import { createRequire } from 'node:module';
import { mkdirSync, writeFileSync } from 'node:fs';
import { dirname, join } from 'node:path';
import { fileURLToPath } from 'node:url';

const require = createRequire(import.meta.url);
const { deserialize } = require('../packages/tts/node_modules/bson');

const __dirname = dirname(fileURLToPath(import.meta.url));

const DEFAULT_MOD_ID = '2668570240';
const modId = process.argv[2] ?? DEFAULT_MOD_ID;

/**
 * Resolve the authoritative `file_url` via the Steam Web API. The item page's
 * embedded `file_url` can point to a preview image instead of the save, so the
 * API is the reliable source.
 */
async function getFileUrlFromApi(id) {
  const params = new URLSearchParams();
  params.append('itemcount', '1');
  params.append('publishedfileids[0]', id);
  const res = await fetch(
    'https://api.steampowered.com/ISteamRemoteStorage/GetPublishedFileDetails/v1/',
    { method: 'POST', body: params },
  );
  if (!res.ok) {
    console.log(`  Steam API responded ${res.status}`);
    return null;
  }
  const json = await res.json();
  const d = json?.response?.publishedfiledetails?.[0];
  if (!d?.file_url) {
    console.log('  Steam API returned no file_url');
    return null;
  }
  return d.file_url;
}

/** True if the bytes look like a BSON document whose length matches. */
function looksLikeBson(buf) {
  if (buf.length < 5) return false;
  const len = buf.readInt32LE(0);
  return len === buf.length;
}

async function main() {
  console.log(`Resolving file_url for mod ${modId} via Steam API...`);
  const fileUrl = await getFileUrlFromApi(modId);
  if (!fileUrl) {
    console.error('Could not resolve a file_url');
    process.exit(1);
  }
  console.log(`file_url: ${fileUrl}`);

  const res = await fetch(fileUrl);
  if (!res.ok) {
    console.error(`Download failed ${res.status}`);
    process.exit(1);
  }
  const buf = Buffer.from(await res.arrayBuffer());
  console.log(`downloaded ${buf.length} bytes`);

  if (!looksLikeBson(buf)) {
    console.error(
      `Not a BSON save (magic ${buf.slice(0, 4).toString('hex')})`,
    );
    process.exit(1);
  }

  const mod = deserialize(buf);
  const outDir = join(__dirname, 'dumps');
  mkdirSync(outDir, { recursive: true });
  const outPath = join(outDir, `${modId}.json`);
  writeFileSync(outPath, JSON.stringify(mod, null, 2));
  console.log(`wrote ${outPath}`);
}

main().catch((err) => {
  console.error(err);
  process.exit(1);
});