Split codebase (#455)

packages/theme/src/appearance.ts

@@ -0,0 +1,44 @@
+import { getCurrentWebviewWindow } from "@tauri-apps/api/webviewWindow";
+
+export type Appearance = "light" | "dark";
+
+export function getCSSAppearance(): Appearance {
+  return window.matchMedia("(prefers-color-scheme: dark)").matches ? "dark" : "light";
+}
+
+export async function getWindowAppearance(): Promise<Appearance> {
+  const appearance = await getCurrentWebviewWindow().theme();
+  return appearance ?? getCSSAppearance();
+}
+
+export function subscribeToWindowAppearanceChange(
+  cb: (appearance: Appearance) => void,
+): () => void {
+  const container = {
+    unsubscribe: () => {},
+  };
+
+  void getCurrentWebviewWindow()
+    .onThemeChanged((theme) => {
+      cb(theme.payload);
+    })
+    .then((listener) => {
+      container.unsubscribe = listener;
+    });
+
+  return () => container.unsubscribe();
+}
+
+export function resolveAppearance(
+  preferredAppearance: Appearance,
+  appearanceSetting: string,
+): Appearance {
+  const appearance = appearanceSetting === "system" ? preferredAppearance : appearanceSetting;
+  return appearance === "dark" ? "dark" : "light";
+}
+
+export function subscribeToPreferredAppearance(cb: (appearance: Appearance) => void) {
+  cb(getCSSAppearance());
+  void getWindowAppearance().then(cb);
+  subscribeToWindowAppearanceChange(cb);
+}