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#ifndef _mdebin_bar_h
#define _mdebin_bar_h

#include "gromacs/mdlib/energyoutput.h"

/* The functions & data structures here describe writing
   energy differences (or their histogram )for use with g_bar */

class delta_h_history_t;
struct t_enxframe;

/* Data for one foreign lambda, or derivative. */
typedef struct
{
    real*        dh;     /* the raw energy data. */
    float*       dhf;    /* raw difference data -- in floats, for storage. */
    unsigned int ndh;    /* number of data points */
    unsigned int ndhmax; /* the maximum number of points */

    int nhist;              /* the number of histograms. There can either be
                               0 (for no histograms)
                               1 (for 'foreign lambda' histograms)
                               2 (for derivative histograms: there's
                                  a 'forward' and 'backward' histogram
                                  containing the minimum and maximum
                                  values, respectively). */
    int*   bin[2];          /* the histogram(s) */
    double dx;              /* the histogram spacing in kJ/mol. This is the
                               same for the two histograms? */
    unsigned int nbins;     /* the number of bins in the histograms*/
    int64_t      x0[2];     /* the starting point in units of spacing
                                       of the histogram */
    unsigned int maxbin[2]; /* highest bin number with data */

    int type;         /* the block type according to dhbtDH, etc. */
    int derivative;   /* The derivative direction (as an index in the lambda
                         vector) if this delta_h contains derivatives */
    double*  lambda;  /* lambda vector (or NULL if not applicable) */
    int      nlambda; /* length of the lambda vector */
    gmx_bool written; /* whether this data has already been written out */

    int64_t subblock_meta_l[5]; /* metadata for an mdebin subblock for
                                           I/O: for histogram counts, etc.*/
    double* subblock_meta_d;    /* metadata subblock for I/O, used for
                                   communicating doubles (i.e. the lambda
                                   vector) */
    int subblock_meta_i[4];     /* metadata subblock for I/O, used for
                                   communicating ints (i.e. derivative indices,
                                   etc.) */
} t_mde_delta_h;

/* the type definition is in mdebin_bar.h */
struct t_mde_delta_h_coll
{
    t_mde_delta_h* dh;  /* the delta h data */
    int            ndh; /* the number of delta_h structures */

    int            nlambda; /* number of bar dU delta_h structures */
    t_mde_delta_h* dh_du;   /* the delta h data (pointer into dh) */

    int            ndhdl;   /* number of bar dU delta_h structures */
    t_mde_delta_h* dh_dhdl; /* the dhdl data (pointer into dh) */

    t_mde_delta_h* dh_energy;   /* energy output block (pointer into dh) */
    t_mde_delta_h* dh_pv;       /* pV output block (pointer into dh) */
    t_mde_delta_h* dh_expanded; /* expanded ensemble output block (pointer
                                   into dh) */

    double   start_time;     /* start time of the current dh collection */
    double   delta_time;     /* time difference between samples */
    gmx_bool start_time_set; /* whether the start time has been set */
    double   start_lambda;   /* starting lambda for continuous motion of state*/
    double   delta_lambda;   /* delta lambda, for continuous motion of state */
    double   temperature;    /* the temperature of the samples*/

    double* native_lambda_vec;     /* The lambda vector describing the current
                                      lambda state if it is set (NULL otherwise) */
    int  n_lambda_vec;             /* the size of the native lambda vector */
    int* native_lambda_components; /* the native lambda (and by extension,
                                      foreign lambda) components in terms
                                      of efptFEP, efptMASS, etc. */
    int lambda_index;              /* the lambda_fep_state */

    double* subblock_d; /* for writing a metadata mdebin subblock for I/O */
    int*    subblock_i; /* for writing a metadata mdebin subblock for I/O */

    double* lambda_vec_subblock; /* native lambda vector data subblock for
                                    I/O */
    int* lambda_index_subblock;  /* lambda vector index data subblock for I/O */
};


/* initialize a collection of delta h histograms/sets
    dhc = the collection
    ir = the input record */

void mde_delta_h_coll_init(t_mde_delta_h_coll* dhc, const t_inputrec* ir);

void done_mde_delta_h_coll(t_mde_delta_h_coll* dhc);

/* add a bunch of samples to the delta_h collection
    dhc = the collection
    dhdl = the hamiltonian derivatives
    U = the array with energies: from enerd->enerpart_lambda.
    time = the current simulation time.
    current_lambda = current lambda values : primarily useful for continuous processes
    fep_state = current fep_state
 */

/* add a bunch of samples - note fep_state is double to allow for better data storage */
void mde_delta_h_coll_add_dh(t_mde_delta_h_coll* dhc,
                             double              fep_state,
                             double              energy,
                             double              pV,
                             double*             dhdl,
                             double*             foreign_dU,
                             double              time);

/* write the data associated with the du blocks collection as a collection
    of mdebin blocks.
    dhc = the collection
    fr = the enxio frame
    nblock = the current number of blocks */
void mde_delta_h_coll_handle_block(t_mde_delta_h_coll* dhc, t_enxframe* fr, int nblock);


/* reset the collection of delta_h buffers for a new round of
   data gathering */
void mde_delta_h_coll_reset(t_mde_delta_h_coll* dhc);


/* set the energyhistory variables to save state */
void mde_delta_h_coll_update_energyhistory(const t_mde_delta_h_coll* dhc, energyhistory_t* enerhist);

/* restore the variables from an energyhistory */
void mde_delta_h_coll_restore_energyhistory(t_mde_delta_h_coll* dhc, const delta_h_history_t* deltaH);

#endif /* _mdebin_bar_h */
