package edu.neu.ccs.evergreen.model;

/**
 * Tracks all of the constraints that have been reduced in the system.
 */
public class Reductions {
	private int reductions[];

	private int constraintCount;

	/**
	 * Create a new reduction holder with the given size.
	 * 
	 * @param constraintCount
	 *            Number of constraints to track.
	 */
	public Reductions(int constraintCount) {
		this.constraintCount = constraintCount;
		reductions = new int[constraintCount];
	}

	/**
	 * @see java.lang.Object#clone()
	 */
	public Reductions clone() {
		Reductions newReductions = new Reductions(constraintCount);
		System.arraycopy(reductions, 0, newReductions.reductions, 0,
				reductions.length);
		return newReductions;
	}

	/**
	 * Add another reduction mapping.
	 * 
	 * @param constraint
	 *            Reduction to add
	 * @param reducedRelationNumber
	 *            New relation number for the constraint
	 */
	public void addReduction(Constraint constraint, int reducedRelationNumber) {
		if (reducedRelationNumber == 0) {
			reducedRelationNumber = -1;
		}
		reductions[constraint.getID()] = reducedRelationNumber;
	}

	/**
	 * Return the reduction in play for the given constraint.
	 * 
	 * @param constraint
	 *            Constraint to find reduction for
	 * @return Relation number for the constraint
	 */
	public int getRelationNumber(Constraint constraint) {
		int reducedRelationNumber = reductions[constraint.getID()];
		if (reducedRelationNumber == 0) {
			return constraint.getRelationNumber();
		}
		if (reducedRelationNumber == -1) {
			return 0;
		}
		return reducedRelationNumber;
	}
}