/*******************************************************************************
 * Copyright (c) 2009 Daniel Le Berre and others. All rights reserved. This
 * program and the accompanying materials are made available under the terms of
 * the Eclipse Public License v1.0 which accompanies this distribution, and is
 * available at http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: Daniel Le Berre - initial API and implementation
 ******************************************************************************/
package org.eclipse.equinox.p2.cudf.solver;

import java.math.BigInteger;
import java.util.*;
import org.eclipse.equinox.p2.cudf.metadata.IRequiredCapability;
import org.eclipse.equinox.p2.cudf.metadata.InstallableUnit;
import org.eclipse.equinox.p2.cudf.query.CapabilityQuery;
import org.eclipse.equinox.p2.cudf.query.Collector;
import org.sat4j.pb.tools.WeightedObject;

public class P2OptimizationFunction extends OptimizationFunction {

	public List createOptimizationFunction(InstallableUnit metaIu) {
		List weightedObjects = new ArrayList();

		Set s = slice.entrySet();
		final BigInteger POWER = BigInteger.valueOf(2);

		BigInteger maxWeight = POWER;
		for (Iterator iterator = s.iterator(); iterator.hasNext();) {
			Map.Entry entry = (Map.Entry) iterator.next();
			HashMap conflictingEntries = (HashMap) entry.getValue();
			if (conflictingEntries.size() == 1) {
				continue;
			}
			List toSort = new ArrayList(conflictingEntries.values());
			Collections.sort(toSort, Collections.reverseOrder());
			BigInteger weight = POWER;
			int count = toSort.size();
			for (int i = 0; i < count; i++) {
				InstallableUnit iu = (InstallableUnit) toSort.get(i);
				weightedObjects.add(WeightedObject.newWO(iu, iu.isInstalled() ? BigInteger.ONE : weight));
				weight = weight.multiply(POWER);
			}
			if (weight.compareTo(maxWeight) > 0)
				maxWeight = weight;
		}

		//		maxWeight = maxWeight.multiply(POWER);
		//
		//		// Weight the no-op variables beneath the abstract variables
		//		for (Iterator iterator = noopVariables.values().iterator(); iterator.hasNext();) {
		//			weightedObjects.add(WeightedObject.newWO(iterator.next(), maxWeight));
		//		}

		maxWeight = maxWeight.multiply(POWER);

		//DISABLED the complete following block because there was a compile error
		//		// Add the abstract variables
		//		BigInteger abstractWeight = maxWeight.negate();
		//		for (Iterator iterator = abstractVariables.iterator(); iterator.hasNext();) {
		//			weightedObjects.add(WeightedObject.newWO(iterator.next(), abstractWeight));
		//		}

		maxWeight = maxWeight.multiply(POWER);

		BigInteger optionalWeight = maxWeight.negate();
		long countOptional = 1;
		List requestedPatches = new ArrayList();
		IRequiredCapability[] reqs = metaIu.getRequiredCapabilities();
		for (int j = 0; j < reqs.length; j++) {
			if (!reqs[j].isOptional())
				continue;
			Collector matches = picker.query(new CapabilityQuery(reqs[j]), new Collector(), null);
			for (Iterator iterator = matches.iterator(); iterator.hasNext();) {
				InstallableUnit match = (InstallableUnit) iterator.next();
				weightedObjects.add(WeightedObject.newWO(match, optionalWeight));
			}
		}

		BigInteger patchWeight = maxWeight.multiply(POWER).multiply(BigInteger.valueOf(countOptional)).negate();
		for (Iterator iterator = requestedPatches.iterator(); iterator.hasNext();) {
			weightedObjects.add(WeightedObject.newWO(iterator.next(), patchWeight));
		}
		if (!weightedObjects.isEmpty()) {
			return weightedObjects;
		}
		return null;
	}

	public String getName() {
		return "p2";
	}

	public void printSolutionValue() {
		// nothing to do

	}
}