Add server plugin loader

src/plugin-loader.js

@@ -0,0 +1,161 @@
+const fs = require('fs');
+const path = require('path');
+const { getConfigValue } = require('./util');
+const enableServerPlugins = getConfigValue('enableServerPlugins', false);
+
+/**
+ * Determine if a file is a CommonJS module.
+ * @param {string} file Path to file
+ * @returns {boolean} True if file is a CommonJS module
+ */
+const isCommonJS = (file) => path.extname(file) === '.js';
+
+/**
+ * Determine if a file is an ECMAScript module.
+ * @param {string} file Path to file
+ * @returns {boolean} True if file is an ECMAScript module
+ */
+const isESModule = (file) => path.extname(file) === '.mjs';
+
+/**
+ * Load and initialize server plugins from a directory if they are enabled.
+ * @param {import('express').Express} app Express app
+ * @param {string} pluginsPath Path to plugins directory
+ * @returns {Promise<any>} Promise that resolves when all plugins are loaded
+ */
+async function loadPlugins(app, pluginsPath) {
+    // Server plugins are disabled.
+    if (!enableServerPlugins) {
+        return;
+    }
+
+    // Plugins directory does not exist.
+    if (!fs.existsSync(pluginsPath)) {
+        return;
+    }
+
+    const files = fs.readdirSync(pluginsPath);
+
+    // No plugins to load.
+    if (files.length === 0) {
+        return;
+    }
+
+    for (const file of files) {
+        const pluginFilePath = path.join(pluginsPath, file);
+
+        if (fs.statSync(pluginFilePath).isDirectory()) {
+            await loadFromDirectory(app, pluginFilePath);
+        }
+
+        // Not a JavaScript file.
+        if (!isCommonJS(file) && !isESModule(file)) {
+            continue;
+        }
+
+        await loadFromFile(app, pluginFilePath);
+    }
+}
+
+async function loadFromDirectory(app, pluginDirectoryPath) {
+    const files = fs.readdirSync(pluginDirectoryPath);
+
+    // No plugins to load.
+    if (files.length === 0) {
+        return;
+    }
+
+    // Plugin is an npm package.
+    const packageJsonFilePath = path.join(pluginDirectoryPath, 'package.json');
+    if (fs.existsSync(packageJsonFilePath)) {
+        if (await loadFromPackage(app, packageJsonFilePath)) {
+            return;
+        }
+    }
+
+    // Plugin is a CommonJS module.
+    const cjsFilePath = path.join(pluginDirectoryPath, 'index.js');
+    if (fs.existsSync(cjsFilePath)) {
+        if (await loadFromFile(app, cjsFilePath)) {
+            return;
+        }
+    }
+
+    // Plugin is an ECMAScript module.
+    const esmFilePath = path.join(pluginDirectoryPath, 'index.mjs');
+    if (fs.existsSync(esmFilePath)) {
+        if (await loadFromFile(app, esmFilePath)) {
+            return;
+        }
+    }
+}
+
+/**
+ * Loads and initializes a plugin from an npm package.
+ * @param {import('express').Express} app Express app
+ * @param {string} packageJsonPath Path to package.json file
+ * @returns {Promise<boolean>} Promise that resolves to true if plugin was loaded successfully
+ */
+async function loadFromPackage(app, packageJsonPath) {
+    try {
+        const packageJson = JSON.parse(fs.readFileSync(packageJsonPath, 'utf8'));
+        if (packageJson.main) {
+            const pluginFilePath = path.join(path.dirname(packageJsonPath), packageJson.main);
+            return await loadFromFile(app, pluginFilePath);
+        }
+    } catch (error) {
+        console.error(`Failed to load plugin from ${packageJsonPath}: ${error}`);
+    }
+    return false;
+}
+
+/**
+ * Loads and initializes a plugin from a file.
+ * @param {import('express').Express} app Express app
+ * @param {string} pluginFilePath Path to plugin directory
+ * @returns {Promise<boolean>} Promise that resolves to true if plugin was loaded successfully
+ */
+async function loadFromFile(app, pluginFilePath) {
+    try {
+        const plugin = await getPluginModule(pluginFilePath);
+        console.log(`Initializing plugin from ${pluginFilePath}`);
+        return await initPlugin(app, plugin);
+    } catch (error) {
+        console.error(`Failed to load plugin from ${pluginFilePath}: ${error}`);
+        return false;
+    }
+}
+
+/**
+ * Initializes a plugin module.
+ * @param {import('express').Express} app Express app
+ * @param {any} plugin Plugin module
+ * @returns {Promise<boolean>} Promise that resolves to true if plugin was initialized successfully
+ */
+async function initPlugin(app, plugin) {
+    if (typeof plugin.init === 'function') {
+        await plugin.init(app);
+        return true;
+    }
+
+    return false;
+}
+
+/**
+ * Loads a module from a file depending on the module type.
+ * @param {string} pluginFilePath Path to plugin file
+ * @returns {Promise<any>} Promise that resolves to plugin module
+ */
+async function getPluginModule(pluginFilePath) {
+    if (isCommonJS(pluginFilePath)) {
+        return require(pluginFilePath);
+    }
+    if (isESModule(pluginFilePath)) {
+        return await import(pluginFilePath);
+    }
+    throw new Error(`Unsupported module type in ${pluginFilePath}`);
+}
+
+module.exports = {
+    loadPlugins,
+};