/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Copyright (C) 2003-2009

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#include <iostream>

#include <vector>

#include <cstring>

#include <lemon/cplex.h>

extern "C" {

#include <ilcplex/cplex.h>

}

///\file

///\brief Implementation of the LEMON-CPLEX lp solver interface.

namespace lemon {

  CplexEnv::LicenseError::LicenseError(int status) {

    if (!CPXgeterrorstring(0, status, _message)) {

      std::strcpy(_message, "Cplex unknown error");

    }

  }

  CplexEnv::CplexEnv() {

    int status;

    _cnt = new int;

    _env = CPXopenCPLEX(&status);

    if (_env == 0) {

      delete _cnt;

      _cnt = 0;

      throw LicenseError(status);

    }

  }

  CplexEnv::CplexEnv(const CplexEnv& other) {

    _env = other._env;

    _cnt = other._cnt;

    ++(*_cnt);

  }

  CplexEnv& CplexEnv::operator=(const CplexEnv& other) {

    _env = other._env;

    _cnt = other._cnt;

    ++(*_cnt);

    return *this;

  }

  CplexEnv::~CplexEnv() {

    --(*_cnt);

    if (*_cnt == 0) {

      delete _cnt;

      CPXcloseCPLEX(&_env);

    }

  }

  CplexBase::CplexBase() : LpBase() {

    int status;

    _prob = CPXcreateprob(cplexEnv(), &status, "Cplex problem");

    messageLevel(MESSAGE_NOTHING);

  }

  CplexBase::CplexBase(const CplexEnv& env)

    : LpBase(), _env(env) {

    int status;

    _prob = CPXcreateprob(cplexEnv(), &status, "Cplex problem");

    messageLevel(MESSAGE_NOTHING);

  }

  CplexBase::CplexBase(const CplexBase& cplex)

    : LpBase() {

    int status;

    _prob = CPXcloneprob(cplexEnv(), cplex._prob, &status);

    rows = cplex.rows;

    cols = cplex.cols;

    messageLevel(MESSAGE_NOTHING);

  }

  CplexBase::~CplexBase() {

    CPXfreeprob(cplexEnv(),&_prob);

  }

  int CplexBase::_addCol() {

    int i = CPXgetnumcols(cplexEnv(), _prob);

    double lb = -INF, ub = INF;

    CPXnewcols(cplexEnv(), _prob, 1, 0, &lb, &ub, 0, 0);

    return i;

  }

  int CplexBase::_addRow() {

    int i = CPXgetnumrows(cplexEnv(), _prob);

    const double ub = INF;

    const char s = 'L';

    CPXnewrows(cplexEnv(), _prob, 1, &ub, &s, 0, 0);

    return i;

  }

  int CplexBase::_addRow(Value lb, ExprIterator b, 

                         ExprIterator e, Value ub) {

    int i = CPXgetnumrows(cplexEnv(), _prob);

    if (lb == -INF) {

      const char s = 'L';

      CPXnewrows(cplexEnv(), _prob, 1, &ub, &s, 0, 0);

    } else if (ub == INF) {

      const char s = 'G';

      CPXnewrows(cplexEnv(), _prob, 1, &lb, &s, 0, 0);

    } else if (lb == ub){

      const char s = 'E';

      CPXnewrows(cplexEnv(), _prob, 1, &lb, &s, 0, 0);

    } else {

      const char s = 'R';

      double len = ub - lb;

      CPXnewrows(cplexEnv(), _prob, 1, &lb, &s, &len, 0);

    }

    std::vector<int> indices;

    std::vector<int> rowlist;

    std::vector<Value> values;

    for(ExprIterator it=b; it!=e; ++it) {

      indices.push_back(it->first);

      values.push_back(it->second);

      rowlist.push_back(i);

    }

    CPXchgcoeflist(cplexEnv(), _prob, values.size(),

                   &rowlist.front(), &indices.front(), &values.front());

    return i;

  }

  void CplexBase::_eraseCol(int i) {

    CPXdelcols(cplexEnv(), _prob, i, i);

  }

  void CplexBase::_eraseRow(int i) {

    CPXdelrows(cplexEnv(), _prob, i, i);

