package mqtt

import (
	"errors"

	mqtt "github.com/eclipse/paho.mqtt.golang"

	"laic-backend/common"
	"laic-backend/logger"
)

var (
	client     mqtt.Client
	subTopics  = map[string]byte{}
	subHandler mqtt.MessageHandler
)

// InitMQTT 初始化 MQTT 客户端（不依赖 service，订阅由上层注册）
func InitMQTT(config *common.MQTT) {
	if config == nil || config.Broker == "" {
		logger.WARN("MQTT broker 为空，跳过初始化")
		return
	}

	opts := mqtt.NewClientOptions().
		AddBroker(config.Broker).
		SetClientID(config.ClientId).
		SetUsername(config.Username).
		SetPassword(config.Password).
		SetAutoReconnect(true).
		SetCleanSession(true).
		SetOnConnectHandler(func(c mqtt.Client) {
			logger.INFO("MQTT 已连接，重新订阅")
			resubscribe(c)
		})

	client = mqtt.NewClient(opts)
	if token := client.Connect(); token.Wait() && token.Error() != nil {
		logger.ERROR("MQTT 连接失败", token.Error())
		return
	}
	logger.INFO("MQTT ready")
}

// Subscribe 记录订阅关系并立即订阅；连接重建时自动重订阅
func Subscribe(topics map[string]byte, handler mqtt.MessageHandler) {
	subHandler = handler
	for topic, qos := range topics {
		subTopics[topic] = qos
	}
	if client != nil && client.IsConnected() {
		resubscribe(client)
	}
}

func resubscribe(c mqtt.Client) {
	for topic, qos := range subTopics {
		if token := c.Subscribe(topic, qos, inboundHandler); token.Wait() && token.Error() != nil {
			logger.ERROR("订阅失败 topic="+topic, token.Error())
		}
	}
}

func inboundHandler(c mqtt.Client, msg mqtt.Message) {
	//logger.INFO("MQTT 收到消息",
	//	"topic="+msg.Topic(),
	//	"qos=", msg.Qos(),
	//	"retained=", msg.Retained(),
	//	"payload="+string(msg.Payload()),
	//)
	if subHandler != nil {
		subHandler(c, msg)
	}
}

// Publish 发布消息到指定 topic
func Publish(topic string, qos byte, retained bool, payload []byte) error {
	if client == nil || !client.IsConnected() {
		return errors.New("mqtt client not connected")
	}
	logger.INFO("MQTT 发送消息",
		"topic="+topic,
		"qos=", qos,
		"retained=", retained,
		"payload="+string(payload),
	)
	token := client.Publish(topic, qos, retained, payload)
	token.Wait()
	return token.Error()
}