#include "cantera/equil/vcs_solve.h"
#include "cantera/equil/vcs_internal.h"
#include "cantera/equil/vcs_species_thermo.h"
#include "cantera/equil/vcs_VolPhase.h"

#include <cstdio>
#include <cstdlib>
#include <cmath>

namespace VCSnonideal
{

/*****************************************************************************/
/*****************************************************************************/
/*****************************************************************************/

int VCS_SOLVE::vcs_TP(int ipr, int ip1, int maxit, double T_arg, double pres_arg)

/**************************************************************************
 *
 * vcs_TP:
 *
 *      Solve an equilibrium problem at a particular fixed temperature
 *      and pressure
 *
 *     ipr = 1 -> Print results to standard output
 *           0 -> don't report on anything
 *     ip1 = 1 -> Print intermediate results.
 *     maxit -> Maximum number of iterations for the algorithm
 *      T = Temperature (Kelvin)
 *    pres = Pressure (pascal)
 *
 * Return Codes
 * ------------------
 *   0 = Equilibrium Achieved
 *   1 = Range space error encountered. The element abundance criteria are
 *       only partially satisfied. Specifically, the first NC= (number of
 *       components) conditions are satisfied. However, the full NE
 *       (number of elements) conditions are not satisfied. The equilibrium
 *       condition is returned.
 * -1 = Maximum number of iterations is exceeded. Convergence was not
 *      found.
 ***************************************************************************/
{
    int retn, iconv;
    /*
     *        Store the temperature and pressure in the private global variables
     */
    m_temperature = T_arg;
    m_pressurePA = pres_arg;
    /*
     *        Evaluate the standard state free energies
     *        at the current temperatures and pressures.
     */
    iconv = vcs_evalSS_TP(ipr, ip1, m_temperature, pres_arg);

    /*
     *        Prepare the problem data:
     *          ->nondimensionalize the free energies using
     *            the divisor, R * T
     */
    vcs_nondim_TP();
    /*
     * Prep the fe field
     */
    vcs_fePrep_TP();
    /*
     *      Decide whether we need an initial estimate of the solution
     *      If so, go get one. If not, then
     */
    if (m_doEstimateEquil) {
        retn = vcs_inest_TP();
        if (retn != VCS_SUCCESS) {
            plogf("vcs_inest_TP returned a failure flag\n");
        }
    }
    /*
     *        Solve the problem at a fixed Temperature and Pressure
     * (all information concerning Temperature and Pressure has already
     *  been derived. The free energies are now in dimensionless form.)
     */
    iconv  = vcs_solve_TP(ipr, ip1, maxit);

    /*
     *        Redimensionalize the free energies using
     *        the reverse of vcs_nondim to add back units.
     */
    vcs_redim_TP();
    /*
     *        Return the convergence success flag.
     */
    return iconv;
}
/*****************************************************************************/
/*****************************************************************************/
/*****************************************************************************/
/*ARGSUSED*/
int VCS_SOLVE::vcs_evalSS_TP(int ipr, int ip1, double Temp, double pres)

/**************************************************************************
 *
 * vcs_evalSS_TP:
 *
 *     IPR = 1 -> Print results to standard output
 *           0 -> don't report on anything
 *     IP1 = 1 -> Print intermediate results.
 *      T = Temperature (Kelvin)
 *    Pres = Pressure (Pascal)
 *
 *    Evaluate the standard state free energies at the current temperature
 *    and pressure. Ideal gas pressure contribution is added in here.
 *
 ***************************************************************************/
{
    // int i;
    //double  R;
    /*
     * At this level of the program, we are still using values
     * for the free energies that have units.
     */
    // R =  vcsUtil_gasConstant(m_VCS_UnitsFormat);

    /*
     *  We need to special case VCS_UNITS_UNITLESS, here.
     *      cpc_ts_GStar_calc() returns units of Kelvin. Also, the temperature
     *      comes into play in calculating the ideal equation of state
     *      contributions, and other equations of state also. Therefore,
     *      we will emulate the VCS_UNITS_KELVIN case, here by changing
     *      the initial gibbs free energy units to Kelvin before feeding
     *      them to the cpc_ts_GStar_calc() routine. Then, we will revert
     *      them back to unitless at the end of this routine.
     */


    /*
     *    Loop over the species calculating the standard state Gibbs free
     *    energies. -> These are energies that only depend upon the Temperature
     *    and possibly on the pressure (i.e., ideal gas, etc).
     */
    // HKM -> We can change this to looks over phases, calling the vcs_VolPhase
    //        object. Working to get rid of VCS_SPECIES_THERMO object
    //for (i = 0; i < m_numSpeciesTot; ++i) {
    // VCS_SPECIES_THERMO *spt = SpeciesThermo[i];
    // ff[i] = R * spt->GStar_R_calc(i, Temp, pres);
    //}

    for (size_t iph = 0; iph < m_numPhases; iph++) {
        vcs_VolPhase* vph = m_VolPhaseList[iph];
        vph->setState_TP(m_temperature, m_pressurePA);
        vph->sendToVCS_GStar(VCS_DATA_PTR(m_SSfeSpecies));
    }

    if (m_VCS_UnitsFormat == VCS_UNITS_UNITLESS) {
        for (size_t i = 0; i < m_numSpeciesTot; ++i) {
            m_SSfeSpecies[i]  /= Temp;
        }
    }
    return VCS_SUCCESS;
} /***************************************************************************/

/*****************************************************************************/
/*****************************************************************************/
/*****************************************************************************/

void  VCS_SOLVE::vcs_fePrep_TP(void)

/**************************************************************************
 *
 *
 ***************************************************************************/
{
    for (size_t i = 0; i < m_numSpeciesTot; ++i) {
        /*
         *        For single species phases, initialize the chemical
         *        potential with the value of the standard state chemical
         *        potential. This value doesn't change during the calculation
         */
        if (m_SSPhase[i]) {
            m_feSpecies_old[i] = m_SSfeSpecies[i];
            m_feSpecies_new[i] = m_SSfeSpecies[i];
        }
    }
} /* vcs_fePrep_TP() ********************************************************/

}