package com.goi.erp.service;

import com.goi.erp.dto.EmployeeRequestDto;
import com.goi.erp.dto.EmployeeResponseDto;
import com.goi.erp.entity.Employee;
import com.goi.erp.entity.EntityChangeLog;
import com.goi.erp.repository.EmployeeRepository;
import com.goi.erp.repository.EntityChangeLogRepository;

import lombok.RequiredArgsConstructor;

import org.springframework.beans.BeanUtils;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.stream.Collectors;

@Service
@RequiredArgsConstructor
@Transactional
public class EmployeeService {

    private final EmployeeRepository employeeRepository;
    private final PasswordEncoder passwordEncoder;  // 비밀번호 암호화 (auth-service처럼)
    private final EntityChangeLogRepository entityChangeLogRepository;

    /**
     * CREATE
     */
    public EmployeeResponseDto createEmployee(EmployeeRequestDto dto) {

        Employee employee = Employee.builder()
                .empUuid(UUID.randomUUID())
                .empNo(dto.getEmpNo())
                .empLoginId(dto.getEmpLoginId())
                .empLoginPassword(passwordEncoder.encode(dto.getEmpLoginPassword()))
                .empFirstName(dto.getEmpFirstName())
                .empMiddleName(dto.getEmpMiddleName())
                .empLastName(dto.getEmpLastName())
                .empPreferredFirstName(dto.getEmpPreferredFirstName())
                .empPreferredLastName(dto.getEmpPreferredLastName())
                .empStatus(dto.getEmpStatus())
                .empFulltime(dto.getEmpFulltime())
                .empEmploymentType(dto.getEmpEmploymentType())
                .empLeaveStatus(dto.getEmpLeaveStatus())
                .empOfferAcceptedDate(dto.getEmpOfferAcceptedDate())
                .empNationality(dto.getEmpNationality())
                .empCitizenshipStatus(dto.getEmpCitizenshipStatus())
                .empPassportNo(dto.getEmpPassportNo())
                .empPassportCountry(dto.getEmpPassportCountry())
                .empPassportIssueDate(dto.getEmpPassportIssueDate())
                .empPassportExpiryDate(dto.getEmpPassportExpiryDate())
                .empVisaType(dto.getEmpVisaType())
                .empVisaIssueDate(dto.getEmpVisaIssueDate())
                .empVisaExpiryDate(dto.getEmpVisaExpiryDate())
                .empVisaCountry(dto.getEmpVisaCountry())
                .empDateOfBirth(dto.getEmpDateOfBirth())
                .empSex(dto.getEmpSex())
                .empSin(dto.getEmpSin())
                .empAccountNo(dto.getEmpAccountNo())
                .empDriverLicenseNo(dto.getEmpDriverLicenseNo())
                .empPersonalEmail(dto.getEmpPersonalEmail())
                .empPersonalPhone(dto.getEmpPersonalPhone())
                .empAddress1(dto.getEmpAddress1())
                .empAddress2(dto.getEmpAddress2())
                .empPostalCode(dto.getEmpPostalCode())
                .empCity(dto.getEmpCity())
                .empProvince(dto.getEmpProvince())
                .empContractStartDate(dto.getEmpContractStartDate())
                .empProbationStartDate(dto.getEmpProbationStartDate())
                .empProbationEndDate(dto.getEmpProbationEndDate())
                .empProbationStatus(dto.getEmpProbationStatus())
                .empJobStartDate(dto.getEmpJobStartDate())
                .empJobEndDate(dto.getEmpJobEndDate())
                .empTerminationDate(dto.getEmpTerminationDate())
                .empTerminationReason(dto.getEmpTerminationReason())
                .empDeptId(dto.getEmpDeptId())
                .empRate(dto.getEmpRate())
                .empRateOt(dto.getEmpRateOt())
                .empRateDot(dto.getEmpRateDot())
                .empOfficeEmail(dto.getEmpOfficeEmail())
                .empOfficeMobile(dto.getEmpOfficeMobile())
                .empOfficePhone(dto.getEmpOfficePhone())
                .empExtensionNo(dto.getEmpExtensionNo())
                .build();

