/* -*- C++ -*-

 *

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

 *

 * Copyright (C) 2003-2008

 * 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.

 *

 */

///\file

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

#include <lemon/mip_cplex.h>

namespace lemon {

  MipCplex::MipCplex() {

    //This is unnecessary: setting integrality constraints on

    //variables will set this, too 

    ///\todo The constant CPXPROB_MIP is

    ///called CPXPROB_MILP in later versions

#if CPX_VERSION < 800

    CPXchgprobtype( env,  lp, CPXPROB_MIP);

#else

    CPXchgprobtype( env,  lp, CPXPROB_MILP);

#endif

  }

  void MipCplex::_colType(int i, MipCplex::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.

    int indices[1];

    indices[0]=i;

    char ctype[1];

    switch (col_type){

      case INT:

	ctype[0]=CPX_INTEGER;//'I'

	break;

      case REAL:

	ctype[0]=CPX_CONTINUOUS	;//'C'

	break;

    default:;

        //FIXME problem

    }

    CPXchgctype (env, lp, 1, indices, ctype);

  }

  MipCplex::ColTypes MipCplex::_colType(int i) const {

    char ctype[1];

    CPXgetctype (env, lp, ctype, i, i);

    switch (ctype[0]){

    case CPX_INTEGER:

      return INT;

    case CPX_CONTINUOUS:

      return REAL;

    default:

      return REAL;//Error!

    }

  }

  LpCplex::SolveExitStatus MipCplex::_solve(){

    status = CPXmipopt (env, lp);

    if (status==0)

      return SOLVED;

    else

      return UNSOLVED;

  }

  LpCplex::SolutionStatus MipCplex::_getMipStatus() const {

    int stat = CPXgetstat(env, lp);

    //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 INFINITE;

      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.

  }  

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

    Value x;

    CPXgetmipx(env, lp, &x, i, i);

    return x;

  }

  MipCplex::Value MipCplex::_getPrimalValue() const {

    Value objval;

    CPXgetmipobjval(env, lp, &objval);

    return objval;

  }

} //END OF NAMESPACE LEMON