/*
 * (C) Copyright 2005- ECMWF.
 *
 * This software is licensed under the terms of the Apache Licence Version 2.0
 * which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
 *
 * In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
 * virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
 */

/**************************************
 *  Enrico Fucile
 **************************************/


#include "grib_api_internal.h"
/*
   This is used by make_class.pl

   START_CLASS_DEF
   CLASS      = accessor
   SUPER      = grib_accessor_class_abstract_vector
   IMPLEMENTS = unpack_double; destroy
   IMPLEMENTS = unpack_string
   IMPLEMENTS = value_count;compare
   IMPLEMENTS = init
   MEMBERS = const char* values
   MEMBERS = const char* missing_value
   END_CLASS_DEF

 */

/* START_CLASS_IMP */

/*

Don't edit anything between START_CLASS_IMP and END_CLASS_IMP
Instead edit values between START_CLASS_DEF and END_CLASS_DEF
or edit "accessor.class" and rerun ./make_class.pl

*/

static int unpack_double(grib_accessor*, double* val, size_t* len);
static int unpack_string(grib_accessor*, char*, size_t* len);
static int value_count(grib_accessor*, long*);
static void destroy(grib_context*, grib_accessor*);
static void init(grib_accessor*, const long, grib_arguments*);
static void init_class(grib_accessor_class*);
static int compare(grib_accessor*, grib_accessor*);

typedef struct grib_accessor_statistics
{
    grib_accessor att;
    /* Members defined in gen */
    /* Members defined in double */
    /* Members defined in abstract_vector */
    double* v;
    int number_of_elements;
    /* Members defined in statistics */
    const char* values;
    const char* missing_value;
} grib_accessor_statistics;

extern grib_accessor_class* grib_accessor_class_abstract_vector;

static grib_accessor_class _grib_accessor_class_statistics = {
    &grib_accessor_class_abstract_vector, /* super                     */
    "statistics",                         /* name                      */
    sizeof(grib_accessor_statistics),     /* size                      */
    0,                                    /* inited */
    &init_class,                          /* init_class */
    &init,                                /* init                      */
    0,                                    /* post_init                      */
    &destroy,                             /* free mem                       */
    0,                                    /* describes himself         */
    0,                                    /* get length of section     */
    0,                                    /* get length of string      */
    &value_count,                         /* get number of values      */
    0,                                    /* get number of bytes      */
    0,                                    /* get offset to bytes           */
    0,                                    /* get native type               */
    0,                                    /* get sub_section                */
    0,                                    /* grib_pack procedures long      */
    0,                                    /* grib_pack procedures long      */
    0,                                    /* grib_pack procedures long      */
    0,                                    /* grib_unpack procedures long    */
    0,                                    /* grib_pack procedures double    */
    &unpack_double,                       /* grib_unpack procedures double  */
    0,                                    /* grib_pack procedures string    */
    &unpack_string,                       /* grib_unpack procedures string  */
    0,                                    /* grib_pack array procedures string    */
    0,                                    /* grib_unpack array procedures string  */
    0,                                    /* grib_pack procedures bytes     */
    0,                                    /* grib_unpack procedures bytes   */
    0,                                    /* pack_expression */
    0,                                    /* notify_change   */
    0,                                    /* update_size   */
    0,                                    /* preferred_size   */
    0,                                    /* resize   */
    0,                                    /* nearest_smaller_value */
    0,                                    /* next accessor    */
    &compare,                             /* compare vs. another accessor   */
    0,                                    /* unpack only ith value          */
    0,                                    /* unpack a subarray         */
    0,                                    /* clear          */
    0,                                    /* clone accessor          */
};


grib_accessor_class* grib_accessor_class_statistics = &_grib_accessor_class_statistics;


