package builder

// UnwindOption is a functional option for configuring the $unwind stage.
type UnwindOption func(*UnwindOpts)

type UnwindOpts struct {
	PreserveNullAndEmptyArrays bool
	IncludeArrayIndex          string
}

// WithPreserveNullAndEmptyArrays tells $unwind to keep docs where the array is null/empty.
func WithPreserveNullAndEmptyArrays() UnwindOption {
	return func(o *UnwindOpts) {
		o.PreserveNullAndEmptyArrays = true
	}
}

// WithIncludeArrayIndex adds an array‐index field named idxField to each unwound doc.
func WithIncludeArrayIndex(idxField string) UnwindOption {
	return func(o *UnwindOpts) {
		o.IncludeArrayIndex = idxField
	}
}