package com.ard.work.config;

import com.ard.work.domain.enums.RouteEvent;
import com.ard.work.domain.enums.RouteState;
import lombok.RequiredArgsConstructor;
import org.springframework.messaging.Message;
import org.springframework.messaging.support.MessageBuilder;
import org.springframework.statemachine.StateMachine;
import org.springframework.statemachine.service.StateMachineService;
import org.springframework.statemachine.support.DefaultExtendedState;
import org.springframework.statemachine.support.DefaultStateMachineContext;
import org.springframework.stereotype.Service;

import java.util.concurrent.ConcurrentHashMap;

@Service
@RequiredArgsConstructor
public class RouteStateMachineService {

    private final StateMachineService<RouteState, RouteEvent> stateMachineService;
    private final RouteStateMachineListener listener;
    private final ConcurrentHashMap<String, Boolean> listenerRegisteredMap = new ConcurrentHashMap<>();

    private StateMachine<RouteState, RouteEvent> getStateMachine(String boxSn) {
        StateMachine<RouteState, RouteEvent> stateMachine =
                stateMachineService.acquireStateMachine(boxSn);

        // 使用原子操作确保 listener 只添加一次
        listenerRegisteredMap.computeIfAbsent(boxSn, k -> {
            stateMachine.addStateListener(listener);
            return true;
        });
        stateMachine.start();
        return stateMachine;
    }

    /**
     * 发送事件到指定boxSn的状态机
     */
    public boolean sendEvent(String boxSn, RouteEvent event) {
        try {
            // 获取/创建指定boxSn的状态机实例
            StateMachine<RouteState, RouteEvent> stateMachine = getStateMachine(boxSn);

            // 构建事件消息（携带boxSn作为头信息）
            Message<RouteEvent> message = MessageBuilder
                    .withPayload(event)
                    .setHeader("boxSn", boxSn)
                    .build();

            // 发送事件并返回执行结果
            return stateMachine.sendEvent(message);
        } catch (Exception e) {
            // 异常处理：日志记录、状态机重置等
            throw new RuntimeException("发送航线状态事件失败，boxSn=" + boxSn + ", event=" + event, e);
        }
    }

    /**
     * 获取指定boxSn的当前状态
     */
    public RouteState getCurrentState(String boxSn) {
        try {
            StateMachine<RouteState, RouteEvent> stateMachine =
                    stateMachineService.acquireStateMachine(boxSn);
            return stateMachine.getState().getId();
        } catch (Exception e) {
            // 未找到状态机实例时返回初始状态
            return RouteState.IDLE;
        }
    }

    /**
     * 释放指定boxSn的状态机实例（可选，节省资源）
     */
    public void releaseStateMachine(String boxSn) {
        stateMachineService.releaseStateMachine(boxSn);
    }

    /**
     * 重置指定boxSn的状态机（恢复到初始状态）
     */
    public void resetStateMachine(String boxSn) {
        try {
            StateMachine<RouteState, RouteEvent> stateMachine =
                    stateMachineService.acquireStateMachine(boxSn);

            // 1️⃣ 停止状态机
            stateMachine.stop();

            // 2️⃣ 构造 ExtendedState（可选，但强烈推荐）
            DefaultExtendedState extendedState = new DefaultExtendedState();
            extendedState.getVariables().put("boxSn", boxSn);

            // 3️⃣ 重置状态机到 IDLE
            stateMachine.getStateMachineAccessor()
                    .doWithAllRegions(accessor -> {
                        accessor.resetStateMachine(
                                new DefaultStateMachineContext<>(
                                        RouteState.IDLE, // 初始状态
                                        null,            // event
                                        null,            // event headers
                                        extendedState    // 扩展状态
                                )
                        );
                    });

            // 4️⃣ 重新启动
            stateMachine.start();

        } catch (Exception e) {
            throw new RuntimeException("重置航线状态机失败，boxSn=" + boxSn, e);
        }
    }
}