import tester.*;

interface IAnimal {
	// Determines whether the animal is less than n lbs
	boolean isLighter(double n);
	IAnimal feed();
}

class Snake implements IAnimal {
	String name;
	int weight;
	String food;
	Snake(String name, int weight, String food) {
		this.name = name;
		this.weight = weight;
		this.food = food;
	}
	
	// Determines whether the name is < n lbs
	public boolean isLighter(double n) {
		return this.weight < n;
	}
	
	// To feed the snake 5 lbs of food
	public Snake feed() {
		return new Snake(this.name,
						this.weight + 5,
					    this.food);
	}
}

class Dillo implements IAnimal {
	double weight;
	boolean isAlive;
	Dillo(double weight, boolean isAlive) {
		this.weight = weight;
		this.isAlive = isAlive;
	}
	
	// To determine whether the dillo is < n lbs
	public boolean isLighter(double n) {
		return this.weight < n;
	}
	
	// To feed the dillo 2 lbs of food if it's alive
	public Dillo feed() {
		if (this.isAlive)
			return new Dillo(this.weight + 2, true);
		else
			return this;
	}
}

class Posn {
	double x;
	double y;
	Posn(double x, double y) {
		this.x = x;
		this.y = y;
	}
}

class Ant implements IAnimal {
	double weight;
	Posn location;
	Ant(double weight, Posn location) {
		this.weight = weight;
		this.location = location;
	}
	
	// To determine whether the ant is < n lbs
	public boolean isLighter(double n) {
		return this.weight < n;
	}
	
	public Ant feed() {
		return new Ant(this.weight + 0.001,
					   this.location);
	}
}

interface IGrade {
}

class NoGrade implements IGrade {
	NoGrade() { }
}

class NumGrade implements IGrade {
	int n;
	NumGrade(int n) {
		this.n = n;
	}
}

// A list-of-num is either
//  - empty-list-of-num
//  - cons-list-of-num

interface IIntList {
	int length();
}

// A empty-list-of-num is
//  - (make-empty-list-of-num)

class EmptyIntList implements IIntList {
	EmptyIntList() { }
	public int length() { return 0; }
}

// A cons-list-of-num is
//  - (make-cons-list-of-num num list-of-num)

class ConsIntList implements IIntList {
	int first;
	IIntList rest;
	ConsIntList(int first, IIntList rest) {
		this.first = first;
		this.rest = rest;
	}
	public int length() {
		return 1 + this.rest.length();
	}
}

class Examples{
  	Snake slinky = new Snake("Slinky", 12, "rats");
  	Dillo dillo1 = new Dillo(7, true);
  	Dillo dillo2 = new Dillo(2, false);
  	Ant ant1 = new Ant(0.001, new Posn(5, 2));
  	Posn home = new Posn(0, 0);
  	Ant ant2 = new Ant(0.0005, home);
  	IAnimal suzy = new Snake("Suzy", 8, "bananas");
  	IGrade notTaken = new NoGrade();
  	IGrade barelyPassed = new NumGrade(75);
  	
  	void tests(Tester t) {
  		t.checkExpect(slinky.isLighter(10), false);
  		t.checkExpect(new Snake("Slimey", 5, "apples").isLighter(10), true);
  		t.checkExpect(dillo1.isLighter(10), true);
  		t.checkExpect(dillo1.isLighter(5), false);
  		t.checkExpect(ant1.isLighter(0.002), true);
  		t.checkExpect(ant2.isLighter(0.0002), false);
  		t.checkExpect(suzy.isLighter(10), true);
  		
  		t.checkExpect(slinky.feed(), new Snake("Slinky", 17, "rats"));
  		t.checkExpect(dillo1.feed(), new Dillo(9, true));
  		t.checkExpect(ant1.feed(), new Ant(0.002, new Posn(5, 2)));
  	}
}