  }

  void CplexBase::_eraseColId(int i) {

    cols.eraseIndex(i);

    cols.shiftIndices(i);

  }

  void CplexBase::_eraseRowId(int i) {

    rows.eraseIndex(i);

    rows.shiftIndices(i);

  }

  void CplexBase::_getColName(int col, std::string &name) const {

    int size;

    CPXgetcolname(cplexEnv(), _prob, 0, 0, 0, &size, col, col);

    if (size == 0) {

      name.clear();

      return;

    }

    size *= -1;

    std::vector<char> buf(size);

    char *cname;

    int tmp;

    CPXgetcolname(cplexEnv(), _prob, &cname, &buf.front(), size,

                  &tmp, col, col);

    name = cname;

  }

  void CplexBase::_setColName(int col, const std::string &name) {

    char *cname;

    cname = const_cast<char*>(name.c_str());

    CPXchgcolname(cplexEnv(), _prob, 1, &col, &cname);

  }

  int CplexBase::_colByName(const std::string& name) const {

    int index;

    if (CPXgetcolindex(cplexEnv(), _prob,

                       const_cast<char*>(name.c_str()), &index) == 0) {

      return index;

    }

    return -1;

  }

  void CplexBase::_getRowName(int row, std::string &name) const {

    int size;

    CPXgetrowname(cplexEnv(), _prob, 0, 0, 0, &size, row, row);

    if (size == 0) {

      name.clear();

      return;

    }

    size *= -1;

    std::vector<char> buf(size);

    char *cname;

    int tmp;

    CPXgetrowname(cplexEnv(), _prob, &cname, &buf.front(), size,

                  &tmp, row, row);

    name = cname;

  }

  void CplexBase::_setRowName(int row, const std::string &name) {

    char *cname;

    cname = const_cast<char*>(name.c_str());

    CPXchgrowname(cplexEnv(), _prob, 1, &row, &cname);

  }

  int CplexBase::_rowByName(const std::string& name) const {

    int index;

    if (CPXgetrowindex(cplexEnv(), _prob,

                       const_cast<char*>(name.c_str()), &index) == 0) {

      return index;

    }

    return -1;

  }

  void CplexBase::_setRowCoeffs(int i, ExprIterator b,

                                      ExprIterator e)

  {

    std::vector<int> indices;

    std::vector<int> rowlist;

    std::vector<Value> values;

    for(ExprIterator it=b; it!=e; ++it) {

      indices.push_back(it->first);

      values.push_back(it->second);

      rowlist.push_back(i);

    }

    CPXchgcoeflist(cplexEnv(), _prob, values.size(),

                   &rowlist.front(), &indices.front(), &values.front());

  }

  void CplexBase::_getRowCoeffs(int i, InsertIterator b) const {

    int tmp1, tmp2, tmp3, length;

    CPXgetrows(cplexEnv(), _prob, &tmp1, &tmp2, 0, 0, 0, &length, i, i);

    length = -length;

    std::vector<int> indices(length);

    std::vector<double> values(length);

    CPXgetrows(cplexEnv(), _prob, &tmp1, &tmp2,

               &indices.front(), &values.front(),

               length, &tmp3, i, i);

    for (int i = 0; i < length; ++i) {

      *b = std::make_pair(indices[i], values[i]);

      ++b;

    }

  }

  void CplexBase::_setColCoeffs(int i, ExprIterator b, ExprIterator e) {

    std::vector<int> indices;

    std::vector<int> collist;

    std::vector<Value> values;

    for(ExprIterator it=b; it!=e; ++it) {

      indices.push_back(it->first);

      values.push_back(it->second);

      collist.push_back(i);

    }

    CPXchgcoeflist(cplexEnv(), _prob, values.size(),

                   &indices.front(), &collist.front(), &values.front());

  }

  void CplexBase::_getColCoeffs(int i, InsertIterator b) const {

    int tmp1, tmp2, tmp3, length;

    CPXgetcols(cplexEnv(), _prob, &tmp1, &tmp2, 0, 0, 0, &length, i, i);

    length = -length;

    std::vector<int> indices(length);

    std::vector<double> values(length);

