Initial commit

frontend/src/hooks/useAccuracy.ts

@@ -0,0 +1,37 @@
+import { useEffect, useState } from "react";
+import bus from "../engine/EventBus";
+import { accuracyTracker } from "../engine/AccuracyTracker";
+
+export interface AccuracyState {
+  correct: number;
+  wrong:   number;
+  missed:  number;
+  score:   number;   // 0-100
+}
+
+const INITIAL: AccuracyState = { correct: 0, wrong: 0, missed: 0, score: 0 };
+
+/**
+ * Returns live accuracy data from AccuracyTracker.
+ * Automatically enables the tracker while the component is mounted.
+ */
+export function useAccuracy(enabled: boolean): AccuracyState {
+  const [state, setState] = useState<AccuracyState>(INITIAL);
+
+  useEffect(() => {
+    accuracyTracker.enable(enabled);
+    if (!enabled) {
+      setState(INITIAL);
+      return;
+    }
+
+    const handler = (data: AccuracyState) => setState({ ...data });
+    bus.on("accuracy:update", handler as never);
+    return () => {
+      bus.off("accuracy:update", handler as never);
+      accuracyTracker.enable(false);
+    };
+  }, [enabled]);
+
+  return state;
+}