//  AdaptiveGridArchive.java
//
//  Author:
//       Antonio J. Nebro <antonio@lcc.uma.es>
//       Juan J. Durillo <durillo@lcc.uma.es>
//
//  Copyright (c) 2011 Antonio J. Nebro, Juan J. Durillo
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU Lesser General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU Lesser General Public License for more details.
// 
//  You should have received a copy of the GNU Lesser General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

package jmetal.util.archive;

import jmetal.core.Solution;
import jmetal.util.AdaptiveGrid;
import jmetal.util.comparators.DominanceComparator;

import java.util.Comparator;
import java.util.Iterator;

/**
 * This class implements an archive based on an adaptive grid used in PAES
 */
public class AdaptiveGridArchive extends Archive {

	/** 
	 * Stores the adaptive grid
	 */
	private AdaptiveGrid grid_;

	/** 
	 * Stores the maximum size of the archive
	 */
	private int maxSize_;

	/**
	 * Stores a <code>Comparator</code> for dominance checking
	 */
	private Comparator dominance_;

	/**
	 * Constructor.
	 * 
	 * @param maxSize The maximum size of the archive
	 * @param bisections The maximum number of bi-divisions for the adaptive
	 * grid.
	 * @param objectives The number of objectives.
	 */
	public AdaptiveGridArchive(int maxSize,int bisections, int objectives) {
		super(maxSize);
		maxSize_   = maxSize;
		dominance_ = new DominanceComparator();
		grid_      = new AdaptiveGrid(bisections,objectives);
	} // AdaptiveGridArchive

	/**
	 * Adds a <code>Solution</code> to the archive. If the <code>Solution</code>
	 * is dominated by any member of the archive then it is discarded. If the 
	 * <code>Solution</code> dominates some members of the archive, these are
	 * removed. If the archive is full and the <code>Solution</code> has to be
	 * inserted, one <code>Solution</code> of the most populated hypercube of the
	 * adaptive grid is removed.
	 * @param solution The <code>Solution</code>
	 * @return true if the <code>Solution</code> has been inserted, false
	 * otherwise.
	 */
	public boolean add(Solution solution) {
		//Iterator of individuals over the list
		Iterator<Solution> iterator = solutionsList_.iterator();

		while (iterator.hasNext()){
			Solution element = iterator.next();
			int flag = dominance_.compare(solution,element);
			if (flag == -1) { // The Individual to insert dominates other 
				// individuals in  the archive
				iterator.remove(); //Delete it from the archive
				int location = grid_.location(element);
				if (grid_.getLocationDensity(location) > 1) {//The hypercube contains 
					grid_.removeSolution(location);            //more than one individual
				} else {
					grid_.updateGrid(this);
				} // else
			} // if 
			else if (flag == 1) { // An Individual into the file dominates the 
				// solution to insert
				return false; // The solution will not be inserted
			} // else if           
		} // while

		// At this point, the solution may be inserted
		if (size() == 0){ //The archive is empty
			solutionsList_.add(solution);
			grid_.updateGrid(this);        
			return true;
		} //

		if (size() < maxSize_){ //The archive is not full              
			grid_.updateGrid(solution,this); // Update the grid if applicable
			int location ;
			location= grid_.location(solution); // Get the location of the solution
			grid_.addSolution(location); // Increment the density of the hypercube
			solutionsList_.add(solution); // Add the solution to the list
			return true;
		} // if

		// At this point, the solution has to be inserted and the archive is full
		grid_.updateGrid(solution,this);
		int location = grid_.location(solution);
		if (location == grid_.getMostPopulated()) { // The solution is in the 
			// most populated hypercube
			return false; // Not inserted
		} 
		else {
			// Remove an solution from most populated area
			iterator = solutionsList_.iterator();
			boolean removed = false;
			while (iterator.hasNext()) {
				if (!removed) {
					Solution element = iterator.next();
					int location2 = grid_.location(element);
					if (location2 == grid_.getMostPopulated()) {
						iterator.remove();
						grid_.removeSolution(location2);
					} // if
				} // if
			} // while
			// A solution from most populated hypercube has been removed, 
			// insert now the solution
			grid_.addSolution(location);
			solutionsList_.add(solution);            
		} // else
		return true;
	} // add

	/**
	 * Returns the AdaptativeGrid used
	 * @return the AdaptativeGrid
	 */
	public AdaptiveGrid getGrid() {
		return grid_;
	} // AdaptativeGrid  
} // AdaptativeGridArchive