package com.student.dao.impl;

import com.student.bean.LeaveRequest;
import com.student.dao.LeaveDao;
import com.student.util.DBUtil;

import java.sql.Connection;
import java.sql.Date;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.List;

public class LeaveDaoImpl implements LeaveDao {

    private static final String BASE_SQL =
            "SELECT l.id, l.student_id, l.start_date, l.end_date, l.reason, l.status, "
                    + "l.approver_id, l.approve_note, l.approve_time, l.create_time, "
                    + "u.real_name AS student_name, u.student_no, a.real_name AS approver_name "
                    + "FROM leave_request l "
                    + "JOIN users u ON l.student_id = u.id "
                    + "LEFT JOIN users a ON l.approver_id = a.id ";

    @Override
    public boolean submit(LeaveRequest request) {
        String sql = "INSERT INTO leave_request (student_id, start_date, end_date, reason, status) "
                + "VALUES (?, ?, ?, ?, ?)";
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            ps.setInt(1, request.getStudentId());
            ps.setDate(2, new Date(request.getStartDate().getTime()));
            ps.setDate(3, new Date(request.getEndDate().getTime()));
            ps.setString(4, request.getReason());
            ps.setInt(5, LeaveRequest.STATUS_PENDING);
            return ps.executeUpdate() > 0;
        } catch (SQLException e) {
            throw new RuntimeException("提交请假申请失败", e);
        } finally {
            DBUtil.close(conn, ps);
        }
    }

    @Override
    public boolean approve(int id, int approverId, String note) {
        return updateStatus(id, approverId, note, LeaveRequest.STATUS_APPROVED);
    }

    @Override
    public boolean reject(int id, int approverId, String note) {
        return updateStatus(id, approverId, note, LeaveRequest.STATUS_REJECTED);
    }

    private boolean updateStatus(int id, int approverId, String note, int status) {
        String sql = "UPDATE leave_request SET status=?, approver_id=?, approve_note=?, approve_time=NOW() WHERE id=?";
        Connection conn = null;
        PreparedStatement ps = null;
        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            ps.setInt(1, status);
            ps.setInt(2, approverId);
            ps.setString(3, note);
            ps.setInt(4, id);
            return ps.executeUpdate() > 0;
        } catch (SQLException e) {
            throw new RuntimeException("审批请假失败", e);
        } finally {
            DBUtil.close(conn, ps);
        }
    }

    @Override
    public List<LeaveRequest> findPending() {
        return queryList(BASE_SQL + " WHERE l.status = 0 ORDER BY l.create_time ASC");
    }

    @Override
    public List<LeaveRequest> findByStudent(int studentId) {
        return queryList(BASE_SQL + " WHERE l.student_id = ? ORDER BY l.create_time DESC", studentId);
    }

    @Override
    public LeaveRequest findById(int id) {
        List<LeaveRequest> list = queryList(BASE_SQL + " WHERE l.id = ?", id);
        return list.isEmpty() ? null : list.get(0);
    }

    private List<LeaveRequest> queryList(String sql, Object... params) {
        List<LeaveRequest> list = new ArrayList<>();
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            conn = DBUtil.getConnection();
            ps = conn.prepareStatement(sql);
            for (int i = 0; i < params.length; i++) {
                ps.setObject(i + 1, params[i]);
            }
            rs = ps.executeQuery();
            while (rs.next()) {
                list.add(mapRow(rs));
            }
        } catch (SQLException e) {
            throw new RuntimeException("查询请假记录失败", e);
        } finally {
            DBUtil.close(conn, ps, rs);
        }
        return list;
    }

    private LeaveRequest mapRow(ResultSet rs) throws SQLException {
        LeaveRequest req = new LeaveRequest();
        req.setId(rs.getInt("id"));
        req.setStudentId(rs.getInt("student_id"));
        Date startDate = rs.getDate("start_date");
        if (startDate != null) {
            req.setStartDate(new java.util.Date(startDate.getTime()));
        }
        Date endDate = rs.getDate("end_date");
        if (endDate != null) {
            req.setEndDate(new java.util.Date(endDate.getTime()));
        }
        req.setReason(rs.getString("reason"));
        req.setStatus(rs.getInt("status"));
        int approverId = rs.getInt("approver_id");
        req.setApproverId(rs.wasNull() ? null : approverId);
        req.setApproveNote(rs.getString("approve_note"));
        Timestamp approveTime = rs.getTimestamp("approve_time");
        if (approveTime != null) {
            req.setApproveTime(new java.util.Date(approveTime.getTime()));
        }
        Timestamp createTime = rs.getTimestamp("create_time");
        if (createTime != null) {
            req.setCreateTime(new java.util.Date(createTime.getTime()));
        }
        req.setStudentName(rs.getString("student_name"));
        req.setStudentNo(rs.getString("student_no"));
        req.setApproverName(rs.getString("approver_name"));
        return req;
    }
}