
         });
     }
 
-    _canEnable() {
-        return this.popup.depth <= this.options.scanning.popupNestingMaxDepth && !this._disabledOverride;
-    }
-
     async _updatePopupPosition() {
-        const textSource = this.getCurrentTextSource();
+        const textSource = this._textScanner.getCurrentTextSource();
         if (textSource !== null && await this.popup.isVisible()) {
             this._showPopupContent(textSource, await this.getOptionsContext());
         }
diff --git a/ext/mixed/js/text-scanner.js b/ext/mixed/js/text-scanner.js
index c582ccd8..774eef44 100644
--- a/ext/mixed/js/text-scanner.js
+++ b/ext/mixed/js/text-scanner.js
@@ -45,6 +45,16 @@ class TextScanner extends EventDispatcher {
         this.preventNextMouseDown = false;
         this.preventNextClick = false;
         this.preventScroll = false;
+
+        this._canClearSelection = true;
+    }
+
+    get canClearSelection() {
+        return this._canClearSelection;
+    }
+
+    set canClearSelection(value) {
+        this._canClearSelection = value;
     }
 
     onMouseOver(e) {
@@ -222,9 +232,9 @@ class TextScanner extends EventDispatcher {
         }
     }
 
-    setEnabled(enabled, canEnable) {
+    setEnabled(enabled) {
         this.eventListeners.removeAllEventListeners();
-        this.enabled = enabled && canEnable;
+        this.enabled = enabled;
         if (this.enabled) {
             this.hookEvents();
         } else {
@@ -233,9 +243,9 @@ class TextScanner extends EventDispatcher {
     }
 
     hookEvents() {
-        let eventListenerInfos = this.getMouseEventListeners();
+        const eventListenerInfos = this.getMouseEventListeners();
         if (this.options.scanning.touchInputEnabled) {
-            eventListenerInfos = eventListenerInfos.concat(this.getTouchEventListeners());
+            eventListenerInfos.push(...this.getTouchEventListeners());
         }
 
         for (const [node, type, listener, options] of eventListenerInfos) {
@@ -264,9 +274,8 @@ class TextScanner extends EventDispatcher {
         ];
     }
 
-    setOptions(options, canEnable=true) {
+    setOptions(options) {
         this.options = options;
-        this.setEnabled(this.options.general.enable, canEnable);
     }
 
     async searchAt(x, y, cause) {
@@ -324,6 +333,7 @@ class TextScanner extends EventDispatcher {
     }
 
     clearSelection(passive) {
+        if (!this._canClearSelection) { return; }
         if (this.textSourceCurrent !== null) {
             if (this.textSourceCurrentSelected) {
                 this.textSourceCurrent.deselect();