/*******************************************************************************
    * 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.pb;
  
  import java.math.BigInteger;
  
  import org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.IConstr;
  import org.sat4j.specs.IVec;
  import org.sat4j.specs.IVecInt;
  import org.sat4j.specs.IteratorInt;
  import org.sat4j.specs.TimeoutException;
  import org.sat4j.tools.DimacsStringSolver;
  
  /**
   * Solver used to display in a string the pb-instance in OPB format.
   * 
   * That solver is useful to produce OPB files to be used by third party solvers.
   * 
   * @author parrain
   * 
   */
  public class OPBStringSolver extends DimacsStringSolver implements IPBSolver {
  
  	private static final String FAKE_I_CONSTR_MSG = "Fake IConstr";
  
  	/**
  	 * 
  	 */
  	private static final long serialVersionUID = 1L;
  
  	private int indxConstrObj;
  
  	private int nbOfConstraints;
  
  	private ObjectiveFunction obj;
  
  	private boolean inserted = false;
  
  	private static final IConstr FAKE_CONSTR = new IConstr() {
  
  		public int size() {
  			throw new UnsupportedOperationException(FAKE_I_CONSTR_MSG);
  		}
  
  		public boolean learnt() {
  			throw new UnsupportedOperationException(FAKE_I_CONSTR_MSG);
  		}
  
  		public double getActivity() {
  			throw new UnsupportedOperationException(FAKE_I_CONSTR_MSG);
  		}
  
  		public int get(int i) {
  			throw new UnsupportedOperationException(FAKE_I_CONSTR_MSG);
  		}
  	};
  
  	/**
  	 * 
  	 */
  	public OPBStringSolver() {
  	}
  
  	/**
  	 * @param initSize
  	 */
  	public OPBStringSolver(int initSize) {
  		super(initSize);
  	}
  
  	@Override
  	public boolean isSatisfiable(IVecInt assumps) throws TimeoutException {
  		for (IteratorInt it = assumps.iterator(); it.hasNext();) {
 			int p = it.next();
 			if (p > 0) {
 				getOut().append("+1 x" + p + " >= 1 ;\n");
 			} else {
 				getOut().append("-1 x" + (-p) + " >= 0 ;\n");
 			}
 			nbOfConstraints++;
 		}
 		throw new TimeoutException();
 	}
 
 	@Override
 	public boolean isSatisfiable(IVecInt assumps, boolean global)
 			throws TimeoutException {
 		// TODO Auto-generated method stub
 		return super.isSatisfiable(assumps, global);
 	}
 
 	public IConstr addPseudoBoolean(IVecInt lits, IVec<BigInteger> coeffs,
 			boolean moreThan, BigInteger d) throws ContradictionException {
 		StringBuffer out = getOut();
 		assert lits.size() == coeffs.size();
 		nbOfConstraints++;
 		if (moreThan) {
 			for (int i = 0; i < lits.size(); i++) {
 				out.append(coeffs.get(i));
 				out.append(" x");
 				out.append(lits.get(i));
 				out.append(" ");
 			}
 			out.append(">= ");
 			out.append(d);
 			out.append(" ;\n");
 		} else {
 			for (int i = 0; i < lits.size(); i++) {
 				out.append(coeffs.get(i).negate());
 				out.append(" x");
 				out.append(lits.get(i));
 				out.append(" ");
 			}
 			out.append(">= ");
 			out.append(d.negate());
 			out.append(" ;\n");
 		}
 		return FAKE_CONSTR;
 	}
 
 	public void setObjectiveFunction(ObjectiveFunction obj) {
 		this.obj = obj;
 	}
 
 	@Override
 	public IConstr addAtLeast(IVecInt literals, int degree)
 			throws ContradictionException {
 		StringBuffer out = getOut();
 		nbOfConstraints++;
 		for (IteratorInt iterator = literals.iterator(); iterator.hasNext();)
 			out.append("+1 x" + iterator.next() + " ");
 		out.append(">= " + degree + " ;\n");
 		return FAKE_CONSTR;
 	}
 
 	@Override
 	public IConstr addAtMost(IVecInt literals, int degree)
 			throws ContradictionException {
 		StringBuffer out = getOut();
 		nbOfConstraints++;
 		for (IteratorInt iterator = literals.iterator(); iterator.hasNext();)
 			out.append("-1 x" + iterator.next() + " ");
 		out.append(">= " + (-degree) + " ;\n");
 		return FAKE_CONSTR;
 	}
 
 	@Override
 	public IConstr addClause(IVecInt literals) throws ContradictionException {
 		StringBuffer out = getOut();
 		nbOfConstraints++;
 		int lit;
 		for (IteratorInt iterator = literals.iterator(); iterator.hasNext();) {
 			lit = iterator.next();
 			if (lit > 0) {
 				out.append("+1 x" + lit + " ");
 			} else {
 				out.append("+1 ~x" + -lit + " ");
 			}
 		}
 		out.append(">= 1 ;\n");
 		return FAKE_CONSTR;
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see org.sat4j.pb.IPBSolver#getExplanation()
 	 */
 	public String getExplanation() {
 		// TODO Auto-generated method stub
 		return null;
 	}
 
 	/*
 	 * (non-Javadoc)
 	 * 
 	 * @see
 	 * org.sat4j.pb.IPBSolver#setListOfVariablesForExplanation(org.sat4j.specs
 	 * .IVecInt)
 	 */
 	public void setListOfVariablesForExplanation(IVecInt listOfVariables) {
 		// TODO Auto-generated method stub
 
 	}
 
 	@Override
 	public String toString() {
 		StringBuffer out = getOut();
 		if (!inserted) {
 			StringBuffer tmp = new StringBuffer();
 			tmp.append("* #variable= ");
 			tmp.append(nVars());
 			tmp.append(" #constraint= ");
 			tmp.append(nbOfConstraints);
 			tmp.append(" \n");
 			if (obj != null) {
 				tmp.append("min: ");
 				tmp.append(obj);
 				tmp.append(" ;\n");
 			}
 			out.insert(indxConstrObj, tmp.toString());
 			inserted = true;
 		}
 		return out.toString();
 	}
 
 	@Override
 	public String toString(String prefix) {
 		return "OPB output solver";
 	}
 
 	@Override
 	public int newVar(int howmany) {
 		StringBuffer out = getOut();
 		setNbVars(howmany);
 		// to add later the number of constraints
 		indxConstrObj = out.length();
 		out.append("\n");
 		return howmany;
 	}
 
 	@Override
 	public void setExpectedNumberOfClauses(int nb) {
 	}
 
 	public ObjectiveFunction getObjectiveFunction() {
 		return obj;
 	}
 
 }