// index.js
import Fastify from "fastify";
import RSS from "rss";
import TTLCache from '@isaacs/ttlcache';
import '@dotenvx/dotenvx/config.js';
import { ApifyClient } from 'apify-client';
import { env } from './env.js';
import packageJson from "./package.json" with { type: "json" };
import cors from '@fastify/cors'

const fastify = Fastify({ logger: true });
fastify.register(cors);

const client = new ApifyClient({
  token: env.APIFY_TOKEN,
});

const cache = new TTLCache({
  max: 5000,
  ttl: 30 * 60 * 1000, // 30 minutes
});

const inflight = new Map();

// Format date as YYYY-MM-DD_HH:mm:ss_UTC
function formatTwitterDate(date) {
  const pad = (n) => String(n).padStart(2, "0");
  const year = date.getUTCFullYear();
  const month = pad(date.getUTCMonth() + 1);
  const day = pad(date.getUTCDate());
  const hours = pad(date.getUTCHours());
  const minutes = pad(date.getUTCMinutes());
  const seconds = pad(date.getUTCSeconds());
  return `${year}-${month}-${day}_${hours}:${minutes}:${seconds}_UTC`;
}

async function getJson(username) {
  // 15 days ago
  const sinceDate = new Date(Date.now() - 15 * 24 * 60 * 60 * 1000);
  const formatted = formatTwitterDate(sinceDate);

  const { defaultDatasetId } = await client.actor('kaitoeasyapi/twitter-x-data-tweet-scraper-pay-per-result-cheapest').call({
    searchTerms: [`from:${username} since:${formatted}`],
    maxItems: 15,
  });

  // Fetches results from the actor's dataset.
  const { items } = await client.dataset(defaultDatasetId).listItems();

  return items;
}


// Helper to build RSS feed
function buildFeed(username, tweets) {
  const feed = new RSS({
    title: `${username} Tweets`,
    description: `Latest tweets from ${username}`,
    feed_url: `https://${env.ORIGIN}/${username}`,
    site_url: `https://x.com/${username}`,
    language: "en",
  });

  tweets.forEach((tweet) => {
    if (tweet.id === -1) return; // skip mock API filler
    feed.item({
      title: tweet.text.substring(0, 100),
      description: tweet.text,
      url: tweet.url,
      guid: tweet.id.toString(),
      date: new Date(tweet.createdAt),
    });
  });

  return feed.xml({ indent: true });
}

fastify.get("/", (request, reply) => {
  return reply
    .code(200)
    .header("Content-Type", "text/html; charset=utf-8")
    .send(`HELLO<br>THIS IS rssapp ${packageJson.version}<br>OK<br>try <a href="/projektmelody">/projektmelody</a>`);
});


fastify.get("/:username", async (request, reply) => {
  const { username } = request.params;
  const key = username.toLowerCase();

  if (!key) {
    return reply.code(401).send({ error: "Username missing" });
  }

  if (!env.WHITELIST.has(key)) {
    return reply.code(403).send({ error: "Forbidden username" });
  }

  // Serve from cache if exists
  const cached = cache.get(key);
  if (cached) {
    fastify.log.info('sending cached data');
    return reply.header("Content-Type", "application/rss+xml").send(cached.xml);
  }

  let dataPromise;

  if (inflight.has(key)) {
    // Wait for the in-progress fetch
    fastify.log.info('waiting for in-flight fetch');
    dataPromise = inflight.get(key);
  } else {
    // Start a new fetch
    dataPromise = getJson(key);
    inflight.set(key, dataPromise);

    // Ensure we remove from inflight map when done
    dataPromise.finally(() => inflight.delete(key));
  }

  const data = await dataPromise;

  const xml = buildFeed(key, data);

  // Cache result
  cache.set(key, { xml, timestamp: Date.now() });

  return reply.header("Content-Type", "application/rss+xml").send(xml);
});

// Start server
const start = async () => {
  try {
    fastify.listen({
      port: process.env.PORT || 3000,
      host: "0.0.0.0"
    });
  } catch (err) {
    fastify.log.error(err);
    process.exit(1);
  }
};

start();