Use user-namespaced keys for idb persistence (#21110)

* add new hooks

* use new hooks for user based keys

* fix layout race condition

web/src/hooks/use-user-persistence.ts

@@ -0,0 +1,199 @@
+import { useEffect, useState, useCallback, useContext, useRef } from "react";
+import { get as getData, set as setData, del as delData } from "idb-keyval";
+import { AuthContext } from "@/context/auth-context";
+
+type useUserPersistenceReturn<S> = [
+  value: S | undefined,
+  setValue: (value: S | undefined) => void,
+  loaded: boolean,
+  deleteValue: () => void,
+];
+
+// Key used to track which keys have been migrated to prevent re-reading old keys
+const MIGRATED_KEYS_STORAGE_KEY = "frigate-migrated-user-keys";
+
+/**
+ * Compute the user-namespaced key for a given base key and username.
+ */
+export function getUserNamespacedKey(
+  key: string,
+  username: string | undefined,
+): string {
+  const isAuthenticated = username && username !== "anonymous";
+  return isAuthenticated ? `${key}:${username}` : key;
+}
+
+/**
+ * Delete a user-namespaced key from storage.
+ * This is useful for clearing user-specific data from settings pages.
+ */
+export async function deleteUserNamespacedKey(
+  key: string,
+  username: string | undefined,
+): Promise<void> {
+  const namespacedKey = getUserNamespacedKey(key, username);
+  await delData(namespacedKey);
+}
+
+/**
+ * Get the set of keys that have already been migrated for a specific user.
+ */
+async function getMigratedKeys(username: string): Promise<Set<string>> {
+  const allMigrated =
+    (await getData<Record<string, string[]>>(MIGRATED_KEYS_STORAGE_KEY)) || {};
+  return new Set(allMigrated[username] || []);
+}
+
+/**
+ * Mark a key as migrated for a specific user.
+ */
+async function markKeyAsMigrated(username: string, key: string): Promise<void> {
+  const allMigrated =
+    (await getData<Record<string, string[]>>(MIGRATED_KEYS_STORAGE_KEY)) || {};
+  const userMigrated = new Set(allMigrated[username] || []);
+  userMigrated.add(key);
+  allMigrated[username] = Array.from(userMigrated);
+  await setData(MIGRATED_KEYS_STORAGE_KEY, allMigrated);
+}
+
+/**
+ * Hook for user-namespaced persistence with automatic migration from legacy keys.
+ *
+ * This hook:
+ * 1. Namespaces storage keys by username to isolate per-user preferences
+ * 2. Automatically migrates data from legacy (non-namespaced) keys on first use
+ * 3. Tracks migrated keys to prevent re-reading stale data after migration
+ * 4. Waits for auth to load before returning values to prevent race conditions
+ *
+ * @param key - The base key name (will be namespaced with username)
+ * @param defaultValue - Default value if no persisted value exists
+ */
+export function useUserPersistence<S>(
+  key: string,
+  defaultValue: S | undefined = undefined,
+): useUserPersistenceReturn<S> {
+  const { auth } = useContext(AuthContext);
+  const [value, setInternalValue] = useState<S | undefined>(defaultValue);
+  const [loaded, setLoaded] = useState<boolean>(false);
+  const migrationAttemptedRef = useRef(false);
+
+  // Compute the user-namespaced key
+  const username = auth?.user?.username;
+  const isAuthenticated =
+    username && username !== "anonymous" && !auth.isLoading;
+  const namespacedKey = isAuthenticated ? `${key}:${username}` : key;
+
+  // Track the key that was used when loading to prevent cross-key writes
+  const loadedKeyRef = useRef<string | null>(null);
+
+  const setValue = useCallback(
+    (newValue: S | undefined) => {
+      // Only allow writes if we've loaded for this key
+      // This prevents stale callbacks from writing to the wrong key
+      if (loadedKeyRef.current !== namespacedKey) {
+        return;
+      }
+      setInternalValue(newValue);
+      async function update() {
+        await setData(namespacedKey, newValue);
+      }
+      update();
+    },
+    [namespacedKey],
+  );
+
+  const deleteValue = useCallback(async () => {
+    if (loadedKeyRef.current !== namespacedKey) {
+      return;
+    }
+    await delData(namespacedKey);
+    setInternalValue(defaultValue);
+  }, [namespacedKey, defaultValue]);
+
+  useEffect(() => {
+    // Don't load until auth is resolved
+    if (auth.isLoading) {
+      return;
+    }
+
+    // Reset state when key changes - this prevents stale writes
+    loadedKeyRef.current = null;
+    migrationAttemptedRef.current = false;
+    setLoaded(false);
+
+    async function loadWithMigration() {
+      // For authenticated users, check if we need to migrate from legacy key
+      if (isAuthenticated && username && !migrationAttemptedRef.current) {
+        migrationAttemptedRef.current = true;
+
+        const migratedKeys = await getMigratedKeys(username);
+
+        // Check if we already have data in the namespaced key
+        const existingNamespacedValue = await getData<S>(namespacedKey);
+
+        if (typeof existingNamespacedValue !== "undefined") {
+          // Already have namespaced data, use it
+          setInternalValue(existingNamespacedValue);
+          loadedKeyRef.current = namespacedKey;
+          setLoaded(true);
+          return;
+        }
+
+        // Check if this key has already been migrated (even if value was deleted)
+        if (migratedKeys.has(key)) {
+          // Already migrated, don't read from legacy key
+          setInternalValue(defaultValue);
+          loadedKeyRef.current = namespacedKey;
+          setLoaded(true);
+          return;
+        }
+
+        // Try to migrate from legacy key
+        const legacyValue = await getData<S>(key);
+        if (typeof legacyValue !== "undefined") {
+          // Migrate: copy to namespaced key, delete legacy key, mark as migrated
+          await setData(namespacedKey, legacyValue);
+          await delData(key);
+          await markKeyAsMigrated(username, key);
+          setInternalValue(legacyValue);
+          loadedKeyRef.current = namespacedKey;
+          setLoaded(true);
+          return;
+        }
+
+        // No legacy value, just mark as migrated so we don't check again
+        await markKeyAsMigrated(username, key);
+        setInternalValue(defaultValue);
+        loadedKeyRef.current = namespacedKey;
+        setLoaded(true);
+        return;
+      }
+
+      // For unauthenticated users or after migration check, just load normally
+      const storedValue = await getData<S>(namespacedKey);
+      if (typeof storedValue !== "undefined") {
+        setInternalValue(storedValue);
+      } else {
+        setInternalValue(defaultValue);
+      }
+      loadedKeyRef.current = namespacedKey;
+      setLoaded(true);
+    }
+
+    loadWithMigration();
+  }, [
+    auth.isLoading,
+    isAuthenticated,
+    username,
+    key,
+    namespacedKey,
+    defaultValue,
+  ]);
+
+  // Don't return a value until auth has finished loading
+  if (auth.isLoading) {
+    return [undefined, setValue, false, deleteValue];
+  }
+
+  return [value, setValue, loaded, deleteValue];
+}