/**
 * Restore configurateur.db from the newest non-empty backup.
 * Safe to run while the server is up: the guarded saver refuses empty overwrites,
 * then restart the server (or let --watch reload) to pick up the restored file.
 */
import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
import initSqlJs from 'sql.js';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const dataDir = path.join(__dirname, '..', 'data');
const dbPath = process.env.DATABASE_PATH || path.join(dataDir, 'configurateur.db');
const backupDir = path.join(dataDir, 'backups');

const SQL = await initSqlJs({
  locateFile: (f) => path.join(__dirname, '..', 'node_modules', 'sql.js', 'dist', f)
});

function countMaterials(filePath) {
  if (!fs.existsSync(filePath)) return 0;
  let db = null;
  try {
    db = new SQL.Database(fs.readFileSync(filePath));
    const r = db.exec('SELECT COUNT(*) FROM formex_materials');
    return Number(r[0]?.values?.[0]?.[0] ?? 0);
  } catch {
    return 0;
  } finally {
    try { db?.close(); } catch { /* ignore */ }
  }
}

const backups = fs.existsSync(backupDir)
  ? fs.readdirSync(backupDir)
      .filter((f) => /^configurateur-.*\.db$/.test(f))
      .map((f) => {
        const full = path.join(backupDir, f);
        return { file: f, full, count: countMaterials(full), mtime: fs.statSync(full).mtimeMs };
      })
      .filter((b) => b.count > 0)
      .sort((a, b) => b.count - a.count || b.mtime - a.mtime)
  : [];

if (backups.length === 0) {
  console.error('No non-empty backup found under server/data/backups/');
  process.exit(1);
}

const best = backups[0];
const currentCount = countMaterials(dbPath);
console.log(`Current DB: ${currentCount} materials`);
console.log(`Restoring from ${best.file} (${best.count} materials)`);

if (fs.existsSync(dbPath) && currentCount > 0) {
  const stamp = new Date().toISOString().replace(/[:.]/g, '-').slice(0, 19);
  const safety = path.join(backupDir, `configurateur-pre-restore-${stamp}.db`);
  fs.copyFileSync(dbPath, safety);
  console.log(`Safety copy of current DB → ${safety}`);
}

fs.copyFileSync(best.full, dbPath);
console.log(`Restored. Disk now has ${countMaterials(dbPath)} materials.`);
console.log('Restart the API server so it reloads this file into memory.');