var toyota = {
    make: "Toyota",
    model: "Corolla",
    year: 2015,
    color: "White",
    passengers: 5,
    convertible: false,
    milage: 58000,
    engineStarted: false,
    fuelCapacityMax: 19,
    fuelLevelCurrent: 0,
    fuelAdd: function(fuelToAdd) {

        var filled = "";

        if (this.fuelLevelCurrent + fuelToAdd > this.fuelCapacityMax) { // topping off the tank
            fuelToAdd = this.fuelCapacityMax - this.fuelLevelCurrent;
            filled = "\nTopped off!"
            this.fuelLevelCurrent = this.fuelLevelCurrent +
                fuelToAdd;
        } else if (this.fuelLevelCurrent + fuelToAdd < this.fuelCapacityMax) { // waiting on salary
            this.fuelLevelCurrent = this.fuelLevelCurrent +
                fuelToAdd;
            filled = "\nJust enough..."
        }
        alert("Added fuel: " + fuelToAdd +
            " gal.\n Current fuel: " +
            this.fuelLevelCurrent + " gal.\n Max fuel: " +
            this.fuelCapacityMax +
            " gal." + filled);
    },
    engineStart: function() {
        if (this.fuelLevelCurrent > 0) {
            this.engineStarted = true;
        } else if (this.fuelLevelCurrent === 0) {
            var askFuel =
                "Current fuel is zero.\nCurrent capacity is: " +
                (this.fuelCapacityMax -
                    this.fuelLevelCurrent).toString() +
                " gal.\nMax capacity is: " + this.fuelCapacityMax
                .toString() +
                " gal.\nHow much would you like to add?";
            this.fuelAdd(parseFloat(prompt(askFuel)));
            this.engineStart();
        }
    },
    engineStop: function() {
        this.engineStarted = false;
    },
    drive: function() {
        if (this.engineStarted) {
            alert("Brooom brooooom!");
        } else {
            alert("Engine must be started first.");
        }
    }
};

toyota.engineStart();
toyota.drive();