/*******************************************************************************
    * 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.ObjectInputStream;
  import java.io.PrintWriter;
  
  import org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.IConstr;
  import org.sat4j.specs.IVecInt;
  import org.sat4j.specs.IteratorInt;
  
  /**
   * Solver used to display in a writer the CNF instance in Dimacs format.
   * 
   * That solver is useful to produce CNF files to be used by third party solvers.
   * 
   * @author leberre
   * 
   */
  public class DimacsOutputSolver extends AbstractOutputSolver {
  
  	/**
       * 
       */
  	private static final long serialVersionUID = 1L;
  
  	private transient PrintWriter out;
  
  	public DimacsOutputSolver() {
  		this(new PrintWriter(System.out, true));
  	}
  
  	public DimacsOutputSolver(PrintWriter pw) {
  		out = pw;
  	}
  
  	private void readObject(ObjectInputStream stream) {
  		out = new PrintWriter(System.out, true);
  	}
  
  	public int newVar() {
  		return 0;
  	}
  
  	public int newVar(int howmany) {
  		out.print("p cnf " + howmany);
  		nbvars = howmany;
  		return 0;
  	}
  
  	public void setExpectedNumberOfClauses(int nb) {
  		out.println(" " + nb);
  		nbclauses = nb;
  		fixedNbClauses = true;
  	}
  
  	public IConstr addClause(IVecInt literals) throws ContradictionException {
  		if (firstConstr) {
  			if (!fixedNbClauses) {
  				out.println(" XXXXXX");
  			}
  			firstConstr = false;
  		}
  		for (IteratorInt iterator = literals.iterator(); iterator.hasNext();) {
  			out.print(iterator.next() + " ");
  		}
  		out.println("0");
  		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 (firstConstr) {
 			if (!fixedNbClauses) {
 				out.println("XXXXXX");
 			}
 			firstConstr = false;
 		}
 		for (int i = 0; i <= literals.size(); i++) {
 			for (int j = i + 1; j < literals.size(); j++) {
 				out.println("" + (-literals.get(i)) + " " + (-literals.get(j))
 						+ " 0");
 			}
 		}
 		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 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 void reset() {
 		fixedNbClauses = false;
 		firstConstr = true;
 
 	}
 
 	public String toString(String prefix) {
 		return "Dimacs output solver";
 	}
 
 	public int nConstraints() {
 		return nbclauses;
 	}
 
 	public int nVars() {
 		return nbvars;
 	}
 
 	/**
 	 * @since 2.1
 	 */
 	public int nextFreeVarId(boolean reserve) {
 		if (reserve) {
 			return ++nbvars;
 		}
 		return nbvars + 1;
 	}
 
 	/**
 	 * @since 2.3.1
 	 */
 	public int[] modelWithInternalVariables() {
 		throw new UnsupportedOperationException();
 	}
 
 	/**
 	 * @since 2.3.1
 	 */
 	public int realNumberOfVariables() {
 		return nbvars;
 	}
 
 	/**
 	 * @since 2.3.1
 	 */
 	public void registerLiteral(int p) {
 		throw new UnsupportedOperationException();
 	}
 }