feat(pricing): add price rule entity (#5050)

**What**
- add price-rule entity to pricing module

blocked by #4977 

Fixes CORE-1497

Co-authored-by: Riqwan Thamir <5105988+riqwan@users.noreply.github.com>
Co-authored-by: Adrien de Peretti <25098370+adrien2p@users.noreply.github.com>

packages/pricing/src/models/index.ts

@@ -3,3 +3,4 @@ export { default as MoneyAmount } from "./money-amount"
 export { default as PriceSet } from "./price-set"
 export { default as PriceSetMoneyAmount } from "./price-set-money-amount"
 export { default as RuleType } from "./rule-type"
+export { default as PriceRule } from "./price-rule"

packages/pricing/src/models/price-rule.ts

@@ -0,0 +1,69 @@
+import {
+  BeforeCreate,
+  Collection,
+  Entity,
+  ManyToMany,
+  ManyToOne,
+  OneToMany,
+  OneToOne,
+  OptionalProps,
+  PrimaryKey,
+  Property,
+} from "@mikro-orm/core"
+
+import MoneyAmount from "./money-amount"
+import PriceSet from "./price-set"
+import PriceSetMoneyAmount from "./price-set-money-amount"
+import RuleType from "./rule-type"
+import { generateEntityId } from "@medusajs/utils"
+
+type OptionalFields = "id" | "is_dynamic" | "priority"
+type OptionalRelations = "price_set" | "rule_type" | "price_set_money_amount"
+
+@Entity()
+export default class PriceRule {
+  [OptionalProps]: OptionalFields | OptionalRelations
+
+  @PrimaryKey({ columnType: "text" })
+  id!: string
+
+  @ManyToOne({
+    entity: () => PriceSet,
+    fieldName: "price_set_id",
+    name: "price_rule_price_set_id_unique",
+  })
+  price_set: PriceSet
+
+  @ManyToOne({
+    entity: () => RuleType,
+    fieldName: "rule_type_id",
+    name: "price_rule_rule_type_id_unique",
+  })
+  rule_type: RuleType
+
+  @Property({ columnType: "boolean", default: false })
+  is_dynamic: boolean
+
+  @Property({ columnType: "text" })
+  value: string
+
+  @Property({ columnType: "integer", default: 0 })
+  priority: number
+
+  @ManyToOne({
+    entity: () => PriceSetMoneyAmount,
+    fieldName: "price_set_money_amount_id",
+    name: "price_set_money_amount_id_unique",
+  })
+  price_set_money_amount: PriceSetMoneyAmount
+
+  @Property({ columnType: "text" })
+  price_list_id!: string
+
+  // TODO: Add price list
+
+  @BeforeCreate()
+  beforeCreate() {
+    this.id = generateEntityId(this.id, "pset")
+  }
+}