package com.evolute.adt;

public class Pair<CARCLASS extends Object, CDRCLASS extends Object> implements Comparable<Pair<? extends CARCLASS,? extends CDRCLASS>>
{
	
	private final CARCLASS left;
	
	private final CDRCLASS right;
	
	public Pair( CARCLASS leftValue, CDRCLASS rightValue )
	{
		this.left = leftValue;
		this.right = rightValue;
	}

	public CARCLASS getLeft()
	{
		return left;
	}

	public CDRCLASS getRight()
	{
		return right;
	}
	
	@SuppressWarnings("unchecked")
	@Override
	public boolean equals(Object obj)
	{
		boolean result = obj != null;
		if( result )
		{
			if( obj instanceof Pair )
			{
				result = ( left == null ? (((Pair) obj).left == null ) : (left.equals(((Pair) obj).left)) );
				result &= ( right == null ? (((Pair) obj).right == null ) : (right.equals(((Pair) obj).right)) );
			}
			else
			{
				result = false;
			}
		}
		return result;
	}

	@Override
	public int compareTo(Pair<? extends CARCLASS, ? extends CDRCLASS> pair)
	{
		int result = compare( left, pair == null ? null : pair.left );
		if( result == 0 )
		{
			result = compare( right, pair == null ? null : pair.right );
		}
		return result;
	}
	
	@SuppressWarnings("unchecked")
	private int compare( Object a, Object b )
	{
		int result = a == null ? (b == null ? 0 : -1 ) : ( b == null ? 1 : 0 );
		if( a != null && b != null )
		{
			if( a.getClass().equals( b.getClass() ) && (a instanceof Comparable) )
			{
				((Comparable)a).compareTo(b);
			}
			else
			{
				result = compare(a.toString(),b.toString());
			}
		}
		return result;
	}
	
	@Override
	public int hashCode()
	{
		int result = super.hashCode();
		if( left != null )
		{
			result = left.hashCode();
			if( right != null )
			{
				result ^= right.hashCode();
			}
		}
		else if( right != null )
		{
			result = right.hashCode();
		}
		return result;
	}
	
	@Override
	public String toString()
	{
		return "<"+left+","+right+">";
	}
	
}