# all files / packages/web3-utils/src/ utils.js

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     /*
     This file is part of web3.js.

     web3.js is free software: you can redistribute it and/or modify
     it under the terms of the GNU Lesser General Public License as published by
     the Free Software Foundation, either version 3 of the License, or
     (at your option) any later version.

     web3.js is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU Lesser General Public License for more details.

     You should have received a copy of the GNU Lesser General Public License
     along with web3.js.  If not, see <http://www.gnu.org/licenses/>.
     */
    /**
     * @file utils.js
     * @author Fabian Vogelsteller <fabian@ethereum.org>
     * @date 2017
     */

    var _ = require('underscore');
    var BN = require('bn.js');
    var numberToBN = require('number-to-bn');
    var utf8 = require('utf8');
    var Hash = require("eth-lib/src/hash");

    /**
     * Returns true if object is BN, otherwise false
     *
     * @method isBN
     * @param {Object} object
     * @return {Boolean}
     */
    var isBN = function (object) {
        return object instanceof BN ||
            (object && object.constructor && object.constructor.name === 'BN');
    };

    /**
     * Returns true if object is BigNumber, otherwise false
     *
     * @method isBigNumber
     * @param {Object} object
     * @return {Boolean}
     */
    var isBigNumber = function (object) {
        return object && object.constructor && object.constructor.name === 'BigNumber';
    };

    /**
     * Takes an input and transforms it into an BN
     *
     * @method toBN
     * @param {Number|String|BN} number, string, HEX string or BN
     * @return {BN} BN
     */
    var toBN = function(number){
        try {
            return numberToBN.apply(null, arguments);
        } catch(e) {
            throw new Error(e + ' Given value: "'+ number +'"');
        }
    };

    /**
     * Checks if the given string is an address
     *
     * @method isAddress
     * @param {String} address the given HEX address
     * @return {Boolean}
     */
    var isAddress = function (address) {
        // check if it has the basic requirements of an address
        if (!/^(0x)?[0-9a-f]{40}$/i.test(address)) {
            return false;
            // If it's ALL lowercase or ALL upppercase
        } else if (/^(0x|0X)?[0-9a-f]{40}$/.test(address) || /^(0x|0X)?[0-9A-F]{40}$/.test(address)) {
            return true;
            // Otherwise check each case
        } else {
            return checkAddressChecksum(address);
        }
    };

    /**
     * Checks if the given string is a checksummed address
     *
     * @method checkAddressChecksum
     * @param {String} address the given HEX address
     * @return {Boolean}
     */
    var checkAddressChecksum = function (address) {
        // Check each case
        address = address.replace(/^0x/i,'');
        var addressHash = sha3(address.toLowerCase()).replace(/^0x/i,'');

        for (var i = 0; i < 40; i++ ) {
            // the nth letter should be uppercase if the nth digit of casemap is 1
            if ((parseInt(addressHash[i], 16) > 7 && address[i].toUpperCase() !== address[i]) || (parseInt(addressHash[i], 16) <= 7 && address[i].toLowerCase() !== address[i])) {
                return false;
            }
        }
        return true;
    };

    /**
     * Should be called to pad string to expected length
     *
     * @method leftPad
     * @param {String} string to be padded
     * @param {Number} chars that result string should have
     * @param {String} sign, by default 0
     * @returns {String} right aligned string
     */
    var leftPad = function (string, chars, sign) {
        var hasPrefix = /^0x/i.test(string) || typeof string === 'number';
        string = string.toString(16).replace(/^0x/i,'');

        var padding = (chars - string.length + 1 >= 0) ? chars - string.length + 1 : 0;

        return (hasPrefix ? '0x' : '') + new Array(padding).join(sign ? sign : "0") + string;
    };

    /**
     * Should be called to pad string to expected length
     *
     * @method rightPad
     * @param {String} string to be padded
     * @param {Number} chars that result string should have
     * @param {String} sign, by default 0
     * @returns {String} right aligned string
     */
    var rightPad = function (string, chars, sign) {
        var hasPrefix = /^0x/i.test(string) || typeof string === 'number';
        string = string.toString(16).replace(/^0x/i,'');

        var padding = (chars - string.length + 1 >= 0) ? chars - string.length + 1 : 0;

        return (hasPrefix ? '0x' : '') + string + (new Array(padding).join(sign ? sign : "0"));
    };

