feat (medication-item): add qty calculation if intervalMultiplier is not nil

internal/use-case/main-use-case/medication-item/helper.go

@@ -29,4 +29,15 @@ func setData[T *e.CreateDto | *e.UpdateDto](input T, data *e.MedicationItem) {
 	data.IsRedeemed = inputSrc.IsRedeemed
 	data.Quantity = inputSrc.Quantity
 	data.Note = inputSrc.Note
+
+	if inputSrc.IntervalMultiplier != nil {
+		data.Quantity = countQty(*inputSrc)
+	}
+}
+
+func countQty(input e.CreateDto) float64 {
+	if input.Frequency != nil && input.Dose != 0 && input.IntervalMultiplier != nil {
+		return (float64(*input.Frequency) * float64(input.Dose)) * float64(*input.IntervalMultiplier)
+	}
+	return 0
 }