package netmgrd

import "C"

import (
	"sync"
	"sync/atomic"
	"syscall"
	"time"

	"github.com/vishvananda/netlink"
	modem "hnyfkj.com.cn/rtu/linux/air720u"
	"hnyfkj.com.cn/rtu/linux/baseapp"
)

const MODULE_NAME = "NetworkManager"

var (
	isOnline        atomic.Bool  // 标记是否联网
	offlineStartTs  atomic.Int64 // 离线开始时间
	isSyncNTPTimeOK atomic.Bool  // 标记本地时间是否已同步成功
	mu1             sync.Mutex
	isRunning1      bool
	exitCh1         chan struct{}
	wg1             sync.WaitGroup
	curNetType      NetType
)

type NetType int

const (
	NetNone NetType = iota
	NetEth          // 有线网络
	NetLTE          // 蜂窝网络
)

const (
	interval1 = time.Duration(1) * time.Second
	interval2 = time.Duration(5) * time.Second
)

func ModuleInit() {
	go serviceRun()
}

// 联网保持服务
func serviceRun() {
	// 1, 首次连接网络
	openNetwork()

	// 2, 监听有线插拔
	eth0PlugCycleCh := make(chan bool, 1)
	done := make(chan struct{})
	defer close(done)
	go monitorEth0PlugCycle(eth0PlugCycleCh, done)

	// 3, 循环监控网络
	t := time.NewTimer(interval1)
	defer t.Stop()
	for {
		select {
		case <-t.C:
			// 3.1, 联网检测-看结果
			dnsOK, pingOK, tcpOK, httpOK := CheckNetwork()
			baseapp.Logger.Infof("[%s] 联网检测: DNS OK=%v, PING OK=%v, TCP OK=%v, HTTP OK=%v", MODULE_NAME, dnsOK, pingOK, tcpOK, httpOK)

			// 3.2, 检测成功-在线时
			if dnsOK && pingOK && tcpOK {
				isOnline.Store(true)
				offlineStartTs.Store(0)

				if isSyncNTPTimeOK.Load() {
					t.Reset(interval2)
					continue
				}

				err := SyncNTPTime()
				if err == nil {
					isSyncNTPTimeOK.Store(true)
					baseapp.Logger.Infof("[%s] NTP时间已同步", MODULE_NAME)
					t.Reset(interval2)
					continue
				} else {
					baseapp.Logger.Errorf("[%s] 同步NTP时间时有错误发生: %v!!", MODULE_NAME, err)
					t.Reset(interval1)
					continue
				}
			}

			// 3.3, 检测失败-离线时
			if isOnline.Load() { // 状态由"1"变为"0"
				isOnline.Store(false)
				offlineStartTs.Store(time.Now().UnixNano()) // 记录离线开始时间
			}

			if offlineDuration() >= (time.Duration(60) * time.Second) {
				baseapp.Logger.Warnf("[%s] 检测到网络长时间断开, 将重新尝试连接网络!", MODULE_NAME)
				openNetwork()
				offlineStartTs.Store(time.Now().UnixNano()) // 重置离线开始时间
			}

			t.Reset(interval1)
		case <-eth0PlugCycleCh: // 有线网口插拔事件, 重新连接网络, 优先有线网
			openNetwork()
			continue
		case <-baseapp.IsExit2():
			return
		} // select end
	} // for end
}

// 返回联网状态
func IsInetAvailable() bool {
	return isOnline.Load()
}

// 时间是否同步
func IsSyncedNtpTime() bool {
	return isSyncNTPTimeOK.Load()
}

// 等待所有成功
func WaitAllOK(timeout time.Duration) bool {
	deadline := time.Now().Add(timeout)
	tick := 50 * time.Millisecond

	for {
		if IsInetAvailable() && IsSyncedNtpTime() {
			return true
		}

		remaining := time.Until(deadline)
		if remaining <= 0 {
			return false
		}

		sleep := min(tick, remaining)
		time.Sleep(sleep)
	}
}

// 返回断网时长
func offlineDuration() time.Duration {
	if IsInetAvailable() {
		return 0
	}
	ts := offlineStartTs.Load()
	if ts == 0 {
		return 0
	}
	return time.Since(time.Unix(0, ts))
}

