package scheduler

import (
	"git.noahlan.cn/noahlan/ntool/nlog"
	"runtime/debug"
	"sync/atomic"
	"time"
)

const (
	messageQueueBacklog = 1 << 10 // 1024
	sessionCloseBacklog = 1 << 8  // 256
)

// LocalScheduler schedules task to a customized goroutine
type LocalScheduler interface {
	Schedule(Task)
}

type Task func()

type Hook func()

var (
	chDie   = make(chan struct{})
	chExit  = make(chan struct{})
	chTasks = make(chan Task, 1<<8)
	started int32
	closed  int32
)

func try(f func()) {
	defer func() {
		if err := recover(); err != nil {
			nlog.Infof("Handle message panic: %+v\n%s", err, debug.Stack())
		}
	}()
	f()
}

func Schedule(timerPrecision time.Duration) {
	if atomic.AddInt32(&started, 1) != 1 {
		return
	}

	if timerPrecision.Seconds() == 0 {
		timerPrecision = time.Second
	}

	ticker := time.NewTicker(timerPrecision)
	defer func() {
		ticker.Stop()
		close(chExit)
	}()

	for {
		select {
		case <-ticker.C:
			cron()

		case f := <-chTasks:
			try(f)

		case <-chDie:
			return
		}
	}
}

func Close() {
	if atomic.AddInt32(&closed, 1) != 1 {
		return
	}
	close(chDie)
	<-chExit
	nlog.Info("Scheduler stopped")
}

func PushTask(task Task) {
	chTasks <- task
}