        employeeRepository.save(employee);

        return mapToDto(employee);
    }

    /**
     * READ - detail
     */
    @Transactional(readOnly = true)
    public EmployeeResponseDto getEmployeeByUuid(UUID empUuid) {
        Employee employee = employeeRepository.findByEmpUuid(empUuid)
                .orElseThrow(() -> new RuntimeException("Employee not found"));

        return mapToDto(employee);
    }

    /**
     * READ - list
     */
    @Transactional(readOnly = true)
    public List<EmployeeResponseDto> getAllEmployees() {
        return employeeRepository.findAll().stream()
                .map(this::mapToDto)
                .collect(Collectors.toList());
    }
    
    /**
     * READ - active
     */
    @Transactional(readOnly = true)
    public List<EmployeeResponseDto> getActiveEmployees() {
        return employeeRepository.findAll().stream()
                .filter(e -> "A".equals(e.getEmpStatus()))
                .map(this::mapToDto)
                .collect(Collectors.toList());
    }
    
    /**
     * READ - inactive
     */
    @Transactional(readOnly = true)
    public List<EmployeeResponseDto> getInactiveEmployees() {
        return employeeRepository.findAll().stream()
                .filter(e -> "I".equals(e.getEmpStatus()))
                .map(this::mapToDto)
                .collect(Collectors.toList());
    }

    /**
     * UPDATE
     */
    public EmployeeResponseDto updateEmployee(UUID empUuid, EmployeeRequestDto newEmp) {

        Employee oldEmployee = employeeRepository.findByEmpUuid(empUuid)
                .orElseThrow(() -> new RuntimeException("Employee not found"));
        
        // 기존 값 복사본 생성
        Employee beforeUpdate = new Employee();
        BeanUtils.copyProperties(oldEmployee, beforeUpdate);
        
