@nervosnetwork/ckb-sdk-utils/lib-esm/reconcilers/extraInputs.js

Utils module of @nervosnetwork/ckb-sdk-core

import JSBI from 'jsbi';
import calculateTransactionFee from '../calculateTransactionFee.js';
import { getTransactionSize } from '../sizes.js';
import { ReconciliationException } from '../exceptions/index.js';
export const extraInputs = (params) => {
    const changeThreshold = JSBI.BigInt(`${params.changeThreshold}`);
    const feeRate = JSBI.BigInt(`${params.feeRate}`);
    const currentChangeOutput = params.tx.outputs[params.tx.outputs.length - 1];
    const currentChange = JSBI.BigInt(currentChangeOutput.capacity);
    const fee = JSBI.BigInt(calculateTransactionFee(`0x${getTransactionSize(params.tx).toString(16)}`, `0x${feeRate.toString(16)}`));
    const lack = JSBI.subtract(JSBI.add(fee, changeThreshold), currentChange);
    if (JSBI.LE(lack, JSBI.BigInt(0))) {
        return Object.assign(Object.assign({}, params.tx), { outputs: [
                ...params.tx.outputs.slice(0, -1),
                Object.assign(Object.assign({}, currentChangeOutput), { capacity: `0x${JSBI.subtract(currentChange, fee).toString(16)}` }),
            ] });
    }
    params.cells.sort((c1, c2) => +JSBI.subtract(JSBI.BigInt(c1.capacity), JSBI.BigInt(c2.capacity)));
    const SIZE_PER_INPUT = JSBI.BigInt(44);
    const FEE_PER_INPUT = JSBI.divide(JSBI.multiply(SIZE_PER_INPUT, feeRate), JSBI.BigInt(1000));
    for (let i = 1; i <= Math.min(params.extraCount, params.cells.length); i++) {
        const extraCost = JSBI.multiply(JSBI.BigInt(i), FEE_PER_INPUT);
        const totalLack = JSBI.add(lack, extraCost);
        const extraCapacity = params.cells
            .slice(0, i)
            .reduce((sum, c) => JSBI.add(sum, JSBI.BigInt(c.capacity)), JSBI.BigInt(0));
        if (JSBI.GE(extraCapacity, totalLack)) {
            const inputs = [
                ...params.tx.inputs,
                ...params.cells.slice(0, i).map(c => ({
                    previousOutput: c.outPoint,
                    since: '0x0',
                })),
            ];
            const change = JSBI.add(changeThreshold, JSBI.subtract(extraCapacity, totalLack));
            const changeOutput = Object.assign(Object.assign({}, currentChangeOutput), { capacity: `0x${change.toString(16)}` });
            const outputs = [...params.tx.outputs.slice(0, -1), changeOutput];
            const tx = Object.assign(Object.assign({}, params.tx), { inputs, outputs });
            return tx;
        }
    }
    throw new ReconciliationException();
};
export default extraInputs;
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