static void init_class(grib_accessor_class* c)
{
    c->dump                   = (*(c->super))->dump;
    c->next_offset            = (*(c->super))->next_offset;
    c->string_length          = (*(c->super))->string_length;
    c->byte_count             = (*(c->super))->byte_count;
    c->byte_offset            = (*(c->super))->byte_offset;
    c->get_native_type        = (*(c->super))->get_native_type;
    c->sub_section            = (*(c->super))->sub_section;
    c->pack_missing           = (*(c->super))->pack_missing;
    c->is_missing             = (*(c->super))->is_missing;
    c->pack_long              = (*(c->super))->pack_long;
    c->unpack_long            = (*(c->super))->unpack_long;
    c->pack_double            = (*(c->super))->pack_double;
    c->pack_string            = (*(c->super))->pack_string;
    c->pack_string_array      = (*(c->super))->pack_string_array;
    c->unpack_string_array    = (*(c->super))->unpack_string_array;
    c->pack_bytes             = (*(c->super))->pack_bytes;
    c->unpack_bytes           = (*(c->super))->unpack_bytes;
    c->pack_expression        = (*(c->super))->pack_expression;
    c->notify_change          = (*(c->super))->notify_change;
    c->update_size            = (*(c->super))->update_size;
    c->preferred_size         = (*(c->super))->preferred_size;
    c->resize                 = (*(c->super))->resize;
    c->nearest_smaller_value  = (*(c->super))->nearest_smaller_value;
    c->next                   = (*(c->super))->next;
    c->unpack_double_element  = (*(c->super))->unpack_double_element;
    c->unpack_double_subarray = (*(c->super))->unpack_double_subarray;
    c->clear                  = (*(c->super))->clear;
    c->make_clone             = (*(c->super))->make_clone;
}

/* END_CLASS_IMP */

static void init(grib_accessor* a, const long l, grib_arguments* c)
{
    grib_accessor_statistics* self = (grib_accessor_statistics*)a;
    int n                          = 0;

    self->missing_value = grib_arguments_get_name(grib_handle_of_accessor(a), c, n++);
    self->values        = grib_arguments_get_name(grib_handle_of_accessor(a), c, n++);
    a->flags |= GRIB_ACCESSOR_FLAG_READ_ONLY;
    a->flags |= GRIB_ACCESSOR_FLAG_FUNCTION;
    a->flags |= GRIB_ACCESSOR_FLAG_HIDDEN;

    self->number_of_elements = 8;
    self->v                  = (double*)grib_context_malloc(a->context,
                                           sizeof(double) * self->number_of_elements);

    a->length = 0;
    a->dirty  = 1;
}

static int unpack_double(grib_accessor* a, double* val, size_t* len)
{
    grib_accessor_statistics* self = (grib_accessor_statistics*)a;
    int ret = 0, i = 0;
    double* values;
    size_t size = 0, real_size = 0;
    double max, min, avg, sd, value, skew, kurt, m2 = 0, m3 = 0, m4 = 0;
    double missing            = 0;
    long missingValuesPresent = 0;
    size_t number_of_missing  = 0;
    grib_context* c           = a->context;
    grib_handle* h            = grib_handle_of_accessor(a);

    if (!a->dirty)
        return GRIB_SUCCESS;

    if (*len != self->number_of_elements)
        return GRIB_ARRAY_TOO_SMALL;

    if ((ret = grib_get_size(h, self->values, &size)) != GRIB_SUCCESS)
        return ret;

    grib_context_log(a->context, GRIB_LOG_DEBUG,
                     "grib_accessor_statistics: computing statistics for %d values", size);

    if ((ret = grib_get_double(h, self->missing_value, &missing)) != GRIB_SUCCESS)
        return ret;
    if ((ret = grib_get_long_internal(h, "missingValuesPresent", &missingValuesPresent)) != GRIB_SUCCESS)
        return ret;

    values = (double*)grib_context_malloc_clear(c, size * sizeof(double));
    if (!values)
        return GRIB_OUT_OF_MEMORY;

    if ((ret = grib_get_double_array_internal(h, self->values, values, &size)) != GRIB_SUCCESS) {
        grib_context_free(c, values);
        return ret;
    }

