feat: move svelte interface to 'src/interface'

src/interface/hooks/SettingsPopup.ts

@@ -0,0 +1,37 @@
+type SettingsPopupCallback = () => void;
+
+/** 
+ * This is a singleton that triggers an update when the settings popup is closed.
+ * This is used to close the colour picker.
+ * Usage:
+ *  settingsPopup.addListener(() => {
+ *    console.log('Settings popup closed');
+ *  });
+*/ 
+class SettingsPopup {
+  private static instance: SettingsPopup;
+  private listeners: Set<SettingsPopupCallback> = new Set();
+
+  private constructor() {}
+
+  public static getInstance(): SettingsPopup {
+    if (!SettingsPopup.instance) {
+      SettingsPopup.instance = new SettingsPopup();
+    }
+    return SettingsPopup.instance;
+  }
+
+  public addListener(callback: SettingsPopupCallback): void {
+    this.listeners.add(callback);
+  }
+
+  public removeListener(callback: SettingsPopupCallback): void {
+    this.listeners.delete(callback);
+  }
+
+  public triggerClose(): void {
+    this.listeners.forEach(callback => callback());
+  }
+}
+
+export const settingsPopup = SettingsPopup.getInstance();