package pool

import "fmt"

type PortAllocator struct {
	ports chan int
}

func NewPortAllocator(lo, hi int) *PortAllocator {
	ch := make(chan int, hi-lo+1)
	for p := lo; p <= hi; p++ {
		ch <- p
	}
	return &PortAllocator{ports: ch}
}

func (pa *PortAllocator) Allocate() (int, error) {
	select {
	case p := <-pa.ports:
		return p, nil
	default:
		return 0, fmt.Errorf("port allocator exhausted")
	}
}

func (pa *PortAllocator) Release(port int) {
	pa.ports <- port
}