/*******************************************************************************
   * SAT4J: a SATisfiability library for Java Copyright (C) 2004-2008 Daniel Le Berre
   *
   * 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++.
  * 
  *******************************************************************************/
  package org.sat4j.tools;
  
  import java.io.PrintStream;
  import java.io.PrintWriter;
  import java.util.Map;
  
  import org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.IConstr;
  import org.sat4j.specs.ISolver;
  import org.sat4j.specs.IVec;
  import org.sat4j.specs.IVecInt;
  import org.sat4j.specs.IteratorInt;
  import org.sat4j.specs.TimeoutException;
  
  /**
   * Solver used to write down a CNF into a String.
   * 
   * It is especially useful compared to the DimacsOutputSolver 
   * because the number of clauses does not need to be known in 
   * advance.
   *  
   * @author leberre
   * 
   */
  public class DimacsStringSolver implements ISolver {
  
      /**
       * 
       */
      private static final long serialVersionUID = 1L;
  
      private StringBuffer out;
  
      private int nbvars;
  
      private int nbclauses;
  
      private boolean fixedNbClauses = false;
  
      private boolean firstConstr = true;
  
      private int firstCharPos;
      
      private final int initBuilderSize;
      
      public DimacsStringSolver() {
          this(16);
      }
  
      public DimacsStringSolver(int initSize) {
          out = new StringBuffer(initSize);
          initBuilderSize = initSize;
      }
  
      public StringBuffer getOut(){
      	return out;
      }
  
      public int newVar() {
          return 0;
      }
  
      public int newVar(int howmany) {
          out.append("p cnf " + howmany);
          setNbVars(howmany);
          return howmany;
      }
      
      protected void setNbVars(int howmany){
      	nbvars = howmany;
      }
  
     public void setExpectedNumberOfClauses(int nb) {
         out.append(" " + nb);
         nbclauses = nb;
         fixedNbClauses = true;
     }
 
     public IConstr addClause(IVecInt literals) throws ContradictionException {
         if (firstConstr) {
             if (!fixedNbClauses) {
                 firstCharPos = 7 + Integer.toString(nbvars).length();
                 out.append("                    ");
                 out.append("\n");
                 nbclauses=0;
             }
             firstConstr = false;
         }
         if (!fixedNbClauses) nbclauses++;
         
         for (IteratorInt iterator = literals.iterator();iterator.hasNext();)
             out.append(iterator.next()).append(" ");
         out.append("0\n");
         return null;        
     }
 
     public boolean removeConstr(IConstr c) {
         throw new UnsupportedOperationException();
     }
 
     public void addAllClauses(IVec<IVecInt> clauses)
             throws ContradictionException {
         throw new UnsupportedOperationException();
     }
 
     public IConstr addAtMost(IVecInt literals, int degree)
             throws ContradictionException {
         if (degree > 1) {
             throw new UnsupportedOperationException(
                     "Not a clausal problem! degree " + degree);
         }
         assert degree == 1;
         if (firstConstr) {
             if (!fixedNbClauses) {
                 firstCharPos = 7 + Integer.toString(nbvars).length();
                 out.append("                    ");
                 out.append("\n");
                 nbclauses=0;
             }
             firstConstr = false;
         }
         
         for (int i = 0; i <= literals.size(); i++) {
             for (int j = i + 1; j < literals.size(); j++) {
                 if (!fixedNbClauses) nbclauses++;
                 out.append("" + (-literals.get(i)) + " " + (-literals.get(j))
                         + " 0\n");
             }
         }
         return null;
     }
 
     public IConstr addAtLeast(IVecInt literals, int degree)
             throws ContradictionException {
         if (degree > 1) {
             throw new UnsupportedOperationException(
                     "Not a clausal problem! degree " + degree);
         }
         assert degree == 1;
         return addClause(literals);
     }
 
     public void setTimeout(int t) {
         // TODO Auto-generated method stub
 
     }
 
     public void setTimeoutMs(long t) {
         // TODO Auto-generated method stub
     }
 
     public int getTimeout() {
         return 0;
     }
 
     public long getTimeoutMs() {
         return 0L;
     }
     
     public void reset() {
         fixedNbClauses = false;
         firstConstr  = true;
         out = new StringBuffer(initBuilderSize);
     }
 
     public void printStat(PrintStream output, String prefix) {
         // TODO Auto-generated method stub
     }
 
     public void printStat(PrintWriter output, String prefix) {
         // TODO Auto-generated method stub
 
     }
 
     public Map<String, Number> getStat() {
         // TODO Auto-generated method stub
         return null;
     }
 
     public String toString(String prefix) {
         return "Dimacs output solver";
     }
 
     public void clearLearntClauses() {
         // TODO Auto-generated method stub
 
     }
 
     public int[] model() {
         throw new UnsupportedOperationException();
     }
 
     public boolean model(int var) {
         throw new UnsupportedOperationException();
     }
 
     public boolean isSatisfiable() throws TimeoutException {
         throw new TimeoutException("There is no real solver behind!");
     }
 
     public boolean isSatisfiable(IVecInt assumps) throws TimeoutException {
         throw new TimeoutException("There is no real solver behind!");
     }
 
     public int[] findModel() throws TimeoutException {
         throw new UnsupportedOperationException();
     }
 
     public int[] findModel(IVecInt assumps) throws TimeoutException {
         throw new UnsupportedOperationException();
     }
 
     public int nConstraints() {
         return nbclauses;
     }
 
     public int nVars() {
         return nbvars;
     }
     
     @Override
     public String toString() {
 //        String numClauses = Integer.toString(nbclauses);
 //        int numClausesLength = numClauses.length();
 //        for (int i = 0; i < numClausesLength; ++i) {
 //            out.setCharAt(firstCharPos + i, numClauses.charAt(i));
 //        }
     	out.insert(firstCharPos, nbclauses);
         return out.toString();
     }
 
     public void expireTimeout() {
         // TODO Auto-generated method stub
         
     }
 
     public boolean isSatisfiable(IVecInt assumps, boolean global)
             throws TimeoutException {
         throw new TimeoutException("There is no real solver behind!");
     }
 
     public boolean isSatisfiable(boolean global) throws TimeoutException {
         throw new TimeoutException("There is no real solver behind!");
     }
 
     public void printInfos(PrintWriter output, String prefix) {        
     }
 
     public void setTimeoutOnConflicts(int count) {
         
     }
 
 	public boolean isDBSimplificationAllowed() {
 		return false;
 	}
 
 	public void setDBSimplificationAllowed(boolean status) {
 		
 	}
 
 }