1 files changed, 122 insertions, 0 deletions
diff --git a/comm/mail/base/content/globalOverlay.js b/comm/mail/base/content/globalOverlay.js
new file mode 100644
index 0000000000..b31751a490
--- /dev/null
+++ b/comm/mail/base/content/globalOverlay.js
@@ -0,0 +1,122 @@
+/* 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/. */
+
+/**
+ * Notifies observers that quitting has been requested.
+ *
+ * @returns {boolean} - True if an observer prevented quitting, false otherwise.
+ */
+function canQuitApplication() {
+  try {
+    let cancelQuit = Cc["@mozilla.org/supports-PRBool;1"].createInstance(
+      Ci.nsISupportsPRBool
+    );
+    Services.obs.notifyObservers(cancelQuit, "quit-application-requested");
+
+    // Something aborted the quit process.
+    if (cancelQuit.data) {
+      return false;
+    }
+  } catch (ex) {}
+  return true;
+}
+
+/**
+ * Quit the application if no `quit-application-requested` observer prevents it.
+ */
+function goQuitApplication() {
+  if (!canQuitApplication()) {
+    return false;
+  }
+
+  Services.startup.quit(Ci.nsIAppStartup.eAttemptQuit);
+  return true;
+}
+
+/**
+ * Gets the first registered controller that returns true for both
+ * `supportsCommand` and `isCommandEnabled`, or null if no controllers
+ * return true for both.
+ *
+ * @param {string} command - The command name to pass to controllers.
+ * @returns {nsIController|null}
+ */
+function getEnabledControllerForCommand(command) {
+  // The first controller for which `supportsCommand` returns true.
+  let controllerA =
+    top.document.commandDispatcher.getControllerForCommand(command);
+  if (controllerA?.isCommandEnabled(command)) {
+    return controllerA;
+  }
+
+  // Didn't find a controller, or `isCommandEnabled` returned false?
+  // Try the other controllers. Note this isn't exactly the same set
+  // of controllers as `commandDispatcher` has.
+  for (let i = 0; i < top.controllers.getControllerCount(); i++) {
+    let controllerB = top.controllers.getControllerAt(i);
+    if (
+      controllerB !== controllerA &&
+      controllerB.supportsCommand(command) &&
+      controllerB.isCommandEnabled(command)
+    ) {
+      return controllerB;
+    }
+  }
+
+  return null;
+}
+
+/**
+ * Updates the enabled state of the element with the ID `command`. The command
+ * is considered enabled if at least one controller returns true for both
+ * `supportsCommand` and `isCommandEnabled`.
+ *
+ * @param {string} command - The command name to pass to controllers.
+ */
+function goUpdateCommand(command) {
+  try {
+    goSetCommandEnabled(command, !!getEnabledControllerForCommand(command));
+  } catch (e) {
+    console.error(`An error occurred updating the ${command} command: ${e}`);
+  }
+}
+
+/**
+ * Calls `doCommand` on the first controller that returns true for both
+ * `supportsCommand` and `isCommandEnabled`.
+ *
+ * @param {string} command - The command name to pass to controllers.
+ * @param {any[]} args - Any number of arguments to pass to the chosen
+ *   controller. Note that passing arguments is not part of the `nsIController`
+ *   interface and only possible for JS controllers.
+ */
+function goDoCommand(command, ...args) {
+  try {
+    let controller = getEnabledControllerForCommand(command);
+    if (controller) {
+      controller = controller.wrappedJSObject ?? controller;
+      controller.doCommand(command, ...args);
+    }
+  } catch (e) {
+    console.error(`An error occurred executing the ${command} command: ${e}`);
+  }
+}
+
+/**
+ * Updates the enabled state of the element with the ID `id`.
+ *
+ * @param {string} id
+ * @param {boolean} enabled
+ */
+function goSetCommandEnabled(id, enabled) {
+  let node = document.getElementById(id);
+
+  if (node) {
+    if (enabled) {
+      node.removeAttribute("disabled");
+    } else {
+      node.setAttribute("disabled", "true");
+    }
+  }
+}