feat: added wallet class and derive address feature

Signed-off-by: theanmolsharma <anmolsharma0234@gmail.com>

.gitignore

@@ -25,3 +25,4 @@ coverage
 
 # test
 test/wallet-db
+test/wallet

src/wallet/wallet.ts

@@ -1 +1,76 @@
-export class Wallet {}
+import { DbInterface } from './db';
+import { NetworkInterface } from './network';
+import { mnemonicToSeedSync } from 'bip39';
+import { payments } from 'bitcoinjs-lib';
+import BIP32Factory from 'bip32';
+import * as ecc from 'tiny-secp256k1';
+
+const bip32 = BIP32Factory(ecc);
+
+export type WalletConfigOptions = {
+    db: DbInterface;
+    networkClient: NetworkInterface;
+};
+
+export class Wallet {
+    private readonly db: DbInterface;
+    private readonly network: NetworkInterface;
+    private seed: string;
+    private receiveDepth: number = 0;
+    private changeDepth: number = 0;
+
+    constructor(config: WalletConfigOptions) {
+        this.db = config.db;
+        this.network = config.networkClient;
+        this.seed = mnemonicToSeedSync(
+            'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about',
+        ).toString('hex');
+    }
+
+    async init() {
+        await this.db.open();
+    }
+
+    async close() {
+        await this.db.setReceiveDepth(this.receiveDepth);
+        await this.db.setChangeDepth(this.changeDepth);
+
+        await this.db.close();
+    }
+
+    async load(mnemonic?: string) {
+        if (mnemonic) {
+            this.seed = mnemonicToSeedSync(mnemonic).toString('hex');
+            await this.db.setSeed(this.seed);
+        } else {
+            this.seed = await this.db.getSeed();
+        }
+    }
+
+    private deriveAddress(path: string): string {
+        const master = bip32.fromSeed(Buffer.from(this.seed, 'hex'));
+        const child = master.derivePath(path);
+        const { address } = payments.p2wpkh({
+            pubkey: child.publicKey,
+            network: this.network.network,
+        });
+
+        return address!;
+    }
+
+    async deriveReceiveAddress(): Promise<string> {
+        const path = `m/84'/0'/0'/0/${this.receiveDepth}`;
+        const address = this.deriveAddress(path);
+        await this.db.saveAddress(address, path);
+        this.receiveDepth++;
+        return address;
+    }
+
+    async deriveChangeAddress(): Promise<string> {
+        const path = `m/84'/0'/0'/1/${this.changeDepth}`;
+        const address = this.deriveAddress(path);
+        await this.db.saveAddress(address, path);
+        this.changeDepth++;
+        return address;
+    }
+}

test/wallet.spec.ts

@@ -0,0 +1,49 @@
+import { EsploraClient, Wallet, WalletDB } from '../src/wallet';
+
+describe('Wallet', () => {
+    let wallet: Wallet;
+
+    beforeAll(async () => {
+        const walletDB = new WalletDB({
+            location: './test/wallet',
+        });
+
+        wallet = new Wallet({
+            db: walletDB,
+            networkClient: new EsploraClient({
+                protocol: 'https',
+                host: 'blockstream.info',
+                network: 'main',
+            }),
+        });
+    });
+
+    it('should initialise the wallet', async () => {
+        await wallet.init();
+    });
+
+    it('should load the wallet', async () => {
+        await wallet.load(
+            'abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about',
+        );
+    });
+
+    it('should derive first receive address', async () => {
+        const address = await wallet.deriveReceiveAddress();
+        expect(address).toBe('bc1qcr8te4kr609gcawutmrza0j4xv80jy8z306fyu');
+    });
+
+    it('should derive second receive address', async () => {
+        const address = await wallet.deriveReceiveAddress();
+        expect(address).toBe('bc1qnjg0jd8228aq7egyzacy8cys3knf9xvrerkf9g');
+    });
+
+    it('should derive first change address', async () => {
+        const address = await wallet.deriveChangeAddress();
+        expect(address).toBe('bc1q8c6fshw2dlwun7ekn9qwf37cu2rn755upcp6el');
+    });
+
+    afterAll(async () => {
+        await wallet.close();
+    });
+});