import initSqlJs, { Database as SqlJsDatabase } from 'sql.js';
import fs from 'fs';
import path from 'path';
import { fileURLToPath } from 'url';
import bcrypt from 'bcryptjs';

const __dirname = path.dirname(fileURLToPath(import.meta.url));
const dbPath = path.join(__dirname, '..', 'data.db');

let db: SqlJsDatabase;

export async function initDb(): Promise<SqlJsDatabase> {
  const SQL = await initSqlJs();

  if (fs.existsSync(dbPath)) {
    const buffer = fs.readFileSync(dbPath);
    db = new SQL.Database(buffer);
  } else {
    db = new SQL.Database();
  }

  db.run('PRAGMA foreign_keys = ON');

  db.run(`
    CREATE TABLE IF NOT EXISTS users (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      username TEXT UNIQUE NOT NULL,
      password_hash TEXT NOT NULL,
      points INTEGER DEFAULT 0,
      is_admin INTEGER DEFAULT 0,
      created_at TEXT DEFAULT (datetime('now'))
    )
  `);

  // Add is_admin column if missing (existing DB migration)
  try { db.run('ALTER TABLE users ADD COLUMN is_admin INTEGER DEFAULT 0'); } catch {}

  // Auto-create admin if not exists
  const admin = queryOne('SELECT id FROM users WHERE username = ?', ['admin']);
  if (!admin) {
    const hash = bcrypt.hashSync('admin123', 10);
    execute('INSERT INTO users (username, password_hash, is_admin) VALUES (?, ?, 1)', ['admin', hash]);
    console.log('Admin user created: admin / admin123');
  }

  db.run(`
    CREATE TABLE IF NOT EXISTS cats (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      user_id INTEGER NOT NULL REFERENCES users(id),
      image_url TEXT NOT NULL,
      caption TEXT DEFAULT '',
      created_at TEXT DEFAULT (datetime('now'))
    )
  `);

  db.run(`
    CREATE TABLE IF NOT EXISTS likes (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      cat_id INTEGER NOT NULL REFERENCES cats(id),
      user_id INTEGER NOT NULL REFERENCES users(id),
      UNIQUE(cat_id, user_id)
    )
  `);

  db.run(`
    CREATE TABLE IF NOT EXISTS comments (
      id INTEGER PRIMARY KEY AUTOINCREMENT,
      cat_id INTEGER NOT NULL REFERENCES cats(id) ON DELETE CASCADE,
      user_id INTEGER NOT NULL REFERENCES users(id),
      text TEXT NOT NULL,
      created_at TEXT DEFAULT (datetime('now'))
    )
  `);

  saveDb();
  return db;
}

export function saveDb(): void {
  const data = db.export();
  const buffer = Buffer.from(data);
  fs.writeFileSync(dbPath, buffer);
}

export function getDb(): SqlJsDatabase {
  return db;
}

export function queryOne(sql: string, params: any[] = []): any {
  const stmt = db.prepare(sql);
  stmt.bind(params);
  const result = stmt.step() ? stmt.getAsObject() : null;
  stmt.free();
  return result;
}

export function queryAll(sql: string, params: any[] = []): any[] {
  const stmt = db.prepare(sql);
  stmt.bind(params);
  const results: any[] = [];
  while (stmt.step()) {
    results.push(stmt.getAsObject());
  }
  stmt.free();
  return results;
}

export function execute(sql: string, params: any[] = []): { changes: number; lastInsertRowid: number } {
  const stmt = db.prepare(sql);
  stmt.bind(params);
  stmt.step();
  const lastId = db.exec('SELECT last_insert_rowid() AS id')[0]?.values[0][0] || 0;
  const changes = db.getRowsModified();
  stmt.free();
  saveDb();
  return { changes, lastInsertRowid: Number(lastId) };
}