Add event sourcing types and deciders for cart management functionality

Author: erikologic

src/libs/types.ts

@@ -0,0 +1,26 @@
+export type HasParamWithDiscriminant<
+  Params extends Array<any>,
+  DiscriminantKey extends keyof any,
+  Value extends string
+> = Params extends [infer First, ...infer Rest] ? First extends { [K in DiscriminantKey]: Value } ? true
+  : HasParamWithDiscriminant<Rest, DiscriminantKey, Value>
+  : false
+
+export type SelectFunctionByDiscriminantValueInParams<
+  FuncUnion extends (...args: Array<any>) => any,
+  DiscriminantKey extends keyof any,
+  Value extends string
+> = FuncUnion extends (...args: infer Params) => any
+  ? HasParamWithDiscriminant<Params, DiscriminantKey, Value> extends true ? FuncUnion
+  : never
+  : never
+
+export type HasNoNever<T> = { [K in keyof T]: T[K] extends never ? K : never }[keyof T] extends never ? true : false
+
+export type AssertMapShape<
+  MapType,
+  KeyUnion extends keyof any,
+  ValueType
+> = MapType extends Record<KeyUnion, ValueType> ? HasNoNever<MapType> extends true ? true
+  : ["Error: MapType contains 'never' values"]
+  : ["Error: MapType shape is invalid"]

src/orderManagement/deciders.ts

@@ -0,0 +1,37 @@
+import type {
+  AddBillingDetailsCommand,
+  AddItemToCartCommand,
+  ExternalCommand,
+  RemoveItemFromCartCommand
+} from "./externalCommands"
+import type { BillingDetailsAddedEvent, ItemAddedEvent, ItemRemovedEvent } from "./internalEvents"
+import type { NewCartState, OpenCartState } from "./states"
+import type { IDecide } from "../functionalEventSourcing/types"
+import type { AssertMapShape, SelectFunctionByDiscriminantValueInParams } from "../libs/types"
+
+export type AddItemToCartDecider = IDecide<
+  AddItemToCartCommand,
+  NewCartState | OpenCartState,
+  ItemAddedEvent
+>
+
+export type RemoveItemFromCartDecider = IDecide<
+  RemoveItemFromCartCommand,
+  OpenCartState,
+  ItemRemovedEvent
+>
+
+export type AddBillingDetailsDecider = IDecide<
+  AddBillingDetailsCommand,
+  OpenCartState,
+  BillingDetailsAddedEvent
+>
+
+export type Decider =
+  | AddItemToCartDecider
+  | RemoveItemFromCartDecider
+
+export type DeciderMap = {
+  [K in ExternalCommand["_tag"]]: SelectFunctionByDiscriminantValueInParams<Decider, "_tag", K>
+}
+const _assertDeciderMapShape: AssertMapShape<DeciderMap, ExternalCommand["_tag"], Decider> = true

src/orderManagement/evolvers.ts

@@ -0,0 +1,15 @@
+import type { BillingDetailsAddedEvent, ItemAddedEvent } from "./internalEvents"
+import type { NewCartState, OpenCartState } from "./states"
+import type { IEvolve } from "../functionalEventSourcing/types"
+
+export type openCartEvolve = IEvolve<
+  NewCartState | OpenCartState,
+  ItemAddedEvent,
+  OpenCartState
+>
+
+export type openCartWithBillingDetailsEvolve = IEvolve<
+  OpenCartState,
+  BillingDetailsAddedEvent,
+  OpenCartState
+>

src/orderManagement/externalCommands.ts

@@ -0,0 +1,18 @@
+import type { ICommand } from "../functionalEventSourcing/types"
+
+export interface AddItemToCartCommand extends ICommand {
+  _tag: "AddItemToCartCommand"
+}
+
+export interface RemoveItemFromCartCommand extends ICommand {
+  _tag: "RemoveItemFromCartCommand"
+}
+
+export interface AddBillingDetailsCommand extends ICommand {
+  _tag: "AddBillingDetailsCommand"
+}
+
+export type ExternalCommand =
+  | AddItemToCartCommand
+  | RemoveItemFromCartCommand
+  | AddBillingDetailsCommand

src/orderManagement/internalEvents.ts

@@ -0,0 +1,13 @@
+import type { IEvent } from "../functionalEventSourcing/types"
+
+export interface ItemAddedEvent extends IEvent {
+  _tag: "ItemAddedEvent"
+}
+
+export interface ItemRemovedEvent extends IEvent {
+  _tag: "ItemRemovedEvent"
+}
+
+export interface BillingDetailsAddedEvent extends IEvent {
+  _tag: "BillingDetailsAddedEvent"
+}

src/orderManagement/states.ts

@@ -0,0 +1,9 @@
+import type { IState } from "../functionalEventSourcing/types"
+
+export interface NewCartState extends IState {
+  _tag: "NewCartState"
+}
+
+export interface OpenCartState extends IState {
+  _tag: "OpenCartState"
+}

tsconfig.base.json

@@ -11,7 +11,7 @@
     "skipLibCheck": true,
     "emitDecoratorMetadata": true,
     "experimentalDecorators": true,
-    "moduleResolution": "NodeNext",
+    "moduleResolution": "bundler",
     "lib": ["ES2022", "DOM", "DOM.Iterable"],
     "types": [],
     "isolatedModules": true,
@@ -35,6 +35,6 @@
     "module": "NodeNext",
     "incremental": true,
     "removeComments": false,
-    "plugins": [{ "name": "@effect/language-service" }]
+    "plugins": [{ "name": "@effect/language-service" }],
   }
 }