        // PATCH: 값이 있는 것만 적용
        if (newEmp.getEmpNo() != null) oldEmployee.setEmpNo(newEmp.getEmpNo());
        if (newEmp.getEmpLoginId() != null) oldEmployee.setEmpLoginId(newEmp.getEmpLoginId());
        if (newEmp.getEmpLoginPassword() != null && !newEmp.getEmpLoginPassword().isEmpty()) oldEmployee.setEmpLoginPassword(passwordEncoder.encode(newEmp.getEmpLoginPassword()));
        if (newEmp.getEmpFirstName() != null) oldEmployee.setEmpFirstName(newEmp.getEmpFirstName());
        if (newEmp.getEmpMiddleName() != null) oldEmployee.setEmpMiddleName(newEmp.getEmpMiddleName());
        if (newEmp.getEmpLastName() != null) oldEmployee.setEmpLastName(newEmp.getEmpLastName());
        if (newEmp.getEmpPreferredFirstName() != null) oldEmployee.setEmpPreferredFirstName(newEmp.getEmpPreferredFirstName());
        if (newEmp.getEmpPreferredLastName() != null) oldEmployee.setEmpPreferredLastName(newEmp.getEmpPreferredLastName());
        if (newEmp.getEmpStatus() != null) oldEmployee.setEmpStatus(newEmp.getEmpStatus());
        if (newEmp.getEmpFulltime() != null) oldEmployee.setEmpFulltime(newEmp.getEmpFulltime());
        if (newEmp.getEmpEmploymentType() != null) oldEmployee.setEmpEmploymentType(newEmp.getEmpEmploymentType());
        if (newEmp.getEmpLeaveStatus() != null) oldEmployee.setEmpLeaveStatus(newEmp.getEmpLeaveStatus());
        if (newEmp.getEmpOfferAcceptedDate() != null) oldEmployee.setEmpOfferAcceptedDate(newEmp.getEmpOfferAcceptedDate());
        if (newEmp.getEmpNationality() != null) oldEmployee.setEmpNationality(newEmp.getEmpNationality());
        if (newEmp.getEmpCitizenshipStatus() != null) oldEmployee.setEmpCitizenshipStatus(newEmp.getEmpCitizenshipStatus());
        if (newEmp.getEmpPassportNo() != null) oldEmployee.setEmpPassportNo(newEmp.getEmpPassportNo());
        if (newEmp.getEmpPassportCountry() != null) oldEmployee.setEmpPassportCountry(newEmp.getEmpPassportCountry());
        if (newEmp.getEmpPassportIssueDate() != null) oldEmployee.setEmpPassportIssueDate(newEmp.getEmpPassportIssueDate());
        if (newEmp.getEmpPassportExpiryDate() != null) oldEmployee.setEmpPassportExpiryDate(newEmp.getEmpPassportExpiryDate());
        if (newEmp.getEmpVisaType() != null) oldEmployee.setEmpVisaType(newEmp.getEmpVisaType());
        if (newEmp.getEmpVisaIssueDate() != null) oldEmployee.setEmpVisaIssueDate(newEmp.getEmpVisaIssueDate());
        if (newEmp.getEmpVisaExpiryDate() != null) oldEmployee.setEmpVisaExpiryDate(newEmp.getEmpVisaExpiryDate());
        if (newEmp.getEmpVisaCountry() != null) oldEmployee.setEmpVisaCountry(newEmp.getEmpVisaCountry());
        if (newEmp.getEmpDateOfBirth() != null) oldEmployee.setEmpDateOfBirth(newEmp.getEmpDateOfBirth());
        if (newEmp.getEmpSex() != null) oldEmployee.setEmpSex(newEmp.getEmpSex());
