@cityofzion/neon-api/lib/api/calculateNetworkFee.js

Neon-API module: High level API for neon-js

import { tx, sc, u, wallet } from "@cityofzion/neon-core";
/**
 * Calculates the network fee required to process the transaction.
 * The fields signers, attributes and script needs to be fully populated for this to work.
 *
 * @param txn - A partially filled out transaction.
 * @param feePerByte - The current feePerByte in Policy contract.
 * @param signingAccts - The accounts that will be signing this.
 *
 * @deprecated use the smartCalculateNetworkFee helper instead.
 */
export function calculateNetworkFee(txn, feePerByte, executionFeeFactor) {
    const feePerByteBigInteger = feePerByte instanceof u.BigInteger
        ? feePerByte
        : u.BigInteger.fromNumber(feePerByte);
    const txClone = new tx.Transaction(txn);
    txClone.witnesses = txn.witnesses.map((w) => {
        const verificationScript = w.verificationScript;
        if (sc.isMultisigContract(verificationScript)) {
            const threshold = wallet.getSigningThresholdFromVerificationScript(verificationScript.toBigEndian());
            return new tx.Witness({
                invocationScript: generateFakeInvocationScript()
                    .toScript()
                    .repeat(threshold),
                verificationScript,
            });
        }
        else {
            return new tx.Witness({
                invocationScript: generateFakeInvocationScript().toScript(),
                verificationScript,
            });
        }
    });
    const verificationExecutionFee = txClone.witnesses.reduce((totalFee, witness) => {
        return totalFee
            .add(sc.calculateExecutionFee(witness.invocationScript.toBigEndian(), executionFeeFactor))
            .add(sc.calculateExecutionFee(witness.verificationScript.toBigEndian(), executionFeeFactor));
    }, u.BigInteger.fromNumber(0));
    const sizeFee = feePerByteBigInteger.mul(txClone.serialize(true).length / 2);
    return sizeFee.add(verificationExecutionFee);
}
function generateFakeInvocationScript() {
    return new sc.OpToken(sc.OpCode.PUSHDATA1, "0".repeat(128));
}
export async function smartCalculateNetworkFee(txn, client) {
    const txClone = new tx.Transaction(txn);
    if (txn.witnesses.length < 1) {
        throw new Error("Cannot calculate network fee without at least one witness");
    }
    txClone.witnesses = txn.witnesses.map((w) => {
        const verificationScript = w.verificationScript;
        if (sc.isMultisigContract(verificationScript)) {
            const threshold = wallet.getSigningThresholdFromVerificationScript(verificationScript.toBigEndian());
            return new tx.Witness({
                invocationScript: generateFakeInvocationScript()
                    .toScript()
                    .repeat(threshold),
                verificationScript,
            });
        }
        else {
            return new tx.Witness({
                invocationScript: generateFakeInvocationScript().toScript(),
                verificationScript,
            });
        }
    });
    const result = await client.calculateNetworkFee(txClone);
    return u.BigInteger.fromNumber(result);
}
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