100 lines
4.7 KiB
TypeScript
100 lines
4.7 KiB
TypeScript
import { z } from 'zod';
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import type { Article } from '../shared/protocol.ts';
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const pageSchema = z.object({
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pageid: z.number().int().positive().max(Number.MAX_SAFE_INTEGER), ns: z.literal(0),
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title: z.string().trim().min(1).max(200), extract: z.string().max(4096).optional(),
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lastrevid: z.number().int().positive().max(Number.MAX_SAFE_INTEGER),
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thumbnail: z.object({ source: z.string().url().max(1500) }).optional(),
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categories: z.array(z.object({ title: z.string().min(1).max(300) })).max(50).optional(),
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});
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const responseSchema = z.object({ query: z.object({ pages: z.array(z.unknown()).max(10) }) });
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const MAX_RESPONSE_BYTES = 512 * 1024;
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const MAX_ATTEMPTS = 3;
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const imageOrigins = new Set(['https://upload.wikimedia.org', 'https://thumb.wikimedia.org']);
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function category(title: string, categories: string[]): string {
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const text = `${title} ${categories.join(' ')}`.toLowerCase();
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if (/astronom|planet|space|galax|moon|star\b/.test(text)) return 'Space';
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if (/animal|plant|species|ocean|biolog|mollusc/.test(text)) return 'Nature';
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if (/births|deaths|people|scientist/.test(text)) return 'People';
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if (/physic|chem|math|science|technolog/.test(text)) return 'Science';
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if (/histor|ancient|archaeolog|empire/.test(text)) return 'History';
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return 'Culture';
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}
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async function readJson(response: Response): Promise<unknown> {
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const length = response.headers.get('content-length');
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if (!response.ok || response.redirected ||
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!/^application\/json(?:\s*;|\s*$)/i.test(response.headers.get('content-type') ?? '') ||
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(length !== null && (!/^\d+$/.test(length) || Number(length) > MAX_RESPONSE_BYTES)) || !response.body) {
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await response.body?.cancel();
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throw new Error('Invalid Wikipedia API response');
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}
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const reader = response.body.getReader();
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const chunks: Uint8Array[] = [];
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let size = 0;
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try {
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for (;;) {
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const { done, value } = await reader.read();
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if (done) break;
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size += value.byteLength;
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if (size > MAX_RESPONSE_BYTES) throw new Error('Wikipedia response too large');
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chunks.push(value);
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}
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return JSON.parse(new TextDecoder('utf-8', { fatal: true }).decode(Buffer.concat(chunks)));
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} finally {
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await reader.cancel();
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reader.releaseLock();
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}
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}
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function pictureUrl(value: string | undefined): string | undefined {
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if (!value) return undefined;
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try {
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const url = new URL(value);
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return url.protocol === 'https:' && imageOrigins.has(url.origin) && !url.username && !url.password && !url.hash
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? url.toString() : undefined;
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} catch { return undefined; }
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}
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export class WikipediaArticleSource {
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private readonly fetcher: typeof globalThis.fetch;
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private active = 0;
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constructor(fetcher: typeof globalThis.fetch = globalThis.fetch) { this.fetcher = fetcher; }
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async random(): Promise<Article> {
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if (this.active >= 4) throw new Error('Wikipedia article service is busy');
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this.active++;
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try {
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for (let attempt = 0; attempt < MAX_ATTEMPTS; attempt++) {
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try {
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const url = new URL('https://en.wikipedia.org/w/api.php');
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url.search = new URLSearchParams({ action: 'query', format: 'json', formatversion: '2',
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generator: 'random', grnnamespace: '0', grnlimit: '10', prop: 'extracts|pageimages|info|categories',
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exintro: '1', explaintext: '1', exchars: '900', piprop: 'thumbnail', pithumbsize: '800', cllimit: '20' }).toString();
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const response = await this.fetcher(url, { signal: AbortSignal.timeout(3500), redirect: 'error',
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headers: { User-Agent: 'Wikideck/0.1 (experimental Wikipedia article cards)', Accept: 'application/json' } });
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const data = responseSchema.parse(await readJson(response));
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for (const rawPage of data.query.pages) {
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const parsedPage = pageSchema.safeParse(rawPage);
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if (!parsedPage.success) continue;
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const page = parsedPage.data;
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const image = pictureUrl(page.thumbnail?.source);
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const extract = page.extract?.trim();
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if (!image || !extract || extract.length < 40) continue;
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return { pageId: page.pageid, title: page.title, extract: extract.slice(0, 900), image,
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url: `https://en.wikipedia.org/?curid=${page.pageid}`, revisionId: page.lastrevid,
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source: 'live', category: category(page.title, page.categories?.map(c => c.title) ?? []) };
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}
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} catch { /* Try another random API response, but keep the number of attempts bounded. */ }
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}
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throw new Error('Wikipedia did not return an article with a picture after three attempts');
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} finally {
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this.active--;
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}
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}
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}
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export const wikipediaArticles = new WikipediaArticleSource();
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