package edu.ucsb.cs.jicos.applications.satsolver;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.util.Set;
import java.util.HashSet;

/**
 * Immutable
 * 
 * @author coakley
 */
public class Sat 
{
    private String title = "";
    private String type;    
    private int numVariables;
    private int numClauses;
    private Set<Integer>[] cnf;
    private Set<Integer>[] trueClauseSet;
    private Set<Integer>[] falseClauseSet;
    
    public Sat( File file) throws Exception
    {
        FileReader in = new FileReader( file );
        BufferedReader bufferedReader = new BufferedReader( in );

        String[] res;
        String input = bufferedReader.readLine();
        while ( input.startsWith("c") ) 
        {
            title += input + "\n";
            input = bufferedReader.readLine();
        }
        if ( input.matches("^p\\s+\\w+\\s+\\d+\\s+\\d+\\s*$") ) 
        {
            res = input.split("\\s+");
            assert res.length == 4;
            type = res[1];
            numVariables = Integer.parseInt(res[2]);
            numClauses = Integer.parseInt(res[3]);
        }
        
        trueClauseSet  = new HashSet[numVariables + 1];
        falseClauseSet = new HashSet[numVariables + 1];
        for ( int v = 1; v <= numVariables; v++ )
        {
             trueClauseSet[v] = new HashSet<Integer>();
            falseClauseSet[v] = new HashSet<Integer>();
        }
        
        cnf = new HashSet[numClauses];
        int clauseIndex = 0;
        while ( (input = bufferedReader.readLine()) != null ) 
        {
            res = input.split("\\s+");
            Set<Integer> clause = new HashSet<Integer>();
            assert res[res.length - 1].equals("0") : clauseIndex;
            for( int i = 0; i < res.length - 1; ++i ) 
            {
                int literal = Integer.parseInt( res[i] );
                clause.add( literal );
                if ( literal > 0 )
                {
                    trueClauseSet[literal].add( clauseIndex );
                }
                else
                {
                    falseClauseSet[-literal].add(clauseIndex);
                }
            }
            assert ! clause.isEmpty();
            cnf[clauseIndex++] = clause;
            assert clauseIndex <= numClauses;            
        }
        // some SATLIB files state the # of clauses incorreclty
        numClauses = clauseIndex; 
        System.gc();
    }
    
    public String getTitle() { return title; }
    
    public String getType() { return type; }
    
    public Set<Integer>[] getCNF() { return cnf; }
    
    public int getNVariables() { return numVariables; }
    
    public int getNClauses() { return numClauses; }
    
    public Set<Integer>[] getTrueClauseSet()  { return  trueClauseSet; }
    public Set<Integer>[] getFalseClauseSet() { return falseClauseSet; }
    
    public String toString()
    {
        StringBuffer sat = new StringBuffer();
        sat.append( getTitle() + "\n" );
        sat.append( "p " + getType() + " " + getNVariables() + " " + 
                    getNClauses() + "\n" );
        int clauseNumber = 0;
        for ( int clauseIndex = 0; clauseIndex < numClauses; clauseIndex++ )
        {
            System.out.println("clauseNumber: " + clauseNumber );
            sat.append( clauseNumber + ":" );
            for ( Integer literal : cnf[clauseIndex] )
            {
                sat.append( " " + literal );
            }
            sat.append(" 0 \n");
            clauseNumber++;
        }
        return new String( sat );
    }
}