//===== Constructor
const Stack = function() {
    // This is the heart of the robot movement architecture.
    // Its elements are of the form { robotId, i, j }
    this.moves = [];

    document.addEventListener('L-arrow', this.msgArrow.bind(this));
    document.addEventListener('G-robots', this.msgRobots.bind(this));
};

Stack.prototype.msgRobots = function(evt) {
    this.moves = evt.detail.body.map(({ id, i, j }) => ({ id, i, j }));

    const evtStack = new CustomEvent('L-stack', { detail: this.moves });
    document.dispatchEvent(evtStack);
};

Stack.prototype.msgArrow = function(evt) {
    this.moves.push(evt.detail);

    const evtStack = new CustomEvent('L-stack', { detail: this.moves });
    document.dispatchEvent(evtStack);
};


// reset destroys stack
// undo decrements from stack
// store chops stack
// moves is stack length
// replay shares stack
// starting spot is present in stack