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

const vacationBalanceModel = {
  async getByUserAndYear(userId, year) {
    const db = getPool();
    const [rows] = await db.query(`
      SELECT
        vb.*,
        vb.balance_type,
        vb.expires_at,
        vt.type_name,
        vt.type_code,
        vt.priority,
        vt.is_special,
        (vb.total_days - vb.used_days) as remaining_days
      FROM sp_vacation_balances vb
      INNER JOIN vacation_types vt ON vb.vacation_type_id = vt.id
      WHERE vb.user_id = ? AND (vb.year = ? OR (vb.balance_type = 'LONG_SERVICE' AND vb.expires_at IS NULL))
      ORDER BY vt.priority ASC, vt.type_name ASC
    `, [userId, year]);
    return rows;
  },

  async getAllByYear(year) {
    const db = getPool();
    const [rows] = await db.query(`
      SELECT
        vb.*,
        vb.balance_type,
        su.name as user_name,
        su.username,
        su.hire_date,
        su.department_id,
        COALESCE(d.department_name, '미배정') as department_name,
        vt.type_name,
        vt.type_code,
        vt.priority,
        (vb.total_days - vb.used_days) as remaining_days
      FROM sp_vacation_balances vb
      INNER JOIN sso_users su ON vb.user_id = su.user_id
      INNER JOIN vacation_types vt ON vb.vacation_type_id = vt.id
      LEFT JOIN departments d ON su.department_id = d.department_id
      WHERE (vb.year = ? OR (vb.balance_type = 'LONG_SERVICE' AND vb.expires_at IS NULL)) AND su.is_active = 1
      ORDER BY su.name ASC, vt.priority ASC
    `, [year]);
    return rows;
  },

  async allocate(data) {
    const db = getPool();
    const balanceType = data.balance_type || 'AUTO';
    const expiresAt = data.expires_at || null;
    const [result] = await db.query(`
      INSERT INTO sp_vacation_balances (user_id, vacation_type_id, year, total_days, used_days, notes, created_by, balance_type, expires_at)
      VALUES (?, ?, ?, ?, 0, ?, ?, ?, ?)
      ON DUPLICATE KEY UPDATE
        total_days = VALUES(total_days),
        notes = VALUES(notes),
        updated_at = NOW()
    `, [data.user_id, data.vacation_type_id, data.year, data.total_days, data.notes || null, data.created_by, balanceType, expiresAt]);
    return result;
  },

  // 차감 우선순위:
  // 1. 특별휴가(배우자출산 등) — vacation_type_id가 정확히 일치하는 잔액 먼저
  // 2. 이월 → 기본연차 → 추가부여 → 장기근속 → 회사부여 순서
  async deductDays(userId, vacationTypeId, year, daysToDeduct, conn) {
    const db = conn || getPool();
    const needRelease = !conn;
    const c = needRelease ? await db.getConnection() : db;
    try {
      if (needRelease) await c.beginTransaction();

      // 1단계: 해당 vacation_type_id와 정확히 매칭되는 잔액 우선 차감 (특별휴가)
      const [exactMatch] = await c.query(`
        SELECT id, total_days, used_days, (total_days - used_days) AS remaining_days, balance_type
        FROM sp_vacation_balances
        WHERE user_id = ? AND year = ? AND vacation_type_id = ? AND (total_days - used_days) > 0
        FOR UPDATE
      `, [userId, year, vacationTypeId]);

      let remaining = daysToDeduct;
      for (const b of exactMatch) {
        if (remaining <= 0) break;
        const toDeduct = Math.min(remaining, parseFloat(b.remaining_days));
        if (toDeduct > 0) {
          await c.query('UPDATE sp_vacation_balances SET used_days = used_days + ?, updated_at = NOW() WHERE id = ?', [toDeduct, b.id]);
          remaining -= toDeduct;
        }
      }

      // 2단계: 남은 차감분을 우선순위 순서로 (이미 차감한 행 제외)
      if (remaining > 0) {
        const deductedIds = exactMatch.map(b => b.id);
        const excludeClause = deductedIds.length > 0 ? `AND id NOT IN (${Array(deductedIds.length).fill('?').join(',')})` : '';
        const queryParams = [userId, year, ...deductedIds];
        const [balances] = await c.query(`
          SELECT id, total_days, used_days, (total_days - used_days) AS remaining_days, balance_type
          FROM sp_vacation_balances
          WHERE user_id = ? AND year = ? AND (total_days - used_days) > 0 ${excludeClause}
          ORDER BY FIELD(balance_type, 'CARRY_OVER', 'AUTO', 'MANUAL', 'LONG_SERVICE', 'COMPANY_GRANT')
          FOR UPDATE
        `, queryParams);

        for (const b of balances) {
          if (remaining <= 0) break;
          const toDeduct = Math.min(remaining, parseFloat(b.remaining_days));
          if (toDeduct > 0) {
            await c.query('UPDATE sp_vacation_balances SET used_days = used_days + ?, updated_at = NOW() WHERE id = ?', [toDeduct, b.id]);
            remaining -= toDeduct;
          }
        }
      }

      if (needRelease) await c.commit();
      return { affectedRows: exactMatch.length };
    } catch (err) {
      if (needRelease) await c.rollback();
      throw err;
    } finally {
      if (needRelease) c.release();
    }
  },

  // 복원: 역순 (회사부여 → 장기근속 → 추가부여 → 기본연차 → 이월)
  async restoreDays(userId, vacationTypeId, year, daysToRestore, conn) {
    const db = conn || getPool();
    const needRelease = !conn;
    const c = needRelease ? await db.getConnection() : db;
    try {
      if (needRelease) await c.beginTransaction();

      const [balances] = await c.query(`
        SELECT id, used_days, balance_type
        FROM sp_vacation_balances
        WHERE user_id = ? AND year = ? AND used_days > 0
        ORDER BY FIELD(balance_type, 'COMPANY_GRANT', 'LONG_SERVICE', 'MANUAL', 'AUTO', 'CARRY_OVER')
        FOR UPDATE
      `, [userId, year]);

      let remaining = daysToRestore;
      for (const b of balances) {
        if (remaining <= 0) break;
        const toRestore = Math.min(remaining, parseFloat(b.used_days));
        if (toRestore > 0) {
          await c.query('UPDATE sp_vacation_balances SET used_days = used_days - ?, updated_at = NOW() WHERE id = ?', [toRestore, b.id]);
          remaining -= toRestore;
        }
      }

      if (needRelease) await c.commit();
      return { affectedRows: balances.length };
    } catch (err) {
      if (needRelease) await c.rollback();
      throw err;
    } finally {
      if (needRelease) c.release();
    }
  },

  calculateAnnualLeaveDays(hireDate, targetYear) {
    const hire = new Date(hireDate);
    const targetDate = new Date(targetYear, 0, 1);
    const monthsDiff = (targetDate.getFullYear() - hire.getFullYear()) * 12
                     + (targetDate.getMonth() - hire.getMonth());
    if (monthsDiff < 12) {
      return Math.floor(monthsDiff);
    }
    const yearsWorked = Math.floor(monthsDiff / 12);
    const additionalDays = Math.floor((yearsWorked - 1) / 2);
    return Math.min(15 + additionalDays, 25);
  },

  async getUserHireDate(userId) {
    const db = getPool();
    const [rows] = await db.query('SELECT hire_date FROM sso_users WHERE user_id = ?', [userId]);
    return rows.length > 0 ? rows[0].hire_date : null;
  }
};

module.exports = vacationBalanceModel;