/**
 * Department Model
 *
 * departments 테이블 CRUD (MariaDB)
 */

const { getPool } = require('./userModel');

async function getAll() {
  const db = getPool();
  const [rows] = await db.query(
    `SELECT d.*
     FROM departments d
     ORDER BY d.display_order ASC, d.department_id ASC`
  );
  return rows;
}

async function getById(id) {
  const db = getPool();
  const [rows] = await db.query(
    `SELECT d.*
     FROM departments d
     WHERE d.department_id = ?`,
    [id]
  );
  return rows[0] || null;
}

async function create({ department_name, description, display_order }) {
  const db = getPool();
  const [result] = await db.query(
    `INSERT INTO departments (department_name, description, display_order)
     VALUES (?, ?, ?)`,
    [department_name, description || null, display_order || 0]
  );
  return getById(result.insertId);
}

async function update(id, data) {
  const db = getPool();
  const fields = [];
  const values = [];

  if (data.department_name !== undefined) { fields.push('department_name = ?'); values.push(data.department_name); }
  if (data.description !== undefined) { fields.push('description = ?'); values.push(data.description || null); }
  if (data.display_order !== undefined) { fields.push('display_order = ?'); values.push(data.display_order); }

  if (fields.length === 0) return getById(id);

  values.push(id);
  await db.query(
    `UPDATE departments SET ${fields.join(', ')} WHERE department_id = ?`,
    values
  );
  return getById(id);
}

async function remove(id) {
  const db = getPool();
  const conn = await db.getConnection();
  try {
    await conn.beginTransaction();
    await conn.query('UPDATE users SET department_id = NULL WHERE department_id = ?', [id]);
    await conn.query('DELETE FROM departments WHERE department_id = ?', [id]);
    await conn.commit();
  } catch (e) {
    await conn.rollback();
    throw e;
  } finally {
    conn.release();
  }
}

module.exports = { getAll, getById, create, update, remove };