feat: refactor exchange rate handling by integrating new ExchangeService and removing CbeExchangeService

packages/api-common/src/services/exchange/exchange.options.ts

@@ -0,0 +1,46 @@
+/** Injection token carrying the resolved {@link ExchangeOptions}. */
+export const EXCHANGE_OPTIONS = Symbol("EXCHANGE_OPTIONS");
+
+/** Configuration for the {@link ExchangeService} and its CBE provider. */
+export interface ExchangeOptions {
+  /**
+   * ethio.forex CBET page scraped for USD buying/selling rates.
+   * @default 'https://ethio.forex/bank/CBET'
+   */
+  scrapeUrl?: string;
+
+  /**
+   * Base USD→ETB rate used when scraping fails and no previously cached rate
+   * exists. The ETB→USD direction is derived as its inverse.
+   * @default 130
+   */
+  fallbackRate?: number;
+
+  /**
+   * How long a successfully fetched rate is cached, in milliseconds.
+   * @default 3_600_000 (1 hour)
+   */
+  cacheTtlMs?: number;
+
+  /**
+   * Timeout for the scrape HTTP request, in milliseconds.
+   * @default 8_000
+   */
+  requestTimeoutMs?: number;
+}
+
+/** Defaults applied to any unset {@link ExchangeOptions} field. */
+export const EXCHANGE_DEFAULTS: Required<ExchangeOptions> = {
+  scrapeUrl: "https://ethio.forex/bank/CBET",
+  fallbackRate: 130,
+  cacheTtlMs: 3_600_000,
+  requestTimeoutMs: 8_000,
+};
+
+/** Factory contract for {@link ExchangeModule.forRootAsync}. */
+export interface ExchangeAsyncOptions {
+  /** Providers to inject into {@link useFactory} (e.g. `[ConfigService]`). */
+  inject?: unknown[];
+  /** Returns the options, possibly async. */
+  useFactory: (...args: never[]) => ExchangeOptions | Promise<ExchangeOptions>;
+}