/***********************************
 *  CS2510 Spring 2011 
 *  Lecture #4.2
 *  Unions, Recursion, and *IF*
 ***********************************/

import tester.*;

// Represents a Train
interface ITrain{
    // Calculate the length of this Train
    int length();
    
    // Calculate the maximum weight of a Car 
    //   in this train
    int maxWeight();
}

// Represents a Kabuse
class Kabuse implements ITrain{
    
    Kabuse(){}

    /* Template
     *   Methods
     *     ... this.length() ... -- int
     *     ... this.maxWeight() ... -- int
     */   

    
    // Calculate the length of this Kabuse
    int length(){
        return 1;
    }
    // Calculate the maximum weight of this Kabuse
    int maxWeight(){
        return 0;
    }
}


// Respresents a Train Car
class Car implements ITrain{
    int weight;
    ITrain next;
    
    Car(int weight, ITrain next){
        this.weight = weight;
        this.next = next;
    }
    
    
    /* Template
     *   Fields
     *     ... this.weight ... -- int
     *     ... this.next ... ITrain
     *
     *   Methods
     *     ... this.length() ... -- int
     *     ... this.maxWeight() ... -- int
     *   
     *   Methods of Fields
     *     ... this.next.length() ... -- int
     *     ... this.next.maxWeight() ... -- int
     *    
     */

    // Calculate the length of this Car
    int length(){
        return 1+this.next.length();
    }

    // Which one is the Maximum?
    int max(int a, int b){
        if(a > b){
            return a;
        }else{
            return b;
        }
    }
    
    // Calculate the maximum weight of this Car
    int maxWeight(){
        return this.max(this.weight, this.next.maxWeight());
    }
}

// Examples and Tests for Trains
class TrainExamples{
    TrainExamples(){}
    
    ITrain t1 = new Kabuse();
    ITrain t2 = new Car(1, t1);
    
    // To Test the length method
    boolean testLength(Tester t){
        return (t.checkExpect(this.t1.length(), 1) &&
                t.checkExpect(this.t2.length(), 2));
    }

    // To Test the maxWeight method
    boolean testMaxWeight(Tester t){
        return (t.checkExpect(this.t1.maxWeight(), 0) &&
                t.checkExpect(this.t2.maxWeight(), 1));
    }
}