    CPXgetcols(cplexEnv(), _prob, &tmp1, &tmp2,

               &indices.front(), &values.front(),

               length, &tmp3, i, i);

    for (int i = 0; i < length; ++i) {

      *b = std::make_pair(indices[i], values[i]);

      ++b;

    }

  }

  void CplexBase::_setCoeff(int row, int col, Value value) {

    CPXchgcoef(cplexEnv(), _prob, row, col, value);

  }

  CplexBase::Value CplexBase::_getCoeff(int row, int col) const {

    CplexBase::Value value;

    CPXgetcoef(cplexEnv(), _prob, row, col, &value);

    return value;

  }

  void CplexBase::_setColLowerBound(int i, Value value) {

    const char s = 'L';

    CPXchgbds(cplexEnv(), _prob, 1, &i, &s, &value);

  }

  CplexBase::Value CplexBase::_getColLowerBound(int i) const {

    CplexBase::Value res;

    CPXgetlb(cplexEnv(), _prob, &res, i, i);

    return res <= -CPX_INFBOUND ? -INF : res;

  }

  void CplexBase::_setColUpperBound(int i, Value value)

  {

    const char s = 'U';

    CPXchgbds(cplexEnv(), _prob, 1, &i, &s, &value);

  }

  CplexBase::Value CplexBase::_getColUpperBound(int i) const {

    CplexBase::Value res;

    CPXgetub(cplexEnv(), _prob, &res, i, i);

    return res >= CPX_INFBOUND ? INF : res;

  }

  CplexBase::Value CplexBase::_getRowLowerBound(int i) const {

    char s;

    CPXgetsense(cplexEnv(), _prob, &s, i, i);

    CplexBase::Value res;

    switch (s) {

    case 'G':

    case 'R':

    case 'E':

      CPXgetrhs(cplexEnv(), _prob, &res, i, i);

      return res <= -CPX_INFBOUND ? -INF : res;

    default:

      return -INF;

    }

  }

  CplexBase::Value CplexBase::_getRowUpperBound(int i) const {

    char s;

    CPXgetsense(cplexEnv(), _prob, &s, i, i);

    CplexBase::Value res;

    switch (s) {

    case 'L':

    case 'E':

      CPXgetrhs(cplexEnv(), _prob, &res, i, i);

      return res >= CPX_INFBOUND ? INF : res;

    case 'R':

      CPXgetrhs(cplexEnv(), _prob, &res, i, i);

      {

        double rng;

        CPXgetrngval(cplexEnv(), _prob, &rng, i, i);

        res += rng;

      }

      return res >= CPX_INFBOUND ? INF : res;

    default:

      return INF;

    }

  }

  //This is easier to implement

  void CplexBase::_set_row_bounds(int i, Value lb, Value ub) {

    if (lb == -INF) {

      const char s = 'L';

      CPXchgsense(cplexEnv(), _prob, 1, &i, &s);

      CPXchgrhs(cplexEnv(), _prob, 1, &i, &ub);

    } else if (ub == INF) {

      const char s = 'G';

      CPXchgsense(cplexEnv(), _prob, 1, &i, &s);

      CPXchgrhs(cplexEnv(), _prob, 1, &i, &lb);

    } else if (lb == ub){

      const char s = 'E';

      CPXchgsense(cplexEnv(), _prob, 1, &i, &s);

      CPXchgrhs(cplexEnv(), _prob, 1, &i, &lb);

    } else {

      const char s = 'R';

      CPXchgsense(cplexEnv(), _prob, 1, &i, &s);

      CPXchgrhs(cplexEnv(), _prob, 1, &i, &lb);

      double len = ub - lb;

      CPXchgrngval(cplexEnv(), _prob, 1, &i, &len);

    }

  }

  void CplexBase::_setRowLowerBound(int i, Value lb)

  {

    LEMON_ASSERT(lb != INF, "Invalid bound");

    _set_row_bounds(i, lb, CplexBase::_getRowUpperBound(i));

  }

  void CplexBase::_setRowUpperBound(int i, Value ub)

