package trace

import "time"

var t *Trace

type Trace struct {
	queue    chan int64
	tick     <-chan time.Time
	ts       int64
	serverId int64
}

func NewTrace(serverId int64) {
	if t != nil {
		return
	}

	t = &Trace{
		queue:    make(chan int64, 1000),
		tick:     time.Tick(time.Second),
		serverId: serverId % 65536,
	}

	t.ts = t.serverId<<47 | time.Now().Unix()<<16
	go func() {
		var i int64 = 0
		for {
			t.queue <- i % 65536
			i++
		}
	}()

	go func() {
		for now := range t.tick {
			t.ts = t.serverId<<47 | now.Unix()<<16
		}
	}()
}

func GenId() int64 {
	if t == nil {
		return 0
	}

	select {
	case seq := <-t.queue:
		return seq | t.ts
	default:
		return 0
	}
}