feat: add pricing service interface

libs/pricing/src/index.ts

@@ -1,2 +1,3 @@
 export * from "./pricing.module";
 export * from "./services/coingecko.service";
+export * from "./interfaces";

libs/pricing/src/interfaces/index.ts

@@ -0,0 +1 @@
+export * from "./pricing.interface";

libs/pricing/src/interfaces/pricing.interface.ts

@@ -0,0 +1,19 @@
+/**
+ * Represents a pricing service that provides token prices.
+ */
+/**
+ * Represents a pricing service that retrieves token prices.
+ */
+export interface IPricingService {
+    /**
+     * Retrieves the prices of the specified tokens.
+     * @param tokenIds - An array of token IDs.
+     * @param [config] - Optional configuration object.
+     * @param config.currency - The currency in which the prices should be returned.
+     * @returns A promise that resolves to a record containing the token IDs as keys and their corresponding prices as values.
+     */
+    getTokenPrices<TokenId extends string = string>(
+        tokenIds: TokenId[],
+        config?: { currency: string },
+    ): Promise<Record<string, number>>;
+}

libs/pricing/src/services/coingecko.service.ts

@@ -1,7 +1,15 @@
 import { Injectable } from "@nestjs/common";
+import { IPricingService } from "@packages/pricing/interfaces";
 
 @Injectable()
-export class CoingeckoService {
+export class CoingeckoService implements IPricingService {
     private readonly API_BASE_URL = "https://api.coingecko.com/api/v3/";
     constructor(private readonly apiKey: string) {}
+
+    async getTokenPrices(
+        _tokenIds: string[],
+        _config: { currency: string } = { currency: "usd" },
+    ): Promise<Record<string, number>> {
+        throw new Error("Method not implemented.");
+    }
 }