  {

    LEMON_ASSERT(ub != -INF, "Invalid bound");

    _set_row_bounds(i, CplexBase::_getRowLowerBound(i), ub);

  }

  void CplexBase::_setObjCoeffs(ExprIterator b, ExprIterator e)

  {

    std::vector<int> indices;

    std::vector<Value> values;

    for(ExprIterator it=b; it!=e; ++it) {

      indices.push_back(it->first);

      values.push_back(it->second);

    }

    CPXchgobj(cplexEnv(), _prob, values.size(),

              &indices.front(), &values.front());

  }

  void CplexBase::_getObjCoeffs(InsertIterator b) const

  {

    int num = CPXgetnumcols(cplexEnv(), _prob);

    std::vector<Value> x(num);

    CPXgetobj(cplexEnv(), _prob, &x.front(), 0, num - 1);

    for (int i = 0; i < num; ++i) {

      if (x[i] != 0.0) {

        *b = std::make_pair(i, x[i]);

        ++b;

      }

    }

  }

  void CplexBase::_setObjCoeff(int i, Value obj_coef)

  {

    CPXchgobj(cplexEnv(), _prob, 1, &i, &obj_coef);

  }

  CplexBase::Value CplexBase::_getObjCoeff(int i) const

  {

    Value x;

    CPXgetobj(cplexEnv(), _prob, &x, i, i);

    return x;

  }

  void CplexBase::_setSense(CplexBase::Sense sense) {

    switch (sense) {

    case MIN:

      CPXchgobjsen(cplexEnv(), _prob, CPX_MIN);

      break;

    case MAX:

      CPXchgobjsen(cplexEnv(), _prob, CPX_MAX);

      break;

    }

  }

  CplexBase::Sense CplexBase::_getSense() const {

    switch (CPXgetobjsen(cplexEnv(), _prob)) {

    case CPX_MIN:

      return MIN;

    case CPX_MAX:

      return MAX;

    default:

      LEMON_ASSERT(false, "Invalid sense");

      return CplexBase::Sense();

    }

  }

  void CplexBase::_clear() {

    CPXfreeprob(cplexEnv(),&_prob);

    int status;

    _prob = CPXcreateprob(cplexEnv(), &status, "Cplex problem");

    rows.clear();

    cols.clear();

  }

  void CplexBase::_messageLevel(MessageLevel level) {

    switch (level) {

    case MESSAGE_NOTHING:

      _message_enabled = false;

      break;

    case MESSAGE_ERROR:

    case MESSAGE_WARNING:

    case MESSAGE_NORMAL:

    case MESSAGE_VERBOSE:

      _message_enabled = true;

      break;

    }

  }

  void CplexBase::_applyMessageLevel() {

    CPXsetintparam(cplexEnv(), CPX_PARAM_SCRIND, 

                   _message_enabled ? CPX_ON : CPX_OFF);

  }

  // CplexLp members

  CplexLp::CplexLp()

    : LpBase(), LpSolver(), CplexBase() {}

  CplexLp::CplexLp(const CplexEnv& env)

    : LpBase(), LpSolver(), CplexBase(env) {}

  CplexLp::CplexLp(const CplexLp& other)

    : LpBase(), LpSolver(), CplexBase(other) {}

  CplexLp::~CplexLp() {}

  CplexLp* CplexLp::newSolver() const { return new CplexLp; }

  CplexLp* CplexLp::cloneSolver() const {return new CplexLp(*this); }

  const char* CplexLp::_solverName() const { return "CplexLp"; }

  void CplexLp::_clear_temporals() {

    _col_status.clear();

    _row_status.clear();

    _primal_ray.clear();

    _dual_ray.clear();

  }

  // The routine returns zero unless an error occurred during the

  // optimization. Examples of errors include exhausting available

  // memory (CPXERR_NO_MEMORY) or encountering invalid data in the

  // CPLEX problem object (CPXERR_NO_PROBLEM). Exceeding a

  // user-specified CPLEX limit, or proving the model infeasible or

  // unbounded, are not considered errors. Note that a zero return

  // value does not necessarily mean that a solution exists. Use query

  // routines CPXsolninfo, CPXgetstat, and CPXsolution to obtain

  // further information about the status of the optimization.

