/*********************                                                        */
/*! \file sat_module.h
 ** \verbatim
 ** Original author: lianah
 ** Major contributors: 
 ** Minor contributors (to current version): 
 ** This file is part of the CVC4 prototype.
 ** Copyright (c) 2009, 2010, 2011  The Analysis of Computer Systems Group (ACSys)
 ** Courant Institute of Mathematical Sciences
 ** New York University
 ** See the file COPYING in the top-level source directory for licensing
 ** information.\endverbatim
 **
 ** \brief SAT Solver.
 **
 ** SAT Solver.
 **/

#include "cvc4_public.h"

#ifndef __CVC4__PROP__SAT_MODULE_H
#define __CVC4__PROP__SAT_MODULE_H

#include <string>
#include <stdint.h>
#include "util/options.h"
#include "util/stats.h"
#include "context/cdlist.h"
#include "prop/sat_solver_types.h"

namespace CVC4 {
namespace prop {

class TheoryProxy; 

class SatSolver {

public:  

  /** Virtual destructor */
  virtual ~SatSolver() { }
  
  /** Assert a clause in the solver. */
  virtual void addClause(SatClause& clause, bool removable) = 0;

  /** Create a new boolean variable in the solver. */
  virtual SatVariable newVar(bool theoryAtom = false) = 0;
 
  /** Create a new (or return an existing) boolean variable representing the constant true */
  virtual SatVariable trueVar() = 0;

  /** Create a new (or return an existing) boolean variable representing the constant false */
  virtual SatVariable falseVar() = 0;

  /** Check the satisfiability of the added clauses */
  virtual SatValue solve() = 0;

  /** Check the satisfiability of the added clauses */
  virtual SatValue solve(long unsigned int&) = 0;
  
  /** Interrupt the solver */
  virtual void interrupt() = 0;

  /** Call value() during the search.*/
  virtual SatValue value(SatLiteral l) = 0;

  /** Call modelValue() when the search is done.*/
  virtual SatValue modelValue(SatLiteral l) = 0;

  virtual void unregisterVar(SatLiteral lit) = 0;
  
  virtual void renewVar(SatLiteral lit, int level = -1) = 0;

  virtual unsigned getAssertionLevel() const = 0;

};


class BVSatSolverInterface: public SatSolver {
public:

  /** Interface for notifications */
  class Notify {
  public:

    virtual ~Notify() {};

    /**
     * If the notify returns false, the solver will break out of whatever it's currently doing
     * with an "unknown" answer.
     */
    virtual bool notify(SatLiteral lit) = 0;

    /**
     * Notify about a learnt clause.
     */
    virtual void notify(SatClause& clause) = 0;
  };

  virtual void setNotify(Notify* notify) = 0; 
  
  virtual void markUnremovable(SatLiteral lit) = 0;

  virtual void getUnsatCore(SatClause& unsatCore) = 0; 

  virtual void addMarkerLiteral(SatLiteral lit) = 0; 

  virtual SatValue propagate() = 0;

  virtual void explain(SatLiteral lit, std::vector<SatLiteral>& explanation) = 0;

  virtual SatValue assertAssumption(SatLiteral lit, bool propagate = false) = 0; 

  virtual void popAssumption() = 0;
}; 


class DPLLSatSolverInterface: public SatSolver {
public:
  virtual void initialize(context::Context* context, prop::TheoryProxy* theoryProxy) = 0; 
  
  virtual void push() = 0;

  virtual void pop() = 0;

  virtual bool properExplanation(SatLiteral lit, SatLiteral expl) const = 0;

  virtual void requirePhase(SatLiteral lit) = 0;

  virtual bool flipDecision() = 0;

  virtual bool isDecision(SatVariable decn) const = 0;

}; 

}/* prop namespace */

inline std::ostream& operator <<(std::ostream& out, prop::SatLiteral lit) {
  out << lit.toString();
  return out;
}

inline std::ostream& operator <<(std::ostream& out, const prop::SatClause& clause) {
  out << "clause:";
  for(unsigned i = 0; i < clause.size(); ++i) {
    out << " " << clause[i];
  }
  out << ";";
  return out;
}

inline std::ostream& operator <<(std::ostream& out, prop::SatValue val) {
  std::string str;
  switch(val) {
  case prop::SAT_VALUE_UNKNOWN:
    str = "_";
    break;
  case prop::SAT_VALUE_TRUE:
    str = "1";
    break;
  case prop::SAT_VALUE_FALSE:
    str = "0";
    break;
  default:
    str = "Error";
    break;
  }

  out << str;
  return out;
}

}/* CVC4 namespace */

#endif /* __CVC4__PROP__SAT_MODULE_H */