feat(pricing): add domain types

Author: ndido98

pricing/src/main/scala/dev/atedeg/mdm/pricing/Types.scala

@@ -0,0 +1,92 @@
+package dev.atedeg.mdm.pricing
+
+import java.util.UUID
+import java.time.LocalDateTime
+
+import dev.atedeg.mdm.products.Product
+import dev.atedeg.mdm.utils.*
+import dev.atedeg.mdm.utils.given
+import cats.data.NonEmptyList
+
+/**
+ * A [[Product product]] with its ordered [[Quantity quantity]].
+ */
+final case class IncomingOrderLine(quantity: Quantity, product: Product)
+
+/**
+ * A quantity of something.
+ */
+final case class Quantity(n: PositiveNumber)
+
+/**
+ * Associates to each [[Product product]] its [[PriceInEuroCents unitary price]].
+ */
+final case class PriceList(priceList: Map[Product, PriceInEuroCents])
+
+/**
+ * A price expressed in cents, the smallest currency unit for euros.
+ */
+final case class PriceInEuroCents(n: PositiveNumber) derives Plus
+
+/**
+ * A physical or legal entity that places [[IncomingOrderLine order lines]].
+ */
+final case class Client(code: ClientID)
+
+/**
+ * An ID which uniquely identifies a [[Client client]].
+ */
+final case class ClientID(id: UUID)
+
+/**
+ * A list of all the promotions for each [[Client client]].
+ */
+final case class PromotionsList(promotions: Map[Client, NonEmptyList[Promotion]])
+
+/**
+ * A promotion for a [[Client client]], with an expiry date.
+ * It can either be fixed or by threshold.
+ * If it is fixed, a product is discounted by a fixed amount;
+ * if it is by threshold, only the products above the threshold are discounted.
+ */
+enum Promotion:
+    /**
+     * A fixed promotion.
+     */
+    case Fixed(client: Client, expiryDate: LocalDateTime, lines: NonEmptyList[PromotionLine.Fixed])
+    /**
+     * A threshold promotion.
+     */
+    case Threshold(client: Client, expiryDate: LocalDateTime, lines: NonEmptyList[PromotionLine.Threshold])
+
+/**
+ * A promotion line, which describes either the
+ * [[Promotion.Fixed fixed]] or the [[Promotion.Threshold threshold]] promotion.
+ */
+enum PromotionLine:
+    /**
+     * A line that describes part of a [[Promotion.Fixed fixed promotion]].
+     * It contains the discounted product and how much to discount it by.
+     * 
+     * Every order line which contains the product is discounted by the specified amount.
+     * 
+     * @note For example, if a 100g casatella normally costs 100 cents and the promotion line specifies
+     * a 50% discount, each 100g casatella will cost 50 cents.
+     */
+    case Fixed(product: Product, discount: DiscountPercentage)
+    /**
+      * A line that describes part of a [[Promotion.Threshold threshold promotion]].
+      * It contains the discounted product, the threshold and how much to discount it by.
+      * 
+      * Only the products above the threshold are discounted; the other ones are at full price.
+      *
+      * @note For example, if a 100g casatella normally costs 100 cents and the promotion line specifies
+      * a 50% discount above 5 casatellas, the first 5 casatella will cost 100 cents, while from the 6th onwards
+      * they will cost 50 cents each.
+      */
+    case Threshold(product: Product, threshold: Quantity, discount: DiscountPercentage)
+
+/**
+ * A discount percentage, expressed as a number between 0 (exclusive) and 100 (inclusive).
+ */
+final case class DiscountPercentage(n: DecimalInOpenClosedRange[0, 100])