Update API and add observables

Author: jonathanhamel4

.changeset/wet-cycles-punch.md

@@ -0,0 +1,5 @@
+---
+'@shopify/ui-extensions': minor
+---
+
+Added subscribable discounts api

packages/ui-extensions/src/surfaces/admin/api/discount-function-settings/discount-function-settings.ts

@@ -2,7 +2,10 @@ import type {BlockExtensionApi} from '../block/block';
 import type {ExtensionTarget as AnyExtensionTarget} from '../../extension-targets';
 
 import {ApplyMetafieldChange} from './metafields';
-import {DiscountFunctionSettingsData} from './launch-options';
+import {
+  DiscountFunctionSettingsData,
+  SubscribableDiscountFields,
+} from './launch-options';
 
 export interface DiscountFunctionSettingsApi<
   ExtensionTarget extends AnyExtensionTarget,
@@ -12,4 +15,5 @@ export interface DiscountFunctionSettingsApi<
    */
   applyMetafieldChange: ApplyMetafieldChange;
   data: DiscountFunctionSettingsData;
+  discounts: SubscribableDiscountFields;
 }

packages/ui-extensions/src/surfaces/admin/api/discount-function-settings/launch-options.ts

@@ -7,23 +7,57 @@ interface Metafield {
   type: string;
 }
 
-export enum DiscountClass {
-  Product = 'PRODUCT',
-  Order = 'ORDER',
-  Shipping = 'SHIPPING',
-}
+type DiscountClass = 'product' | 'order' | 'shipping';
 
-interface Discount {
-  /**
-   * the discount's gid
-   */
-  id: string;
+type DiscountMethod = 'automatic' | 'code';
+
+type PurchaseType = 'one_time_purchase' | 'subscription' | 'both';
+
+type Result<T> =
+  | {success: true; value: T}
+  | {success: false; errors: ValidationError[]};
+
+interface ValidationError {
+  type: 'error';
+  message: string;
+  code: string;
+  issues?: {
+    message: string;
+    path: string[];
+  }[];
 }
 
 /**
  * The object that exposes the validation with its settings.
  */
 export interface DiscountFunctionSettingsData {
-  id: Discount;
+  id: string;
   metafields: Metafield[];
 }
+
+/**
+ * Represents a reactive signal interface that provides both immediate value access and subscription-based updates. Enables real-time synchronization with changing data through the observer pattern.
+ */
+export interface ReadonlySignalLike<T> {
+  /**
+   * The current value of the field.
+   */
+  readonly value: T;
+  /**
+   * Subscribes to field changes and calls the provided function whenever the field updates. Returns an unsubscribe function to clean up the subscription.
+   */
+  subscribe(fn: (value: T) => void): () => void;
+}
+
+type UpdateFunction<T> = (value: T) => Result<T>;
+
+export interface SubscribableDiscountFields {
+  discountClasses: ReadonlySignalLike<DiscountClass[]>;
+  updateDiscountClasses: UpdateFunction<DiscountClass[]>;
+  method: ReadonlySignalLike<DiscountMethod>;
+  updateMethod: UpdateFunction<DiscountMethod>;
+  purchaseType: ReadonlySignalLike<PurchaseType>;
+  updatePurchaseType: UpdateFunction<PurchaseType>;
+  recurringCycleLimit: ReadonlySignalLike<number | null | undefined>;
+  updateRecurringCycleLimit: UpdateFunction<number | null | undefined>;
+}