const vacationRequestModel = require('../models/vacationRequestModel');
const vacationBalanceModel = require('../models/vacationBalanceModel');
const companyHolidayModel = require('../models/companyHolidayModel');
const { getPool } = require('../middleware/auth');

const vacationController = {
  // ─── 휴가 신청 ───

  async createRequest(req, res) {
    try {
      const { vacation_type_id, start_date, end_date, days_used, reason } = req.body;
      const user_id = req.user.user_id || req.user.id;

      if (!vacation_type_id || !start_date || !end_date || !days_used) {
        return res.status(400).json({ success: false, error: '필수 필드가 누락되었습니다' });
      }
      if (new Date(end_date) < new Date(start_date)) {
        return res.status(400).json({ success: false, error: '종료일은 시작일보다 이후여야 합니다' });
      }

      const overlapRows = await vacationRequestModel.checkOverlap(user_id, start_date, end_date);
      if (overlapRows[0].count > 0) {
        return res.status(400).json({ success: false, error: '해당 기간에 이미 신청된 휴가가 있습니다' });
      }

      const result = await vacationRequestModel.create({
        user_id, vacation_type_id, start_date, end_date,
        days_used, reason: reason || null, status: 'pending'
      });

      res.status(201).json({
        success: true,
        message: '휴가 신청이 완료되었습니다',
        data: { request_id: result.insertId }
      });
    } catch (error) {
      console.error('휴가 신청 생성 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  async getRequests(req, res) {
    try {
      const role = (req.user.role || '').toLowerCase();
      const userId = req.user.user_id || req.user.id;
      const filters = {
        status: req.query.status,
        start_date: req.query.start_date,
        end_date: req.query.end_date,
        vacation_type_id: req.query.vacation_type_id
      };

      if (!['admin', 'system'].includes(role)) {
        filters.user_id = userId;
      } else if (req.query.user_id) {
        filters.user_id = req.query.user_id;
      }

      const results = await vacationRequestModel.getAll(filters);
      res.json({ success: true, data: results });
    } catch (error) {
      console.error('휴가 신청 목록 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  async getRequestById(req, res) {
    try {
      const results = await vacationRequestModel.getById(req.params.id);
      if (results.length === 0) {
        return res.status(404).json({ success: false, error: '해당 휴가 신청을 찾을 수 없습니다' });
      }
      const request = results[0];
      const role = (req.user.role || '').toLowerCase();
      const userId = req.user.user_id || req.user.id;
      if (!['admin', 'system'].includes(role) && userId !== request.user_id) {
        return res.status(403).json({ success: false, error: '권한이 없습니다' });
      }
      res.json({ success: true, data: request });
    } catch (error) {
      console.error('휴가 신청 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  async updateRequest(req, res) {
    try {
      const { id } = req.params;
      const { start_date, end_date, days_used, reason, vacation_type_id } = req.body;

      const results = await vacationRequestModel.getById(id);
      if (results.length === 0) {
        return res.status(404).json({ success: false, error: '해당 휴가 신청을 찾을 수 없습니다' });
      }

      const existing = results[0];
      const role = (req.user.role || '').toLowerCase();
      const userId = req.user.user_id || req.user.id;
      if (!['admin', 'system'].includes(role) && userId !== existing.user_id) {
        return res.status(403).json({ success: false, error: '권한이 없습니다' });
      }
      if (existing.status !== 'pending') {
        return res.status(400).json({ success: false, error: '대기 중인 신청만 수정할 수 있습니다' });
      }

      const updateData = {};
      if (vacation_type_id) updateData.vacation_type_id = vacation_type_id;
      if (start_date) updateData.start_date = start_date;
      if (end_date) updateData.end_date = end_date;
      if (days_used) updateData.days_used = days_used;
      if (reason !== undefined) updateData.reason = reason;

      if (start_date || end_date) {
        const newStart = start_date || existing.start_date;
        const newEnd = end_date || existing.end_date;
        const overlapRows = await vacationRequestModel.checkOverlap(existing.user_id, newStart, newEnd, id);
        if (overlapRows[0].count > 0) {
          return res.status(400).json({ success: false, error: '해당 기간에 이미 신청된 휴가가 있습니다' });
        }
      }

      await vacationRequestModel.update(id, updateData);
      res.json({ success: true, message: '휴가 신청이 수정되었습니다' });
    } catch (error) {
      console.error('휴가 신청 수정 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  async cancelRequest(req, res) {
    const db = getPool();
    const conn = await db.getConnection();
    try {
      const { id } = req.params;
      const results = await vacationRequestModel.getById(id);
      if (results.length === 0) {
        return res.status(404).json({ success: false, error: '해당 휴가 신청을 찾을 수 없습니다' });
      }

      const existing = results[0];
      const role = (req.user.role || '').toLowerCase();
      const userId = req.user.user_id || req.user.id;
      if (!['admin', 'system'].includes(role) && userId !== existing.user_id) {
        return res.status(403).json({ success: false, error: '권한이 없습니다' });
      }
      if (existing.status === 'cancelled') {
        return res.status(400).json({ success: false, error: '이미 취소된 신청입니다' });
      }

      await conn.beginTransaction();

