Differential D13960 Diff 40519 apps/alias-server/src/script.js

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apps/alias-server/src/script.js

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				// Copyright (c) 2023 The Bitcoin developers
				// Distributed under the MIT software license, see the accompanying
				// file COPYING or http://www.opensource.org/licenses/mit-license.php.
				'use strict';
				module.exports = {
				/**
				* consume
				* @param {object} stack an object containing a hex string outputScript of an eCash tx, e.g. {remainingHex: '6a...'}
				* An object is used for 'stack' to allow in-place modification without returning the input
				* @param {integer} byteCount integer
				* @throws {Error} if input is not supported,
				* i.e. if byteCount is not an integer or if byteCount exceeds outputScript bytes
				* @returns {string} consumed, a hex string of byteCount bytes
				* The stack object is modified in place so that consumed bytes are removed
				*/
				consume: function (stack, byteCount) {
				/**
				* Validation for stack
				* 1. Stack must be an object with key remainingHex
				* 2. remainingHex must have a value that is a string
				* 3. The length of remainingHex must be even, i.e. divisible by bytes
				*/
				console.log(`typeof stack.remainingHex`, typeof stack.remainingHex);
				if (
				typeof stack !== 'object' \|\|
				typeof stack.remainingHex !== 'string'
				) {
				throw new Error(
				'Invalid input. Stack must be an object with string stored at key remainingHex.',
				);
				}
				if (stack.remainingHex.length % 2 === 1) {
				throw new Error(
				'Invalid input: stack.remainingHex must be divisible by bytes, i.e. have an even length.',
				);
				}
				// Throw an error if byteCount input is not an integer
				if (!Number.isInteger(byteCount)) {
				throw new Error(
				`byteCount must be an integer, received ${byteCount}`,
				);
				}
				// One byte is 2 characters of a hex string
				const byteLength = 2;

				// Get byte slice size
				const byteSliceSize = byteCount * byteLength;

				// Throw an error if byteCount is greater than consumable hex bytes in outputScript
				if (byteSliceSize > stack.remainingHex.length) {
				throw new Error(
				`consume called with byteCount (${byteCount}) greater than remaining bytes in outputScript (${
				stack.remainingHex.length / byteLength
				})`,
				);
				}
				// Get consumed bytes
				const consumed = stack.remainingHex.slice(0, byteSliceSize);
				// Remove consumed from the stack
				stack.remainingHex = stack.remainingHex.slice(byteSliceSize);
				return consumed;
				},
				};