/*******************************************************************************
   * 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.IOException;
  import java.io.InputStream;
  import java.io.PrintWriter;
  
  import org.sat4j.specs.ContradictionException;
  import org.sat4j.specs.IProblem;
  import org.sat4j.specs.ISolver;
  import org.sat4j.tools.GateTranslator;
  
  /**
   * Reader for the Binary And Inverter Graph format defined by Armin Biere.
   * 
   * @author daniel
   *
   */
  public class AIGReader extends Reader {
  
      private final static int FALSE = 0;
  
      private final static int TRUE = 1;
  
      private final GateTranslator solver;
  
      private int maxvarid;
  
      private int nbinputs;
  
      AIGReader(ISolver s) {
          solver = new GateTranslator(s);
      }
  
      @Override
      public String decode(int[] model) {
          StringBuffer stb = new StringBuffer();
          for (int i = 0; i < nbinputs; i++) {
              stb.append(model[i]>0?1:0);
          }
          return stb.toString();
      }
  
      @Override
      public void decode(int[] model, PrintWriter out) {
          for (int i = 0; i < nbinputs; i++) {
              out.print(model[i]>0?1:0);
          }
      }
  
      int parseInt(InputStream in, char expected) throws IOException,
              ParseFormatException {
          int res, ch;
          ch = in.read();
  
          if (ch < '0' || ch > '9')
              throw new ParseFormatException("expected digit");
          res = ch - '0';
  
          while ((ch = in.read()) >= '0' && ch <= '9')
              res = 10 * res + (ch - '0');
  
          if (ch != expected)
              throw new ParseFormatException("unexpected character");
  
          return res;
      }
  
      /*
       * (non-Javadoc)
       * 
       * @see org.sat4j.reader.Reader#parseInstance(java.io.InputStream)
       */
     @Override
     public IProblem parseInstance(InputStream in) throws ParseFormatException,
             ContradictionException, IOException {
         if (in.read() != 'a' || in.read() != 'i' || in.read() != 'g'
                 || in.read() != ' ') {
             throw new ParseFormatException("AIG format only!");
         }
         maxvarid = parseInt(in, ' ');
         nbinputs = parseInt(in, ' ');
         int nblatches = parseInt(in, ' ');
         if (nblatches > 0) {
             throw new ParseFormatException(
                     "CNF conversion cannot handle latches!");
         }
         int nboutputs = parseInt(in, ' ');
         if (nboutputs > 1) {
             throw new ParseFormatException(
                     "CNF conversion allowed for single output circuit only!");
         }
         int nbands = parseInt(in, '\n');
         solver.newVar(maxvarid + 1);
         solver.setExpectedNumberOfClauses(3 * nbands + 2);
         if (nboutputs > 0) {
             assert nboutputs == 1;
             int output0 = parseInt(in, '\n');
             readAnd(nbands, output0, in, 2 * (nbinputs + 1));
         }
         return solver;
     }
 
     static int safeGet(InputStream in) throws IOException, ParseFormatException {
         int ch = in.read();
         if (ch == -1) {
             throw new ParseFormatException("AIG Error, EOF met too early");
         }
         return ch;
     }
 
     static int decode(InputStream in) throws IOException, ParseFormatException {
         int x = 0, i = 0;
         int ch;
 
         while (((ch = safeGet(in)) & 0x80) > 0) {
             System.out.println("=>" + ch);
             x |= (ch & 0x7f) << (7 * i++);
         }
         return x | (ch << (7 * i));
     }
 
     private void readAnd(int nbands, int output0, InputStream in, int startid)
             throws ContradictionException, IOException, ParseFormatException {
         int lhs = startid;
         for (int i = 0; i < nbands; i++) {
             int delta0 = decode(in);
             int delta1 = decode(in);
             int rhs0 = lhs - delta0;
             int rhs1 = rhs0 - delta1;
             solver.and(toDimacs(lhs), toDimacs(rhs0), toDimacs(rhs1));
             lhs += 2;
         }
         solver.gateTrue(maxvarid + 1);
         solver.gateTrue(toDimacs(output0));
     }
 
     private int toDimacs(int v) {
         if (v == FALSE) {
             return -(maxvarid + 1);
         }
         if (v == TRUE) {
             return maxvarid + 1;
         }
         int var = v >> 1;
         if ((v & 1) == 0) {
             return var;
         }
         return -var;
     }
 
     @Override
     public IProblem parseInstance(java.io.Reader in)
             throws ParseFormatException, ContradictionException, IOException {
         throw new UnsupportedOperationException();
     }
 
 }