      // 승인된 건 취소 시 잔여일 복구
      if (existing.status === 'approved') {
        const year = new Date(existing.start_date).getFullYear();
        await vacationBalanceModel.restoreDays(
          existing.user_id, existing.vacation_type_id, year, parseFloat(existing.days_used), conn
        );
      }

      await vacationRequestModel.updateStatus(id, {
        status: 'cancelled',
        reviewed_by: userId,
        review_note: '취소됨'
      }, conn);
      await conn.commit();

      res.json({ success: true, message: '휴가 신청이 취소되었습니다' });
    } catch (error) {
      await conn.rollback();
      console.error('휴가 취소 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    } finally {
      conn.release();
    }
  },

  // ─── 승인/반려 (관리자) ───

  async getPending(req, res) {
    try {
      const results = await vacationRequestModel.getAllPending();
      res.json({ success: true, data: results });
    } catch (error) {
      console.error('대기 목록 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  async approveRequest(req, res) {
    const db = getPool();
    const conn = await db.getConnection();
    try {
      const { id } = req.params;
      const { review_note } = req.body;
      const reviewed_by = req.user.user_id || req.user.id;

      const results = await vacationRequestModel.getById(id);
      if (results.length === 0) {
        return res.status(404).json({ success: false, error: '해당 휴가 신청을 찾을 수 없습니다' });
      }
      if (results[0].status !== 'pending') {
        return res.status(400).json({ success: false, error: '이미 처리된 신청입니다' });
      }

      const request = results[0];
      const year = new Date(request.start_date).getFullYear();

      await conn.beginTransaction();
      await vacationBalanceModel.deductDays(
        request.user_id, request.vacation_type_id, year, parseFloat(request.days_used), conn
      );
      await vacationRequestModel.updateStatus(id, { status: 'approved', reviewed_by, review_note }, conn);
      await conn.commit();

      res.json({ success: true, message: '휴가 신청이 승인되었습니다' });
    } catch (error) {
      await conn.rollback();
      console.error('휴가 승인 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    } finally {
      conn.release();
    }
  },

  async rejectRequest(req, res) {
    try {
      const { id } = req.params;
      const { review_note } = req.body;
      const reviewed_by = req.user.user_id || req.user.id;

      const results = await vacationRequestModel.getById(id);
      if (results.length === 0) {
        return res.status(404).json({ success: false, error: '해당 휴가 신청을 찾을 수 없습니다' });
      }
      if (results[0].status !== 'pending') {
        return res.status(400).json({ success: false, error: '이미 처리된 신청입니다' });
      }

      await vacationRequestModel.updateStatus(id, { status: 'rejected', reviewed_by, review_note });
      res.json({ success: true, message: '휴가 신청이 반려되었습니다' });
    } catch (error) {
      console.error('휴가 반려 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  // ─── 내 휴가 현황 ───

  async getMyStatus(req, res) {
    try {
      const userId = req.user.user_id || req.user.id;
      const year = parseInt(req.query.year) || new Date().getFullYear();
      const startOfYear = `${year}-01-01`;
      const endOfYear = `${year}-12-31`;
      const [balances, requests, holidays] = await Promise.all([
        vacationBalanceModel.getByUserAndYear(userId, year),
        vacationRequestModel.getAll({ user_id: userId, start_date: startOfYear, end_date: endOfYear }),
        companyHolidayModel.getByYear(year)
      ]);
      res.json({
        success: true,
        data: { balances, requests, company_holidays: holidays, overtime_hours: null }
      });
    } catch (error) {
      console.error('내 휴가 현황 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  // ─── 잔여일 ───

  async getMyBalance(req, res) {
    try {
      const userId = req.user.user_id || req.user.id;
      const year = parseInt(req.query.year) || new Date().getFullYear();
      const balances = await vacationBalanceModel.getByUserAndYear(userId, year);
      const hireDate = await vacationBalanceModel.getUserHireDate(userId);
      res.json({ success: true, data: { balances, hire_date: hireDate } });
    } catch (error) {
      console.error('잔여일 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  async getUserBalance(req, res) {
    try {
      const { userId } = req.params;
      const requestedId = parseInt(userId);
      const currentUserId = req.user.user_id || req.user.id;
      const role = (req.user.role || '').toLowerCase();
      if (requestedId !== currentUserId && !['admin', 'system'].includes(role)) {
        return res.status(403).json({ success: false, error: '접근 권한이 없습니다' });
      }
      const year = parseInt(req.query.year) || new Date().getFullYear();
      const balances = await vacationBalanceModel.getByUserAndYear(userId, year);
      const hireDate = await vacationBalanceModel.getUserHireDate(userId);
      res.json({ success: true, data: { balances, hire_date: hireDate } });
    } catch (error) {
      console.error('사용자 잔여일 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  async allocateBalance(req, res) {
    try {
      const { user_id, vacation_type_id, year, total_days, notes } = req.body;
      const created_by = req.user.user_id || req.user.id;

