/*******************************************************************************
    * 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 org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.IConstr;
  import org.sat4j.specs.IVecInt;
  import org.sat4j.specs.IteratorInt;
  
  /**
   * 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 extends AbstractOutputSolver {
  
      /**
       * 
       */
      private static final long serialVersionUID = 1L;
  
      private StringBuffer out;
  
      private int firstCharPos;
  
      private final int initBuilderSize;
  
      private int maxvarid = 0;
  
      public DimacsStringSolver() {
          this(16);
      }
  
      public DimacsStringSolver(int initSize) {
          this.out = new StringBuffer(initSize);
          this.initBuilderSize = initSize;
      }
  
      public StringBuffer getOut() {
          return this.out;
      }
  
      public int newVar() {
          return 0;
      }
  
      @Override
      public int newVar(int howmany) {
          setNbVars(howmany);
          return howmany;
      }
  
      protected void setNbVars(int howmany) {
          this.nbvars = howmany;
          this.maxvarid = howmany;
      }
  
      public void setExpectedNumberOfClauses(int nb) {
          this.out.append(" ");
          this.out.append(nb);
          this.nbclauses = nb;
          this.fixedNbClauses = true;
      }
  
      public IConstr addClause(IVecInt literals) throws ContradictionException {
          if (this.firstConstr) {
              if (!this.fixedNbClauses) {
                  this.firstCharPos = 7 + Integer.toString(this.nbvars).length();
                 this.out.append("                    ");
                 this.out.append("\n");
                 this.nbclauses = 0;
             }
             this.firstConstr = false;
         }
         if (!this.fixedNbClauses) {
             this.nbclauses++;
         }
         for (IteratorInt iterator = literals.iterator(); iterator.hasNext();) {
             this.out.append(iterator.next()).append(" ");
         }
         this.out.append("0\n");
         return null;
     }
 
     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 (this.firstConstr) {
             this.firstCharPos = 0;
             this.out.append("                    ");
             this.out.append("\n");
             this.nbclauses = 0;
             this.firstConstr = false;
         }
 
         for (int i = 0; i <= literals.size(); i++) {
             for (int j = i + 1; j < literals.size(); j++) {
                 if (!this.fixedNbClauses) {
                     this.nbclauses++;
                 }
                 this.out.append(-literals.get(i));
                 this.out.append(" ");
                 this.out.append(-literals.get(j));
                 this.out.append(" 0\n");
             }
         }
         return null;
     }
 
     public IConstr addExactly(IVecInt literals, int n)
             throws ContradictionException {
         if (n > 1) {
             throw new UnsupportedOperationException(
                     "Not a clausal problem! degree " + n);
         }
         assert n == 1;
         addAtMost(literals, n);
         addAtLeast(literals, 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 reset() {
         this.fixedNbClauses = false;
         this.firstConstr = true;
         this.out = new StringBuffer(this.initBuilderSize);
         this.maxvarid = 0;
     }
 
     public String toString(String prefix) {
         return "Dimacs output solver";
     }
 
     @Override
     public int nConstraints() {
         return this.nbclauses;
     }
 
     @Override
     public int nVars() {
         return this.maxvarid;
     }
 
     @Override
     public String toString() {
         this.out.insert(this.firstCharPos, "p cnf " + this.maxvarid + " "
                 + this.nbclauses);
         return this.out.toString();
     }
 
     /**
      * @since 2.1
      */
     public int nextFreeVarId(boolean reserve) {
         if (reserve) {
             return ++this.maxvarid;
         }
         return this.maxvarid + 1;
     }
 
     /**
      * @since 2.3.1
      */
     public int[] modelWithInternalVariables() {
         throw new UnsupportedOperationException();
     }
 
     public int realNumberOfVariables() {
         return this.maxvarid;
     }
 
     public void registerLiteral(int p) {
         throw new UnsupportedOperationException();
     }
 
     /**
      * @since 2.3.2
      */
     public boolean primeImplicant(int p) {
         throw new UnsupportedOperationException();
     }
 }