Initial commit

frontend/src/hooks/useFingerprint.js

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+import { useState, useEffect } from 'react';
+import FingerprintJS from '@fingerprintjs/fingerprintjs';
+
+const FINGERPRINT_KEY = 'gamercomp_device_fp';
+
+// Cache fingerprint in memory and localStorage
+let cachedFingerprint = null;
+
+export function useFingerprint() {
+  const [fingerprint, setFingerprint] = useState(() => {
+    // Try to get from memory cache first
+    if (cachedFingerprint) return cachedFingerprint;
+    // Then from localStorage
+    const stored = localStorage.getItem(FINGERPRINT_KEY);
+    if (stored) {
+      cachedFingerprint = stored;
+      return stored;
+    }
+    return null;
+  });
+  const [loading, setLoading] = useState(!fingerprint);
+
+  useEffect(() => {
+    if (fingerprint) {
+      setLoading(false);
+      return;
+    }
+
+    let cancelled = false;
+
+    async function generateFingerprint() {
+      try {
+        const fp = await FingerprintJS.load();
+        const result = await fp.get();
+        const visitorId = result.visitorId;
+
+        if (!cancelled) {
+          cachedFingerprint = visitorId;
+          localStorage.setItem(FINGERPRINT_KEY, visitorId);
+          setFingerprint(visitorId);
+          setLoading(false);
+        }
+      } catch (err) {
+        console.error('Failed to generate fingerprint:', err);
+        if (!cancelled) {
+          // Generate a fallback random ID
+          const fallback = 'fb_' + Math.random().toString(36).substring(2) + Date.now().toString(36);
+          cachedFingerprint = fallback;
+          localStorage.setItem(FINGERPRINT_KEY, fallback);
+          setFingerprint(fallback);
+          setLoading(false);
+        }
+      }
+    }
+
+    generateFingerprint();
+
+    return () => {
+      cancelled = true;
+    };
+  }, [fingerprint]);
+
+  return { fingerprint, loading };
+}
+
+// Sync getter for API client
+export function getFingerprint() {
+  if (cachedFingerprint) return cachedFingerprint;
+  const stored = localStorage.getItem(FINGERPRINT_KEY);
+  if (stored) {
+    cachedFingerprint = stored;
+    return stored;
+  }
+  return null;
+}
+
+export default useFingerprint;