// 打开有线网络
func openEth0Net() bool {
	mu1.Lock()
	defer mu1.Unlock()

	if isRunning1 {
		return true
	}

	killAllUdhcpc()
	err := disableEthBut0()
	if err != nil {
		baseapp.Logger.Errorf("[%s] 错误: %v!!", MODULE_NAME, err)
		return false
	}

	bExists, _ := udhcpcEth0Exists()
	if bExists {
		killEth0Udhcpc()
	}

	err = dialupEth0()
	if err != nil {
		baseapp.Logger.Errorf("[%s] 拨号连接\"eth0\"时发生错误: %v!!", MODULE_NAME, err)
		return false
	}
	ipv4, mask, err := getEth0Addr()
	if err != nil {
		baseapp.Logger.Errorf("[%s] 读取\"eth0\"地址时发生错误: %v!!", MODULE_NAME, err)
		return false
	}
	baseapp.Logger.Infof("[%s] \"eth0\"分配的地址: %s/%s", MODULE_NAME, ipv4, mask)

	exitCh1 = make(chan struct{})
	wg1.Add(1)
	go func() { // 启动携程守护"eth0"网卡上的 "udhcpc"后台服务进程
		defer wg1.Done()
		monitorEth0Udhcpc(exitCh1)
	}()

	isRunning1 = true
	return isRunning1
}

// 断开有线网络
func closeEth0Net() {
	mu1.Lock()
	defer mu1.Unlock()

	if !isRunning1 {
		return
	}

	close(exitCh1)
	wg1.Wait() // 等待守护"eth0"网卡上的 "udhcpc"后台服务进程的携程退出

	bExists, _ := udhcpcEth0Exists()
	if bExists {
		killEth0Udhcpc()
	}

	isRunning1 = false
}

// 打开连接网络
func openNetwork() {
	closeEth0Net()
	modem.CloseEth2Net()

	eth0CableOK, _ := isEth0CableConnected()
	if eth0CableOK && curNetType != NetEth && openEth0Net() {
		curNetType = NetEth
		baseapp.Logger.Infof("[%s] ✅ 有线网络已连接", MODULE_NAME)
		return
	}

	tryOpenLTE := func() bool {
		if eth2CableOK, _ := modem.IsEth2CableConnected(); eth2CableOK {
			if modem.OpenEth2Net() {
				return true
			}
			// 重试: 4G模组重新上电初始化
			modem.ModuleExit()
			modem.ModuleInit(true)
			return modem.OpenEth2Net()
		}
		return false
	}

	if tryOpenLTE() {
		curNetType = NetLTE
		enableEth0() // 保持 eth0 可用, 以便监听网线的插拔, 触发切换网络
		baseapp.Logger.Infof("[%s] ✅ 蜂窝网络已连接", MODULE_NAME)
		return
	}

	curNetType = NetNone
	baseapp.Logger.Warnf("[%s] 没有可用的网络连接！", MODULE_NAME)
}

// 监控网线插拔
func monitorEth0PlugCycle(plugCycle chan bool, done chan struct{}) error {
	updates := make(chan netlink.LinkUpdate)
	if err := netlink.LinkSubscribe(updates, done); err != nil {
		return err
	}

	link, err := netlink.LinkByName("eth0")
	if err != nil {
		return err
	}

	isUp := link.Attrs().Flags&syscall.IFF_RUNNING != 0
	waitingForPlug := false

	for u := range updates {
		if u.Link.Attrs().Name != "eth0" {
			continue
		}

		newUp := u.IfInfomsg.Flags&syscall.IFF_RUNNING != 0
		if newUp == isUp {
			continue
		}
		isUp = newUp

		if !isUp {
			baseapp.Logger.Warnf("[%s] ❌ eth0 cable unplugged!", MODULE_NAME)
			waitingForPlug = true
		} else if waitingForPlug {
			baseapp.Logger.Infof("[%s] ✅ eth0 cable plugged in", MODULE_NAME)
			select {
			case plugCycle <- true:
			case <-done:
				return nil
			}
			waitingForPlug = false
		}
	}

	return nil
}

//export RTU_IsInetAvailable
func RTU_IsInetAvailable() C.int {
	if IsInetAvailable() {
		return 1
	}
	return 0
}

//export RTU_IsSyncedNtpTime
func RTU_IsSyncedNtpTime() C.int {
	if IsSyncedNtpTime() {
		return 1
	}
	return 0
}