    /**
     * Should be called to get hex representation (prefixed by 0x) of utf8 string
     *
     * @method utf8ToHex
     * @param {String} str
     * @returns {String} hex representation of input string
     */
    var utf8ToHex = function(str) {
        str = utf8.encode(str);
        var hex = "";

        // remove \u0000 padding from either side
        str = str.replace(/^(?:\u0000)*/,'');
        str = str.split("").reverse().join("");
        str = str.replace(/^(?:\u0000)*/,'');
        str = str.split("").reverse().join("");

        for(var i = 0; i < str.length; i++) {
            var code = str.charCodeAt(i);
            // if (code !== 0) {
            var n = code.toString(16);
            hex += n.length < 2 ? '0' + n : n;
            // }
        }

        return "0x" + hex;
    };

    /**
     * Should be called to get utf8 from it's hex representation
     *
     * @method hexToUtf8
     * @param {String} hex
     * @returns {String} ascii string representation of hex value
     */
    var hexToUtf8 = function(hex) {
        Iif (!isHex(hex))
            throw new Error('The parameter "'+ hex +'" must be a valid HEX string.');

        var str = "";
        var code = 0;
        hex = hex.replace(/^0x/i,'');

        // remove 00 padding from either side
        hex = hex.replace(/^(?:00)*/,'');
        hex = hex.split("").reverse().join("");
        hex = hex.replace(/^(?:00)*/,'');
        hex = hex.split("").reverse().join("");

        var l = hex.length;

        for (var i=0; i < l; i+=2) {
            code = parseInt(hex.substr(i, 2), 16);
            // if (code !== 0) {
            str += String.fromCharCode(code);
            // }
        }

        return utf8.decode(str);
    };

    /**
     * Converts value to it's number representation
     *
     * @method hexToNumber
     * @param {String|Number|BN} value
     * @return {String}
     */
    var hexToNumber = function (value) {
        if (!value) {
            return value;
        }

        return toBN(value).toNumber();
    };

    /**
     * Converts value to it's decimal representation in string
     *
     * @method hexToNumberString
     * @param {String|Number|BN} value
     * @return {String}
     */
    var hexToNumberString = function (value) {
        Iif (!value) return value;

        return toBN(value).toString(10);
    };

    /**
     * Converts value to it's hex representation
     *
     * @method numberToHex
     * @param {String|Number|BN} value
     * @return {String}
     */
    var numberToHex = function (value) {
        Iif (!isFinite(value) && !_.isString(value)) {
            return value;
        }

        var number = toBN(value);
        var result = number.toString(16);

        return number.lt(new BN(0)) ? '-0x' + result.substr(1) : '0x' + result;
    };

    /**
     * Convert a byte array to a hex string
     *
     * Note: Implementation from crypto-js
     *
     * @method bytesToHex
     * @param {Array} bytes
     * @return {String} the hex string
     */
    var bytesToHex = function(bytes) {
        for (var hex = [], i = 0; i < bytes.length; i++) {
            /* jshint ignore:start */
            hex.push((bytes[i] >>> 4).toString(16));
            hex.push((bytes[i] & 0xF).toString(16));
            /* jshint ignore:end */
        }
        return '0x'+ hex.join("");
    };

    /**
     * Convert a hex string to a byte array
     *
     * Note: Implementation from crypto-js
     *
     * @method hexToBytes
     * @param {string} hex
     * @return {Array} the byte array
     */
    var hexToBytes = function(hex) {
        hex = hex.toString(16);

        Iif (!isHex(hex)) {
            throw new Error('Given value "'+ hex +'" is not a valid hex string.');
        }

        hex = hex.replace(/^0x/i,'');

        for (var bytes = [], c = 0; c < hex.length; c += 2)
            bytes.push(parseInt(hex.substr(c, 2), 16));
        return bytes;
    };

