/**
* @Author: Aceld
* @Date: 2019/5/8 17:43
* @Mail: danbing.at@gmail.com
*
*  时间轮调度器
*   依赖模块，delayfunc.go  timer.go timewheel.go
 */
package ztimer

import (
	"github.com/aceld/zinx/zlog"
	"math"
	"sync"
	"time"
)

const (
	//默认缓冲触发函数队列大小
	MAX_CHAN_BUFF = 2048
	//默认最大误差时间
	MAX_TIME_DELAY = 100
)

type TimerScheduler struct {
	//当前调度器的最高级时间轮
	tw *TimeWheel
	//定时器编号累加器
	idGen uint32
	//已经触发定时器的channel
	triggerChan chan *DelayFunc
	//互斥锁
	sync.RWMutex
	//所有注册的timerId集合
	ids []uint32
}

/*
	返回一个定时器调度器

	主要创建分层定时器，并做关联，并依次启动
*/
func NewTimerScheduler() *TimerScheduler {

	//创建秒级时间轮
	second_tw := NewTimeWheel(SECOND_NAME, SECOND_INTERVAL, SECOND_SCALES, TIMERS_MAX_CAP)
	//创建分钟级时间轮
	minute_tw := NewTimeWheel(MINUTE_NAME, MINUTE_INTERVAL, MINUTE_SCALES, TIMERS_MAX_CAP)
	//创建小时级时间轮
	hour_tw := NewTimeWheel(HOUR_NAME, HOUR_INTERVAL, HOUR_SCALES, TIMERS_MAX_CAP)

	//将分层时间轮做关联
	hour_tw.AddTimeWheel(minute_tw)
	minute_tw.AddTimeWheel(second_tw)

	//时间轮运行
	second_tw.Run()
	minute_tw.Run()
	hour_tw.Run()

	return &TimerScheduler{
		tw:          hour_tw,
		triggerChan: make(chan *DelayFunc, MAX_CHAN_BUFF),
		ids:         make([]uint32, 0),
	}
}

//创建一个定点Timer 并将Timer添加到分层时间轮中， 返回Timer的tid
func (this *TimerScheduler) CreateTimerAt(df *DelayFunc, unixNano int64) (uint32, error) {
	this.Lock()
	defer this.Unlock()

	this.idGen++
	this.ids = append(this.ids, this.idGen)
	return this.idGen, this.tw.AddTimer(this.idGen, NewTimerAt(df, unixNano))
}

//创建一个延迟Timer 并将Timer添加到分层时间轮中， 返回Timer的tid
func (this *TimerScheduler) CreateTimerAfter(df *DelayFunc, duration time.Duration) (uint32, error) {
	this.Lock()
	defer this.Unlock()

	this.idGen++
	this.ids = append(this.ids, this.idGen)
	return this.idGen, this.tw.AddTimer(this.idGen, NewTimerAfter(df, duration))
}

//删除timer
func (this *TimerScheduler) CancelTimer(tid uint32) {
	this.Lock()
	this.Unlock()
	//this.tw.RemoveTimer(tid)  这个方法无效
	//删除timerId
	var index = -1
	for i := 0; i < len(this.ids); i++ {
		if this.ids[i] == tid {
			index = i
		}
	}

	if index > -1 {
		this.ids = append(this.ids[:index], this.ids[index+1:]...)
	}
}

//获取计时结束的延迟执行函数通道
func (this *TimerScheduler) GetTriggerChan() chan *DelayFunc {
	return this.triggerChan
}

func (this *TimerScheduler) HasTimer(tid uint32) bool {
	for i := 0; i < len(this.ids); i++ {
		if this.ids[i] == tid {
			return true
		}
	}
	return false
}

//非阻塞的方式启动timerSchedule
func (this *TimerScheduler) Start() {
	go func() {
		for {
			//当前时间
			now := UnixMilli()
			//获取最近MAX_TIME_DELAY 毫秒的超时定时器集合
			timerList := this.tw.GetTimerWithIn(MAX_TIME_DELAY * time.Millisecond)
			for tid, timer := range timerList {
				if math.Abs(float64(now-timer.unixts)) > MAX_TIME_DELAY {
					//已经超时的定时器，报警
					zlog.Error("want call at ", timer.unixts, "; real call at", now, "; delay ", now-timer.unixts)
				}
				if this.HasTimer(tid) {
					//将超时触发函数写入管道
					this.triggerChan <- timer.delayFunc
				}
			}
			time.Sleep(MAX_TIME_DELAY / 2 * time.Millisecond)
		}
	}()
}

//时间轮定时器 自动调度
func NewAutoExecTimerScheduler() *TimerScheduler {
	//创建一个调度器
	autoExecScheduler := NewTimerScheduler()
	//启动调度器
	autoExecScheduler.Start()

	//永久从调度器中获取超时 触发的函数 并执行
	go func() {
		delayFuncChan := autoExecScheduler.GetTriggerChan()
		for df := range delayFuncChan {
			go df.Call()
		}
	}()

	return autoExecScheduler
}