        if (newEmp.getEmpSin() != null) oldEmployee.setEmpSin(newEmp.getEmpSin());
        if (newEmp.getEmpAccountNo() != null) oldEmployee.setEmpAccountNo(newEmp.getEmpAccountNo());
        if (newEmp.getEmpDriverLicenseNo() != null) oldEmployee.setEmpDriverLicenseNo(newEmp.getEmpDriverLicenseNo());
        if (newEmp.getEmpPersonalEmail() != null) oldEmployee.setEmpPersonalEmail(newEmp.getEmpPersonalEmail());
        if (newEmp.getEmpPersonalPhone() != null) oldEmployee.setEmpPersonalPhone(newEmp.getEmpPersonalPhone());
        if (newEmp.getEmpAddress1() != null) oldEmployee.setEmpAddress1(newEmp.getEmpAddress1());
        if (newEmp.getEmpAddress2() != null) oldEmployee.setEmpAddress2(newEmp.getEmpAddress2());
        if (newEmp.getEmpPostalCode() != null) oldEmployee.setEmpPostalCode(newEmp.getEmpPostalCode());
        if (newEmp.getEmpCity() != null) oldEmployee.setEmpCity(newEmp.getEmpCity());
        if (newEmp.getEmpProvince() != null) oldEmployee.setEmpProvince(newEmp.getEmpProvince());
        if (newEmp.getEmpContractStartDate() != null) oldEmployee.setEmpContractStartDate(newEmp.getEmpContractStartDate());
        if (newEmp.getEmpProbationStartDate() != null) oldEmployee.setEmpProbationStartDate(newEmp.getEmpProbationStartDate());
        if (newEmp.getEmpProbationEndDate() != null) oldEmployee.setEmpProbationEndDate(newEmp.getEmpProbationEndDate());
        if (newEmp.getEmpProbationStatus() != null) oldEmployee.setEmpProbationStatus(newEmp.getEmpProbationStatus());
        if (newEmp.getEmpJobStartDate() != null) oldEmployee.setEmpJobStartDate(newEmp.getEmpJobStartDate());
        if (newEmp.getEmpJobEndDate() != null) oldEmployee.setEmpJobEndDate(newEmp.getEmpJobEndDate());
        if (newEmp.getEmpTerminationDate() != null) oldEmployee.setEmpTerminationDate(newEmp.getEmpTerminationDate());
        if (newEmp.getEmpTerminationReason() != null) oldEmployee.setEmpTerminationReason(newEmp.getEmpTerminationReason());
        if (newEmp.getEmpDeptId() != null) oldEmployee.setEmpDeptId(newEmp.getEmpDeptId());
        if (newEmp.getEmpRate() != null) oldEmployee.setEmpRate(newEmp.getEmpRate());
        if (newEmp.getEmpRateOt() != null) oldEmployee.setEmpRateOt(newEmp.getEmpRateOt());
        if (newEmp.getEmpRateDot() != null) oldEmployee.setEmpRateDot(newEmp.getEmpRateDot());
        if (newEmp.getEmpOfficeEmail() != null) oldEmployee.setEmpOfficeEmail(newEmp.getEmpOfficeEmail());
        if (newEmp.getEmpOfficeMobile() != null) oldEmployee.setEmpOfficeMobile(newEmp.getEmpOfficeMobile());
        if (newEmp.getEmpOfficePhone() != null) oldEmployee.setEmpOfficePhone(newEmp.getEmpOfficePhone());
        if (newEmp.getEmpExtensionNo() != null) oldEmployee.setEmpExtensionNo(newEmp.getEmpExtensionNo());
        