    /**
     * Auto converts any given value into it's hex representation.
     *
     * And even stringifys objects before.
     *
     * @method toHex
     * @param {String|Number|BN|Object} value
     * @param {Boolean} returnType
     * @return {String}
     */
    var toHex = function (value, returnType) {
        /*jshint maxcomplexity: false */

        if (isAddress(value)) {
            return returnType ? 'address' : '0x'+ value.toLowerCase().replace(/^0x/i,'');
        }

        if (_.isBoolean(value)) {
            return returnType ? 'bool' : value ? '0x01' : '0x00';
        }

        if (_.isObject(value) && !isBigNumber(value) && !isBN(value)) {
            return returnType ? 'string' : utf8ToHex(JSON.stringify(value));
        }

        // if its a negative number, pass it through numberToHex
        if (_.isString(value)) {
            if (value.indexOf('-0x') === 0 || value.indexOf('-0X') === 0) {
                return returnType ? 'int256' : numberToHex(value);
            } else if(value.indexOf('0x') === 0 || value.indexOf('0X') === 0) {
                return returnType ? 'bytes' : value;
            } else if (!isFinite(value)) {
                return returnType ? 'string' : utf8ToHex(value);
            }
        }

        return returnType ? (value < 0 ? 'int256' : 'uint256') : numberToHex(value);
    };

    /**
     * Check if string is HEX
     *
     * @method isHex
     * @param {String} hex to be checked
     * @returns {Boolean}
     */
    var isHex = function (hex) {
        return ((_.isString(hex) || _.isNumber(hex)) && /^(-)?0x[0-9a-f]+$/i.test(hex));
    };

    /**
     * Returns true if given string is a valid Ethereum block header bloom.
     *
     * TODO UNDOCUMENTED
     *
     * @method isBloom
     * @param {String} hex encoded bloom filter
     * @return {Boolean}
     */
    var isBloom = function (bloom) {
        Iif (!/^(0x)?[0-9a-f]{512}$/i.test(bloom)) {
            return false;
        } else Eif (/^(0x)?[0-9a-f]{512}$/.test(bloom) || /^(0x)?[0-9A-F]{512}$/.test(bloom)) {
            return true;
        }
        return false;
    };

    /**
     * Returns true if given string is a valid log topic.
     *
     * TODO UNDOCUMENTED
     *
     * @method isTopic
     * @param {String} hex encoded topic
     * @return {Boolean}
     */
    var isTopic = function (topic) {
        Iif (!/^(0x)?[0-9a-f]{64}$/i.test(topic)) {
            return false;
        } else Eif (/^(0x)?[0-9a-f]{64}$/.test(topic) || /^(0x)?[0-9A-F]{64}$/.test(topic)) {
            return true;
        }
        return false;
    };

    /**
     * Hashes values to a sha3 hash using keccak 256
     *
     * To hash a HEX string the hex must have 0x in front.
     *
     * @method sha3
     * @return {String} the sha3 string
     */
    var SHA3_NULL_S = '0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470';

    var sha3 = function (value) {
        if (isHex(value) && /^0x/i.test((value).toString())) {
            value = hexToBytes(value);
        }

        var returnValue = Hash.keccak256(value); // jshint ignore:line

        Iif(returnValue === SHA3_NULL_S) {
            return null;
        } else {
            return returnValue;
        }
    };
    // expose the under the hood keccak256
    sha3._Hash = Hash;

    module.exports = {
        BN: BN,
        isBN: isBN,
        isBigNumber: isBigNumber,
        toBN: toBN,
        isAddress: isAddress,
        isBloom: isBloom, // TODO UNDOCUMENTED
        isTopic: isTopic, // TODO UNDOCUMENTED
        checkAddressChecksum: checkAddressChecksum,
        utf8ToHex: utf8ToHex,
        hexToUtf8: hexToUtf8,
        hexToNumber: hexToNumber,
        hexToNumberString: hexToNumberString,
        numberToHex: numberToHex,
        toHex: toHex,
        hexToBytes: hexToBytes,
        bytesToHex: bytesToHex,
        isHex: isHex,
        leftPad: leftPad,
        rightPad: rightPad,
        sha3: sha3
    };