/*
  Copyright 2012 SINTEF ICT, Applied Mathematics.

  This file is part of the Open Porous Media project (OPM).

  OPM is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  OPM is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef OPM_WELLS_H_INCLUDED
#define OPM_WELLS_H_INCLUDED


/**
 * \file
 *
 * Main OPM-Core well data structure along with functions
 * to create, populate and destroy it.
 */


#ifdef __cplusplus
extern "C" {
#endif

/**
 * Well type indicates desired/expected well behaviour.
 */
enum WellType {
    INJECTOR,  /**< Well is an injector */
    PRODUCER   /**< Well is a producer */
};

/**
 * Type of well control equation or inequality constraint.
 */
enum WellControlType  {
    BHP,              /**< Well constrained by BHP target */
    RESERVOIR_RATE,   /**< Well constrained by reservoir volume flow rate */
    SURFACE_RATE      /**< Well constrained by surface volume flow rate */
};

/**
 * Controls for a single well.
 * Each control specifies a well rate or bottom-hole pressure. Only
 * one control can be active at a time, indicated by current. The
 * meaning of each control's target value depends on the control type:
 *
 *  - BHP            -> target pressure in Pascal.
 *  - RESERVOIR_RATE -> target reservoir volume rate in cubic(meter)/second
 *  - SURFACE_RATE   -> target surface volume rate in cubic(meter)/second
 *
 * The sign convention for RATE targets is as follows:
 *
 *  - (+) Fluid flowing into reservoir, i.e. injecting.
 *  - (-) Fluid flowing out of reservoir, i.e. producing.
 *
 * For *_RATE controls, the distribution of phases used for the control
 * is also needed. For example, a total rate control should have 1.0
 * for each phase, whereas a control on oil rate should have 1.0 for
 * the oil phase and 0.0 for the rest. For BHP controls, this is unused.
 * The active control acts as an equality constraint, whereas the
 * non-active controls should be interpreted as inequality
 * constraints (upper or lower bounds).  For instance, a PRODUCER's
 * BHP constraint defines a minimum acceptable bottom-hole pressure
 * value for the well.
 */
struct WellControls
{
    /**
     * Number of controls.
     */
    int num;

    /**
     * Array of control types.
     */
    enum WellControlType *type;

    /**
     * Array of control targets
     */
    double *target;

    /**
     * Array of rate control distributions,
     * <CODE>Wells::number_of_phases</CODE> numbers for each control
     */
    double *distr;

    /**
     * Index of current active control.
     */
    int current;

    /**
     * Internal management structure.
     */
    void *data;
};



/**
 *  Data structure aggregating static information about all wells in a scenario.
 */
struct Wells
{
    int number_of_wells;  /**< Number of wells. */
    int number_of_phases; /**< Number of phases. */

    /**
     * Array of well types.
     */
    enum WellType *type;

    /**
     * Array of well reference depths.
     */
    double *depth_ref;

    /**
     * Component fractions for each well.  Array of size
     * <CODE>number_of_wells * number_of_phases</CODE>.
     * This is intended to be used for injection wells. For production wells
     * the component fractions will vary and cannot be specified a priori.
     */
    double *comp_frac;

    /**
     * Array of indices into well_cells (and WI).  For a well @c w,
     * <CODE>well_connpos[w]</CODE> and <CODE>well_connpos[w+1]</CODE> are start
     * and one-beyond-end indices into the @c well_cells array for accessing
     * @c w's perforation cell indices.
     */
    int *well_connpos;

    /**
     * Array of perforation cell indices.
     * Size is number of perforations (== well_connpos[number_of_wells]).
     */
    int *well_cells;

    /**
     *  Well productivity index, same size and structure as well_cells.
     */
    double *WI;


    /**
     * Well controls, one set of controls for each well.
     */
    struct WellControls **ctrls;

    /**
     * Well names. One string for each well.
     */
    char **name;

    /**
     * Internal management structure.
     */
    void *data;
};


/**
 * Data structure aggregating dynamic information about all wells in a scenario.
 * All arrays in this structure contain data for each perforation, ordered the
 * same as Wells::well_cells and Wells:WI.  The array sizes are, respectively,
 *
 *     wdp        NP
 *     A          n²*NP (matrix in column-major (i.e., Fortran) order).
 *     phasemob   n*NP
 *
 * in which "n" denotes the number of active fluid phases (and constituent
 * components) and "NP" is the total number of perforations,
 * <CODE>well_connpos[ number_of_wells ]</CODE>.
 */
struct CompletionData
{
    /**
     * Gravity potentials.
     */
    double *wdp;

