import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

/**
 * This class represents a triangle.  A triangle has three points.
 *
 * @author Franck van Breugel
 */
public class Triangle
{
    private Point first;
    private Point second;
    private Point third;
    //@ invariant this.first != null && this.second != null && this.third != null

    /**
     * Initializes this triangle with the given points.
     *
     * @param first a point of this triangle.
     * @pre. first != null
     * @param second a point of this triangle.
     * @pre. second != null
     * @param third a point of this triangle.
     * @pre. third != null
     */
    public Triangle(Point first, Point second, Point third)
    {
	this.setFirst(first);
	this.setSecond(second);
	this.setThird(third);
    }
    
    /**
     * Initializes this triangle as a deep copy of the triangle.
     *
     * @param triangle a triangle.
     * @pre. triangle != null
     */
    public Triangle(Triangle triangle)
    {
	this(new Point(triangle.getFirst().getX(), triangle.getFirst().getY()),
	     new Point(triangle.getSecond().getX(), triangle.getSecond().getY()),
	     new Point(triangle.getThird().getX(), triangle.getThird().getY()));
    }

    /**
     * Returns the first point of this triangle.
     *
     * @return the first point of this triangle.
     */
    public Point getFirst()
    {
	return this.first;
    }

    /**
     * Sets the first point of this triangle to the given point.
     * 
     * @param first the new first point of this triangle.
     * @pre. first != null
     */
    private void setFirst(Point first)
    {
	this.first = first;
    }

    /**
     * Returns the second point of this triangle.
     *
     * @return the second point of this triangle.
     */
    public Point getSecond()
    {
	return this.second;
    }

    /**
     * Sets the second point of this triangle to the given point.
     * 
     * @param second the new second point of this triangle.
     * @pre. second != null
     */
    private void setSecond(Point second)
    {
	this.second = second;
    }

    /**
     * Returns the third point of this triangle.
     *
     * @return the third point of this triangle.
     */
    public Point getThird()
    {
	return this.third;
    }

    /**
     * Sets the third point of this triangle to the given point.
     * 
     * @param third the new third point of this triangle.
     * @pre. third != null
     */
    private void setThird(Point third)
    {
	this.third = third;
    }

    /**
     * Returns the hash code of this triangle.
     * 
     * @return the hash code of this triangle.
     */
    public int hashCode()
    {
	return this.getFirst().hashCode() + this.getSecond().hashCode() + this.getThird().hashCode();
    }

    /**
     * Returns the points of this triangle as a sorted list.
     * 
     * @return the points of this triangle as a sorted list.
     */
    private List<Point> toList()
    {
	List<Point> list = new ArrayList<Point>();
	list.add(this.getFirst());
	list.add(this.getSecond());
	list.add(this.getThird());
	Collections.sort(list);
	return list;
    }
    
    /**
     * Tests whether this triangle is the same as the given object.
     * Two triangles are the same if they have the same points.
     * 
     * @param object an object.
     * @return true if this triangle is the same as the given object,
     * false otherwise.
     */
    public boolean equals(Object object)
    {
	boolean equal;
	if (object != null && this.getClass() == object.getClass())
	{
	    Triangle other = (Triangle) object;
	    equal = this.toList().equals(other.toList());
	}
	else
	{
	    equal = false;
	}
	return equal;
    }

    /**
     * Returns a string representation of this triangle.
     * 
     * @return a string representation of this triangle.
     */
    public String toString()
    {
	return this.toList().toString();
    }
    
    /**
     * Returns an alias of this triangle.
     * 
     * @return an alias of this triangle.
     */
    public Triangle getAlias()
    {
	return this;
    }
    
    /**
     * Returns a shallow copy of this triangle.
     * 
     * @return a shallow copy of this triangle.
     */
    public Triangle getShallowCopy()
    {
	return new Triangle(this.getFirst(), this.getSecond(), this.getThird());
    }
    
    /**
     * Returns a deep copy of this triangle.
     * 
     * @return a deep copy of this triangle.
     */
    public Triangle deepCopy()
    {
	Point first = new Point(this.getFirst().getX(), this.getFirst().getY());
	Point second = new Point(this.getSecond().getX(), this.getSecond().getY());
	Point third = new Point(this.getThird().getX(), this.getThird().getY());
	return new Triangle(first, second, third);
    }
}