/*******************************************************************************
    * 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.reader;
  
  import java.io.BufferedInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.PrintWriter;
  import java.io.Serializable;
  
  import org.sat4j.core.VecInt;
  import org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.IProblem;
  import org.sat4j.specs.ISolver;
  import org.sat4j.specs.IVecInt;
  
  /**
   * Dimacs Reader written by Frederic Laihem. It is much faster than DimacsReader
   * because it does not split the input file into strings but reads and interpret
   * the input char by char. Hence, it is a bit more difficult to read and to
   * modify than DimacsReader.
   * 
   * This reader is used during the SAT Competitions.
   * 
   * @author laihem
   * @author leberre
   */
  public class LecteurDimacs extends Reader implements Serializable {
  
  	private static final long serialVersionUID = 1L;
  
  	/* taille du buffer */
  	private final static int TAILLE_BUF = 16384;
  
  	private final ISolver s;
  
  	private transient BufferedInputStream in;
  
  	/* nombre de literaux dans le fichier */
  	private int nbVars = -1;
  
  	private int nbClauses = -1;
  
  	private static final char EOF = (char) -1;
  
  	/*
  	 * nomFichier repr?sente le nom du fichier ? lire
  	 */
  	public LecteurDimacs(ISolver s) {
  		this.s = s;
  	}
  
  	@Override
  	public final IProblem parseInstance(final InputStream input)
  			throws ParseFormatException, ContradictionException, IOException {
  
  		this.in = new BufferedInputStream(input, LecteurDimacs.TAILLE_BUF);
  		s.reset();
  		passerCommentaire();
  		if (nbVars < 0)
  			throw new ParseFormatException(
  					"DIMACS error: wrong max number of variables");
  		s.newVar(nbVars);
  		s.setExpectedNumberOfClauses(nbClauses);
  		char car = passerEspaces();
  		if (nbClauses > 0) {
  			if (car == EOF)
  				throw new ParseFormatException(
  						"DIMACS error: the clauses are missing");
  			ajouterClauses(car);
  		}
  		input.close();
  		return s;
  	}
 
 	/** on passe les commentaires et on lit le nombre de literaux */
 	private char passerCommentaire() throws IOException {
 		char car;
 		for (;;) {
 			car = passerEspaces();
 			if (car == 'p') {
 				car = lectureNombreLiteraux();
 			}
 			if (car != 'c' && car != 'p')
 				break; /* fin des commentaires */
 			car = nextLine(); /* on passe la ligne de commentaire */
 			if (car == EOF)
 				break;
 		}
 		return car;
 	}
 
 	/** lit le nombre repr?sentant le nombre de literaux */
 	private char lectureNombreLiteraux() throws IOException {
 		char car = nextChiffre(); /* on lit le prchain chiffre */
 		if (car != EOF) {
 			nbVars = car - '0';
 			for (;;) { /* on lit le chiffre repr?sentant le nombre de literaux */
 				car = (char) in.read();
 				if (car < '0' || car > '9')
 					break;
 				nbVars = 10 * nbVars + (car - '0');
 			}
 			car = nextChiffre();
 			nbClauses = car - '0';
 			for (;;) { /* on lit le chiffre repr?sentant le nombre de literaux */
 				car = (char) in.read();
 				if (car < '0' || car > '9')
 					break;
 				nbClauses = 10 * nbClauses + (car - '0');
 			}
 			if (car != '\n' && car != EOF)
 				nextLine(); /* on lit la fin de la ligne */
 		}
 		return car;
 	}
 
 	/**
 	 * lit les clauses et les ajoute dans le vecteur donn? en param?tre
 	 * 
 	 * @throws ParseFormatException
 	 */
 	private void ajouterClauses(char car) throws IOException,
 			ContradictionException, ParseFormatException {
 		final IVecInt lit = new VecInt();
 		int val = 0;
 		boolean neg = false;
 		for (;;) {
 			/* on lit le signe du literal */
 			if (car == '-') {
 				neg = true;
 				car = (char) in.read();
 			} else if (car == '+')
 				car = (char) in.read();
 			else /* on le 1er chiffre du literal */
 			if (car >= '0' && car <= '9') {
 				val = car - '0';
 				car = (char) in.read();
 			} else
 				throw new ParseFormatException("Unknown character " + car);
 			/* on lit la suite du literal */
 			while (car >= '0' && car <= '9') {
 				val = (val * 10) + car - '0';
 				car = (char) in.read();
 			}
 			if (val == 0) { // on a lu toute la clause
 				s.addClause(lit);
 				lit.clear();
 			} else {
 				/* on ajoute le literal au vecteur */
 				// s.newVar(val-1);
 				lit.push(neg ? -val : val);
 				neg = false;
 				val = 0; /* on reinitialise les variables */
 			}
 			if (car != EOF)
 				car = passerEspaces();
 			if (car == EOF) {
 				if (!lit.isEmpty()) {
 					s.addClause(lit);
 				}
 				break; /* on a lu tout le fichier */
 			}
 		}
 	}
 
 	/** passe tout les caract?res d'espacement (espace ou \n) */
 	private char passerEspaces() throws IOException {
 		char car;
 
 		do {
 			car = (char) in.read();
 		} while (car == ' ' || car == '\n');
 
 		return car;
 	}
 
 	/** passe tout les caract?res jusqu? rencontrer une fin de la ligne */
 	private char nextLine() throws IOException {
 		char car;
 		do {
 			car = (char) in.read();
 		} while ((car != '\n') && (car != EOF));
 		return car;
 	}
 
 	/** passe tout les caract?re jusqu'? rencontrer un chiffre */
 	private char nextChiffre() throws IOException {
 		char car;
 		do {
 			car = (char) in.read();
 		} while ((car < '0') || (car > '9') && (car != EOF));
 		return car;
 	}
 
 	@Override
 	public String decode(int[] model) {
 		StringBuffer stb = new StringBuffer();
 		for (int i = 0; i < model.length; i++) {
 			stb.append(model[i]);
 			stb.append(" ");
 		}
 		stb.append("0");
 		return stb.toString();
 	}
 
 	@Override
 	public void decode(int[] model, PrintWriter out) {
 		for (int i = 0; i < model.length; i++) {
 			out.print(model[i]);
 			out.print(" ");
 		}
 		out.print("0");
 	}
 }