/*******************************************************************************
    * 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.ASolverFactory;
  import org.sat4j.core.VecInt;
  import org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.ISolver;
  import org.sat4j.specs.IVecInt;
  import org.sat4j.specs.TimeoutException;
  
  /**
   * This is a tool for computing all the MUSes (Minimum Unsatisfiable Sets) of a
   * set of clauses.
   * 
   * @author sroussel
   * @since 2.3.3
   */
  public class AllMUSes {
  
      private AbstractClauseSelectorSolver<ISolver> css;
      private final List<IVecInt> mssList;
      private final List<IVecInt> secondPhaseClauses;
      private final List<IVecInt> musList;
      private final ASolverFactory<? extends ISolver> factory;
  
      public AllMUSes(boolean group, ASolverFactory<? extends ISolver> factory) {
          if (!group) {
              this.css = new FullClauseSelectorSolver<ISolver>(
                      factory.defaultSolver(), false);
          } else {
              this.css = new GroupClauseSelectorSolver<ISolver>(
                      factory.defaultSolver());
          }
          this.mssList = new ArrayList<IVecInt>();
          this.musList = new ArrayList<IVecInt>();
          this.secondPhaseClauses = new ArrayList<IVecInt>();
          this.factory = factory;
      }
  
      public AllMUSes(ASolverFactory<? extends ISolver> factory) {
          this(false, factory);
      }
  
      /**
       * Gets an instance of ISolver that can be used to compute all MUSes
       * 
       * @return the instance of ISolver to which the clauses will be added
       */
      public <T extends ISolver> T getSolverInstance() {
          return (T) this.css;
      }
  
      public List<IVecInt> computeAllMUSes() {
          return computeAllMUSes(SolutionFoundListener.VOID);
      }
  
      /**
       * Computes all the MUSes associated to the set of constraints added to the
       * solver
       * 
       * @param solver
       *            the <code>ISolver</code> that contains the set of clauses
       * @return a list containing all the MUSes
       */
      public List<IVecInt> computeAllMUSes(SolutionFoundListener listener) {
          if (secondPhaseClauses.isEmpty()) {
              computeAllMSS();
          }
         ISolver solver = factory.defaultSolver();
         for (IVecInt v : secondPhaseClauses) {
             try {
                 solver.addClause(v);
             } catch (ContradictionException e) {
                 return musList;
             }
         }
         AbstractMinimalModel minSolver = new Minimal4InclusionModel(solver,
                 Minimal4InclusionModel.positiveLiterals(solver));
         return computeAllMUSes(listener, minSolver);
     }
 
     public List<IVecInt> computeAllMUSesOrdered(SolutionFoundListener listener) {
         if (secondPhaseClauses.isEmpty()) {
             computeAllMSS();
         }
         ISolver solver = factory.defaultSolver();
         for (IVecInt v : secondPhaseClauses) {
             try {
                 solver.addClause(v);
             } catch (ContradictionException e) {
                 return musList;
             }
         }
         AbstractMinimalModel minSolver = new Minimal4CardinalityModel(solver,
                 Minimal4InclusionModel.positiveLiterals(solver));
         return computeAllMUSes(listener, minSolver);
     }
 
     private List<IVecInt> computeAllMUSes(SolutionFoundListener listener,
             ISolver minSolver) {
         if (css.isVerbose()) {
             System.out.println(css.getLogPrefix() + "Computing all MUSes ...");
         }
         css.internalState();
 
         IVecInt mus;
 
         IVecInt blockingClause;
 
         try {
 
             while (minSolver.isSatisfiable()) {
                 blockingClause = new VecInt();
                 mus = new VecInt();
 
                 int[] model = minSolver.model();
 
                 for (int i = 0; i < model.length; i++) {
                     if (model[i] > 0) {
                         blockingClause.push(-model[i]);
                         mus.push(model[i]);
                     }
                 }
                 musList.add(mus);
                 listener.onSolutionFound(mus);
 
                 minSolver.addBlockingClause(blockingClause);
             }
 
         } catch (ContradictionException e) {
         } catch (TimeoutException e) {
             e.printStackTrace();
         }
         if (css.isVerbose()) {
             System.out.println(css.getLogPrefix() + "... done.");
         }
         css.externalState();
         return musList;
     }
 
     public List<IVecInt> computeAllMSS() {
         return computeAllMSS(SolutionFoundListener.VOID);
     }
 
     public List<IVecInt> computeAllMSS(SolutionFoundListener listener) {
         IVecInt pLits = new VecInt();
         for (Integer i : css.getAddedVars()) {
             pLits.push(i);
         }
 
         AbstractMinimalModel min4Inc = new Minimal4InclusionModel(css, pLits);
         return computeAllMSS(listener, min4Inc, pLits);
     }
 
     public List<IVecInt> computeAllMSSOrdered(SolutionFoundListener listener) {
         IVecInt pLits = new VecInt();
         for (Integer i : css.getAddedVars()) {
             pLits.push(i);
         }
 
         AbstractMinimalModel min4Inc = new Minimal4CardinalityModel(css, pLits);
         return computeAllMSS(listener, min4Inc, pLits);
     }
 
     private List<IVecInt> computeAllMSS(SolutionFoundListener listener,
             ISolver min4Inc, IVecInt pLits) {
         if (css.isVerbose()) {
             System.out.println(css.getLogPrefix() + "Computing all MSSes ...");
         }
         css.internalState();
         int nVar = css.nVars();
 
         IVecInt blockingClause;
 
         IVecInt secondPhaseClause;
 
         IVecInt fullMSS = new VecInt();
         IVecInt mss;
 
         int clause;
 
         for (int i = 0; i < css.getAddedVars().size(); i++) {
             fullMSS.push(i + 1);
         }
 
         // first phase
         try {
 
             while (min4Inc.isSatisfiable()) {
                 int[] fullmodel = min4Inc.modelWithInternalVariables();
 
                 mss = new VecInt();
                 fullMSS.copyTo(mss);
 
                 blockingClause = new VecInt();
                 secondPhaseClause = new VecInt();
                 for (int i = 0; i < pLits.size(); i++) {
                     clause = Math.abs(pLits.get(i));
                     if (fullmodel[clause - 1] > 0) {
                         blockingClause.push(-clause);
                         secondPhaseClause.push(clause - nVar);
                         mss.remove(clause - nVar);
                     }
                 }
 
                 mssList.add(mss);
 
                 listener.onSolutionFound(mss);
 
                 secondPhaseClauses.add(secondPhaseClause);
                 css.addBlockingClause(blockingClause);
 
             }
 
         } catch (TimeoutException e) {
             e.printStackTrace();
         } catch (ContradictionException e) {
 
         }
         if (css.isVerbose()) {
             System.out.println(css.getLogPrefix() + "... done.");
         }
         css.externalState();
         return mssList;
     }
 
     public List<IVecInt> getMssList() {
         return mssList;
     }
 
 }