Create index.js

index.js

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+const express  = require('express');
+const multer   = require('multer');
+const AdmZip   = require('adm-zip');
+const path     = require('path');
+const fs       = require('fs');
+const os       = require('os');
+const { execSync, spawnSync } = require('child_process');
+const axios    = require('axios');
+
+const app  = express();
+const PORT = 3000;
+
+app.use(express.json({ limit: '200mb' }));
+app.use(express.static(path.join(__dirname, 'public')));
+
+// Multer: store APK uploads in temp dir
+const upload = multer({
+  dest: os.tmpdir(),
+  limits: { fileSize: 200 * 1024 * 1024 },
+  fileFilter: (req, file, cb) => {
+    if (file.originalname.endsWith('.apk')) cb(null, true);
+    else cb(new Error('Only .apk files accepted'));
+  }
+});
+
+// ── KEYSTORE ────────────────────────────────────────────────────────────────
+// We generate a debug keystore once and reuse it for all re-signs.
+const KEYSTORE_PATH = path.join(__dirname, 'debug.keystore');
+const KEY_ALIAS     = 'supercity';
+const KEY_PASS      = 'supercity123';
+const STORE_PASS    = 'supercity123';
+
+function ensureKeystore() {
+  if (fs.existsSync(KEYSTORE_PATH)) return;
+  console.log('Generating debug keystore...');
+  const result = spawnSync('keytool', [
+    '-genkeypair', '-v',
+    '-keystore',   KEYSTORE_PATH,
+    '-alias',      KEY_ALIAS,
+    '-keyalg',     'RSA',
+    '-keysize',    '2048',
+    '-validity',   '10000',
+    '-storepass',  STORE_PASS,
+    '-keypass',    KEY_PASS,
+    '-dname',      'CN=SuperCityEditor, OU=Mod, O=Local, L=Local, S=Local, C=US',
+  ], { encoding: 'utf8' });
+
+  if (result.status !== 0) {
+    throw new Error('keytool failed: ' + (result.stderr || result.stdout));
+  }
+  console.log('Keystore created at', KEYSTORE_PATH);
+}
+
+// ── TOOL CHECK ───────────────────────────────────────────────────────────────
+function checkTools() {
+  const tools = { keytool: false, zipalign: false, apksigner: false, jarsigner: false };
+  for (const t of Object.keys(tools)) {
+    try { execSync(`which ${t}`, { stdio: 'ignore' }); tools[t] = true; } catch {}
+  }
+  return tools;
+}
+
+// ── ROUTES ───────────────────────────────────────────────────────────────────
+
+// GET /tools  — let frontend know what's available
+app.get('/tools', (req, res) => {
+  res.json(checkTools());
+});
+
+// POST /upload  — receive APK, extract characters.txt, return it as text
+app.post('/upload', upload.single('apk'), (req, res) => {
+  try {
+    const apkPath = req.file.path;
+    const zip     = new AdmZip(apkPath);
+    const entry   = zip.getEntry('assets/characters.txt');
+    if (!entry) {
+      fs.unlinkSync(apkPath);
+      return res.status(400).json({ error: 'assets/characters.txt not found in APK' });
+    }
+    const content = entry.getData().toString('utf8');
+    // Keep the apk on disk temporarily, send back a session token
+    const token = Date.now() + '_' + Math.random().toString(36).slice(2);
+    const sessionDir = path.join(os.tmpdir(), token);
+    fs.mkdirSync(sessionDir);
+    fs.renameSync(apkPath, path.join(sessionDir, 'original.apk'));
+    fs.writeFileSync(path.join(sessionDir, 'original_name.txt'), req.file.originalname);
+    res.json({ token, characters: content });
+  } catch (err) {
+    try { fs.unlinkSync(req.file.path); } catch {}
+    res.status(500).json({ error: err.message });
+  }
+});
+
+// POST /upload-url  — fetch APK from a URL, extract characters.txt
+app.post('/upload-url', express.json(), async (req, res) => {
+  const { url } = req.body;
+  if (!url || !url.toLowerCase().endsWith('.apk')) {
+    return res.status(400).json({ error: 'URL must point to a .apk file' });
+  }
+
+  const token      = Date.now() + '_' + Math.random().toString(36).slice(2);
+  const sessionDir = path.join(os.tmpdir(), token);
+  fs.mkdirSync(sessionDir);
+  const apkPath = path.join(sessionDir, 'original.apk');
+
+  try {
+    const response = await axios.get(url, { responseType: 'arraybuffer', maxContentLength: 200 * 1024 * 1024 });
+    fs.writeFileSync(apkPath, response.data);
+
+    const zip   = new AdmZip(apkPath);
+    const entry = zip.getEntry('assets/characters.txt');
+    if (!entry) {
+      fs.rmSync(sessionDir, { recursive: true, force: true });
+      return res.status(400).json({ error: 'assets/characters.txt not found in APK' });
+    }
+
+    const content = entry.getData().toString('utf8');
