/*******************************************************************************
    * 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.SearchListener;
  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;
  
  	private int maxvarid = 0;
  
  	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) {
  		setNbVars(howmany);
  		return howmany;
  	}
  
  	protected void setNbVars(int howmany) {
  		nbvars = howmany;
  		maxvarid = 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) {
 			firstCharPos = 0;
 			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;
 	}
 
 	/**
 	 * @since 2.1
 	 */
 	public long getTimeoutMs() {
 		return 0L;
 	}
 
 	public void reset() {
 		fixedNbClauses = false;
 		firstConstr = true;
 		out = new StringBuffer(initBuilderSize);
 		maxvarid = 0;
 	}
 
 	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 maxvarid;
 	}
 
 	@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, "p cnf " + maxvarid + " " + 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) {
 
 	}
 
 	/**
 	 * @since 2.1
 	 */
 	public void setSearchListener(SearchListener sl) {
 	}
 
 	/**
 	 * @since 2.1
 	 */
 	public int nextFreeVarId(boolean reserve) {
 		if (reserve) {
 			maxvarid++;
 			return maxvarid;
 		}
 		return maxvarid;
 	}
 
 	/**
 	 * @since 2.1
 	 */
 	public boolean removeSubsumedConstr(IConstr c) {
 		return false;
 	}
 
 	/**
 	 * @since 2.1
 	 */
 	public IConstr addBlockingClause(IVecInt literals)
 			throws ContradictionException {
 		throw new UnsupportedOperationException();
 	}
 }