    /**
     * Volumes to surface-components matrix, A = RB^{-1}.
     */
    double *A;

    /**
     * Phase mobilities for all perforations, stored consecutively with the
     * phase index cycling the most rapidly.
     */
    double *phasemob;
};

/**
 * Construct a Wells object initially capable of managing a given
 * number of wells and total number of well connections
 * (perforations).
 *
 * Function add_well() is used to populate the Wells object.  No
 * reallocation occurs in function add_well() as long as the
 * initially indicated capacities are sufficient.  Call function
 * destroy_wells() to dispose of the Wells object and its allocated
 * memory resources.
 *
 * \param[in] nphases Number of active phases in simulation scenario.
 *
 * \param[in] nwells  Expected number of wells in simulation scenario.
 *                    Pass zero if the total number of wells is unknown.
 *
 * \param[in] nperf   Expected total number of well connections
 *                    (perforations) for all wells in simulation
 *                    scenario.  Pass zero if the total number of well
 *                    connections is unknown.
 *
 * \return A valid Wells object with no wells if successful, and NULL
 * otherwise.
 */
struct Wells *
create_wells(int nphases, int nwells, int nperf);


/**
 * Append a new well to an existing Wells object.
 *
 * Increments W->number_of_wells by one if successful.  The new well
 * does not include operational constraints.  Such information is
 * specified using function append_well_controls().  The current
 * control index is set to -1 (invalid).
 *
 * \param[in] type       Type of well.
 * \param[in] depth_ref  Reference depth for well's BHP.
 * \param[in] nperf      Number of perforations.
 * \param[in] comp_frac  Injection fraction array (size equal to W->number_of_phases) or NULL.
 * \param[in] cells      Grid cells in which well is perforated.  Should
 *                       ideally be track ordered.
 * \param[in] WI         Well production index per perforation, or NULL.
 * \param[in] name       Name of new well. NULL if no name.
 * \param[in,out] W      Existing set of wells to which new well will
 *                       be added.
 *
 * \return Non-zero (true) if successful and zero otherwise.
 */
int
add_well(enum WellType  type     ,
         double         depth_ref,
         int            nperf    ,
         const double  *comp_frac,
         const int     *cells    ,
         const double  *WI       ,
         const char    *name     ,
         struct Wells  *W        );


/**
 * Append operational constraint to an existing well.
 *
 * Increments ctrl->num by one if successful.  Introducing a new
 * operational constraint does not affect the well's notion of the
 * currently active constraint represented by ctrl->current.
 * Note that *_RATE controls now require a phase distribution array
 * to be associated with the control, see WellControls.
 *
 * \param[in] type       Control type.
 * \param[in] target     Target value for the control.
 * \param[in] distr      Array of size W->number_of_phases or NULL.
 * \param[in] well_index Index of well to receive additional control.
 * \param[in,out] W  Existing set of well controls.
 * \return Non-zero (true) if successful and zero (false) otherwise.
 */
int
append_well_controls(enum WellControlType type  ,
                     double               target,
                     const double        *distr,
                     int                  well_index,
                     struct Wells        *W);

/**
 * Set the current control for a single well.
 */
void
set_current_control(int well_index, int current_control, struct Wells *W);

/**
 * Clear all controls from a single well.
 *
 * Does not affect the control set capacity. */
void
clear_well_controls(int well_index, struct Wells *W);


/**
 * Wells object destructor.
 *
 * Disposes of all resources managed by the Wells object.
 *
 * The Wells object must be built using function create_wells() and
 * subsequently populated using function add_well().
 */
void
destroy_wells(struct Wells *W);


/**
 * Create a deep-copy (i.e., clone) of an existing Wells object, including its
 * controls.
 *
 * @param[in] W Existing Wells object.
 * @return Complete clone of the input object.  Dispose of resources using
 * function destroy_wells() when no longer needed.  Returns @c NULL in case of
 * allocation failure.
 */
struct Wells *
clone_wells(const struct Wells *W);


#ifdef __cplusplus
}
#endif

#endif /* OPM_WELLS_H_INCLUDED */