/*******************************************************************************
    * 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.Collection;
  
  import org.sat4j.core.VecInt;
  import org.sat4j.specs.ISolver;
  import org.sat4j.specs.IVecInt;
  import org.sat4j.specs.IteratorInt;
  import org.sat4j.specs.TimeoutException;
  
  public abstract class AbstractClauseSelectorSolver<T extends ISolver> extends
          SolverDecorator<T> {
  
      private static final long serialVersionUID = 1L;
      private int lastCreatedVar;
      private boolean pooledVarId = false;
  
      private interface SelectorState {
  
          boolean isSatisfiable(boolean global) throws TimeoutException;
  
          boolean isSatisfiable() throws TimeoutException;
  
          boolean isSatisfiable(IVecInt assumps) throws TimeoutException;
  
          boolean isSatisfiable(IVecInt assumps, boolean global)
                  throws TimeoutException;
  
      }
  
      private final SelectorState external = new SelectorState() {
  
          private IVecInt getNegatedSelectors() {
              IVecInt assumps = new VecInt();
              for (int var : getAddedVars()) {
                  assumps.push(-var);
              }
              return assumps;
          }
  
          public boolean isSatisfiable(boolean global) throws TimeoutException {
              return decorated().isSatisfiable(getNegatedSelectors(), global);
          }
  
          public boolean isSatisfiable(IVecInt assumps, boolean global)
                  throws TimeoutException {
              IVecInt all = getNegatedSelectors();
              assumps.copyTo(all);
              return decorated().isSatisfiable(all, global);
          }
  
          public boolean isSatisfiable() throws TimeoutException {
              return decorated().isSatisfiable(getNegatedSelectors());
          }
  
          public boolean isSatisfiable(IVecInt assumps) throws TimeoutException {
              IVecInt all = getNegatedSelectors();
              assumps.copyTo(all);
              return decorated().isSatisfiable(all);
          }
  
      };
  
      private final SelectorState internal = new SelectorState() {
  
          public boolean isSatisfiable(boolean global) throws TimeoutException {
              return decorated().isSatisfiable(global);
          }
  
          public boolean isSatisfiable() throws TimeoutException {
             return decorated().isSatisfiable();
         }
 
         public boolean isSatisfiable(IVecInt assumps) throws TimeoutException {
             return decorated().isSatisfiable(assumps);
         }
 
         public boolean isSatisfiable(IVecInt assumps, boolean global)
                 throws TimeoutException {
             return decorated().isSatisfiable(assumps, global);
         }
     };
 
     private SelectorState selectedState = external;
 
     public AbstractClauseSelectorSolver(T solver) {
         super(solver);
     }
 
     public abstract Collection<Integer> getAddedVars();
 
     /**
      * 
      * @param literals
      * @return
      * @since 2.1
      */
     protected int createNewVar(IVecInt literals) {
         for (IteratorInt it = literals.iterator(); it.hasNext();) {
             if (Math.abs(it.next()) > nextFreeVarId(false)) {
                 throw new IllegalStateException(
                         "Please call newVar(int) before adding constraints!!!");
             }
         }
         if (this.pooledVarId) {
             this.pooledVarId = false;
             return this.lastCreatedVar;
         }
         this.lastCreatedVar = nextFreeVarId(true);
         return this.lastCreatedVar;
     }
 
     protected void discardLastestVar() {
         this.pooledVarId = true;
     }
 
     @Override
     public boolean isSatisfiable(boolean global) throws TimeoutException {
         return selectedState.isSatisfiable(global);
     }
 
     @Override
     public boolean isSatisfiable(IVecInt assumps, boolean global)
             throws TimeoutException {
         return selectedState.isSatisfiable(assumps, global);
     }
 
     @Override
     public boolean isSatisfiable() throws TimeoutException {
         return selectedState.isSatisfiable();
     }
 
     @Override
     public boolean isSatisfiable(IVecInt assumps) throws TimeoutException {
         return selectedState.isSatisfiable(assumps);
     }
 
     /**
      * In the internal state, the solver will allow the selector variables to be
      * satisfied. As such, the solver will answer "true" to isSatisfiable() on
      * an UNSAT problem. it is the responsibility of the user to take into
      * account the meaning of the selector variables.
      */
     public void internalState() {
         this.selectedState = internal;
     }
 
     /**
      * In external state, the solver will prevent the selector variables to be
      * satisfied. As a consequence, from an external point of view, an UNSAT
      * problem will answer "false" to isSatisfiable().
      */
 
     public void externalState() {
         this.selectedState = external;
     }
 }