twitter2rss/index.ts

import { Tweet, TwitterClient } from './twitter.ts';
import { SqliteStore, Store } from './store.ts';
import { StaticTokenProvider } from './token.ts';
import { timelineAsHTML, timelineAsJSON } from './format.ts';
import { z } from "https://deno.land/x/zod@v3.8.0/mod.ts";

const MAX_INT = "9223372036854775807";

class Server {
  constructor(
    readonly store: Store,
    readonly client: TwitterClient,
  ) {}

  async getLatestTweets(username: string, interval: number = 600): Promise<Tweet[]> {
    const storedAuthorId = this.store.getAuthorId(username);
    const latestTweet = storedAuthorId === null ? null : this.store.getLatestTweet(storedAuthorId);
    let authorId = storedAuthorId;

    let timeline = await this.client.getTimeline(username, latestTweet?.id_str);
    console.log(`Fetched ${timeline.length} new tweets`);
    for (const tweet of timeline) {
      this.store.saveTweet(tweet);
    }

    const newerThan = new Date();
    newerThan.setSeconds(newerThan.getSeconds() - interval);

    if (timeline.length === 0) {
      if (storedAuthorId === null) {
        return [];
      } else {
        timeline = this.store.getLatestTweets(storedAuthorId, MAX_INT, newerThan);
      }
    } else {
      const lastTweet = timeline[timeline.length - 1];
      const olderTweets = this.store.getLatestTweets(lastTweet.user.id_str, lastTweet.id_str, newerThan);
      timeline = timeline.concat(olderTweets);
      authorId = lastTweet.user.id_str;
    }

    timeline = timeline.filter(({ in_reply_to_user_id_str }) => {
      return in_reply_to_user_id_str === null || in_reply_to_user_id_str === authorId;
    });
    return timeline;
  }

  async start() {
    const server = Deno.listen({ port: 8000 });
    console.log("Server running at http://localhost:8000");

    for await (const conn of server) {
      this.serveHttp(conn);
    }
  }

  async serveHttp(conn: Deno.Conn) {
    const httpConn = Deno.serveHttp(conn);
    for await (const requestEvent of httpConn) {
      this.handle(requestEvent)
        .then(response => requestEvent.respondWith(response))
        .catch(err => console.error(err));
    }
  }

  async handle(requestEvent: Deno.RequestEvent): Promise<Response> {
    const url = new URL(requestEvent.request.url);
    const path = url.pathname;
    if (path === '/__proxy') {
      const target = url.searchParams.get('target');
      return this.handleProxy(requestEvent.request.headers, target);
    } else if (path.startsWith('/timeline/')) {
      const username = path.substring(10);
      return this.handleTimeline(username);
    } else if (path.startsWith('/json/')) {
      const username = path.substring(6);
      return this.handleJson(username);
    } else {
      return new Response('Not found', {
        status: 404,
      });
    }
  }

  async handleTimeline(username: string): Promise<Response> {
    const tweets = await this.getLatestTweets(username, 24 * 60 * 60);
    console.time('renderHTML');
    const html = timelineAsHTML(tweets);
    console.timeEnd('renderHTML');
    return new Response(html, {
      status: 200,
      headers: {
        'Content-Type': 'text/html; charset=utf-8'
      }
    });
  }

  async handleJson(username: string): Promise<Response> {
    const tweets = await this.getLatestTweets(username, 24 * 60 * 60);
    console.time('renderJSON');
    const html = timelineAsJSON(username, tweets);
    console.timeEnd('renderJSON');
    return new Response(html, {
      status: 200,
      headers: {
        'Content-Type': 'application/feed+json; charset=utf-8'
      }
    });
  }

  async handleProxy(headers: Headers, target: string | null): Promise<Response> {
    if (target !== null) {
      console.log(`Proxying ${target}`);
      try {
        const proxyRequest = await fetch(target, {
          headers: headers,
        });
        return new Response(proxyRequest.body, {
          status: proxyRequest.status,
          headers: proxyRequest.headers,
        });
      } catch (e) {
        return new Response('Bad request', {
          status: 400,
        });
      }
    } else {
      return new Response('Not found', {
        status: 404,
      });
    }
  }
}

const ConfigSchema = z.strictObject({
  bearer: z.string(),
  store: z.string(),
});

const configFile = Deno.args.length === 0 ? 'config.json' : Deno.args[0];
const json = JSON.parse(Deno.readTextFileSync(configFile));
const config = ConfigSchema.parse(json);

const fetcher = new Server(
  new SqliteStore(config.store),
  new TwitterClient(new StaticTokenProvider(config.bearer)),
);

fetcher.start();