// Package hello
// @Author: Pei Xinyuan
// @Description:
// @Version: 0.1.0
// @Date: 2022/7/14 14:49
// @Copyright: MIN-Group；国家重大科技基础设施——未来网络北大实验室；深圳市信息论与未来网络重点实验室
//

package hello

import (
	common2 "minlib/common"
	"minlib/component"
	"minlib/logicface"
	"minlib/packet"
	"minlib/security"
	"mlsr/common"
	"mlsr/lsa"
	"mlsr/lsdb"
	"mlsr/route"
	"mlsr/utils"
)

//  用于hello兴趣包的名称的组件
const INFO_COMPONENT = "INFO"
const MLSR_COMPONENT = "mlsr"

// 正常收到数据包的触发函数
type DataCallback = func(interest *packet.Interest, data *packet.Data)

// 收到NACK的触发函数
type NackCallback = func(interest *packet.Interest, nack *packet.Nack)

// 超时未响应的触发函数
type TimeoutCallback = func(interest *packet.Interest)

//type OptionalNack = *packet.Nack

type HelloProtocol struct {
	m_face          *logicface.LogicFace
	m_scheduler     *lsdb.MlsrScheduler
	m_keychain      *security.KeyChain
	mlsrConfig      *common.MlsrConfig
	m_routingTable  *route.RoutingTable
	m_lsdb          *lsdb.Lsdb
	m_adjacencyList *lsa.AdjLsaAdjacenctList

	// 收包池
	receivePacketQue chan *packet.Interest // 从其它路由器收包后，放入该队列
	state            bool                  // 程序生成状态， true 为正常运行， false 为关闭状态

	// 接收到hello响应数据包后的信号量触发
	OnInitialHelloDataValidated *utils.Signal
}

//
//  Init
//  @Description: Hello协议-初始化
//  @receiver hp
//  @param face
//  @param scheduler
//  @param keychain
//  @param mlsrConfig
//  @param routingTable
//  @param mlsdb
//
func (hp *HelloProtocol) Init(face *logicface.LogicFace,
	scheduler *lsdb.MlsrScheduler,
	keychain *security.KeyChain, mlsrConfig *common.MlsrConfig,
	routingTable *route.RoutingTable, mlsdb *lsdb.Lsdb) {
	// 信号量初始化
	hp.OnInitialHelloDataValidated = utils.NewSignal()

	// 其它数据结构
	hp.m_face = face
	hp.m_scheduler = scheduler
	hp.m_keychain = keychain
	hp.mlsrConfig = mlsrConfig
	hp.m_routingTable = routingTable
	hp.m_lsdb = mlsdb
	hp.m_adjacencyList = mlsrConfig.GetAdjacencys()

	// logicface相关
	// 构造接收hello兴趣包的前缀
	name, err := component.CreateIdentifierByString(
		hp.mlsrConfig.GetRouterPrefix().ToUri() + "/" + MLSR_COMPONENT + "/" + INFO_COMPONENT)
	if err != nil {
		common2.LogFatal("HelloProtocol Setting interest filter for Hello interest error, interest generate wrong.", err)
		return
	}
	// 设置监听前缀
	err = hp.m_face.RegisterPullIdentifier(name, 3000)
	if err != nil {
		common2.LogFatal("HelloProtocol Setting interest filter for Hello interest error, identifier register wrong.", err)
		return
	}
	// 开一个线程去接收前缀为hello协议所监听前缀的兴趣包，并进行处理
	hp.receivePacketQue = make(chan *packet.Interest, 1000)
	hp.state = true
	// 启动处理接收到的包的协程
	go hp.dealWithRecvPktRoutine()
	// 启动从客户端接收包的协程
	go hp.recvPacketFromClientRoutine()
}

//
//  expressInterest
//  @Description: 根据传入的兴趣包名称和兴趣包过期时间，构建兴趣包，并发出去
//  @receiver hp
//  @param interestName
//  @param _millseconds
//
func (hp *HelloProtocol) expressInterest(interestName *component.Identifier, _millseconds uint32) {
	common2.LogDebug("HelloProtocol Expressing Interest: " + interestName.ToUri())
	interest := packet.NewInterest()
	interest.SetName(interestName)
	interest.SetInterestLifeTime(uint64(_millseconds))
	// todo 这里需要实现的是，将兴趣包通过face发出，并对超时、nack、正常应答三种情况进行处理
}