+    const fname   = url.split('/').pop();
+    fs.writeFileSync(path.join(sessionDir, 'original_name.txt'), fname);
+    res.json({ token, characters: content });
+
+  } catch (err) {
+    fs.rmSync(sessionDir, { recursive: true, force: true });
+    const msg = err.response ? `Remote returned ${err.response.status}` : err.message;
+    res.status(500).json({ error: msg });
+  }
+});
+
+// POST /patch  — receive edited characters text + token, repack + sign APK
+app.post('/patch', express.json({ limit: '10mb' }), (req, res) => {
+  const { token, characters } = req.body;
+  if (!token || !characters) return res.status(400).json({ error: 'Missing token or characters' });
+
+  const sessionDir   = path.join(os.tmpdir(), token);
+  const originalApk  = path.join(sessionDir, 'original.apk');
+  const patchedApk   = path.join(sessionDir, 'patched_unsigned.apk');
+  const alignedApk   = path.join(sessionDir, 'patched_aligned.apk');
+  const signedApk    = path.join(sessionDir, 'patched_signed.apk');
+
+  if (!fs.existsSync(originalApk)) {
+    return res.status(404).json({ error: 'Session expired or not found. Re-upload the APK.' });
+  }
+
+  try {
+    ensureKeystore();
+    const tools = checkTools();
+
+    // 1. Open APK as zip, replace assets/characters.txt
+    const zip = new AdmZip(originalApk);
+    zip.updateFile('assets/characters.txt', Buffer.from(characters, 'utf8'));
+
+    // 2. Delete META-INF (old signature) so re-sign works cleanly
+    const toDelete = [];
+    zip.getEntries().forEach(e => {
+      if (e.entryName.startsWith('META-INF/')) toDelete.push(e.entryName);
+    });
+    toDelete.forEach(name => zip.deleteFile(name));
+
+    zip.writeZip(patchedApk);
+
+    // 3. zipalign (align before signing for v2/v3; v1 is fine either way)
+    let toSign = patchedApk;
+    if (tools.zipalign) {
+      const zr = spawnSync('zipalign', ['-f', '-v', '4', patchedApk, alignedApk], { encoding: 'utf8' });
+      if (zr.status === 0) toSign = alignedApk;
+      else console.warn('zipalign failed, skipping alignment:', zr.stderr);
+    }
+
+    // 4. Sign — prefer apksigner (v1+v2), fallback to jarsigner (v1 only)
+    if (tools.apksigner) {
+      const sr = spawnSync('apksigner', [
+        'sign',
+        '--ks',           KEYSTORE_PATH,
+        '--ks-pass',      `pass:${STORE_PASS}`,
+        '--key-pass',     `pass:${KEY_PASS}`,
+        '--ks-key-alias', KEY_ALIAS,
+        '--out',          signedApk,
+        toSign
+      ], { encoding: 'utf8' });
+      if (sr.status !== 0) throw new Error('apksigner failed: ' + sr.stderr);
+    } else if (tools.jarsigner) {
+      // jarsigner signs in-place; copy first
+      fs.copyFileSync(toSign, signedApk);
+      const sr = spawnSync('jarsigner', [
+        '-verbose',
+        '-sigalg',   'SHA256withRSA',
+        '-digestalg', 'SHA-256',
+        '-keystore',  KEYSTORE_PATH,
+        '-storepass', STORE_PASS,
+        '-keypass',   KEY_PASS,
+        signedApk,
+        KEY_ALIAS
+      ], { encoding: 'utf8' });
+      if (sr.status !== 0) throw new Error('jarsigner failed: ' + sr.stderr);
+    } else {
+      throw new Error('No signing tool found. Install JDK (keytool+jarsigner) or Android SDK build-tools (apksigner+zipalign) and make sure they are on PATH.');
+    }
+
+    // 5. Stream signed APK back
+    const origName    = fs.existsSync(path.join(sessionDir, 'original_name.txt'))
+      ? fs.readFileSync(path.join(sessionDir, 'original_name.txt'), 'utf8').trim()
+      : 'SuperCity.apk';
+    const outName     = origName.replace(/\.apk$/i, '_modded.apk');
+
+    res.setHeader('Content-Disposition', `attachment; filename="${outName}"`);
+    res.setHeader('Content-Type', 'application/vnd.android.package-archive');
+    const stream = fs.createReadStream(signedApk);
+    stream.pipe(res);
+    stream.on('end', () => {
+      // Cleanup session after download
+      try { fs.rmSync(sessionDir, { recursive: true, force: true }); } catch {}
+    });
+
+  } catch (err) {
+    console.error(err);
+    res.status(500).json({ error: err.message });
+  }
+});
+
+// ── START ─────────────────────────────────────────────────────────────────────
+app.listen(7860, () => {
+  console.log(`\n🦸 Super City Editor backend running at http://localhost:${PORT}`);
+  console.log('Open that URL in your browser to use the editor.\n');
+  try { ensureKeystore(); } catch (e) { console.warn('Keystore not ready yet:', e.message); }
+});