  CplexLp::SolveExitStatus CplexLp::convertStatus(int status) {

#if CPX_VERSION >= 800

    if (status == 0) {

      switch (CPXgetstat(cplexEnv(), _prob)) {

      case CPX_STAT_OPTIMAL:

      case CPX_STAT_INFEASIBLE:

      case CPX_STAT_UNBOUNDED:

        return SOLVED;

      default:

        return UNSOLVED;

      }

    } else {

      return UNSOLVED;

    }

#else

    if (status == 0) {

      //We want to exclude some cases

      switch (CPXgetstat(cplexEnv(), _prob)) {

      case CPX_OBJ_LIM:

      case CPX_IT_LIM_FEAS:

      case CPX_IT_LIM_INFEAS:

      case CPX_TIME_LIM_FEAS:

      case CPX_TIME_LIM_INFEAS:

        return UNSOLVED;

      default:

        return SOLVED;

      }

    } else {

      return UNSOLVED;

    }

#endif

  }

  CplexLp::SolveExitStatus CplexLp::_solve() {

    _clear_temporals();

    _applyMessageLevel();

    return convertStatus(CPXlpopt(cplexEnv(), _prob));

  }

  CplexLp::SolveExitStatus CplexLp::solvePrimal() {

    _clear_temporals();

    _applyMessageLevel();

    return convertStatus(CPXprimopt(cplexEnv(), _prob));

  }

  CplexLp::SolveExitStatus CplexLp::solveDual() {

    _clear_temporals();

    _applyMessageLevel();

    return convertStatus(CPXdualopt(cplexEnv(), _prob));

  }

  CplexLp::SolveExitStatus CplexLp::solveBarrier() {

    _clear_temporals();

    _applyMessageLevel();

    return convertStatus(CPXbaropt(cplexEnv(), _prob));

  }

  CplexLp::Value CplexLp::_getPrimal(int i) const {

    Value x;

    CPXgetx(cplexEnv(), _prob, &x, i, i);

    return x;

  }

  CplexLp::Value CplexLp::_getDual(int i) const {

    Value y;

    CPXgetpi(cplexEnv(), _prob, &y, i, i);

    return y;

  }

  CplexLp::Value CplexLp::_getPrimalValue() const {

    Value objval;

    CPXgetobjval(cplexEnv(), _prob, &objval);

    return objval;

  }

  CplexLp::VarStatus CplexLp::_getColStatus(int i) const {

    if (_col_status.empty()) {

      _col_status.resize(CPXgetnumcols(cplexEnv(), _prob));

      CPXgetbase(cplexEnv(), _prob, &_col_status.front(), 0);

    }

    switch (_col_status[i]) {

    case CPX_BASIC:

      return BASIC;

    case CPX_FREE_SUPER:

      return FREE;

    case CPX_AT_LOWER:

      return LOWER;

    case CPX_AT_UPPER:

      return UPPER;

    default:

      LEMON_ASSERT(false, "Wrong column status");

      return CplexLp::VarStatus();

    }

  }

  CplexLp::VarStatus CplexLp::_getRowStatus(int i) const {

    if (_row_status.empty()) {

      _row_status.resize(CPXgetnumrows(cplexEnv(), _prob));

      CPXgetbase(cplexEnv(), _prob, 0, &_row_status.front());

    }

    switch (_row_status[i]) {

    case CPX_BASIC:

      return BASIC;

    case CPX_AT_LOWER:

      {

        char s;

        CPXgetsense(cplexEnv(), _prob, &s, i, i);

        return s != 'L' ? LOWER : UPPER;

      }

    case CPX_AT_UPPER:

      return UPPER;

    default:

      LEMON_ASSERT(false, "Wrong row status");

      return CplexLp::VarStatus();

    }

  }

  CplexLp::Value CplexLp::_getPrimalRay(int i) const {

    if (_primal_ray.empty()) {

      _primal_ray.resize(CPXgetnumcols(cplexEnv(), _prob));

      CPXgetray(cplexEnv(), _prob, &_primal_ray.front());

    }

    return _primal_ray[i];

  }

  CplexLp::Value CplexLp::_getDualRay(int i) const {

    if (_dual_ray.empty()) {

    }

    return _dual_ray[i];

  }

  // Cplex 7.0 status values

  // This table lists the statuses, returned by the CPXgetstat()

  // routine, for solutions to LP problems or mixed integer problems. If

  // no solution exists, the return value is zero.

