package com.ruoyi.unattended.telemetry.service;

import com.ruoyi.unattended.telemetry.dto.DeviceMonitorVo;
import lombok.extern.slf4j.Slf4j;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;

import java.io.IOException;
import java.time.LocalDateTime;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * 设备报警 SSE 推送中心。
 */
@Slf4j
@Component
public class DeviceAlarmPushService {

    private final List<SseEmitter> clients = new CopyOnWriteArrayList<>();

    public SseEmitter subscribe() {
        SseEmitter emitter = new SseEmitter(0L);
        clients.add(emitter);
        emitter.onCompletion(() -> clients.remove(emitter));
        emitter.onTimeout(() -> clients.remove(emitter));
        emitter.onError(error -> clients.remove(emitter));
        try {
            emitter.send(SseEmitter.event()
                    .name("connected")
                    .data(Collections.singletonMap("time", LocalDateTime.now().toString())));
        } catch (IOException e) {
            clients.remove(emitter);
        }
        return emitter;
    }

    public void publish(DeviceMonitorVo alarm) {
        for (SseEmitter client : clients) {
            try {
                String eventId = alarm.getDeviceId() + "-" + System.currentTimeMillis();
                client.send(SseEmitter.event().id(eventId).name("alarm").data(alarm));
            } catch (Exception e) {
                clients.remove(client);
            }
        }
    }

    /** 保持代理和浏览器之间的长连接，及时清理已断开的客户端。 */
    @Scheduled(fixedRate = 25000L)
    public void heartbeat() {
        for (SseEmitter client : clients) {
            try {
                client.send(SseEmitter.event()
                        .name("heartbeat")
                        .data(Collections.singletonMap("time", LocalDateTime.now().toString())));
            } catch (Exception e) {
                clients.remove(client);
            }
        }
    }
}