/*********************                                                        */
/*! \file kissat.cpp
 ** \verbatim
 ** Top contributors (to current version):
 **   Aina Niemetz
 ** This file is part of the CVC4 project.
 ** Copyright (c) 2009-2021 by the authors listed in the file AUTHORS
 ** in the top-level source directory and their institutional affiliations.
 ** All rights reserved.  See the file COPYING in the top-level source
 ** directory for licensing information.\endverbatim
 **
 ** \brief Wrapper for Kissat SAT Solver.
 **
 ** Wrapper for the Kissat SAT solver (for theory of bit-vectors).
 **/

#include "prop/kissat.h"

#ifdef CVC4_USE_KISSAT

#include "base/check.h"

namespace CVC4 {
namespace prop {

using KissatLit = int32_t;
using KissatVar = int32_t;

// helper functions
namespace {

SatValue toSatValue(int32_t result)
{
  if (result == 10) return SAT_VALUE_TRUE;
  if (result == 20) return SAT_VALUE_FALSE;
  Assert(result == 0);
  return SAT_VALUE_UNKNOWN;
}

/**
 * Helper to convert the value of a literal as returned by Kissat to the
 * corresponding true/false SAT_VALUE.
 * Note: Kissat returns lit/-lit for true/false. Older versions returned 1/-1.
 */
SatValue toSatValueLit(int value)
{
  if (value > 0) return SAT_VALUE_TRUE;
  Assert(value < 0);
  return SAT_VALUE_FALSE;
}

/** Helper to convert SatLiteral to KissatLit. */
KissatLit toKissatLit(const SatLiteral lit)
{
  return lit.isNegated() ? -lit.getSatVariable() : lit.getSatVariable();
}

/** Helper to convert a SatVariable to a KissatVar. */
KissatVar toKissatVar(SatVariable var) { return var; }

}  // namespace

KissatSolver::KissatSolver(StatisticsRegistry* registry,
                           const std::string& name)
    : d_solver(kissat_init()),
      // Note: Kissat variables start with index 1 rather than 0 since negated
      //       literals are represented as the negation of the index.
      d_nextVarIdx(1),
      d_statistics(registry, name)
{
}

void KissatSolver::init()
{
  d_true = newVar();
  d_false = newVar();
  kissat_add(d_solver, toKissatVar(d_true));
  kissat_add(d_solver, 0);
  kissat_add(d_solver, -toKissatVar(d_false));
  kissat_add(d_solver, 0);
}

KissatSolver::~KissatSolver() { kissat_release(d_solver); }

ClauseId KissatSolver::addClause(SatClause& clause, bool removable)
{
  for (const SatLiteral& lit : clause)
  {
    kissat_add(d_solver, toKissatLit(lit));
  }
  kissat_add(d_solver, 0);
  ++d_statistics.d_numClauses;
  return ClauseIdError;
}

ClauseId KissatSolver::addXorClause(SatClause& clause, bool rhs, bool removable)
{
  Unreachable() << "Kissat does not support adding XOR clauses.";
}

SatVariable KissatSolver::newVar(bool isTheoryAtom,
                                 bool preRegister,
                                 bool canErase)
{
  ++d_statistics.d_numVariables;
  return d_nextVarIdx++;
}

SatVariable KissatSolver::trueVar() { return d_true; }

SatVariable KissatSolver::falseVar() { return d_false; }

SatValue KissatSolver::solve()
{
  TimerStat::CodeTimer codeTimer(d_statistics.d_solveTime);
  SatValue res = toSatValue(kissat_solve(d_solver));
  d_okay = (res == SAT_VALUE_TRUE);
  ++d_statistics.d_numSatCalls;
  return res;
}

SatValue KissatSolver::solve(long unsigned int&)
{
  Unimplemented() << "Setting limits for Kissat not supported yet";
};

SatValue KissatSolver::solve(const std::vector<SatLiteral>& assumptions)
{
  Unimplemented() << "Incremental solving with Kissat not supported yet";
}

void KissatSolver::interrupt() { kissat_terminate(d_solver); }

SatValue KissatSolver::value(SatLiteral l)
{
  Assert(d_okay);
  return toSatValueLit(kissat_value(d_solver, toKissatLit(l)));
}

SatValue KissatSolver::modelValue(SatLiteral l)
{
  Assert(d_okay);
  return value(l);
}

unsigned KissatSolver::getAssertionLevel() const
{
  Unreachable() << "Kissat does not support assertion levels.";
}

bool KissatSolver::ok() const { return d_okay; }

KissatSolver::Statistics::Statistics(StatisticsRegistry* registry,
                                     const std::string& prefix)
    : d_registry(registry),
      d_numSatCalls("theory::bv::" + prefix + "::Kissat::calls_to_solve", 0),
      d_numVariables("theory::bv::" + prefix + "::Kissat::variables", 0),
      d_numClauses("theory::bv::" + prefix + "::Kissat::clauses", 0),
      d_solveTime("theory::bv::" + prefix + "::Kissat::solve_time")
{
  d_registry->registerStat(&d_numSatCalls);
  d_registry->registerStat(&d_numVariables);
  d_registry->registerStat(&d_numClauses);
  d_registry->registerStat(&d_solveTime);
}

KissatSolver::Statistics::~Statistics()
{
  d_registry->unregisterStat(&d_numSatCalls);
  d_registry->unregisterStat(&d_numVariables);
  d_registry->unregisterStat(&d_numClauses);
  d_registry->unregisterStat(&d_solveTime);
}

}  // namespace prop
}  // namespace CVC4

#endif  // CVC4_USE_KISSAT