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src/utils.js


const R = require('ramda');
const BN = require('bn.js');
const assert = require('assert');


const bb = require('./ballotBox');


/**
 * This will take an Ethereum hex string (or a normal hex string) and
 * output a normal hex string (no '0x' header) or throw an error on a
 * bad hex string.
 *
 * @param {string} hex
 *
 * @returns {string}
 *  the hex string.
 */
export const cleanEthHex = hex => {
    if (hex === "0x0") {
        return "00";
    }

    // hex must be even - only exception above
    if (hex.length % 2 !== 0) {
        throw Error(`Bad hex string: ${hex}`);
    }

    // this covers the case hex=="0x" => ""
    if (hex.slice(0, 2) === "0x") {
        return hex.slice(2);
    }

    return hex;
}


/**
 * This compares ethereum addresses (taking into account case, etc)
 *
 * @param {string} addr1
 * @param {string} addr2
 *
 * @returns {bool}
 */
export const ethAddrEq = (addr1, addr2) => {
    const _clean = a => module.exports.cleanEthHex(a).toLowerCase()
    // throw a length check in there to ensure we have valid addresses
    return _clean(addr1) === _clean(addr2) && addr1.length === 42
}


export const mkPacked = bb.mkPacked;
export const mkSubmissionBits = bb.mkSubmissionBits;


// this is from the bech32 spec (Bitcoin)
const B32_ALPHA = "qpzry9x8gf2tvdw0s3jn54khce6mua7l";
const toAlphabet = arr => {
    ret = "";
    for (let i = 0; i < arr.length; i++) {
        ret += B32_ALPHA.charAt(arr[i]);
    }
    return ret;
}


/**
 * This will convert a hex string to Base32 in the bech32 format WITHOUT a checksum.
 *
 * @param {string} hex
 *  The hex string to convert to Base32 - can be an EthHex or plain hex string.
 *
 * @returns {string}
 *  The Base32 version of the hex string.
 */
export const hexToBase32 = hex => {
    const _hex = cleanEthHex(hex);

    const buf = Buffer.from(_hex, 'hex');
    const digits = [0];
    let digitlength = 1;

    let carry;
    for (let i = 0; i < buf.length; ++i) {
        carry = buf[i];
        for (let j = 0; j < digitlength; ++j) {
            carry += digits[j] * 256;
            digits[j] = carry % 32;
            carry = (carry / 32) | 0;
        }

        while (carry > 0) {
            digits[digitlength] = carry % 32;
            digitlength++;
            carry = (carry / 32) | 0;
        }
    }

    return toAlphabet(R.reverse(digits.slice(0,digitlength)));
}