/*******************************************************************************
    * SAT4J: a SATisfiability library for Java Copyright (C) 2004, 2012 Artois University and CNRS
    *
    * 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
    *
    * Alternatively, the contents of this file may be used under the terms of
   * either the GNU Lesser General Public License Version 2.1 or later (the
   * "LGPL"), in which case the provisions of the LGPL are applicable instead
   * of those above. If you wish to allow use of your version of this file only
   * under the terms of the LGPL, and not to allow others to use your version of
   * this file under the terms of the EPL, indicate your decision by deleting
   * the provisions above and replace them with the notice and other provisions
   * required by the LGPL. If you do not delete the provisions above, a recipient
   * may use your version of this file under the terms of the EPL or the LGPL.
   *
   * Based on the original MiniSat specification from:
   *
   * An extensible SAT solver. Niklas Een and Niklas Sorensson. Proceedings of the
   * Sixth International Conference on Theory and Applications of Satisfiability
   * Testing, LNCS 2919, pp 502-518, 2003.
   *
   * See www.minisat.se for the original solver in C++.
   *
   * Contributors:
   *   CRIL - initial API and implementation
   *******************************************************************************/
  package org.sat4j.tools;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.sat4j.core.VecInt;
  import org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.IConstr;
  import org.sat4j.specs.IOptimizationProblem;
  import org.sat4j.specs.ISolver;
  import org.sat4j.specs.IVecInt;
  import org.sat4j.specs.IteratorInt;
  import org.sat4j.specs.TimeoutException;
  
  public class LexicoDecorator<T extends ISolver> extends SolverDecorator<T>
          implements IOptimizationProblem {
  
      protected final List<IVecInt> criteria = new ArrayList<IVecInt>();
  
      protected int currentCriterion = 0;
  
      private IConstr prevConstr;
  
      private Number currentValue = -1;
  
      protected int[] prevfullmodel;
      protected boolean[] prevboolmodel;
  
      private boolean isSolutionOptimal;
  
      /**
  	 * 
  	 */
      private static final long serialVersionUID = 1L;
  
      public LexicoDecorator(T solver) {
          super(solver);
      }
  
      public void addCriterion(IVecInt literals) {
          IVecInt copy = new VecInt(literals.size());
          literals.copyTo(copy);
          this.criteria.add(copy);
      }
  
      public boolean admitABetterSolution() throws TimeoutException {
          return admitABetterSolution(VecInt.EMPTY);
      }
  
      public boolean admitABetterSolution(IVecInt assumps)
              throws TimeoutException {
          this.isSolutionOptimal = false;
          if (decorated().isSatisfiable(assumps, true)) {
              this.prevboolmodel = new boolean[nVars()];
              for (int i = 0; i < nVars(); i++) {
                  this.prevboolmodel[i] = decorated().model(i + 1);
              }
              this.prevfullmodel = decorated().model();
              calculateObjective();
              return true;
          }
          return manageUnsatCase();
      }
  
      private boolean manageUnsatCase() {
          if (this.currentCriterion < numberOfCriteria() - 1) {
              if (this.prevConstr != null) {
                  super.removeConstr(this.prevConstr);
                  this.prevConstr = null;
              }
             try {
                 fixCriterionValue();
             } catch (ContradictionException e) {
                 throw new IllegalStateException(e);
             }
             if (isVerbose()) {
                 System.out.println(getLogPrefix()
                         + "Found optimal criterion number "
                         + (this.currentCriterion + 1));
             }
             this.currentCriterion++;
             calculateObjective();
             return true;
         }
         if (isVerbose()) {
             System.out.println(getLogPrefix()
                     + "Found optimal solution for the last criterion ");
         }
         this.isSolutionOptimal = true;
         if (this.prevConstr != null) {
             super.removeConstr(this.prevConstr);
             this.prevConstr = null;
         }
         return false;
     }
 
     protected int numberOfCriteria() {
         return this.criteria.size();
     }
 
     protected void fixCriterionValue() throws ContradictionException {
         super.addAtMost(this.criteria.get(this.currentCriterion),
                 this.currentValue.intValue());
         super.addAtLeast(this.criteria.get(this.currentCriterion),
                 this.currentValue.intValue());
     }
 
     @Override
     public int[] model() {
         return this.prevfullmodel;
     }
 
     @Override
     public boolean model(int var) {
         return this.prevboolmodel[var - 1];
     }
 
     public boolean hasNoObjectiveFunction() {
         return false;
     }
 
     public boolean nonOptimalMeansSatisfiable() {
         return true;
     }
 
     public Number calculateObjective() {
         this.currentValue = evaluate();
         return this.currentValue;
     }
 
     public Number getObjectiveValue() {
         return this.currentValue;
     }
 
     public void forceObjectiveValueTo(Number forcedValue)
             throws ContradictionException {
         throw new UnsupportedOperationException();
     }
 
     public void discard() throws ContradictionException {
         discardCurrentSolution();
 
     }
 
     public void discardCurrentSolution() throws ContradictionException {
         if (this.prevConstr != null) {
             super.removeSubsumedConstr(this.prevConstr);
         }
         try {
             this.prevConstr = discardSolutionsForOptimizing();
         } catch (ContradictionException c) {
             this.prevConstr = null;
             if (!manageUnsatCase()) {
                 throw c;
             }
         }
 
     }
 
     protected IConstr discardSolutionsForOptimizing()
             throws ContradictionException {
         return super.addAtMost(this.criteria.get(this.currentCriterion),
                 this.currentValue.intValue() - 1);
     }
 
     protected Number evaluate() {
         int value = 0;
         int lit;
         for (IteratorInt it = this.criteria.get(this.currentCriterion)
                 .iterator(); it.hasNext();) {
             lit = it.next();
             if (lit > 0 && this.prevboolmodel[lit - 1] || lit < 0
                     && !this.prevboolmodel[-lit - 1]) {
                 value++;
             }
         }
         return value;
     }
 
     public boolean isOptimal() {
         return this.isSolutionOptimal;
     }
 
 }