antigravity one shot

src/hooks/usePitchDetector.ts

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+import { useEffect, useRef, useState, useCallback } from 'react';
+import { PitchAnalyzer } from '../audio/PitchAnalyzer';
+import { frequencyToMidi, getNoteDetails } from '../music/NoteUtils';
+
+interface PitchData {
+    frequency: number;
+    midi: number;
+    note: string;
+    cents: number;
+    clarity: number; // Placeholder for now, maybe uses probability if YIN exposes it
+}
+
+export function usePitchDetector(active: boolean) {
+    const analyzerRef = useRef<PitchAnalyzer | null>(null);
+    const [pitchData, setPitchData] = useState<PitchData | null>(null);
+    const [isListening, setIsListening] = useState(false);
+    const [error, setError] = useState<string | null>(null);
+    const animationRef = useRef<number | null>(null);
+
+    const updatePitch = useCallback(() => {
+        if (!analyzerRef.current) return;
+
+        const freq = analyzerRef.current.getPitch();
+        if (freq) {
+            const midi = frequencyToMidi(freq);
+            const { scientific } = getNoteDetails(midi);
+
+            // Calculate cents off purely for display if needed, 
+            // but for training we usually care if midi matches.
+
+            setPitchData({
+                frequency: freq,
+                midi,
+                note: scientific,
+                cents: 0,
+                clarity: 1
+            });
+        }
+
+        animationRef.current = requestAnimationFrame(updatePitch);
+    }, []);
+
+    useEffect(() => {
+        if (active) {
+            if (!analyzerRef.current) {
+                analyzerRef.current = new PitchAnalyzer();
+            }
+
+            analyzerRef.current.start()
+                .then(() => {
+                    setIsListening(true);
+                    updatePitch();
+                })
+                .catch(err => {
+                    console.error(err);
+                    setError("Could not access microphone.");
+                    setIsListening(false);
+                });
+        } else {
+            if (analyzerRef.current) {
+                analyzerRef.current.stop();
+                analyzerRef.current = null;
+            }
+            setIsListening(false);
+            if (animationRef.current) cancelAnimationFrame(animationRef.current);
+        }
+
+        return () => {
+            if (animationRef.current) cancelAnimationFrame(animationRef.current);
+            if (analyzerRef.current) {
+                analyzerRef.current.stop();
+            }
+        };
+    }, [active, updatePitch]);
+
+    return { pitchData, isListening, error };
+}