  // For Simplex, Barrier

  // 1          CPX_OPTIMAL

  //          Optimal solution found

  // 2          CPX_INFEASIBLE

  //          Problem infeasible

  // 3    CPX_UNBOUNDED

  //          Problem unbounded

  // 4          CPX_OBJ_LIM

  //          Objective limit exceeded in Phase II

  // 5          CPX_IT_LIM_FEAS

  //          Iteration limit exceeded in Phase II

  // 6          CPX_IT_LIM_INFEAS

  //          Iteration limit exceeded in Phase I

  // 7          CPX_TIME_LIM_FEAS

  //          Time limit exceeded in Phase II

  // 8          CPX_TIME_LIM_INFEAS

  //          Time limit exceeded in Phase I

  // 9          CPX_NUM_BEST_FEAS

  //          Problem non-optimal, singularities in Phase II

  // 10         CPX_NUM_BEST_INFEAS

  //          Problem non-optimal, singularities in Phase I

  // 11         CPX_OPTIMAL_INFEAS

  //          Optimal solution found, unscaled infeasibilities

  // 12         CPX_ABORT_FEAS

  //          Aborted in Phase II

  // 13         CPX_ABORT_INFEAS

  //          Aborted in Phase I

  // 14          CPX_ABORT_DUAL_INFEAS

  //          Aborted in barrier, dual infeasible

  // 15          CPX_ABORT_PRIM_INFEAS

  //          Aborted in barrier, primal infeasible

  // 16          CPX_ABORT_PRIM_DUAL_INFEAS

  //          Aborted in barrier, primal and dual infeasible

  // 17          CPX_ABORT_PRIM_DUAL_FEAS

  //          Aborted in barrier, primal and dual feasible

  // 18          CPX_ABORT_CROSSOVER

  //          Aborted in crossover

  // 19          CPX_INForUNBD

  //          Infeasible or unbounded

  // 20   CPX_PIVOT

  //       User pivot used

  //

  // Pending return values

  // ??case CPX_ABORT_DUAL_INFEAS

  // ??case CPX_ABORT_CROSSOVER

  // ??case CPX_INForUNBD

  // ??case CPX_PIVOT

  //Some more interesting stuff:

  // CPX_PARAM_PROBMETHOD  1062  int  LPMETHOD

  // 0 Automatic

  // 1 Primal Simplex

  // 2 Dual Simplex

  // 3 Network Simplex

  // 4 Standard Barrier

  // Default: 0

  // Description: Method for linear optimization.

  // Determines which algorithm is used when CPXlpopt() (or "optimize"

  // in the Interactive Optimizer) is called. Currently the behavior of

  // the "Automatic" setting is that CPLEX simply invokes the dual

  // simplex method, but this capability may be expanded in the future

  // so that CPLEX chooses the method based on problem characteristics

#if CPX_VERSION < 900

  void statusSwitch(CPXENVptr cplexEnv(),int& stat){

    int lpmethod;

    CPXgetintparam (cplexEnv(),CPX_PARAM_PROBMETHOD,&lpmethod);

    if (lpmethod==2){

      if (stat==CPX_UNBOUNDED){

        stat=CPX_INFEASIBLE;

      }

      else{

        if (stat==CPX_INFEASIBLE)

          stat=CPX_UNBOUNDED;

