fix: remediate branch review findings

src/lib/stores/offlineSync.ts

@@ -0,0 +1,169 @@
+import { writable } from 'svelte/store';
+import { PUBLIC_USE_LOCAL_POKEMON_SPRITE_FOLDER } from '$env/static/public';
+import type { OfflineSnapshot } from '$lib/models/OfflineSnapshot';
+import { resolveSpriteUrl } from '$lib/utils/spriteUrl';
+
+export type OfflineSyncStatus = {
+	state: 'idle' | 'syncing' | 'ready' | 'partial' | 'error';
+	generatedAt: string | null;
+	message: string | null;
+};
+
+export const offlineSyncStatus = writable<OfflineSyncStatus>({
+	state: 'idle',
+	generatedAt: null,
+	message: null
+});
+
+const SYNC_EVENT = 'livingdex:offline-sync';
+const OFFLINE_CACHE_PREFIX = 'livingdex-offline-';
+const OFFLINE_META_CACHE = `${OFFLINE_CACHE_PREFIX}meta-v1`;
+const OFFLINE_META_URL = '/__offline/current';
+
+async function workerMessage(
+	message: unknown,
+	timeoutMs = 120_000,
+	waitForReady = true
+): Promise<Record<string, unknown>> {
+	if (!('serviceWorker' in navigator)) throw new Error('Service workers are unavailable');
+	const registration = waitForReady
+		? await navigator.serviceWorker.ready
+		: await navigator.serviceWorker.getRegistration();
+	if (!registration?.active) throw new Error('Offline worker is not active');
+	return new Promise((resolve, reject) => {
+		const channel = new MessageChannel();
+		const timeout = window.setTimeout(
+			() => reject(new Error('Offline worker timed out')),
+			timeoutMs
+		);
+		channel.port1.onmessage = (event) => {
+			window.clearTimeout(timeout);
+			const result = event.data as Record<string, unknown>;
+			if (result?.ok) resolve(result);
+			else reject(new Error(String(result?.error ?? 'Offline worker failed')));
+		};
+		registration.active?.postMessage(message, [channel.port2]);
+	});
+}
+
+export function requestOfflineSync(): void {
+	if (typeof window !== 'undefined') window.dispatchEvent(new Event(SYNC_EVENT));
+}
+
+async function deleteOfflineCaches(): Promise<void> {
+	if (typeof window === 'undefined' || !('caches' in window)) return;
+	const names = await caches.keys();
+	await Promise.all(
+		names.filter((name) => name.startsWith(OFFLINE_CACHE_PREFIX)).map((name) => caches.delete(name))
+	);
+}
+
+export async function claimOfflineData(userId: string): Promise<void> {
+	if (typeof window === 'undefined') return;
+	if ('caches' in window) {
+		const names = await caches.keys();
+		if (names.includes(OFFLINE_META_CACHE)) {
+			const response = await (await caches.open(OFFLINE_META_CACHE)).match(OFFLINE_META_URL);
+			const meta = await response?.json().catch(() => null);
+			if (typeof meta?.userId !== 'string' || meta.userId !== userId) await deleteOfflineCaches();
+		}
+	}
+	if ('serviceWorker' in navigator && (await navigator.serviceWorker.getRegistration())?.active) {
+		await workerMessage({ type: 'CLAIM_OFFLINE_USER', userId }, 10_000, false);
+	}
+}
+
+export async function clearOfflineData(): Promise<void> {
+	if (typeof window === 'undefined') return;
+	await deleteOfflineCaches();
+	if ('serviceWorker' in navigator && (await navigator.serviceWorker.getRegistration())?.active) {
+		await workerMessage({ type: 'CLEAR_OFFLINE_DATA' }, 10_000, false);
+	}
+	offlineSyncStatus.set({ state: 'idle', generatedAt: null, message: null });
+}
+
+export function startOfflineSync(getUserId: () => string | null): () => void {
+	let timer: number | null = null;
+	let stopped = false;
+	let running = false;
+	let rerun = false;
+	let lastGeneratedAt: string | null = null;
+
+	const synchronize = async () => {
+		if (stopped || !navigator.onLine) return;
+		if (running) {
+			rerun = true;
+			return;
+		}
+		const userId = getUserId();
+		if (!userId || !('serviceWorker' in navigator)) return;
+		running = true;
+		offlineSyncStatus.set({ state: 'syncing', generatedAt: null, message: null });
+		try {
+			await claimOfflineData(userId);
+			const response = await fetch('/api/offline-snapshot', {
+				credentials: 'include',
+				headers: { Accept: 'application/json' }
+			});
+			if (!response.ok) throw new Error(`Snapshot request failed (${response.status})`);
+			const snapshot = (await response.json()) as OfflineSnapshot;
+			if (snapshot.userId !== userId) throw new Error('Snapshot owner did not match the session');
+			const useLocal = PUBLIC_USE_LOCAL_POKEMON_SPRITE_FOLDER === 'true';
+			const artworkUrls = Array.from(
+				new Set(
+					snapshot.pokedexes.flatMap(({ pokedex, entries }) =>
+						entries.map(({ pokedexEntry }) => {
+							const url = resolveSpriteUrl(pokedexEntry, pokedex.isShinyDex, useLocal);
+							(
+								pokedexEntry as typeof pokedexEntry & { offlineSpriteUrl: string }
+							).offlineSpriteUrl = url;
+							return url;
+						})
+					)
+				)
+			);
+			const result = await workerMessage({
+				type: 'SYNC_OFFLINE_SNAPSHOT',
+				snapshot,
+				artworkUrls
+			});
+			const failed = Number(result.failedArtwork ?? 0);
+			offlineSyncStatus.set({
+				state: failed > 0 ? 'partial' : 'ready',
+				generatedAt: snapshot.generatedAt,
+				message: failed > 0 ? `${failed} artwork files could not be cached` : null
+			});
+			lastGeneratedAt = snapshot.generatedAt;
+		} catch (error) {
+			offlineSyncStatus.set({
+				state: 'error',
+				generatedAt: lastGeneratedAt,
+				message: error instanceof Error ? error.message : String(error)
+			});
+		} finally {
+			running = false;
+			if (rerun && !stopped) {
+				rerun = false;
+				schedule();
+			}
+		}
+	};
+
+	const schedule = () => {
+		if (timer !== null) window.clearTimeout(timer);
+		timer = window.setTimeout(() => {
+			timer = null;
+			void synchronize();
+		}, 1_000);
+	};
+
+	window.addEventListener(SYNC_EVENT, schedule);
+	window.addEventListener('online', schedule);
+	schedule();
+	return () => {
+		stopped = true;
+		if (timer !== null) window.clearTimeout(timer);
+		window.removeEventListener(SYNC_EVENT, schedule);
+		window.removeEventListener('online', schedule);
+	};
+}