// @ts-check
import { task } from './trace';
import { SHARED_DESCRIPTION } from './constants/description';
import { RulesetOutput } from './lib/rules/ruleset';
import { getTelegramBackupIPFromBase64 } from './lib/get-telegram-backup-ip';
import picocolors from 'picocolors';
import { $$fetch } from './lib/fetch-retry';
import dns from 'node:dns/promises';
import { createReadlineInterfaceFromResponse } from './lib/fetch-text-by-line';
import { fastIpVersion } from 'foxts/fast-ip-version';
import { fastStringArrayJoin } from 'foxts/fast-string-array-join';

export const buildTelegramCIDR = task(require.main === module, __filename)(async (span) => {
  const { timestamp, ipcidr, ipcidr6 } = await span.traceChildAsync('get telegram cidr', async () => {
    const resp = await $$fetch('https://core.telegram.org/resources/cidr.txt');
    const lastModified = resp.headers.get('last-modified');
    const date = lastModified ? new Date(lastModified) : new Date();

    const ipcidr: string[] = [
      // Unused secret Telegram backup CIDR, announced by AS62041
      '95.161.64.0/20'
    ];
    const ipcidr6: string[] = [];

    for await (const cidr of createReadlineInterfaceFromResponse(resp, true)) {
      const v = fastIpVersion(cidr);
      if (v === 4) {
        ipcidr.push(cidr);
      } else if (v === 6) {
        ipcidr6.push(cidr);
      }
    }

    const backupIPs = new Set<string>();

    // https://github.com/tdlib/td/blob/master/td/telegram/ConfigManager.cpp

    const resolvers = ['8.8.8.8', '1.0.0.1'].map((ip) => {
      const resolver = new dns.Resolver();
      resolver.setServers([ip]);
      return Object.assign(resolver, { server: ip });
    });

    // Backup IP Source 1 (DNS)
    await Promise.all(resolvers.flatMap((resolver) => [
      'apv3.stel.com', // prod
      'tapv3.stel.com' // test
    ].map(async (domain) => {
      try {
        // tapv3.stel.com was for testing server
        const resp = await resolver.resolveTxt(domain);
        const strings = resp.map(r => fastStringArrayJoin(r, '')); // flatten
        if (strings.length !== 2) {
          throw new TypeError(`Unexpected TXT record count: ${strings.length}`);
        }

        const str = strings[0].length > strings[1].length
          ? strings[0] + strings[1]
          : strings[1] + strings[0];

        const ips = getTelegramBackupIPFromBase64(str);
        ips.forEach(i => backupIPs.add(i.ip));

        console.log('[telegram backup ip]', picocolors.green('DNS TXT'), { domain, ips, server: resolver.server });
      } catch (e) {
        console.error('[telegram backup ip]', picocolors.red('DNS TXT error'), { domain }, e);
      }
    })));

    // Backup IP Source 2: Firebase Realtime Database (test server not supported)
    try {
      const text = await (await $$fetch('https://reserve-5a846.firebaseio.com/ipconfigv3.json')).json();
      if (typeof text === 'string' && text.length === 344) {
        const ips = getTelegramBackupIPFromBase64(text);
        ips.forEach(i => backupIPs.add(i.ip));

        console.log('[telegram backup ip]', picocolors.green('Firebase Realtime DB'), { ips });
      }
    } catch (e) {
      console.error('[telegram backup ip]', picocolors.red('Firebase Realtime DB error'), e);
      // ignore all errors
    }

    // Backup IP Source 3: Firebase Value Store (test server not supported)
    try {
      const json = await (await $$fetch('https://firestore.googleapis.com/v1/projects/reserve-5a846/databases/(default)/documents/ipconfig/v3', {
        headers: {
          Accept: '*/*',
          Origin: undefined // Without this line, Google API will return "Bad request: Origin doesn't match Host for XD3.". Probably have something to do with sqlite cache store
        }
      })).json();

      if (
        json && typeof json === 'object'
        && 'fields' in json && typeof json.fields === 'object' && json.fields
        && 'data' in json.fields && typeof json.fields.data === 'object' && json.fields.data
        && 'stringValue' in json.fields.data && typeof json.fields.data.stringValue === 'string' && json.fields.data.stringValue.length === 344
      ) {
        const ips = getTelegramBackupIPFromBase64(json.fields.data.stringValue);
        ips.forEach(i => backupIPs.add(i.ip));

        console.log('[telegram backup ip]', picocolors.green('Firebase Value Store'), { ips });
      } else {
        console.error('[telegram backup ip]', picocolors.red('Firebase Value Store data format invalid'), { json });
      }
    } catch (e) {
      console.error('[telegram backup ip]', picocolors.red('Firebase Value Store error'), e);
    }

    // Backup IP Source 4: Google App Engine
    await Promise.all([
      'https://dns-telegram.appspot.com',
      'https://dns-telegram.appspot.com/test'
    ].map(async (url) => {
      try {
        const text = await (await $$fetch(url)).text();
        if (text.length === 344) {
          const ips = getTelegramBackupIPFromBase64(text);
          ips.forEach(i => backupIPs.add(i.ip));

          console.log('[telegram backup ip]', picocolors.green('Google App Engine'), { url, ips });
        }
      } catch (e) {
        console.error('[telegram backup ip]', picocolors.red('Google App Engine error'), { url }, e);
      }
    }));

    // tcdnb.azureedge.net no longer works

    console.log('[telegram backup ip]', `Found ${backupIPs.size} backup IPs:`, backupIPs);

    ipcidr.push(...Array.from(backupIPs).map(i => i + '/32'));

    return { timestamp: date.getTime(), ipcidr, ipcidr6 };
  });

  if (ipcidr.length + ipcidr6.length === 0) {
    throw new Error('Failed to fetch data!');
  }

  const description = [
    ...SHARED_DESCRIPTION,
    'Data from:',
    ' - https://core.telegram.org/resources/cidr.txt'
  ];

  return new RulesetOutput(span, 'telegram', 'ip')
    .withTitle('Sukka\'s Ruleset - Telegram IP CIDR')
    .withDescription(description)
    // .withDate(date) // With extra data source, we no longer use last-modified for file date
    .appendDataSource(
      'https://core.telegram.org/resources/cidr.txt (last updated: ' + new Date(timestamp).toISOString() + ')'
    )
    .bulkAddCIDR4NoResolve(ipcidr)
    .bulkAddCIDR6NoResolve(ipcidr6)
    .write();
});

export const ___ = '';