      }

    }

  }

#else

  void statusSwitch(CPXENVptr,int&){}

#endif

  CplexLp::ProblemType CplexLp::_getPrimalType() const {

    // Unboundedness not treated well: the following is from cplex 9.0 doc

    // About Unboundedness

    // The treatment of models that are unbounded involves a few

    // subtleties. Specifically, a declaration of unboundedness means that

    // ILOG CPLEX has determined that the model has an unbounded

    // ray. Given any feasible solution x with objective z, a multiple of

    // the unbounded ray can be added to x to give a feasible solution

    // with objective z-1 (or z+1 for maximization models). Thus, if a

    // feasible solution exists, then the optimal objective is

    // unbounded. Note that ILOG CPLEX has not necessarily concluded that

    // a feasible solution exists. Users can call the routine CPXsolninfo

    // to determine whether ILOG CPLEX has also concluded that the model

    // has a feasible solution.

    int stat = CPXgetstat(cplexEnv(), _prob);

#if CPX_VERSION >= 800

    switch (stat)

      {

      case CPX_STAT_OPTIMAL:

        return OPTIMAL;

      case CPX_STAT_UNBOUNDED:

        return UNBOUNDED;

      case CPX_STAT_INFEASIBLE:

        return INFEASIBLE;

      default:

        return UNDEFINED;

      }

#else

    statusSwitch(cplexEnv(),stat);

    //CPXgetstat(cplexEnv(), _prob);

    switch (stat) {

    case 0:

      return UNDEFINED; //Undefined

    case CPX_OPTIMAL://Optimal

      return OPTIMAL;

    case CPX_UNBOUNDED://Unbounded

      return INFEASIBLE;//In case of dual simplex

      //return UNBOUNDED;

    case CPX_INFEASIBLE://Infeasible

      //    case CPX_IT_LIM_INFEAS:

      //     case CPX_TIME_LIM_INFEAS:

      //     case CPX_NUM_BEST_INFEAS:

      //     case CPX_OPTIMAL_INFEAS:

      //     case CPX_ABORT_INFEAS:

      //     case CPX_ABORT_PRIM_INFEAS:

      //     case CPX_ABORT_PRIM_DUAL_INFEAS:

      return UNBOUNDED;//In case of dual simplex

      //return INFEASIBLE;

      //     case CPX_OBJ_LIM:

      //     case CPX_IT_LIM_FEAS:

      //     case CPX_TIME_LIM_FEAS:

      //     case CPX_NUM_BEST_FEAS:

      //     case CPX_ABORT_FEAS:

      //     case CPX_ABORT_PRIM_DUAL_FEAS:

      //       return FEASIBLE;

    default:

      return UNDEFINED; //Everything else comes here

      //FIXME error

    }

#endif

  }

  // Cplex 9.0 status values

  // CPX_STAT_ABORT_DUAL_OBJ_LIM

  // CPX_STAT_ABORT_IT_LIM

  // CPX_STAT_ABORT_OBJ_LIM

  // CPX_STAT_ABORT_PRIM_OBJ_LIM

  // CPX_STAT_ABORT_TIME_LIM

  // CPX_STAT_ABORT_USER

  // CPX_STAT_FEASIBLE_RELAXED

  // CPX_STAT_INFEASIBLE

  // CPX_STAT_INForUNBD

  // CPX_STAT_NUM_BEST

  // CPX_STAT_OPTIMAL

  // CPX_STAT_OPTIMAL_FACE_UNBOUNDED

  // CPX_STAT_OPTIMAL_INFEAS

  // CPX_STAT_OPTIMAL_RELAXED

  // CPX_STAT_UNBOUNDED

  CplexLp::ProblemType CplexLp::_getDualType() const {

    int stat = CPXgetstat(cplexEnv(), _prob);

#if CPX_VERSION >= 800

    switch (stat) {

    case CPX_STAT_OPTIMAL:

      return OPTIMAL;

    case CPX_STAT_UNBOUNDED:

      return INFEASIBLE;

    default:

      return UNDEFINED;

    }

#else

    statusSwitch(cplexEnv(),stat);

    switch (stat) {

    case 0:

      return UNDEFINED; //Undefined

    case CPX_OPTIMAL://Optimal

      return OPTIMAL;

    case CPX_UNBOUNDED:

      return INFEASIBLE;

    default:

      return UNDEFINED; //Everything else comes here

      //FIXME error

    }

#endif

  }

  // CplexMip members

  CplexMip::CplexMip()

