package com.ruoyi.system.utils;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import org.springframework.stereotype.Component;
import com.ruoyi.system.domain.enums.TaskStatus;

/**
 * 任务状态流转验证器
 * 
 * @author ruoyi
 */
@Component
public class TaskStatusValidator {
    
    private static final Map<TaskStatus, Set<TaskStatus>> ALLOWED_TRANSITIONS = new HashMap<>();
    
    static {
        // PENDING -> IN_PROGRESS, CANCELLED
        Set<TaskStatus> pendingTransitions = new HashSet<>();
        pendingTransitions.add(TaskStatus.IN_PROGRESS);
        pendingTransitions.add(TaskStatus.CANCELLED);
        ALLOWED_TRANSITIONS.put(TaskStatus.PENDING, pendingTransitions);
        
        // IN_PROGRESS -> COMPLETED, CANCELLED, PENDING
        Set<TaskStatus> inProgressTransitions = new HashSet<>();
        inProgressTransitions.add(TaskStatus.COMPLETED);
        inProgressTransitions.add(TaskStatus.CANCELLED);
        inProgressTransitions.add(TaskStatus.PENDING);
        ALLOWED_TRANSITIONS.put(TaskStatus.IN_PROGRESS, inProgressTransitions);
        
        // COMPLETED -> 不允许任何状态变更
        ALLOWED_TRANSITIONS.put(TaskStatus.COMPLETED, new HashSet<>());
        // CANCELLED -> 不允许任何状态变更
        ALLOWED_TRANSITIONS.put(TaskStatus.CANCELLED, new HashSet<>());
    }
    
    /**
     * 验证状态流转是否合法
     * 
     * @param from 原状态
     * @param to 目标状态
     * @return 是否允许流转
     */
    public boolean canTransition(TaskStatus from, TaskStatus to) {
        if (from == null || to == null) {
            return false;
        }
        return ALLOWED_TRANSITIONS.get(from).contains(to);
    }
    
    /**
     * 获取允许的状态流转列表
     * 
     * @param from 原状态
     * @return 允许的目标状态集合
     */
    public Set<TaskStatus> getAllowedTransitions(TaskStatus from) {
        if (from == null) {
            return new HashSet<>();
        }
        return ALLOWED_TRANSITIONS.get(from);
    }
}