package meta

const (
	FieldsMaskCapacity    = 4
	FieldsMaskPartBitSize = 64
)

func MakeFieldsMaskFromInt64(v int64) FieldsMask {
	var mask FieldsMask
	mask.SetPartFromInt64(0, v)

	return mask
}

type FieldsMaskPart uint64

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

type FieldsMask struct {
	parts [FieldsMaskCapacity]FieldsMaskPart
}

func (fm *FieldsMask) SetPartFromUint64(index int, value uint64) {
	fm.parts[index] = FieldsMaskPart(value)
}

func (fm *FieldsMask) SetPartFromInt64(index int, value int64) {
	fm.parts[index] = FieldsMaskPart(value)
}

func (fm FieldsMask) FieldChanged(index uint64) bool {
	partIndex := fm.partIndex(index)
	fieldIndex := fm.fieldIndex(index)
	part := fm.parts[partIndex]
	return part.FieldIsDirty(fieldIndex)
}

func (fm *FieldsMask) SetFieldChanged(index uint64) {
	partIndex := fm.partIndex(index)
	fieldIndex := fm.fieldIndex(index)
	fm.parts[partIndex] |= (1 << fieldIndex)
}

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

func (fm FieldsMask) partIndex(index uint64) uint64 {
	return index / FieldsMaskPartBitSize
}

func (fm FieldsMask) fieldIndex(index uint64) uint64 {
	return index % FieldsMaskPartBitSize
}