package main

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"sync/atomic"
	"time"

	mqtt "github.com/eclipse/paho.mqtt.golang"
	"hnyfkj.com.cn/rtu/linux/baseapp"
)

const MODULE_NAME = "YFKJ_SSH_CLIENT"

var (
	Coupler *MQTTCoupler
)

const (
	MqttQos1     byte = 1               //// 消息至少送达一次
	FastInterval      = 1 * time.Second //// 快速检测时间间隔
	SlowInterval      = 5 * time.Second //// 慢速检测时间间隔
)

var (
	Version               = "0.0.0.1"
	coupler               *MQTTCoupler
	ErrBrokerAddressEmpty = errors.New("mqtt server address is empty")
	ErrIMEINotAvailable   = errors.New("device imei is not available")
)

type MQTTCoupler struct {
	broker, username, password string
	client                     mqtt.Client

	imei     string // 设备唯一标识
	subTopic string // 订阅应答主题:/yfkj/device/rpc/imei/ack
	pubTopic string // 发布指令主题:/yfkj/device/rpc/imei/cmd
	cwd      string // 当前工作目录

	ctx    context.Context
	cancel context.CancelFunc

	isConnected atomic.Bool /// 标记是否已连接MQTT的Broker服务
}

func init() {
	if err := loadAppConfig(); err != nil {
		msg := fmt.Sprintf("[%s] 加载配置文件失败: %v!!", MODULE_NAME, err)
		panic(msg)
	}

	ctx, cancel := context.WithCancel(context.Background())

	coupler = &MQTTCoupler{
		broker:      CfgServers.MQTTSrv.Address,
		username:    CfgServers.MQTTSrv.Username,
		password:    CfgServers.MQTTSrv.Password,
		cwd:         "/",
		ctx:         ctx,
		cancel:      cancel,
		isConnected: atomic.Bool{},
	}
}

func main() {
	if baseapp.IsArgsParam("-h") {
		help()
		return
	}

	if baseapp.IsArgsParam("-v") {
		fmt.Println("程序版本:", Version, "\n构建时间:", baseapp.BuildTime)
		return
	}

	devIMEI := baseapp.GetArgsParamStr("-c", "")
	if devIMEI == "" {
		help()
		return
	}

	coupler.imei = devIMEI
	if err := Coupler.init2(); err != nil {
		fmt.Printf("[%s] 错误: %v!!", MODULE_NAME, err)
		return
	}

	for {
	}
}

func help() {
	h := `
-h 显示帮助提示
-v 当前程序版本
-c 连接目标设备(IMEI), 例如: -c 869523059113051
`

	fmt.Println(h)
}

func (c *MQTTCoupler) init2() error {
	template := "/yfkj/device/rpc/imei"
	c.subTopic = strings.ReplaceAll(template+"/ack", "imei", c.imei)
	c.pubTopic = strings.ReplaceAll(template+"/cmd", "imei", c.imei)

	opts := mqtt.NewClientOptions().
		AddBroker(c.broker).
		SetUsername(c.username).SetPassword(c.password).
		SetConnectRetry(false).SetAutoReconnect(false).SetCleanSession(true).
		SetKeepAlive(10 * time.Second).SetPingTimeout(5 * time.Second). // Ping心跳间隔, 超时时间
		SetOrderMatters(false)

	opts.OnConnect = func(client mqtt.Client) {
		if !c.isConnected.Swap(true) {
			baseapp.Logger.Infof("[%s] MQTT Broker连接成功", MODULE_NAME)
		}
	}

	opts.OnConnectionLost = func(client mqtt.Client, err error) {
		if c.isConnected.Swap(false) {
			baseapp.Logger.Warnf("[%s] MQTT Broker连接丢失: %v!", MODULE_NAME, err)
		}
	}

	c.client = mqtt.NewClient(opts)
	go Coupler.keepOnline()

	return nil
}

func (c *MQTTCoupler) keepOnline() {
	t := time.NewTimer(FastInterval)
	defer t.Stop()

	for {
		select {
		case <-c.ctx.Done():
			return
		case <-t.C:
			t.Reset(c.tick())
		} // end select
	} // end for
}

func (c *MQTTCoupler) tick() time.Duration {
	if c.isConnected.Load() {
		return FastInterval
	}

	if err := c.connect(); err != nil {
		baseapp.Logger.Errorf("[%s] MQTT Broker连接失败: %v!!", MODULE_NAME, err)
	}

	return SlowInterval
}

func (c *MQTTCoupler) connect() error {
	if c.client.IsConnected() {
		return nil
	}

	token := c.client.Connect()
	select {
	case <-c.ctx.Done():
		return nil
	case <-token.Done():
	}

	return token.Error()
}