        // 변경 로그 기록
        //compareAndLogChanges(oldData, oldEmployee, changedBy);

        return mapToDto(oldEmployee);
    }


    /**
     * INACTIVATE (Soft Delete)
     * 직원 삭제하지 않고 emp_status = 'I' 로 비활성화
     */
    public EmployeeResponseDto inactivateEmployee(UUID empUuid) {

        Employee employee = employeeRepository.findByEmpUuid(empUuid)
                .orElseThrow(() -> new RuntimeException("Employee not found"));

        employee.setEmpStatus("I");  // Inactive

        return mapToDto(employee);
    }

    /**
     * ENTITY → DTO 변환
     */
    private EmployeeResponseDto mapToDto(Employee e) {
        EmployeeResponseDto dto = new EmployeeResponseDto();

        dto.setEmpId(e.getEmpId());
        dto.setEmpUuid(e.getEmpUuid());
        dto.setEmpNo(e.getEmpNo());
        dto.setEmpLoginId(e.getEmpLoginId());
        dto.setEmpFirstName(e.getEmpFirstName());
        dto.setEmpMiddleName(e.getEmpMiddleName());
        dto.setEmpLastName(e.getEmpLastName());
        dto.setEmpPreferredFirstName(e.getEmpPreferredFirstName());
        dto.setEmpPreferredLastName(e.getEmpPreferredLastName());
        dto.setEmpStatus(e.getEmpStatus());
        dto.setEmpFulltime(e.getEmpFulltime());
        dto.setEmpEmploymentType(e.getEmpEmploymentType());
        dto.setEmpLeaveStatus(e.getEmpLeaveStatus());
        dto.setEmpOfferAcceptedDate(e.getEmpOfferAcceptedDate());
        dto.setEmpCreatedAt(e.getEmpCreatedAt());
        dto.setEmpUpdatedAt(e.getEmpUpdatedAt());
        dto.setEmpCreatedBy(e.getEmpCreatedBy());
        dto.setEmpUpdatedBy(e.getEmpUpdatedBy());
        dto.setEmpNationality(e.getEmpNationality());
        dto.setEmpCitizenshipStatus(e.getEmpCitizenshipStatus());
        dto.setEmpPassportNo(e.getEmpPassportNo());
        dto.setEmpPassportCountry(e.getEmpPassportCountry());
        dto.setEmpPassportIssueDate(e.getEmpPassportIssueDate());
        dto.setEmpPassportExpiryDate(e.getEmpPassportExpiryDate());
        dto.setEmpVisaType(e.getEmpVisaType());
        dto.setEmpVisaIssueDate(e.getEmpVisaIssueDate());
        dto.setEmpVisaExpiryDate(e.getEmpVisaExpiryDate());
        dto.setEmpVisaCountry(e.getEmpVisaCountry());
        dto.setEmpDateOfBirth(e.getEmpDateOfBirth());
        dto.setEmpSex(e.getEmpSex());
        dto.setEmpSin(e.getEmpSin());
        dto.setEmpAccountNo(e.getEmpAccountNo());
        dto.setEmpDriverLicenseNo(e.getEmpDriverLicenseNo());
        dto.setEmpPersonalEmail(e.getEmpPersonalEmail());
        dto.setEmpPersonalPhone(e.getEmpPersonalPhone());
        dto.setEmpAddress1(e.getEmpAddress1());
        dto.setEmpAddress2(e.getEmpAddress2());
        dto.setEmpPostalCode(e.getEmpPostalCode());
        dto.setEmpCity(e.getEmpCity());
        dto.setEmpProvince(e.getEmpProvince());
        dto.setEmpContractStartDate(e.getEmpContractStartDate());
        dto.setEmpProbationStartDate(e.getEmpProbationStartDate());
        dto.setEmpProbationEndDate(e.getEmpProbationEndDate());
        dto.setEmpProbationStatus(e.getEmpProbationStatus());
        dto.setEmpJobStartDate(e.getEmpJobStartDate());
        dto.setEmpJobEndDate(e.getEmpJobEndDate());
        dto.setEmpTerminationDate(e.getEmpTerminationDate());
        dto.setEmpTerminationReason(e.getEmpTerminationReason());
        dto.setEmpDeptId(e.getEmpDeptId());
        dto.setEmpRate(e.getEmpRate());
        dto.setEmpRateOt(e.getEmpRateOt());
        dto.setEmpRateDot(e.getEmpRateDot());
        dto.setEmpOfficeEmail(e.getEmpOfficeEmail());
        dto.setEmpOfficeMobile(e.getEmpOfficeMobile());
        dto.setEmpOfficePhone(e.getEmpOfficePhone());
        dto.setEmpExtensionNo(e.getEmpExtensionNo());

        return dto;
    }
    
    private void compareAndLogChanges(Employee oldData, Employee newData, String changedBy) {

