//1.实现3节点选举
//2.改造代码成分布式选举代码,加入Rpc调用
//3.演示完整代码 自动选主  日志复制


//定义3节点常量
const raftCount =3

/**
    Leader对象
    Term int             任期 还没上任为0
    LeaderId int         leaderId 编号 没有编号为-1
 */
type Leader struct {
    Term int
    LeaderId int
}

/**raft的声明

锁                                                     mu                             sync.Mutex
节点编号                                               me                              int
当前任期                                               currentTerm               int
为哪个节点投票 -1代表谁都不投             vatedFor                     int
0.follower 1.candidate 2.leader  state                        int
发送最后一条消息的时间                         lastMessaheTime           int64
当前节点的leader                               currentLeader             int
节点间发送信息的通道                            message                        chan bool
选举通道                                              electCh                        chan bool
心跳信号的通道                                    heartBeat                    chan bool
返回心跳信号的通道                                 heartbeatRe                  chan bool
超时时间                                              timeout                        int
 */
type Raft struct{
    mu              sync.Mutex
    me              int
    currentTerm     int
    votedFor        int
    state           int
    lastMessaheTime int64
    currentLeader   int
    message         chan bool
    electCh         chan bool
    heartBeat       chan bool
    heartbeatRe     chan bool
    timeout         int
}

var leader = Leader{0,-1}
func main() {
    //过程:有三个节点,最初都是follower
    //如果有candidate状态,进行投票和拉票
    //会产生leader
    //会产生3个节点
    for i:=0;i<raftCount;i++{
        //穿件三个raft节点
        Make(i)
    }

}

func Make(me int ) *Raft  {
    rf:=&Raft{}
    rf.me=me
    rf.votedFor=-1
    rf.state=0
    rf.timeout=0
    rf.currentLeader=-1
    rf.setTerm(0)
    rf.message=make(chan bool)
    rf.electCh=make(chan bool)
    rf.heartBeat=make(chan bool)
    rf.heartbeatRe=make(chan bool)
    //设置随机种子
    rand.Seed(time.Now().UnixNano())
    //选举协程
     go rf.election()
    //心跳检测协程
    go rf.sendLeaderHeartBeat()
    return rf
}
/** setTerm for currentTerm
    for Raft struct
    params term int which one item number
 */
func (rf *Raft)setTerm(term int ){
    rf.currentTerm=term
}
/** election for leader
 */
func (rf *Raft)election()  {
    var result bool
    for  {
        timeout :=randRage(150,300)
        rf.lastMessaheTime=millisecond()
        select {
        case <-time.After(time.Duration(timeout)*time.Microsecond):
            fmt.Println("当前节点状态为:",rf.state)
        }
        result=false
        for !result{
            result=rf.election_one_round(&leader)
        }
    }
}

/* randRange set time out
 */
func randRage(min,max int64) int64  {
    return  rand.Int63n(max-min)+min
}
/**get the lastMessage send time
 */
func millisecond() int64 {
    return time.Now().UnixNano()/int64(time.Microsecond)
}
/**
implementation of select leader
 */
func (rf *Raft)election_one_round(leader *Leader) bool  {
    //set time out
    var timeout int64
    timeout = 100
    //number of vote
    var vote int
    //heartbeat
    var triggerHeartbeat bool
    var success bool
    //time
    last :=millisecond()
    //change the item be canditate
    rf.mu.Lock()
    //change state
    rf.becomeCandidate()
    rf.mu.Unlock()
    fmt.Println("staet electing leader")
    //range all item
    for{
        for i:=0;i<raftCount;i++ {
            if i!=rf.me{
                // canvass vote
                go func() {
                    if leader.LeaderId<0{
                            rf.electCh<-true
                    }
                }()
            }
        }
        vote  = 1
        for i:=0;i<raftCount;i++{
            //calculate the number of vote
            select {
            case ok:=<-rf.electCh:
                if ok{
                    //vote number add 1
                    vote++
                    //if vote great than node one-second ,successful
                    success=vote>raftCount/2
                    if success&&!triggerHeartbeat{
                        //change be the leader success
                        //trigger the hearbeat detection
                        triggerHeartbeat =true
                        rf.mu.Lock()
                        rf.becomeLeader()
                        rf.mu.Unlock()
                        rf.heartBeat<- true
                        fmt.Println(rf.me,"号节点成为leader")
                        fmt.Println("leader 开始发送心跳信号")
                    }
                }
            }
        }
        //final check
        //if don't time out and the vote great then node one-second ,than impelmention select leader successful.
        if timeout+last<millisecond()||(vote>raftCount/2||rf.currentLeader>-1){
            break
        }else{
            select {
            case <-time.After(time.Duration(10)*time.Microsecond):
            }
        }

    }
    return success

}

/**
change state with candidate
 */
func (rf *Raft)becomeCandidate()  {
    rf.state=1
    rf.setTerm(rf.currentTerm+1)
    rf.votedFor=rf.me
    rf.currentLeader=-1
}

/**
change state with leader
 */
func(rf *Raft)becomeLeader(){
 rf.state=2
 rf.currentLeader=rf.me
}

/**
  leader send heartBeat
  complete data synchronization
 */
func (rf *Raft) sendLeaderHeartBeat()  {
    //infinity loop
    for{
        select {
        case <-rf.heartBeat:
            rf.sendAppendEntriesImpl()
        }
    }
}
/**
return info to the leader
 */
func (rf *Raft)sendAppendEntriesImpl()  {
    if rf.currentLeader == rf.me{
        //the time  is  leader
        //number of record to confirm single node
        var success_count =0
        for i:=0;i<raftCount;i++{
            if i!=rf.me{
                go func() {
                    rf.heartbeatRe<-true
                }()
            }
            //complete the sigle node of return confirm
            for i:=0;i<raftCount;i++{
                select {
                case ok:=<-rf.heartbeatRe:
                    if ok{
                        success_count++
                        if success_count>raftCount/2{
                            fmt.Println("投票选举成功,心跳信号Ok")
                            log.Fatal("程序结束")
                        }
                    }

                }
            }
        }
    }
}