Rollux/diceRolling.js

module.exports = {
    roll: function (req) {
        if (typeof req !== "string") {
            return "Mollux! You don goofed!"
        }

        // Splits request into segments. Example "3d6+3+5d2" => ["3d6", "+3", "+5d2"]
        var segments = req.replace(/\s/g, '').match(/([+\-]?\d{0,}d\d{1,})|([+\-*/]\d{1,})/gi)

        var message = '';

        var i = -1
        var results = []
        var curResult = 0
        var curMod = 1
        segments.forEach(e => {
            if (e.match(/([+\-]?\d{0,}d\d{1,})/gi)) { // xdy
                // if not first add previous result and resetting curResult
                if (i >= 0) {
                    curResult *= curMod
                    results[i] = curResult

                    curResult = 0
                }
                i++;

                // Set modifier for dice group
                curMod = (e.substring(0, 1) === '-') ? -1 : 1

                // dice[0] = number of rolls, dice[1] = sides of dice rolled
                var dice = e.replace(/[+\-]?/, '').split(/d/i)
                var rolls = []
                for (var l = 0; l < parseInt(dice[0] === '' ? 1 : dice[0]); l++) {
                    rolls[l] = rollDice(dice[1])
                    curResult += rolls[l]
                }

                // add result to message
                var sign = e.match(/[+\-]/)
                message += ((sign === null) ? ' ' :  ' ' + sign) + '[' + rolls.toString() + ']'
            } else if (e.match(/([+\-*/]\d{1,})/gi)) { // Modifier
                switch (e.substring(0, 1)) {
                    case '+':
                        curResult += parseInt(e.substring(1))
                        break;
                    case '-':
                        curResult -= parseInt(e.substring(1))
                        break;
                    case '*':
                    case 'x':
                        curResult *= parseInt(e.substring(1))
                        break;
                    case '/':
                        curResult /= parseInt(e.substring(1))
                        break;
                }
                message += e
            }
        })
        curResult *= curMod
        results[i] = curResult

        
        // Adding the sum to the message
        var sum = 0
        if (results.length > 1){
            sum = results.reduce(getSum)
        } else if (results.length === 1){
            sum = results[0]
        }
        message += ' = ' + sum
        
        console.log(results.toString())
        console.log(i)
        console.log(sum)

        return message
    }
}

/**
 * Roll one dice, returns result
 * @param {int} dice Amount of sides od dice rolled
 */
function rollDice(dice) {
    return parseInt((Math.random() * dice) + 1)
}

function getSum(total, num) {
    return total + num
}