import { createWriteStream, mkdirSync, unlinkSync } from 'fs';
import { createGzip } from 'zlib';
import { join } from 'path';
import { spawn } from 'child_process';
import { getBackupData } from './phpdb';

export function triggerBackup(): void {
  setImmediate(() => runBackup().catch((e) => console.error('[backup] Fehler:', e)));
}

async function dumpToFile(filePath: string): Promise<void> {
  const { tables } = await getBackupData();

  const gzip = createGzip();
  const file = createWriteStream(filePath);
  gzip.pipe(file);

  const write = (s: string) => new Promise<void>((res, rej) =>
    gzip.write(s, (e) => e ? rej(e) : res())
  );

  const now = new Date().toISOString();
  await write(`-- Führungsbuch Backup ${now}\n-- Logbuch-Tabellen\n\nSET FOREIGN_KEY_CHECKS=0;\n\n`);

  for (const { name, createSql, rows } of tables) {
    await write(`DROP TABLE IF EXISTS \`${name}\`;\n`);
    await write(`${createSql};\n\n`);

    if (rows.length > 0) {
      const cols = Object.keys(rows[0]).map((c) => `\`${c}\``).join(', ');
      const batchSize = 200;
      for (let i = 0; i < rows.length; i += batchSize) {
        const batch = rows.slice(i, i + batchSize);
        const values = batch.map((row) =>
          '(' + Object.values(row).map((v) => {
            if (v === null) return 'NULL';
            if (typeof v === 'number') return String(v);
            return `'${String(v).replace(/\\/g, '\\\\').replace(/'/g, "\\'")}'`;
          }).join(', ') + ')'
        ).join(',\n  ');
        await write(`INSERT INTO \`${name}\` (${cols}) VALUES\n  ${values};\n`);
      }
      await write('\n');
    }
  }

  await write('SET FOREIGN_KEY_CHECKS=1;\n');

  await new Promise<void>((resolve, reject) => {
    gzip.end();
    file.on('close', resolve);
    file.on('error', reject);
  });
}

async function runBackup(): Promise<void> {
  const sshUrl = process.env.BACKUP_SSH_URL || '';
  const localDir = process.env.BACKUP_LOCAL_DIR || '/tmp/logbuch-backup';

  const ts = new Date().toISOString().replace('T', '_').replace(/:/g, '-').slice(0, 19);
  const filename = `sternwarte_${ts}.sql.gz`;

  mkdirSync(localDir, { recursive: true });
  const localPath = join(localDir, filename);

  await dumpToFile(localPath);
  console.log(`[backup] Dump geschrieben: ${localPath}`);

  try {
    if (!sshUrl) return;

    const match = sshUrl.match(/^([^:]+):(.+)$/);
    if (!match) {
      console.error('[backup] BACKUP_SSH_URL muss das Format user@host:/pfad haben');
      return;
    }
    const [, sshHost, remotePath] = match;

    const rawKeyPath = process.env.BACKUP_SSH_KEY_PATH || '';
    const keyPath = rawKeyPath.startsWith('~')
      ? rawKeyPath.replace('~', process.env.HOME || '/root')
      : rawKeyPath;

    const sshOpts = [
      ...(keyPath ? ['-i', keyPath] : []),
      '-o', 'StrictHostKeyChecking=no',
      '-o', 'BatchMode=yes',
      '-o', 'ConnectTimeout=15',
    ];

    await new Promise<void>((resolve, reject) => {
      const ssh = spawn('ssh', [...sshOpts, sshHost, `mkdir -p ${remotePath}`]);
      ssh.on('error', reject);
      ssh.on('close', (code) => code === 0 ? resolve() : reject(new Error(`mkdir -p exit ${code}`)));
    });

    await new Promise<void>((resolve, reject) => {
      const scp = spawn('scp', [...sshOpts, localPath, `${sshHost}:${remotePath}/${filename}`]);
      let scpErr = '';
      scp.stderr.on('data', (d: Buffer) => { scpErr += d.toString(); });
      scp.on('error', reject);
      scp.on('close', (code) =>
        code === 0 ? resolve() : reject(new Error(`scp exit ${code}${scpErr ? ': ' + scpErr.trim() : ''}`))
      );
    });

    console.log(`[backup] ${filename} → ${sshHost}:${remotePath}`);

    await new Promise<void>((resolve) => {
      const ssh = spawn('ssh', [
        ...sshOpts, sshHost,
        `find ${remotePath} -name 'sternwarte_*.sql.gz' -mtime +30 -delete`,
      ]);
      ssh.on('error', (e) => { console.error('[backup] Cleanup spawn-Fehler:', e.message); resolve(); });
      ssh.on('close', (code) => {
        if (code !== 0) console.error('[backup] Cleanup fehlgeschlagen (exit ' + code + ')');
        resolve();
      });
    });
  } finally {
    try { unlinkSync(localPath); } catch { /* bereits gelöscht oder nie angelegt */ }
  }
}