1 files changed, 135 insertions, 0 deletions
diff --git a/remote/shared/messagehandler/Module.sys.mjs b/remote/shared/messagehandler/Module.sys.mjs
new file mode 100644
index 0000000000..30b26938e2
--- /dev/null
+++ b/remote/shared/messagehandler/Module.sys.mjs
@@ -0,0 +1,135 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  error: "chrome://remote/content/shared/webdriver/Errors.sys.mjs",
+  Log: "chrome://remote/content/shared/Log.sys.mjs",
+});
+
+ChromeUtils.defineLazyGetter(lazy, "disabledExperimentalAPI", () => {
+  return !Services.prefs.getBoolPref("remote.experimental.enabled");
+});
+
+ChromeUtils.defineLazyGetter(lazy, "logger", () => lazy.Log.get());
+
+export class Module {
+  #messageHandler;
+
+  /**
+   * Create a new module instance.
+   *
+   * @param {MessageHandler} messageHandler
+   *     The MessageHandler instance which owns this Module instance.
+   */
+  constructor(messageHandler) {
+    this.#messageHandler = messageHandler;
+  }
+
+  /**
+   * Clean-up the module instance.
+   */
+  destroy() {
+    lazy.logger.warn(
+      `Module ${this.constructor.name} is missing a destroy method`
+    );
+  }
+
+  /**
+   * Emit a message handler event.
+   *
+   * Such events should bubble up to the root of a MessageHandler network.
+   *
+   * @param {string} name
+   *     Name of the event. Protocol level events should be of the
+   *     form [module name].[event name].
+   * @param {object} data
+   *     The event's data.
+   * @param {ContextInfo=} contextInfo
+   *     The event's context info, see MessageHandler:emitEvent. Optional.
+   */
+  emitEvent(name, data, contextInfo) {
+    this.messageHandler.emitEvent(name, data, contextInfo);
+  }
+
+  /**
+   * Intercept an event and modify the payload.
+   *
+   * It's required to be implemented in windowglobal-in-root modules.
+   *
+   * @param {string} name
+   *     Name of the event.
+   * @param {object} payload
+   *    The event's payload.
+   * @returns {object}
+   *     The modified event payload.
+   */
+  interceptEvent(name, payload) {
+    throw new Error(
+      `Could not intercept event ${name}, interceptEvent is not implemented in windowglobal-in-root module`
+    );
+  }
+
+  /**
+   * Assert if experimental commands are enabled.
+   *
+   * @param {string} methodName
+   *     Name of the command.
+   *
+   * @throws {UnknownCommandError}
+   *     If experimental commands are disabled.
+   */
+  assertExperimentalCommandsEnabled(methodName) {
+    // TODO: 1778987. Move it to a BiDi specific place.
+    if (lazy.disabledExperimentalAPI) {
+      throw new lazy.error.UnknownCommandError(methodName);
+    }
+  }
+
+  /**
+   * Assert if experimental events are enabled.
+   *
+   * @param {string} moduleName
+   *     Name of the module.
+   *
+   * @param {string} event
+   *     Name of the event.
+   *
+   * @throws {InvalidArgumentError}
+   *     If experimental events are disabled.
+   */
+  assertExperimentalEventsEnabled(moduleName, event) {
+    // TODO: 1778987. Move it to a BiDi specific place.
+    if (lazy.disabledExperimentalAPI) {
+      throw new lazy.error.InvalidArgumentError(
+        `Module ${moduleName} does not support event ${event}`
+      );
+    }
+  }
+
+  /**
+   * Instance shortcut for supportsMethod to avoid reaching the constructor for
+   * consumers which directly deal with an instance.
+   */
+  supportsMethod(methodName) {
+    return this.constructor.supportsMethod(methodName);
+  }
+
+  get messageHandler() {
+    return this.#messageHandler;
+  }
+
+  static get supportedEvents() {
+    return [];
+  }
+
+  static supportsEvent(event) {
+    return this.supportedEvents.includes(event);
+  }
+
+  static supportsMethod(methodName) {
+    return typeof this.prototype[methodName] === "function";
+  }
+}