opnet/build/contracts/TransactionHelpper.js

The perfect library for building Bitcoin-based applications.

import { AddressTypes, AddressVerificator } from '@btc-vision/transaction';
export class TransactionHelper {
    static estimateMiningCost(utxos, extraOutputs, opReturnLen, network, feeRate) {
        const vBytes = this.estimateVBytes(utxos, extraOutputs, opReturnLen, network);
        return BigInt(Math.ceil(vBytes * feeRate));
    }
    static varIntLen(n) {
        return n < 0xfd ? 1 : n <= 0xffff ? 3 : n <= 0xffffffff ? 5 : 9;
    }
    static estimateVBytes(utxos, extraOutputs, scriptLength, network) {
        const INPUT_WU = {
            [AddressTypes.P2PKH]: 148 * 4,
            [AddressTypes.P2SH_OR_P2SH_P2WPKH]: 91 * 4 + 107,
            [AddressTypes.P2WPKH]: 41 * 4 + 107,
            [AddressTypes.P2TR]: 41 * 4 + 65,
            [AddressTypes.P2PK]: 148 * 4,
            [AddressTypes.P2WSH]: 41 * 4 + (1 + 73 + 1 + 33),
            [AddressTypes.P2OP]: 41 * 4 + 107,
            [AddressTypes.P2WDA]: 41 * 4 + 253,
        };
        const OUTPUT_BYTES = {
            [AddressTypes.P2PKH]: 34,
            [AddressTypes.P2SH_OR_P2SH_P2WPKH]: 32,
            [AddressTypes.P2WPKH]: 31,
            [AddressTypes.P2TR]: 43,
            [AddressTypes.P2PK]: 34,
            [AddressTypes.P2OP]: 32,
            [AddressTypes.P2WSH]: 43,
            [AddressTypes.P2WDA]: 43,
        };
        const ins = utxos.length ? utxos : new Array(3).fill(null);
        let weight = 0;
        weight += 8 * 4;
        const usesWitness = utxos.length === 0 ||
            utxos.some((u) => {
                const t = AddressVerificator.detectAddressType(u?.scriptPubKey?.address ?? '', network);
                return (t === AddressTypes.P2WPKH ||
                    t === AddressTypes.P2SH_OR_P2SH_P2WPKH ||
                    t === AddressTypes.P2TR ||
                    t === AddressTypes.P2OP ||
                    t === AddressTypes.P2WSH);
            });
        if (usesWitness)
            weight += 2 * 4;
        weight += this.varIntLen(ins.length) * 4;
        weight += this.varIntLen(extraOutputs.length) * 4;
        for (const u of ins) {
            const t = utxos.length === 0
                ? AddressTypes.P2TR
                : (AddressVerificator.detectAddressType(u?.scriptPubKey?.address ?? '', network) ?? AddressTypes.P2PKH);
            weight += INPUT_WU[t] ?? 110 * 4;
        }
        for (const o of extraOutputs) {
            if ('address' in o) {
                const t = AddressVerificator.detectAddressType(o.address, network) ?? AddressTypes.P2PKH;
                weight += (OUTPUT_BYTES[t] ?? 40) * 4;
            }
            else if ('script' in o) {
                const scriptLen = o.script.length;
                const bytes = 8 + this.varIntLen(scriptLen) + scriptLen;
                weight += bytes * 4;
            }
            else {
                weight += 34 * 4;
            }
        }
        const witnessBytes = 1 + 3 * (this.varIntLen(32) + 32);
        weight += witnessBytes;
        const stackItemScript = this.varIntLen(scriptLength) + scriptLength;
        const controlBlock = 1 + 33;
        weight += stackItemScript + controlBlock;
        return Math.ceil(weight / 4);
    }
}