var RollCalculator = function() {
        this.pattern = "";
    };

    RollCalculator.prototype = {
        setStrategy: function(pattern) {
            this.pattern = pattern;
        },

        calculate: function(rolls) {
            let wallWidth = document.getElementById("wallWidth").value;
            let wallHeight = document.getElementById("wallHeight").value;
            let rollWidth = document.getElementById("rollWidth").value / 100;
            let rollLength = document.getElementById("rollLength").value;
            let repeat = document.getElementById("repeat").value / 100;
            return this.pattern.calculate(wallWidth, wallHeight, rollLength, rollWidth, repeat);
        }
    };

    var StraightMatch = function() {
        this.calculate = function(wallWidth, wallHeight, rollLength, rollWidth, repeat) {
            let drops = wallWidth / rollWidth;
            let wastePerDrop = (repeat - (wallHeight % repeat));
            let totalLengthPerDrop = parseFloat(wallHeight) + parseFloat(wastePerDrop);
            let totalAddExtra = totalLengthPerDrop + (totalLengthPerDrop * (10 / 100));
            let dropsPerRoll = Math.floor(rollLength / totalAddExtra);
            let totalRolls = document.getElementById("rolls").value = drops / dropsPerRoll;
            return document.getElementById("rollsRounded").value = Math.ceil(totalRolls);
        }
    };

    var log = (function() {
        var log = "";

        return {
            add: function(msg) {
                log += msg + "\n";
            },
            show: function() {
                alert(log);
                log = "";
            }
        }
    })();

    function run() {
        var straightMatch = new StraightMatch();

        var rollCalculator = new RollCalculator();

        rollCalculator.setStrategy(straightMatch);
        log.add("Straight Match: " + rollCalculator.calculate());

        log.show();
    }