    : LpBase(), MipSolver(), CplexBase() {

#if CPX_VERSION < 800

    CPXchgprobtype(cplexEnv(),  _prob, CPXPROB_MIP);

#else

    CPXchgprobtype(cplexEnv(),  _prob, CPXPROB_MILP);

#endif

  }

  CplexMip::CplexMip(const CplexEnv& env)

    : LpBase(), MipSolver(), CplexBase(env) {

#if CPX_VERSION < 800

    CPXchgprobtype(cplexEnv(),  _prob, CPXPROB_MIP);

#else

    CPXchgprobtype(cplexEnv(),  _prob, CPXPROB_MILP);

#endif

  }

  CplexMip::CplexMip(const CplexMip& other)

    : LpBase(), MipSolver(), CplexBase(other) {}

  CplexMip::~CplexMip() {}

  CplexMip* CplexMip::newSolver() const { return new CplexMip; }

  CplexMip* CplexMip::cloneSolver() const {return new CplexMip(*this); }

  const char* CplexMip::_solverName() const { return "CplexMip"; }

  void CplexMip::_setColType(int i, CplexMip::ColTypes col_type) {

    // Note If a variable is to be changed to binary, a call to CPXchgbds

    // should also be made to change the bounds to 0 and 1.

    switch (col_type){

    case INTEGER: {

      const char t = 'I';

      CPXchgctype (cplexEnv(), _prob, 1, &i, &t);

    } break;

    case REAL: {

      const char t = 'C';

      CPXchgctype (cplexEnv(), _prob, 1, &i, &t);

    } break;

    default:

      break;

    }

  }

  CplexMip::ColTypes CplexMip::_getColType(int i) const {

    char t;

    CPXgetctype (cplexEnv(), _prob, &t, i, i);

    switch (t) {

    case 'I':

      return INTEGER;

    case 'C':

      return REAL;

    default:

      LEMON_ASSERT(false, "Invalid column type");

      return ColTypes();

    }

  }

  CplexMip::SolveExitStatus CplexMip::_solve() {

    int status;

    _applyMessageLevel();

    status = CPXmipopt (cplexEnv(), _prob);

    if (status==0)

      return SOLVED;

    else

      return UNSOLVED;

  }

  CplexMip::ProblemType CplexMip::_getType() const {

    int stat = CPXgetstat(cplexEnv(), _prob);

    //Fortunately, MIP statuses did not change for cplex 8.0

    switch (stat) {

    case CPXMIP_OPTIMAL:

      // Optimal integer solution has been found.

    case CPXMIP_OPTIMAL_TOL:

      // Optimal soluton with the tolerance defined by epgap or epagap has

      // been found.

      return OPTIMAL;

      //This also exists in later issues

      //    case CPXMIP_UNBOUNDED:

      //return UNBOUNDED;

      case CPXMIP_INFEASIBLE:

        return INFEASIBLE;

    default:

      return UNDEFINED;

    }

    //Unboundedness not treated well: the following is from cplex 9.0 doc

    // About Unboundedness

    // The treatment of models that are unbounded involves a few

    // subtleties. Specifically, a declaration of unboundedness means that

    // ILOG CPLEX has determined that the model has an unbounded

    // ray. Given any feasible solution x with objective z, a multiple of

    // the unbounded ray can be added to x to give a feasible solution

    // with objective z-1 (or z+1 for maximization models). Thus, if a

    // feasible solution exists, then the optimal objective is

    // unbounded. Note that ILOG CPLEX has not necessarily concluded that

    // a feasible solution exists. Users can call the routine CPXsolninfo

    // to determine whether ILOG CPLEX has also concluded that the model

    // has a feasible solution.

  }

  CplexMip::Value CplexMip::_getSol(int i) const {

    Value x;

    CPXgetmipx(cplexEnv(), _prob, &x, i, i);

    return x;

  }

  CplexMip::Value CplexMip::_getSolValue() const {

    Value objval;

    CPXgetmipobjval(cplexEnv(), _prob, &objval);

    return objval;

  }

} //namespace lemon