script.js

class Ship {
  constructor(itinerary) {
    this.itinerary = itinerary;
    this.currentPort = itinerary.ports[0];
    this.previousPort = null;
    this.remainingPort = [...itinerary.ports];
    this.currentPort.addShip(this);
  }

  setSail() {
    if (this.remainingPort.length < 2) {
      throw new Error("End of Itinerary reached");
    } else {
      this.currentPort.removeShip(this);
      this.previousPort = this.currentPort;
      this.currentPort = null;
      this.remainingPort.shift();
    }
  }

  dock() {
    this.currentPort = this.remainingPort[0];
    this.currentPort.addShip(this);
  }
  get nextPort() {
    let itin = this.itinerary.ports;
    let nextPortIndex = itin.indexOf(this.currentPort);
    return itin[nextPortIndex + 1];
  }
}

class Port {
  constructor(name) {
    this.name = name;
    this.dockedShips = [];
  }

  addShip(ship) {
    this.dockedShips.push(ship);
  }

  removeShip(ship) {
    this.dockedShips = this.dockedShips.filter((e) => e !== ship);
  }
}

class Itinerary {
  constructor(ports) {
    this.ports = ports;
  }
}

if (typeof module !== "undefined" && module.exports) {
  module.exports = { Ship, Port, Itinerary };
} else {
  window.Port = Port;
  window.Ship = Ship;
  window.Itinerary = Itinerary;
}