package meta

const (
	FieldsMaskCapacity    = 4
	FieldsMaskItemBitSize = 64
)

func MakeFieldsMaskFromInt64(v int64) FieldsMask {
	var mask FieldsMask
	mask.SetItemFromInt64(0, v)

	return mask
}

type FieldsMaskItem uint64

func (fmi FieldsMaskItem) FieldIsDirty(index uint64) bool {
	return (1<<index)&fmi != 0
}

type FieldsMask struct {
	masks [FieldsMaskCapacity]FieldsMaskItem
}

func (fm *FieldsMask) SetItemFromUint64(index int, value uint64) {
	fm.masks[index] = FieldsMaskItem(value)
}

func (fm *FieldsMask) SetItemFromInt64(index int, value int64) {
	fm.masks[index] = FieldsMaskItem(value)
}

func (fm FieldsMask) FieldChanged(index uint64) bool {
	itemIndex := fm.itemIndex(index)
	maskIndex := fm.maskIndex(index)
	mask := fm.masks[itemIndex]
	return mask.FieldIsDirty(maskIndex)
}

func (fm *FieldsMask) SetFieldChanged(index uint64) {
	itemIndex := fm.itemIndex(index)
	maskIndex := fm.maskIndex(index)
	fm.masks[itemIndex] |= (1 << maskIndex)
}

func (fm FieldsMask) IsFilled() bool {
	for _, mask := range fm.masks {
		if mask > 0 {
			return true
		}
	}
	return false
}

func (fm FieldsMask) itemIndex(index uint64) uint64 {
	return index / FieldsMaskItemBitSize
}

func (fm FieldsMask) maskIndex(index uint64) uint64 {
	return index % FieldsMaskItemBitSize
}