//===== 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('L-submit', this.msgSubmit.bind(this));
    document.addEventListener('L-undo', this.msgUndo.bind(this));
    document.addEventListener('L-reset', this.msgReset.bind(this));

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

Stack.prototype.getInitialPositions = function() {
    const moves = this.moves.reduce((acc, move) => {
        if (!acc[move.id]) {
            acc[move.id] = move;
        }

        return acc;
    }, {});

    return Object.values(moves);
};

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);

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

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

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

Stack.prototype.msgReset = function() {
    this.moves = this.getInitialPositions();

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

Stack.prototype.msgSubmit = function() {
    this.moves = this.getInitialPositions();

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

Stack.prototype.msgUndo = function() {
    this.moves.pop();

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