1 files changed, 109 insertions, 0 deletions
diff --git a/comm/mail/themes/BuiltInThemes.sys.mjs b/comm/mail/themes/BuiltInThemes.sys.mjs
new file mode 100644
index 0000000000..1409f49f52
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+++ b/comm/mail/themes/BuiltInThemes.sys.mjs
@@ -0,0 +1,109 @@
+/* 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, {
+  AddonManager: "resource://gre/modules/AddonManager.sys.mjs",
+});
+
+// List of themes built in to the browser. The themes are represented by objects
+// containing their id, current version, and path relative to
+// resource://builtin-themes/.
+const STANDARD_THEMES = new Map([
+  [
+    "thunderbird-compact-light@mozilla.org",
+    {
+      version: "1.2",
+      path: "light/",
+    },
+  ],
+  [
+    "thunderbird-compact-dark@mozilla.org",
+    {
+      version: "1.2",
+      path: "dark/",
+    },
+  ],
+]);
+
+class _BuiltInThemes {
+  constructor() {}
+
+  /**
+   * @param {string} id An addon's id string.
+   * @returns {string}
+   *   If `id` refers to a built-in theme, returns a path pointing to the
+   *   theme's preview image. Null otherwise.
+   */
+  previewForBuiltInThemeId(id) {
+    if (STANDARD_THEMES.has(id)) {
+      return `resource://builtin-themes/${
+        STANDARD_THEMES.get(id).path
+      }preview.svg`;
+    }
+
+    return null;
+  }
+
+  /**
+   * @param {string} id An addon's id string.
+   * @returns {boolean}
+   *   True if the theme with id `id` is a monochromatic theme.
+   */
+  isMonochromaticTheme(id) {
+    return id.endsWith("-colorway@mozilla.org");
+  }
+
+  /**
+   * @param {string} id
+   *   The theme's id.
+   * @returns {boolean}
+   *   True if the theme with id `id` is both expired and retained. That is,
+   *   the user has the ability to use it after its expiry date.
+   *   Or it would - this is just a shim not to break assumptions...
+   */
+  isRetainedExpiredTheme(id) {
+    return false;
+  }
+
+  /**
+   * If the active theme is built-in, this function calls
+   * AddonManager.maybeInstallBuiltinAddon for that theme.
+   */
+  maybeInstallActiveBuiltInTheme() {
+    let activeThemeID = Services.prefs.getStringPref(
+      "extensions.activeThemeID",
+      "default-theme@mozilla.org"
+    );
+    let activeBuiltInTheme = STANDARD_THEMES.get(activeThemeID);
+    if (activeBuiltInTheme) {
+      lazy.AddonManager.maybeInstallBuiltinAddon(
+        activeThemeID,
+        activeBuiltInTheme.version,
+        `resource://builtin-themes/${activeBuiltInTheme.path}`
+      );
+    }
+  }
+
+  /**
+   * Ensures that all built-in themes are installed.
+   */
+  async ensureBuiltInThemes() {
+    let installPromises = [];
+    for (let [id, { version, path }] of STANDARD_THEMES.entries()) {
+      installPromises.push(
+        lazy.AddonManager.maybeInstallBuiltinAddon(
+          id,
+          version,
+          `resource://builtin-themes/${path}`
+        )
+      );
+    }
+
+    await Promise.all(installPromises);
+  }
+}
+
+export var BuiltInThemes = new _BuiltInThemes();