wehub-resource-sync
82 lines
2.2 KiB
TypeScript
82 lines
2.2 KiB
TypeScript
/**
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* Reddit 数据懒加载器
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*
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* 使用 fetch() + JSON.parse() 加载数据（避开 Vite ESM 转换管线，避免阻塞 dev server）。
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* 单例缓存：首次加载后后续调用直接返回缓存数据。
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*/
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import type { RedditPost } from '../types';
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import { processPosts } from './index';
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const postsUrl = new URL('./posts.json', import.meta.url).href;
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function createLoader<T>(url: string) {
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let cache: T | null = null;
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let loading: Promise<T> | null = null;
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const load = (): Promise<T> => {
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if (cache) return Promise.resolve(cache);
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if (!loading) {
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loading = fetch(url)
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.then(r => {
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if (!r.ok) throw new Error(`HTTP ${r.status} for ${url}`);
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return r.json();
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})
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.then(data => { cache = data as T; return cache; })
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.catch(err => { loading = null; throw err; });
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}
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return loading;
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};
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const getSync = (): T | null => cache;
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return { load, getSync };
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}
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interface RawRedditData {
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posts: any[];
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}
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const rawData = createLoader<RawRedditData>(postsUrl);
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let processedCache: RedditPost[] | null = null;
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let processedLoading: Promise<RedditPost[]> | null = null;
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const subscribers = new Set<() => void>();
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function notifySubscribers(): void {
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for (const fn of subscribers) {
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try { fn(); } catch { /* swallow listener errors */ }
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}
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}
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export function loadPosts(): Promise<RedditPost[]> {
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if (processedCache) return Promise.resolve(processedCache);
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if (!processedLoading) {
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processedLoading = rawData.load().then(data => {
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processedCache = processPosts(data.posts);
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notifySubscribers();
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return processedCache;
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});
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}
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return processedLoading;
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}
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export function getPostsSync(): RedditPost[] | null {
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return processedCache;
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}
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/**
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* Subscribe to fixture-posts cache updates. Used by `useSyncExternalStore`
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* to re-render once `loadPosts()` resolves and `getPostsSync()` flips from
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* null to the processed array. Returns the unsubscribe function.
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*/
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export function subscribePosts(listener: () => void): () => void {
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subscribers.add(listener);
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return () => { subscribers.delete(listener); };
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}
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export async function preload(): Promise<void> {
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await loadPosts();
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}
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