/*******************************************************************************
    * 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;
  
  import java.io.PrintWriter;
  
  import org.sat4j.core.VecInt;
  import org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.IOptimizationProblem;
  import org.sat4j.specs.IVecInt;
  import org.sat4j.specs.TimeoutException;
  
  /**
   * Utility class to use optimization solvers instead of simple SAT solvers in
   * code meant for SAT solvers.
   * 
   * @author daniel
   */
  public class OptToPBSATAdapter extends PBSolverDecorator {
  
      /**
       * 
       */
      private static final long serialVersionUID = 1L;
  
      IOptimizationProblem problem;
  
      boolean modelComputed = false;
  
      private final IVecInt assumps = new VecInt();
  
      private long begin;
  
      public OptToPBSATAdapter(IOptimizationProblem problem) {
          super((IPBSolver) problem);
          this.problem = problem;
      }
  
      @Override
      public boolean isSatisfiable() throws TimeoutException {
          this.modelComputed = false;
          this.assumps.clear();
          this.begin = System.currentTimeMillis();
          if (this.problem.hasNoObjectiveFunction()) {
              return this.modelComputed = this.problem.isSatisfiable();
          }
          return this.problem.admitABetterSolution();
      }
  
      @Override
      public boolean isSatisfiable(boolean global) throws TimeoutException {
          return isSatisfiable();
      }
  
      @Override
      public boolean isSatisfiable(IVecInt myAssumps, boolean global)
              throws TimeoutException {
          return isSatisfiable(myAssumps);
      }
  
      @Override
      public boolean isSatisfiable(IVecInt myAssumps) throws TimeoutException {
          this.modelComputed = false;
          this.assumps.clear();
          myAssumps.copyTo(this.assumps);
          this.begin = System.currentTimeMillis();
          if (this.problem.hasNoObjectiveFunction()) {
              return this.modelComputed = this.problem.isSatisfiable(myAssumps);
          }
          return this.problem.admitABetterSolution(myAssumps);
      }
  
     @Override
     public int[] model() {
         return model(new PrintWriter(System.out, true));
     }
 
     /**
      * Compute a minimal model according to the objective function of the
      * IPBProblem decorated.
      * 
      * @param out
      *            a writer to display information in verbose mode
      * @since 2.3.2
      */
     public int[] model(PrintWriter out) {
         if (this.modelComputed) {
             return this.problem.model();
         }
         try {
             assert this.problem.admitABetterSolution(this.assumps);
             assert !this.problem.hasNoObjectiveFunction();
             do {
                 this.problem.discardCurrentSolution();
                 if (isVerbose()) {
                     out.println(getLogPrefix()
                             + "Current objective function value: "
                             + this.problem.getObjectiveValue() + "("
                             + (System.currentTimeMillis() - this.begin)
                             / 1000.0 + "s)");
                 }
             } while (this.problem.admitABetterSolution(this.assumps));
             if (isVerbose()) {
                 out.println(getLogPrefix()
                         + "Optimal objective function value: "
                         + this.problem.getObjectiveValue() + "("
                         + (System.currentTimeMillis() - this.begin) / 1000.0
                         + "s)");
             }
         } catch (TimeoutException e) {
             if (isVerbose()) {
                 out.println(getLogPrefix() + "Solver timed out after "
                         + (System.currentTimeMillis() - this.begin) / 1000.0
                         + "s)");
             }
         } catch (ContradictionException e) {
             // OK, optimal model found
         }
         this.modelComputed = true;
         return this.problem.model();
     }
 
     @Override
     public boolean model(int var) {
         if (!this.modelComputed) {
             model();
         }
         return this.problem.model(var);
     }
 
     @Override
     public String toString(String prefix) {
         return prefix + "Optimization to Pseudo Boolean adapter\n"
                 + super.toString(prefix);
     }
 
     public boolean isOptimal() {
         return this.problem.isOptimal();
     }
 
     /**
      * Return the value of the objective function in the last model found.
      * 
      * @return
      * @since 2.3.2
      */
     public Number getCurrentObjectiveValue() {
         return this.problem.getObjectiveValue();
     }
 
     /**
      * Allow to set a specific timeout when the solver is in optimization mode.
      * The solver internal timeout will be set to that value once it has found a
      * solution. That way, the original timeout of the solver may be reduced if
      * the solver finds quickly a solution, or increased if the solver finds
      * regularly new solutions (thus giving more time to the solver each time).
      * 
      * @see IOptimizationProblem#setTimeoutForFindingBetterSolution(int)
      */
     public void setTimeoutForFindingBetterSolution(int seconds) {
         this.problem.setTimeoutForFindingBetterSolution(seconds);
     }
 }