nullcart/backend/src/modules/bitcoinWallet/services/ElectrumWalletRpcClient.ts

import { Injectable } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import axios from 'axios';
import type { Config } from '../../../types/Config';
import { addAtomic } from '../../../utils/atomic/addAtomic';
import { convertBtcToBtcAtomic } from '../../../utils/bitcoin/convertBtcToBtcAtomic';
import type { ElectrumWalletAddressHistoryEntry } from '../types/ElectrumWalletAddressHistoryEntry';
import type { ElectrumWalletDeserializedTransaction } from '../types/ElectrumWalletDeserializedTransaction';
import type { ElectrumWalletGetBalanceResult } from '../types/ElectrumWalletGetBalanceResult';
import type { ElectrumWalletGetInfoResult } from '../types/ElectrumWalletGetInfoResult';
import type { ElectrumWalletIncomingTransfer } from '../types/ElectrumWalletIncomingTransfer';
import type { ElectrumWalletRpcResponse } from '../types/ElectrumWalletRpcResponse';

@Injectable()
export class ElectrumWalletRpcClient {
    constructor(private readonly configService: ConfigService) {}

    private async call<T>(
        method: string,
        params: Record<string, unknown> | unknown[] = {},
        options: { timeoutMs?: number } = {}
    ): Promise<T> {
        const { rpcUrl, username, password, rpcTimeoutMs } = this.configService.get(
            'electrumWallet'
        ) as Config['electrumWallet'];

        const { data } = await axios.post<ElectrumWalletRpcResponse<T>>(
            rpcUrl,
            {
                jsonrpc: '2.0',
                id: 'nullcart',
                method,
                params
            },
            {
                timeout: options.timeoutMs ?? rpcTimeoutMs,
                auth: {
                    username,
                    password
                }
            }
        );

        if (data.error) {
            throw new Error(data.error.message);
        }

        if (data.result === undefined) {
            throw new Error(`Electrum wallet RPC ${method} returned no result`);
        }

        return data.result;
    }

    async getVersion(): Promise<string> {
        const version = await this.call<string>('version');

        if (!version) {
            throw new Error('Electrum wallet RPC version returned no version');
        }

        return version;
    }

    async isSynchronized(): Promise<boolean> {
        return this.call<boolean>('is_synchronized');
    }

    async getInfo(): Promise<ElectrumWalletGetInfoResult> {
        return this.call<ElectrumWalletGetInfoResult>('getinfo');
    }

    async getBalance(): Promise<{ balanceAtomic: string; confirmedBalanceAtomic: string }> {
        const { confirmed, unconfirmed } = await this.call<ElectrumWalletGetBalanceResult>('getbalance');

        if (confirmed === undefined) {
            throw new Error('Electrum wallet RPC getbalance returned incomplete result');
        }

        const confirmedAtomic = convertBtcToBtcAtomic(confirmed);

        const unconfirmedAtomic =
            unconfirmed !== undefined && unconfirmed !== '0' ? convertBtcToBtcAtomic(unconfirmed) : '0';

        return {
            balanceAtomic: addAtomic(confirmedAtomic, unconfirmedAtomic),
            confirmedBalanceAtomic: confirmedAtomic
        };
    }

    async sweepAll(
        destinationAddress: string,
        feeRateSatVbyte: number
    ): Promise<{ txHash: string; amountAtomic: string }> {
        const signedTransaction = await this.payToMax(destinationAddress, feeRateSatVbyte);
        const transaction = await this.deserializeTransaction(signedTransaction);

        const amountAtomic = this.sumOutputValueAtomic(transaction, destinationAddress);

        if (amountAtomic === '0') {
            throw new Error('Withdrawal transaction has no spendable output to the destination address');
        }

        const txHash = await this.broadcast(signedTransaction);

        return { txHash, amountAtomic };
    }

    private async payToMax(destinationAddress: string, feeRateSatVbyte: number): Promise<string> {
        const { walletPassword } = this.configService.get('electrumWallet') as Config['electrumWallet'];

        const signedTransaction = await this.call<string>(
            'payto',
            {
                destination: destinationAddress,
                amount: '!',
                feerate: String(feeRateSatVbyte),
                password: walletPassword
            },
            { timeoutMs: 120_000 }
        );

        if (!signedTransaction) {
            throw new Error('Electrum wallet RPC payto returned no transaction');
        }

        return signedTransaction;
    }

    private async broadcast(signedTransaction: string): Promise<string> {
        const txHash = await this.call<string>('broadcast', { tx: signedTransaction });

        if (!txHash) {
            throw new Error('Electrum wallet RPC broadcast returned no transaction hash');
        }

        return txHash;
    }

    private async deserializeTransaction(signedTransaction: string): Promise<ElectrumWalletDeserializedTransaction> {
        return this.call<ElectrumWalletDeserializedTransaction>('deserialize', { tx: signedTransaction });
    }

    private sumOutputValueAtomic(transaction: ElectrumWalletDeserializedTransaction, address: string): string {
        if (!Array.isArray(transaction.outputs)) {
            return '0';
        }

        return transaction.outputs.reduce((sum, output) => {
            if (output.address !== address || !Number.isFinite(output.value_sats) || output.value_sats <= 0) {
                return sum;
            }

            return addAtomic(sum, String(output.value_sats));
        }, '0');
    }

    async getSeed(): Promise<string> {
        const { walletPassword } = this.configService.get('electrumWallet') as Config['electrumWallet'];

        const mnemonic = await this.call<string>('getseed', { password: walletPassword });

        if (!mnemonic) {
            throw new Error('Electrum wallet RPC getseed returned no mnemonic');
        }

        return mnemonic;
    }

    async createAddress(label?: string): Promise<string> {
        const address = await this.call<string>('createnewaddress');

        if (!address) {
            throw new Error('Electrum wallet RPC createnewaddress returned no address');
        }

        if (label) {
            await this.call('setlabel', { key: address, label });
        }

        return address;
    }

    async getIncomingTransfers(address: string, blockHeight: number | null): Promise<ElectrumWalletIncomingTransfer[]> {
        const history = await this.call<ElectrumWalletAddressHistoryEntry[]>('getaddresshistory', {
            address
        });

        if (!Array.isArray(history)) {
            throw new Error('Electrum wallet RPC getaddresshistory returned invalid result');
        }

        const transfers = await Promise.all(
            history.map(async entry => {
                const txHash = entry.tx_hash;

                if (!txHash) {
                    return null;
                }

                const serializedTransaction = await this.call<string>('gettransaction', { txid: txHash });
                const transaction = await this.deserializeTransaction(serializedTransaction);
                const amountAtomic = this.sumOutputValueAtomic(transaction, address);

                return this.mapIncomingTransfer(entry, amountAtomic, blockHeight);
            })
        );

        return transfers.filter((transfer): transfer is ElectrumWalletIncomingTransfer => transfer !== null);
    }

    private mapIncomingTransfer(
        entry: ElectrumWalletAddressHistoryEntry,
        amountAtomic: string,
        blockHeight: number | null
    ): ElectrumWalletIncomingTransfer | null {
        const txHash = entry.tx_hash;

        if (!txHash || amountAtomic === '0') {
            return null;
        }

        const confirmations =
            entry.height > 0 && blockHeight !== null ? Math.max(blockHeight - entry.height + 1, 0) : 0;

        return {
            txHash,
            amountAtomic,
            confirmations
        };
    }
}