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+/*
+ * Copyright (C) 2021 Yomichan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/**
+ * This class is used to apply CSS styles to elements using a consistent method
+ * that is the same across different browsers.
+ */
+class CssStyleApplier {
+ /**
+ * Creates a new instance of the class.
+ * @param styleDataUrl The local URL to the JSON file continaing the style rules.
+ * The style rules should be of the format:
+ * [
+ * {
+ * selectors: [(selector:string)...],
+ * styles: [
+ * [(property:string), (value:string)]...
+ * ]
+ * }...
+ * ]
+ */
+ constructor(styleDataUrl) {
+ this._styleDataUrl = styleDataUrl;
+ this._styleData = [];
+ this._cachedRules = new Map();
+ }
+
+ /**
+ * Loads the data file for use.
+ */
+ async prepare() {
+ this._styleData = await this._fetchJsonAsset(this._styleDataUrl);
+ }
+
+ /**
+ * Applies CSS styles directly to the "style" attribute using the "class" attribute.
+ * This only works for elements with a single class.
+ * @param elements An iterable collection of HTMLElement objects.
+ */
+ applyClassStyles(elements) {
+ const elementStyles = [];
+ for (const element of elements) {
+ const {className} = element;
+ if (className.length === 0) { continue; }
+ let cssTextNew = '';
+ for (const {selectorText, styles} of this._getRulesForClass(className)) {
+ if (!element.matches(selectorText)) { continue; }
+ cssTextNew += this._getCssText(styles);
+ }
+ cssTextNew += element.style.cssText;
+ elementStyles.push({element, style: cssTextNew});
+ }
+ for (const {element, style} of elementStyles) {
+ element.removeAttribute('class');
+ if (style.length > 0) {
+ element.setAttribute('style', style);
+ } else {
+ element.removeAttribute('style');
+ }
+ }
+ }
+
+ // Private
+
+ async _fetchJsonAsset(url) {
+ const response = await fetch(url, {
+ method: 'GET',
+ mode: 'no-cors',
+ cache: 'default',
+ credentials: 'omit',
+ redirect: 'follow',
+ referrerPolicy: 'no-referrer'
+ });
+ if (!response.ok) {
+ throw new Error(`Failed to fetch ${url}: ${response.status}`);
+ }
+ return await response.json();
+ }
+
+ _getRulesForClass(className) {
+ let rules = this._cachedRules.get(className);
+ if (typeof rules !== 'undefined') { return rules; }
+
+ rules = [];
+ this._cachedRules.set(className, rules);
+
+ const classNamePattern = new RegExp(`.${className}(?![0-9a-zA-Z-])`, '');
+ for (const {selectors, styles} of this._styleData) {
+ const selectorText = selectors.join(',');
+ if (!classNamePattern.test(selectorText)) { continue; }
+ rules.push({selectorText, styles});
+ }
+
+ return rules;
+ }
+
+ _getCssText(styles) {
+ let cssText = '';
+ for (const [property, value] of styles) {
+ cssText += `${property}:${value};`;
+ }
+ return cssText;
+ }
+}