      if (!user_id || !vacation_type_id || !year || total_days === undefined) {
        return res.status(400).json({ success: false, error: '필수 필드가 누락되었습니다' });
      }

      await vacationBalanceModel.allocate({ user_id, vacation_type_id, year, total_days, notes, created_by });
      res.json({ success: true, message: '휴가 잔여일이 배정되었습니다' });
    } catch (error) {
      console.error('잔여일 배정 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  async getAllBalances(req, res) {
    try {
      const year = parseInt(req.query.year) || new Date().getFullYear();
      const balances = await vacationBalanceModel.getAllByYear(year);
      res.json({ success: true, data: balances });
    } catch (error) {
      console.error('전체 잔여일 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  // ─── 참조 데이터 ───

  async getVacationTypes(req, res) {
    try {
      const db = getPool();
      const [rows] = await db.query('SELECT * FROM vacation_types ORDER BY priority ASC, type_name ASC');
      res.json({ success: true, data: rows });
    } catch (error) {
      console.error('휴가 유형 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  // ─── 사용자 목록 (관리자 - 배정용) ───

  async getUsers(req, res) {
    try {
      const db = getPool();
      const [rows] = await db.query(`
        SELECT user_id, username, name, hire_date
        FROM sso_users
        WHERE is_active = 1
        ORDER BY name ASC
      `);
      res.json({ success: true, data: rows });
    } catch (error) {
      console.error('사용자 목록 조회 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    }
  },

  // ─── 관리자 보정 ───

  async adminCreateRequest(req, res) {
    const db = getPool();
    const conn = await db.getConnection();
    try {
      const { user_id, vacation_type_id, start_date, end_date, days_used, reason } = req.body;
      if (!user_id || !vacation_type_id || !start_date || !end_date || !days_used) {
        return res.status(400).json({ success: false, error: '필수 필드가 누락되었습니다' });
      }
      const daysVal = parseFloat(days_used);
      if (daysVal <= 0 || daysVal > 30) {
        return res.status(400).json({ success: false, error: '일수는 0 초과 30 이하여야 합니다' });
      }
      if (new Date(start_date).getFullYear() !== new Date(end_date).getFullYear()) {
        return res.status(400).json({ success: false, error: '연도를 걸친 휴가는 연도별로 분리하여 입력해주세요' });
      }

      const adminId = req.user.user_id || req.user.id;
      const year = new Date(start_date).getFullYear();

      await conn.beginTransaction();
      const result = await vacationRequestModel.create({
        user_id, vacation_type_id, start_date, end_date,
        days_used: daysVal, reason: reason || null,
        status: 'approved', reviewed_by: adminId, review_note: '관리자 보정 추가'
      }, conn);
      await vacationBalanceModel.deductDays(user_id, vacation_type_id, year, daysVal, conn);
      await conn.commit();

      res.status(201).json({ success: true, message: '휴가가 등록되었습니다', data: { request_id: result.insertId } });
    } catch (error) {
      await conn.rollback();
      console.error('관리자 보정 추가 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    } finally {
      conn.release();
    }
  },

  async adminDeleteRequest(req, res) {
    const db = getPool();
    const conn = await db.getConnection();
    try {
      const { id } = req.params;
      const results = await vacationRequestModel.getById(id);
      if (results.length === 0) {
        return res.status(404).json({ success: false, error: '해당 휴가 기록을 찾을 수 없습니다' });
      }
      const existing = results[0];
      if (existing.status !== 'approved') {
        return res.status(400).json({ success: false, error: '승인된 기록만 삭제할 수 있습니다' });
      }

      const adminId = req.user.user_id || req.user.id;
      const year = new Date(existing.start_date).getFullYear();

      await conn.beginTransaction();
      await vacationBalanceModel.restoreDays(existing.user_id, existing.vacation_type_id, year, parseFloat(existing.days_used), conn);
      await vacationRequestModel.updateStatus(id, {
        status: 'cancelled', reviewed_by: adminId, review_note: '관리자 보정 삭제'
      }, conn);
      await conn.commit();

      res.json({ success: true, message: '휴가가 삭제되었습니다' });
    } catch (error) {
      await conn.rollback();
      console.error('관리자 보정 삭제 오류:', error);
      res.status(500).json({ success: false, error: '서버 오류가 발생했습니다' });
    } finally {
      conn.release();
    }
  }
};

module.exports = vacationController;