//
//  SendHelloInterest
//  @Description: 向指定邻居路由器发送hello探测包
//  @receiver hp
//  @param neighbor
//
func (hp *HelloProtocol) SendHelloInterest(neighbor *component.Identifier) {
	// 查找关于某个邻居路由器的邻接信息
	adjInfo := hp.m_adjacencyList.FindAdjacencyByRouterIdentifier(neighbor)

	// 如果没有找到，则不做处理
	if adjInfo == nil {
		return
	}

	// 如果找到了，且有对应的faceID，则发送一个hello探测包
	if adjInfo.LogicFaceId() != 0 {
		// interest name: /<neighbor>/NLSR/INFO/<router>
		name, err := component.CreateIdentifierByString(adjInfo.GetNeighborRouterIdentifier().ToUri() +
			"/" + MLSR_COMPONENT + "/" + INFO_COMPONENT +
			"/" + GetSinglePrefixForHelloProtocol(hp.mlsrConfig.GetRouterPrefix()))
		if err != nil {
			common2.LogDebug("HelloProtocol SendHelloInterest error, hello name create wrong.", err)
			return
		}
		// 将data发出去
		hp.expressInterest(name, hp.mlsrConfig.GetInterestResendTime())
		common2.LogDebug("HelloProtocol Sending HELLO interest: " + name.ToUri())
	}

	// 安排按照配置文件中的时间，若干秒后【默认一分钟】发送下一个hello兴趣包
	job, err := hp.m_scheduler.ScheduleTaskAfterDuration(hp.mlsrConfig.GetInfoInterestInterval(), 1).
		Do(hp.SendHelloInterest, neighbor)
	job.LimitRunsTo(1)
	hp.m_scheduler.StartAsync()
	if err != nil {
		common2.LogError("HelloProtocol ScheduleTask to send hello interest error. ", err.Error())
	}
}

//
//  processInterestTimedOut
//  @Description: 发送兴趣包给邻居路由器，当超时或nack时，执行本函数
//  @receiver hp
//  @param interest
//
func (hp *HelloProtocol) processInterestTimedOut(interest *packet.Interest) {
	// interest name: /<neighbor>/NLSR/INFO/<router>
	interestName := interest.GetName()
	// 取出兴趣包倒数第二个组件，对其进行校验
	infoComponent, err := interestName.Get(-2)
	if err != nil {
		common2.LogDebug("HelloProtocol processInterestTimedOut error, get(-2) err ", err)
		return
	}
	if infoComponent.ToUri() != INFO_COMPONENT {
		common2.LogDebug("HelloProtocol processInterestTimedOut error, INFO_COMPONENT not found in interestName ", err)
		return
	}
	// 取"/NLSR"之前的所有组件组成的前缀，也即邻居路由器的前缀
	neighborIdentifier, err := interestName.GetPrefix(-3)
	if err != nil {
		common2.LogDebug("HelloProtocol processInterestTimedOut error, interestName.GetPrefix error.", err)
		return
	}
	// 将本机邻居列表中该邻居的超时次数增加1
	err = hp.m_adjacencyList.IncrementTimedOutInterestCount(neighborIdentifier)
	if err != nil {
		common2.LogDebug("HelloProtocol processInterestTimedOut error, IncrementTimedOutInterestCount error.", err)
		return
	}
	// 查找该邻居的状态
	status, err := hp.m_adjacencyList.GetStatusOfNeighbor(neighborIdentifier)
	if err != nil {
		common2.LogDebug("HelloProtocol processInterestTimedOut error, GetStatusOfNeighbor error.", err)
		return
	}
	// 查找该邻居的超时次数
	infoIntTimedOutCount, err := hp.m_adjacencyList.GetTimedOutInterestCount(neighborIdentifier)
	if err != nil {
		common2.LogDebug("HelloProtocol processInterestTimedOut error, GetTimedOutInterestCount error.", err)
		return
	}
	common2.LogDebug("HelloProtocol processInterestTimedOut Status: ", status)
	common2.LogDebug("HelloProtocol processInterestTimedOut TimeoutCount: ", infoIntTimedOutCount)
	// 如果超时次数小于阈值。则继续探测
	if infoIntTimedOutCount < hp.mlsrConfig.GetInterestResendTime() {
		name, err := component.CreateIdentifierByString(neighborIdentifier.ToUri() +
			"/" + MLSR_COMPONENT + "/" + INFO_COMPONENT +
			"/" + GetSinglePrefixForHelloProtocol(hp.mlsrConfig.GetRouterPrefix()))
		if err != nil {
			common2.LogDebug("HelloProtocol processInterestTimedOut error, hello name create wrong.")
			return
		}
		common2.LogDebug("HelloProtocol processInterestTimedOut Resending interest: " + interestName.ToUri())
		// 将兴趣包再次发出去
		hp.expressInterest(name, hp.mlsrConfig.GetInterestResendTime())
	} else if status == lsa.STATUS_ACTIVE {
		// 如果重传次数达到阈值，且该路由器旧状态为激活状态，则将其修改为未激活
		err = hp.m_adjacencyList.SetStatusOfNeighbor(neighborIdentifier, lsa.STATUS_INACTIVE)
		if err != nil {
			common2.LogDebug("HelloProtocol processInterestTimedOut error, set status error. ", err)
		}
		common2.LogDebug("HelloProtocol processInterestTimedOut, change status of " +
			neighborIdentifier.ToUri() + " to IN-ACTIVE")
		// 安排lsdb的邻接lsa重新构建
		hp.m_lsdb.ScheduleAdjLsaBuild()
	}
}

