import { createWriteStream } from 'node:fs';
import { rename, mkdir } from 'node:fs/promises';
import { pipeline } from 'node:stream/promises';
import { createGunzip } from 'node:zlib';
import { Readable } from 'node:stream';
import { join } from 'node:path';
import { TMDBINTEGRAL_DIR, TMDB_EXPORTS_BASE } from '../config.js';

function formatMMDDYYYY(date) {
  const mm = String(date.getUTCMonth() + 1).padStart(2, '0');
  const dd = String(date.getUTCDate()).padStart(2, '0');
  const yyyy = date.getUTCFullYear();
  return `${mm}_${dd}_${yyyy}`;
}

async function tryDownload(url, outPath) {
  console.log(`Downloading: "${url}"`);
  const res = await fetch(url);
  if (res.status === 403 || res.status === 404) {
    console.log(`Not published yet (HTTP ${res.status}): ${url}`);
    return false;
  }
  if (!res.ok || !res.body) {
    throw new Error(`Failed to fetch ${url}: HTTP ${res.status}`);
  }
  const tmp = `${outPath}.tmp`;
  await pipeline(Readable.fromWeb(res.body), createGunzip(), createWriteStream(tmp));
  await rename(tmp, outPath);
  console.log(`Wrote ${outPath}`);
  return true;
}

// TMDb publishes the daily export around 08:00 UTC. If we run before that, the
// current-day file returns 403. Try today, then fall back to yesterday.
async function downloadExport(prefix, outName) {
  const now = new Date();
  const yesterday = new Date(now.getTime() - 86400 * 1000);
  const out = join(TMDBINTEGRAL_DIR, outName);
  for (const d of [now, yesterday]) {
    const url = `${TMDB_EXPORTS_BASE}/${prefix}_${formatMMDDYYYY(d)}.json.gz`;
    if (await tryDownload(url, out)) return;
  }
  throw new Error(`No TMDb ${prefix} export available for today or yesterday`);
}

export async function syncExports() {
  await mkdir(TMDBINTEGRAL_DIR, { recursive: true });
  await downloadExport('movie_ids', 'movie.json');
  await downloadExport('tv_series_ids', 'tv.json');
}

if (import.meta.url === `file://${process.argv[1]}`) {
  syncExports().catch((err) => {
    console.error(err);
    process.exit(1);
  });
}