package locker

import (
	"runtime"
	"testing"
)

func TestLockCounter(t *testing.T) {
	l := &lockCtr{}
	l.inc()

	if l.waiters != 1 {
		t.Fatal("counter inc failed")
	}

	l.dec()
	if l.waiters != 0 {
		t.Fatal("counter dec failed")
	}
}

func TestLockerLock(t *testing.T) {
	l := New()
	l.Lock("test")
	ctr := l.locks["test"]

	if ctr.count() != 0 {
		t.Fatalf("expected waiters to be 0, got :%d", ctr.waiters)
	}

	chDone := make(chan struct{})
	go func() {
		l.Lock("test")
		close(chDone)
	}()

	runtime.Gosched()

	select {
	case <-chDone:
		t.Fatal("lock should not have returned while it was still held")
	default:
	}

	if ctr.count() != 1 {
		t.Fatalf("expected waiters to be 1, got: %d", ctr.count())
	}

	if err := l.Unlock("test"); err != nil {
		t.Fatal(err)
	}
	runtime.Gosched()

	select {
	case <-chDone:
	default:
		// one more time just to be sure
		runtime.Gosched()
		select {
		case <-chDone:
		default:
			t.Fatalf("lock should have completed")
		}
	}

	if ctr.count() != 0 {
		t.Fatalf("expected waiters to be 0, got: %d", ctr.count())
	}
}

func TestLockerUnlock(t *testing.T) {
	l := New()

	l.Lock("test")
	l.Unlock("test")

	chDone := make(chan struct{})
	go func() {
		l.Lock("test")
		close(chDone)
	}()

	runtime.Gosched()

	select {
	case <-chDone:
	default:
		t.Fatalf("lock should not be blocked")
	}
}