package emqx

import (
	"context"
	"fmt"
	"sync"
	"time"

	mqttlib "github.com/eclipse/paho.mqtt.golang"
	"github.com/gogf/gf/v2/frame/g"
	"github.com/gogf/gf/v2/os/glog"
	"server/utility/mqtt"
)

type emqxClient struct {
	client mqttlib.Client
	once   sync.Once
}

// New 创建并连接 EMQX 客户端实例，连接成功才返回
func New(broker, clientID, username, password string) mqtt.MqttClient {
	opts := mqttlib.NewClientOptions().
		AddBroker(broker).
		SetClientID(clientID).
		SetUsername(username).
		SetPassword(password).
		SetAutoReconnect(true).
		SetConnectTimeout(5 * time.Second)

	c := &emqxClient{
		client: mqttlib.NewClient(opts),
	}

	// 立即连接
	err := c.connect()
	if err != nil {
		glog.Errorf(context.Background(), "连接EMQX失败: %v", err)
		panic(fmt.Sprintf("连接EMQX失败: %v", err))
	}
	glog.Infof(context.Background(), "EMQX客户端连接成功")
	return c
}

// connect 内部只调用一次连接
func (e *emqxClient) connect() error {
	var err error
	e.once.Do(func() {
		token := e.client.Connect()
		if token.Wait() && token.Error() != nil {
			err = fmt.Errorf("EMQX连接失败: %w", token.Error())
			glog.Errorf(context.Background(), err.Error())
			return
		}
		glog.Infof(context.Background(), "EMQX连接成功")
	})
	return err
}

// Publish 实现接口 Publish
func (e *emqxClient) Publish(topic string, payload []byte) error {
	token := e.client.Publish(topic, 0, false, payload)
	token.Wait()
	err := token.Error()
	if err != nil {
		glog.Errorf(context.Background(), "发布消息失败，topic=%s，错误：%v", topic, err)
	} else {
		glog.Infof(context.Background(), "成功发布消息，topic=%s，消息大小=%d字节", topic, len(payload))
	}
	return err
}

// Subscribe 实现接口 Subscribe
func (e *emqxClient) Subscribe(topic string, handler func(topic string, payload []byte)) error {
	token := e.client.Subscribe(topic, 0, func(client mqttlib.Client, msg mqttlib.Message) {
		handler(msg.Topic(), msg.Payload())
	})
	token.Wait()
	err := token.Error()
	if err != nil {
		glog.Errorf(context.Background(), "订阅失败，topic=%s，错误：%v", topic, err)
	} else {
		glog.Infof(context.Background(), "成功订阅主题，topic=%s", topic)
	}
	return err
}

// init 注册emqx客户端
func init() {
	ctx := context.Background()
	cfg := g.Config()
	host := cfg.MustGet(ctx, "mqtt.emqx.host").String()
	port := cfg.MustGet(ctx, "mqtt.emqx.port").Int()
	username := cfg.MustGet(ctx, "mqtt.emqx.username").String()
	password := cfg.MustGet(ctx, "mqtt.emqx.password").String()
	clientId := cfg.MustGet(ctx, "mqtt.emqx.clientId").String()

	broker := fmt.Sprintf("tcp://%s:%d", host, port)
	client := New(broker, clientId, username, password)

	mqtt.Register("emqx", client)
	glog.Infof(ctx, "EMQX客户端注册完成，broker=%s, clientID=%s", broker, clientId)
}