//
//  onContent
//  @Description: 发送兴趣包给邻居路由器，当收到data包时，执行本函数
//  @receiver hp
//  @param data
//
func (hp *HelloProtocol) onContent(interest *packet.Interest, data *packet.Data) {
	common2.LogDebug("HelloProtocol Received data for INFO(name): " + data.GetName().ToUri())
	// todo 这里先跳过签名验证，执行验证通过后的处理
	// 取出数据包名称的倒数第三个组件，对其进行校验
	infoComponent, err := data.GetName().Get(-3)
	if err != nil {
		common2.LogDebug("HelloProtocol onContent error, get(-3) err ", err)
		return
	}
	if infoComponent.ToUri() != INFO_COMPONENT {
		common2.LogDebug("HelloProtocol onContent error, INFO_COMPONENT not found in dataName ", err)
		return
	}
	// 取"/NLSR"之前的所有组件组成的前缀，也即邻居路由器的前缀
	neighborIdentifier, err := data.GetName().GetPrefix(-4)
	if err != nil {
		common2.LogDebug("HelloProtocol onContent error, dataName.GetPrefix error.", err)
		return
	}
	// 查找该邻居的状态
	oldStatus, err := hp.m_adjacencyList.GetStatusOfNeighbor(neighborIdentifier)
	if err != nil {
		common2.LogDebug("HelloProtocol onContent error, get old status error.", err)
		return
	}
	// 设置该路由器的状态及超时次数
	err = hp.m_adjacencyList.SetStatusOfNeighbor(neighborIdentifier, lsa.STATUS_ACTIVE)
	if err != nil {
		common2.LogDebug("HelloProtocol onContent error, set status error.", err)
		return
	}
	err = hp.m_adjacencyList.SetTimedOutInterestCount(neighborIdentifier, 0)
	if err != nil {
		common2.LogDebug("HelloProtocol onContent error, set timeout count error.", err)
		return
	}
	// 查找该邻居的新状态
	newStatus, err := hp.m_adjacencyList.GetStatusOfNeighbor(neighborIdentifier)
	if err != nil {
		common2.LogDebug("HelloProtocol onContent error, get new status error.", err)
		return
	}
	common2.LogDebug("HelloProtocol onContent, neighbor: ", neighborIdentifier.ToUri(),
		", old status: ", oldStatus, ", new status: ", newStatus)
	// 如果状态发生了更改，则安排邻接Lsa进行重新构建，并发射信号给fib，使其更新mir中的该face状态
	if newStatus != oldStatus {
		hp.m_lsdb.ScheduleAdjLsaBuild()
		hp.OnInitialHelloDataValidated.Emit(neighborIdentifier)
	}
}