package lock

import (
	"sync"
	"sync/atomic"
)

var _ Locker = (*locker)(nil)

type Locker interface {
	condition() bool
	Lock()
	Unlock()
}

type locker struct {
	lock *sync.Mutex
	cond *sync.Cond
	v    int32
}

func NewLocker() Locker {
	lock := new(sync.Mutex)
	return &locker{
		lock: lock,
		cond: sync.NewCond(lock),
		v:    0,
	}
}

func (l *locker) condition() bool {
	return atomic.LoadInt32(&l.v) == 1
}

func (l *locker) Lock() {
	l.cond.L.Lock()
	for l.condition() {
		l.cond.Wait()
	}
	atomic.StoreInt32(&l.v, 1)
}

func (l *locker) Unlock() {
	atomic.StoreInt32(&l.v, 0)
	l.cond.L.Unlock()
	l.cond.Signal()
}