/*******************************************************************************
    * 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.pb.core;
  
  import org.sat4j.core.Vec;
  import org.sat4j.minisat.core.Constr;
  import org.sat4j.minisat.core.IOrder;
  import org.sat4j.minisat.core.LearningStrategy;
  import org.sat4j.minisat.core.Pair;
  import org.sat4j.minisat.core.RestartStrategy;
  import org.sat4j.minisat.core.SearchParams;
  import org.sat4j.minisat.restarts.MiniSATRestarts;
  import org.sat4j.pb.constraints.pb.ConflictMap;
  import org.sat4j.pb.constraints.pb.IConflict;
  import org.sat4j.pb.constraints.pb.PBConstr;
  import org.sat4j.specs.IVec;
  import org.sat4j.specs.TimeoutException;
  
  /**
   * @author parrain To change the template for this generated type comment go to
   *         Window - Preferences - Java - Code Generation - Code and Comments
   */
  public class PBSolverCP extends PBSolver {
  
      private static final long serialVersionUID = 1L;
  
      /**
       * @param acg
       * @param learner
       * @param dsf
       */
      public PBSolverCP(LearningStrategy<PBDataStructureFactory> learner,
              PBDataStructureFactory dsf, IOrder order) {
          super(learner, dsf, new SearchParams(1.5, 100), order,
                  new MiniSATRestarts());
      }
  
      public PBSolverCP(LearningStrategy<PBDataStructureFactory> learner,
              PBDataStructureFactory dsf, SearchParams params, IOrder order,
              RestartStrategy restarter) {
          super(learner, dsf, params, order, restarter);
      }
  
      public PBSolverCP(LearningStrategy<PBDataStructureFactory> learner,
              PBDataStructureFactory dsf, SearchParams params, IOrder order) {
          super(learner, dsf, params, order, new MiniSATRestarts());
      }
  
      @Override
      public void analyze(Constr myconfl, Pair results) throws TimeoutException {
          if (someCriteria()) {
              analyzeCP(myconfl, results);
          } else {
              super.analyze(myconfl, results);
          }
      }
  
      public void analyzeCP(Constr myconfl, Pair results) throws TimeoutException {
          int litImplied = this.trail.last();
          int currentLevel = this.voc.getLevel(litImplied);
          IConflict confl = chooseConflict((PBConstr) myconfl, currentLevel);
          assert confl.slackConflict().signum() < 0;
          while (!confl.isAssertive(currentLevel)) {
              if (!this.undertimeout) {
                  throw new TimeoutException();
              }
              PBConstr constraint = (PBConstr) this.voc.getReason(litImplied);
              // result of the resolution is in the conflict (confl)
              confl.resolve(constraint, litImplied, this);
              updateNumberOfReductions(confl);
              assert confl.slackConflict().signum() <= 0;
              // implication trail is reduced
             if (this.trail.size() == 1) {
                 break;
             }
             undoOne();
             // assert decisionLevel() >= 0;
             if (decisionLevel() == 0) {
                 break;
             }
             litImplied = this.trail.last();
             if (this.voc.getLevel(litImplied) != currentLevel) {
                 this.trailLim.pop();
                 confl.updateSlack(this.voc.getLevel(litImplied));
             }
             assert this.voc.getLevel(litImplied) <= currentLevel;
             currentLevel = this.voc.getLevel(litImplied);
             assert confl.slackIsCorrect(currentLevel);
             assert currentLevel == decisionLevel();
             assert litImplied > 1;
         }
         assert confl.isAssertive(currentLevel) || this.trail.size() == 1
                 || decisionLevel() == 0;
 
         assert currentLevel == decisionLevel();
         undoOne();
 
         updateNumberOfReducedLearnedConstraints(confl);
         // necessary informations to build a PB-constraint
         // are kept from the conflict
         if (confl.size() == 0
                 || (decisionLevel() == 0 || this.trail.size() == 0)
                 && confl.slackConflict().signum() < 0) {
             results.reason = null;
             results.backtrackLevel = -1;
             return;
         }
 
         // assertive PB-constraint is build and referenced
         PBConstr resConstr = (PBConstr) this.dsfactory
                 .createUnregisteredPseudoBooleanConstraint(confl);
         this.slistener.learn(resConstr);
         results.reason = resConstr;
         getSearchListener().learn(resConstr);
 
         // the conflict give the highest decision level for the backtrack
         // (which is less than current level)
         // assert confl.isAssertive(currentLevel);
         if (decisionLevel() == 0 || this.trail.size() == 0) {
             results.backtrackLevel = -1;
         } else {
             results.backtrackLevel = confl.getBacktrackLevel(currentLevel);
         }
     }
 
     IConflict chooseConflict(PBConstr myconfl, int level) {
         return ConflictMap.createConflict(myconfl, level);
     }
 
     @Override
     public String toString(String prefix) {
         return prefix + "Cutting planes based inference ("
                 + this.getClass().getName() + ")\n" + super.toString(prefix);
     }
 
     private final IVec<String> conflictVariables = new Vec<String>();
     private final IVec<String> conflictConstraints = new Vec<String>();
 
     void initExplanation() {
         this.conflictVariables.clear();
         this.conflictConstraints.clear();
     }
 
     boolean someCriteria() {
         return true;
     }
 
     protected void updateNumberOfReductions(IConflict confl) {
     }
 
     protected void updateNumberOfReducedLearnedConstraints(IConflict confl) {
     }
 
 }