package com.labelsys.backend.service;

import com.labelsys.backend.context.LoginUser;
import com.labelsys.backend.entity.BizDataRecord;
import com.labelsys.backend.enums.UserRole;
import com.labelsys.backend.mapper.BizDataRecordMapper;
import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;

import lombok.RequiredArgsConstructor;
import org.springframework.stereotype.Service;

@Service
@RequiredArgsConstructor
public class DataPermissionService {

    private final BizDataRecordMapper bizDataRecordMapper;

    public List<BizDataRecord> listVisibleRecords(LoginUser currentUser) {
        return switch (currentUser.role()) {
            case EMPLOYEE -> bizDataRecordMapper.listVisibleByEmployee(currentUser.companyId(), currentUser.userId());
            case MANAGER -> bizDataRecordMapper.listVisibleByManager(currentUser.companyId());
            case ENGINEER -> bizDataRecordMapper.listVisibleByEngineer(currentUser.companyId());
        };
    }

    public boolean canAccessCreator(LoginUser currentUser, Long creatorId, UserRole creatorRole) {
        return switch (currentUser.role()) {
            case EMPLOYEE -> currentUser.userId().equals(creatorId);
            case MANAGER -> creatorRole == UserRole.EMPLOYEE || creatorRole == UserRole.MANAGER;
            case ENGINEER -> true;
        };
    }

     /**
     * 通用数据过滤方法
     *
     * @param currentUser 当前登录用户
     * @param allRecords 待过滤的全量数据列表
     * @param roleExtractor 从数据对象中提取“关联角色”或“创建者角色”的函数
     * @param ownerIdExtractor 从数据对象中提取“所有者ID”的函数（用于员工只能看自己的情况）
     * @param <T> 数据类型
     * @return 过滤后的数据列表
     */
    public <T> List<T> filterByRole(
            LoginUser currentUser,
            List<T> allRecords,
            Function<T, UserRole> roleExtractor,
            Function<T, Long> ownerIdExtractor) {
        
        if (allRecords == null || allRecords.isEmpty()) {
            return List.of();
        }

        UserRole currentRole = currentUser.role();
        Long currentUserId = currentUser.userId();

        return allRecords.stream()
                .filter(record -> {
                    UserRole recordRole = roleExtractor.apply(record);
                    Long recordOwnerId = ownerIdExtractor.apply(record);

                    return switch (currentRole) {
                        case EMPLOYEE -> 
                            // 员工只能查看自己创建/拥有的数据
                            currentUserId.equals(recordOwnerId);
                        
                        case MANAGER -> 
                            // 经理可以查看员工和经理的数据，不能查看总工程师的数据
                            recordRole == UserRole.EMPLOYEE || recordRole == UserRole.MANAGER;
                        
                        case ENGINEER -> 
                            // 总工程师可以查看所有数据
                            true;
                    };
                })
                .collect(Collectors.toList());
    }

    /**
     * 针对 BizDataRecord 的便捷调用方法
     */
    // public List<BizDataRecord> listVisibleRecordsGeneric(LoginUser currentUser, List<BizDataRecord> allRecords) {
    //     return filterByRole(
    //             currentUser,
    //             allRecords,
    //             BizDataRecord::
    //             BizDataRecord::getCreatorRole, // 提取创建者角色
    //             BizDataRecord::getCreatorId    // 提取创建者ID
    //     );
    // }
}