1 files changed, 133 insertions, 0 deletions
diff --git a/ext/js/dom/style-util.js b/ext/js/dom/style-util.js
new file mode 100644
index 00000000..90dddd9e
--- /dev/null
+++ b/ext/js/dom/style-util.js
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2023  Yomitan 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/>.
+ */
+
+import {yomitan} from '../yomitan.js';
+
+/** @type {Map<string, ?HTMLStyleElement|HTMLLinkElement>} */
+const injectedStylesheets = new Map();
+/** @type {WeakMap<Node, Map<string, ?HTMLStyleElement|HTMLLinkElement>>} */
+const injectedStylesheetsWithParent = new WeakMap();
+
+/**
+ * @param {string} id
+ * @param {?Node} parentNode
+ * @returns {?HTMLStyleElement|HTMLLinkElement|undefined}
+ */
+function getInjectedStylesheet(id, parentNode) {
+    if (parentNode === null) {
+        return injectedStylesheets.get(id);
+    }
+    const map = injectedStylesheetsWithParent.get(parentNode);
+    return typeof map !== 'undefined' ? map.get(id) : void 0;
+}
+
+/**
+ * @param {string} id
+ * @param {?Node} parentNode
+ * @param {?HTMLStyleElement|HTMLLinkElement} value
+ */
+function setInjectedStylesheet(id, parentNode, value) {
+    if (parentNode === null) {
+        injectedStylesheets.set(id, value);
+        return;
+    }
+    let map = injectedStylesheetsWithParent.get(parentNode);
+    if (typeof map === 'undefined') {
+        map = new Map();
+        injectedStylesheetsWithParent.set(parentNode, map);
+    }
+    map.set(id, value);
+}
+
+/**
+ * @param {string} id
+ * @param {'code'|'file'|'file-content'} type
+ * @param {string} value
+ * @param {boolean} [useWebExtensionApi]
+ * @param {?Node} [parentNode]
+ * @returns {Promise<?HTMLStyleElement|HTMLLinkElement>}
+ * @throws {Error}
+ */
+export async function loadStyle(id, type, value, useWebExtensionApi = false, parentNode = null) {
+    if (useWebExtensionApi && yomitan.isExtensionUrl(window.location.href)) {
+        // Permissions error will occur if trying to use the WebExtension API to inject into an extension page
+        useWebExtensionApi = false;
+    }
+
+    let styleNode = getInjectedStylesheet(id, parentNode);
+    if (typeof styleNode !== 'undefined') {
+        if (styleNode === null) {
+            // Previously injected via WebExtension API
+            throw new Error(`Stylesheet with id ${id} has already been injected using the WebExtension API`);
+        }
+    } else {
+        styleNode = null;
+    }
+
+    if (type === 'file-content') {
+        value = await yomitan.api.getStylesheetContent(value);
+        type = 'code';
+        useWebExtensionApi = false;
+    }
+
+    if (useWebExtensionApi) {
+        // Inject via WebExtension API
+        if (styleNode !== null && styleNode.parentNode !== null) {
+            styleNode.parentNode.removeChild(styleNode);
+        }
+
+        setInjectedStylesheet(id, parentNode, null);
+        await yomitan.api.injectStylesheet(type, value);
+        return null;
+    }
+
+    // Create node in document
+    let parentNode2 = parentNode;
+    if (parentNode2 === null) {
+        parentNode2 = document.head;
+        if (parentNode2 === null) {
+            throw new Error('No parent node');
+        }
+    }
+
+    // Create or reuse node
+    const isFile = (type === 'file');
+    const tagName = isFile ? 'link' : 'style';
+    if (styleNode === null || styleNode.nodeName.toLowerCase() !== tagName) {
+        if (styleNode !== null && styleNode.parentNode !== null) {
+            styleNode.parentNode.removeChild(styleNode);
+        }
+        styleNode = document.createElement(tagName);
+    }
+
+    // Update node style
+    if (isFile) {
+        /** @type {HTMLLinkElement} */ (styleNode).rel = 'stylesheet';
+        /** @type {HTMLLinkElement} */ (styleNode).href = value;
+    } else {
+        styleNode.textContent = value;
+    }
+
+    // Update parent
+    if (styleNode.parentNode !== parentNode2) {
+        parentNode2.appendChild(styleNode);
+    }
+
+    // Add to map
+    setInjectedStylesheet(id, parentNode, styleNode);
+    return styleNode;
+}