feat(sdk): add mempool client (#394)

sdk/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@gobob/bob-sdk",
-  "version": "3.0.0",
+  "version": "3.0.1",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
   "scripts": {

sdk/src/index.ts

@@ -5,3 +5,4 @@ export * from './ordinals';
 export * from './helpers';
 export * from './wallet';
 export * from './gateway';
+export * from './mempool';

sdk/src/mempool.ts

@@ -0,0 +1,102 @@
+/**
+ * Base path for the mainnet Memopool API.
+ * @default "https://btc-mainnet.gobob.xyz"
+ */
+export const MAINNET_MEMPOOL_BASE_PATH = 'https://mempool.space/api/v1/';
+/**
+ * Base path for the testnet Memopool API.
+ * @default "https://btc-testnet.gobob.xyz"
+ */
+export const TESTNET_MEMPOOL_BASE_PATH = 'https://mempool.space/testnet4/api/v1';
+/**
+ * Base path for the regtest Memopool API.
+ * @default "http://localhost:3003"
+ */
+export const REGTEST_MEMPOOL_BASE_PATH = 'http://localhost:3003';
+
+/**
+ * @ignore
+ */
+export type MempoolRecomendedFee = {
+    fastestFee: number;
+    halfHourFee: number;
+    hourFee: number;
+    economyFee: number;
+    minimumFee: number;
+};
+
+export class MempoolClient {
+    private basePath: string;
+
+    /**
+     * Create an instance of the `MempoolPool` with the specified network or URL.
+     * If the `networkOrUrl` parameter is omitted, it defaults to "mainnet."
+     *
+     * @param networkOrUrl The Bitcoin network (e.g., "mainnet," "testnet," "regtest")
+     *
+     * @returns An instance of the `MempoolPool` configured for the specified network or URL.
+     *
+     * @example
+     * const BITCOIN_NETWORK = "regtest";
+     * const mempoolClient = new MempoolPool(BITCOIN_NETWORK);
+     *
+     * @example
+     * // Create a client for the mainnet using the default URL.
+     * const mempoolClientMainnet = new MempoolPool();
+     */
+    constructor(networkOrUrl: string = 'mainnet') {
+        switch (networkOrUrl) {
+            case 'mainnet':
+                this.basePath = MAINNET_MEMPOOL_BASE_PATH;
+                break;
+            case 'testnet':
+                this.basePath = TESTNET_MEMPOOL_BASE_PATH;
+                break;
+            case 'regtest':
+                this.basePath = REGTEST_MEMPOOL_BASE_PATH;
+                break;
+            default:
+                this.basePath = networkOrUrl;
+        }
+    }
+
+    /**
+     * Get the recommended Bitcoin transaction fee rates from the Mempool API.
+     *
+     * This method returns the fee estimates in satoshis per virtual byte (sat/vB)
+     * for different confirmation targets, including:
+     *
+     * - `fastestFee`: The fee rate for transactions that are likely to be included
+     *   in the next block (fastest possible confirmation).
+     * - `halfHourFee`: The fee rate for transactions that are likely to be confirmed
+     *   within 30 minutes.
+     * - `hourFee`: The fee rate for transactions that are likely to be confirmed
+     *   within an hour.
+     * - `economyFee`: The fee rate for transactions that are likely to be confirmed
+     *   in a longer period (low priority).
+     * - `minimumFee`: The lowest fee rate that is still accepted by miners.
+     *
+     * @returns {Promise<MempoolRecomendedFee>} A promise that resolves to an object containing
+     * the recommended fees for various confirmation times.
+     *
+     * @example
+     * const mempoolClient = new MempoolClient();
+     * mempoolClient.getRecommendedFees()
+     *   .then(fees => console.log(fees))
+     *   .catch(error => console.error('Failed to fetch fees:', error));
+     */
+    async getRecommendedFees(): Promise<MempoolRecomendedFee> {
+        return this.getJson<MempoolRecomendedFee>(`${this.basePath}/fees/recommended`);
+    }
+
+    /**
+     * @ignore
+     */
+    private async getJson<T>(url: string): Promise<T> {
+        const response = await fetch(url);
+        if (!response.ok) {
+            throw new Error(response.statusText);
+        }
+        return (await response.json()) as Promise<T>;
+    }
+}

sdk/test/mempool.test.ts

@@ -0,0 +1,41 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { MempoolClient } from '../src/mempool';
+
+const MOCKS = {
+    fees: {
+        recommended: {
+            fastestFee: 100,
+            halfHourFee: 80,
+            hourFee: 60,
+            economyFee: 40,
+            minimumFee: 10,
+        },
+    },
+};
+
+describe('Mempool Tests', () => {
+    const client = new MempoolClient();
+
+    beforeEach(() => {
+        // Mock the fetch API only for URLs including /fees/recommended
+        global.fetch = vi.fn((url) => {
+            if (url.includes('/fees/recommended')) {
+                return Promise.resolve({
+                    ok: true,
+                    json: () => Promise.resolve(MOCKS.fees.recommended),
+                } as Response);
+            }
+            return Promise.reject(new Error('Unexpected URL'));
+        });
+    });
+
+    afterEach(() => {
+        vi.clearAllMocks();
+    });
+
+    it('should get recommended fee', async () => {
+        const fees = await client.getRecommendedFees();
+
+        expect(fees).toEqual(MOCKS.fees.recommended);
+    });
+});