csgo/helpers/sharecode.js

'use strict';

var packJS = require('./pack.js');
var StringIO = require('./stringio.js');
var BigNumber = require('bignumber.js');
BigNumber.config({
	DECIMAL_PLACES: 43,
	EXPONENTIAL_AT: 50
});

class ByteReader {
	constructor(io) {
		this.io = io;
	}

	get read_int64() {
		var temp = this.io.read(8);
		var unpacked = packJS.unpack("C*", temp);
		var result = new BigNumber(0);
		Object.keys(unpacked).forEach(function(key) {
			var index = key - 1;
			var byte = unpacked[key];

			var a = new BigNumber(256).toPower(new BigNumber(index));
			var b = new BigNumber(byte).times(a);

			result = result.plus(b)
		});
		return result.toString();
	}

	get read_short() {
		var temp = this.io.read(2);
		var unpacked = packJS.unpack("S*", temp);
		return unpacked[''].toString();
	}
}

class SharecodeDecoder {
	constructor(code) {
		this.code = this.sanitize_code(code);
		this.originalCode = code;

		this.DICTIONARY = "ABCDEFGHJKLMNOPQRSTUVWXYZabcdefhijkmnopqrstuvwxyz23456789";
		this.DICTIONARY_LENGTH = this.DICTIONARY.length
	}

	decode() {
		var reader 		= new ByteReader(this.io);
		var matchId 	= reader.read_int64;
		var outcomeId	= reader.read_int64;
		var tokenId 	= reader.read_short;

		return {
			matchId: matchId,
			outcomeId: outcomeId,
			tokenId: tokenId
		};
	}

	sanitize_code(str) {
		return str.replace(/CSGO|\-/g, '');
	}

	get io() {
		return new StringIO.StringIO(this.decoded_code);
	}

	get decoded_code() {
		var self = this;
		var result = new Array(18).fill(0);
		var reversed = this.code.split('').reverse();
		reversed.forEach(function(char, index) {
			var addval = self.DICTIONARY.indexOf(char);
			var tmp = new Array(18).fill(0);
			var carry = 0;
			var v = 0;
			for(var t = 17; t >= 0; t--) {
				carry = 0;
				for(var s = t; s >= 0; s--) {
					if(t - s == 0) {
						v = tmp[s] + result[t] * 57;
					}else {
						v = 0;
					}
					v = v + carry;
					carry = v >> 8;
					tmp[s] = v & 0xFF;
				}
			}
			result = tmp;
			carry = 0;

			for(var t = 17; t >= 0; t--) {
				if(t == 17) {
					v = result[t] + addval;
				}else {
					v = result[t];
				}
				v = v + carry;
				carry = v >> 8;
				result[t] = v & 0xFF;
			}
		});

		result.unshift('C*');
		return packJS.pack.apply(this, result);	
	}
}

exports.SharecodeDecoder = SharecodeDecoder;