        Map<String, String> fieldToColumn = Map.ofEntries(
                Map.entry("empNo", "emp_no"),
                Map.entry("empLoginId", "emp_login_id"),
                Map.entry("empFirstName", "emp_first_name"),
                Map.entry("empMiddleName", "emp_middle_name"),
                Map.entry("empLastName", "emp_last_name"),
                Map.entry("empPreferredFirstName", "emp_preferred_first_name"),
                Map.entry("empPreferredLastName", "emp_preferred_last_name"),
                Map.entry("empStatus", "emp_status"),
                Map.entry("empFulltime", "emp_fulltime"),
                Map.entry("empEmploymentType", "emp_employment_type"),
                Map.entry("empLeaveStatus", "emp_leave_status"),
                Map.entry("empOfferAcceptedDate", "emp_offer_accepted_date"),
                Map.entry("empNationality", "emp_nationality"),
                Map.entry("empCitizenshipStatus", "emp_citizenship_status"),
                Map.entry("empPassportNo", "emp_passport_no"),
                Map.entry("empPassportCountry", "emp_passport_country"),
                Map.entry("empPassportIssueDate", "emp_passport_issue_date"),
                Map.entry("empPassportExpiryDate", "emp_passport_expiry_date"),
                Map.entry("empVisaType", "emp_visa_type"),
                Map.entry("empVisaIssueDate", "emp_visa_issue_date"),
                Map.entry("empVisaExpiryDate", "emp_visa_expiry_date"),
                Map.entry("empVisaCountry", "emp_visa_country"),
                Map.entry("empDateOfBirth", "emp_date_of_birth"),
                Map.entry("empSex", "emp_sex"),
                Map.entry("empSin", "emp_sin"),
                Map.entry("empAccountNo", "emp_account_no"),
                Map.entry("empDriverLicenseNo", "emp_driver_license_no"),
                Map.entry("empPersonalEmail", "emp_personal_email"),
                Map.entry("empPersonalPhone", "emp_personal_phone"),
                Map.entry("empAddress1", "emp_address1"),
                Map.entry("empAddress2", "emp_address2"),
                Map.entry("empPostalCode", "emp_postal_code"),
                Map.entry("empCity", "emp_city"),
                Map.entry("empProvince", "emp_province"),
                Map.entry("empContractStartDate", "emp_contract_start_date"),
                Map.entry("empProbationStartDate", "emp_probation_start_date"),
                Map.entry("empProbationEndDate", "emp_probation_end_date"),
                Map.entry("empProbationStatus", "emp_probation_status"),
                Map.entry("empJobStartDate", "emp_job_start_date"),
                Map.entry("empJobEndDate", "emp_job_end_date"),
                Map.entry("empTerminationDate", "emp_termination_date"),
                Map.entry("empTerminationReason", "emp_termination_reason"),
                Map.entry("empDeptId", "emp_dept_id"),
                Map.entry("empRate", "emp_rate"),
                Map.entry("empRateOt", "emp_rate_ot"),
                Map.entry("empRateDot", "emp_rate_dot"),
                Map.entry("empOfficeEmail", "emp_office_email"),
                Map.entry("empOfficeMobile", "emp_office_mobile"),
                Map.entry("empOfficePhone", "emp_office_phone"),
                Map.entry("empExtensionNo", "emp_extension_no")
        );

        Class<?> clazz = Employee.class;

        for (var entry : fieldToColumn.entrySet()) {
            String fieldName = entry.getKey();
            String columnName = entry.getValue();

            try {
                Field field = clazz.getDeclaredField(fieldName);
                field.setAccessible(true);

                Object oldVal = field.get(oldData);
                Object newVal = field.get(newData);

                if (valuesAreDifferent(oldVal, newVal)) {

                    entityChangeLogRepository.save(
                        EntityChangeLog.builder()
                            .eclEntityType("Employee")
                            .eclEntityId(newData.getEmpId())
                            .eclFieldName(fieldName)
                            .eclColumnName(columnName)
                            .eclOldValue(oldVal == null ? null : oldVal.toString())
                            .eclNewValue(newVal == null ? null : newVal.toString())
                            .eclChangedBy(changedBy)
                            .eclChangedAt(LocalDateTime.now())
                            .eclEffectiveDate(LocalDate.now())
                            .build()
                    );
                }

            } catch (Exception e) {
                throw new RuntimeException("Failed to compare field: " + fieldName, e);
            }
        }
    }

    
    private boolean valuesAreDifferent(Object oldVal, Object newVal) {

        if (oldVal == null && newVal == null) return false;
        if (oldVal == null || newVal == null) return true;

        // BigDecimal (numeric 비교)
        if (oldVal instanceof BigDecimal oldNum && newVal instanceof BigDecimal newNum) {
            return oldNum.compareTo(newNum) != 0;
        }

        // LocalDate
        if (oldVal instanceof LocalDate oldDate && newVal instanceof LocalDate newDate) {
            return !oldDate.isEqual(newDate);
        }

        // LocalDateTime
        if (oldVal instanceof LocalDateTime oldDt && newVal instanceof LocalDateTime newDt) {
            return !oldDt.equals(newDt);
        }

        // Boolean
        if (oldVal instanceof Boolean && newVal instanceof Boolean) {
            return !oldVal.equals(newVal);
        }

        // 기본 equals
        return !oldVal.equals(newVal);
    }
}