package carbon

import (
	"sync"
	"sync/atomic"
)

// FrozenNow defines a FrozenNow struct.
type FrozenNow struct {
	isFrozen int32
	testNow  *Carbon
	rw       sync.RWMutex
}

var frozenNow = &FrozenNow{}

// SetTestNow sets a test Carbon instance for now.
func SetTestNow(c *Carbon) {
	if c == nil {
		return
	}

	frozenNow.rw.Lock()
	defer frozenNow.rw.Unlock()

	frozenNow.testNow = c
	atomic.StoreInt32(&frozenNow.isFrozen, 1)
}

// ClearTestNow clears the test Carbon instance for now.
func ClearTestNow() {
	frozenNow.rw.Lock()
	defer frozenNow.rw.Unlock()

	frozenNow.testNow = nil
	atomic.StoreInt32(&frozenNow.isFrozen, 0)
}

// IsTestNow reports whether is testing time.
func IsTestNow() bool {
	return atomic.LoadInt32(&frozenNow.isFrozen) == 1
}