    number_of_missing = 0;
    if (missingValuesPresent) {
        i = 0;
        while (i < size && values[i] == missing) {
            i++;
            number_of_missing++;
        }
        if (number_of_missing == size) {
            /* ECC-649: All values are missing */
            min = max = avg = missing;
        }
        else {
            max = values[i];
            min = values[i];
            avg = values[i];
            for (i = number_of_missing + 1; i < size; i++) {
                value = values[i];
                if (value > max && value != missing)
                    max = value;
                if (value < min && value != missing)
                    min = value;
                if (value != missing)
                    avg += value;
                else
                    number_of_missing++;
            }
        }
    }
    else {
        max = values[0];
        min = values[0];
        avg = values[0];
        for (i = 1; i < size; i++) {
            value = values[i];
            if (value > max)
                max = value;
            if (value < min)
                min = value;
            avg += value;
        }
    }
    /*printf("stats.......... number_of_missing=%ld\n", number_of_missing);*/
    /* Don't divide by zero if all values are missing! */
    if (size != number_of_missing) {
        avg /= (size - number_of_missing);
    }

    sd   = 0;
    skew = 0;
    kurt = 0;
    for (i = 0; i < size; i++) {
        int valueNotMissing = 1;
        if (missingValuesPresent) {
            valueNotMissing = (values[i] != missing);
        }
        if (valueNotMissing) {
            double v   = values[i] - avg;
            double tmp = v * v;
            m2 += tmp;
            m3 += v * tmp;
            m4 += tmp * tmp;
        }
    }

    real_size = size - number_of_missing;
    if (real_size != 0) {
        m2 /= real_size;
        m3 /= real_size;
        m4 /= real_size;
        sd = sqrt(m2);
    }
    if (m2 != 0) {
        skew = m3 / (sd * sd * sd);
        kurt = m4 / (m2 * m2) - 3.0;
    }
    a->dirty = 0;

    grib_context_free(c, values);

    self->v[0] = max;
    self->v[1] = min;
    self->v[2] = avg;
    self->v[3] = number_of_missing;
    self->v[4] = sd;
    self->v[5] = skew;
    self->v[6] = kurt;
    self->v[7] = sd == 0 ? 1 : 0;

    for (i = 0; i < self->number_of_elements; i++)
        val[i] = self->v[i];

    return ret;
}

static int value_count(grib_accessor* a, long* count)
{
    grib_accessor_statistics* self = (grib_accessor_statistics*)a;
    *count                         = self->number_of_elements;
    return 0;
}

static void destroy(grib_context* c, grib_accessor* a)
{
    grib_accessor_statistics* self = (grib_accessor_statistics*)a;
    grib_context_free(c, self->v);
}

static int compare(grib_accessor* a, grib_accessor* b)
{
    int retval   = GRIB_SUCCESS;
    double* aval = 0;
    double* bval = 0;

    size_t alen = 0;
    size_t blen = 0;
    int err     = 0;
    long count  = 0;

    err = grib_value_count(a, &count);
    if (err)
        return err;
    alen = count;

    err = grib_value_count(b, &count);
    if (err)
        return err;
    blen = count;

    if (alen != blen)
        return GRIB_COUNT_MISMATCH;

    aval = (double*)grib_context_malloc(a->context, alen * sizeof(double));
    bval = (double*)grib_context_malloc(b->context, blen * sizeof(double));

    b->dirty = 1;
    a->dirty = 1;

    grib_unpack_double(a, aval, &alen);
    grib_unpack_double(b, bval, &blen);

    while (alen != 0) {
        if (*bval != *aval)
            retval = GRIB_DOUBLE_VALUE_MISMATCH;
        alen--;
    }

    grib_context_free(a->context, aval);
    grib_context_free(b->context, bval);

    return retval;
}

static int unpack_string(grib_accessor* a, char* v, size_t* len)
{
    return GRIB_NOT_IMPLEMENTED;
}
