/*
 * (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.
 */

#include "grib_api_internal.h"
#define PNG_ANYBITS

/*
   This is used by make_class.pl

   START_CLASS_DEF
   CLASS      = accessor
   SUPER      = grib_accessor_class_values
   IMPLEMENTS = init
   IMPLEMENTS = unpack_double
   IMPLEMENTS = pack_double
   IMPLEMENTS = value_count
   MEMBERS=const char*   number_of_values
   MEMBERS=const char*   reference_value
   MEMBERS=const char*   binary_scale_factor
   MEMBERS=const char*   decimal_scale_factor
   MEMBERS=const char*   bits_per_value
   MEMBERS=const char*   ni
   MEMBERS=const char*   nj
   MEMBERS=const char*   list_defining_points
   MEMBERS=const char*   number_of_data_points
   MEMBERS=const char*   scanning_mode

   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 pack_double(grib_accessor*, const double* val, size_t* len);
static int unpack_double(grib_accessor*, double* val, size_t* len);
static int value_count(grib_accessor*, long*);
static void init(grib_accessor*, const long, grib_arguments*);
static void init_class(grib_accessor_class*);

typedef struct grib_accessor_data_png_packing
{
    grib_accessor att;
    /* Members defined in gen */
    /* Members defined in values */
    int carg;
    const char* seclen;
    const char* offsetdata;
    const char* offsetsection;
    int dirty;
    /* Members defined in data_png_packing */
    const char* number_of_values;
    const char* reference_value;
    const char* binary_scale_factor;
    const char* decimal_scale_factor;
    const char* bits_per_value;
    const char* ni;
    const char* nj;
    const char* list_defining_points;
    const char* number_of_data_points;
    const char* scanning_mode;
} grib_accessor_data_png_packing;

extern grib_accessor_class* grib_accessor_class_values;

static grib_accessor_class _grib_accessor_class_data_png_packing = {
    &grib_accessor_class_values,            /* super                     */
    "data_png_packing",                     /* name                      */
    sizeof(grib_accessor_data_png_packing), /* size                      */
    0,                                      /* inited */
    &init_class,                            /* init_class */
    &init,                                  /* init                      */
    0,                                      /* post_init                      */
    0,                                      /* 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    */
    &pack_double,                           /* grib_pack procedures double    */
    &unpack_double,                         /* grib_unpack procedures double  */
    0,                                      /* grib_pack procedures string    */
    0,                                      /* 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    */
    0,                                      /* compare vs. another accessor   */
    0,                                      /* unpack only ith value          */
    0,                                      /* unpack a subarray         */
    0,                                      /* clear          */
    0,                                      /* clone accessor          */
};


grib_accessor_class* grib_accessor_class_data_png_packing = &_grib_accessor_class_data_png_packing;


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_string            = (*(c->super))->pack_string;
    c->unpack_string          = (*(c->super))->unpack_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->compare                = (*(c->super))->compare;
    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 v, grib_arguments* args)
{
    grib_accessor_data_png_packing* self = (grib_accessor_data_png_packing*)a;

    self->number_of_values     = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);
    self->reference_value      = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);
    self->binary_scale_factor  = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);
    self->decimal_scale_factor = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);
    self->bits_per_value       = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);

    self->ni = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);
    self->nj = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);

    self->list_defining_points  = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);
    self->number_of_data_points = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);
    self->scanning_mode         = grib_arguments_get_name(grib_handle_of_accessor(a), args, self->carg++);
    a->flags |= GRIB_ACCESSOR_FLAG_DATA;
}

static int value_count(grib_accessor* a, long* n_vals)
{
    grib_accessor_data_png_packing* self = (grib_accessor_data_png_packing*)a;
    *n_vals                              = 0;
    return grib_get_long_internal(grib_handle_of_accessor(a), self->number_of_values, n_vals);
}

#if HAVE_LIBPNG

#include <png.h>

typedef struct png_read_callback_data
{
    unsigned char* buffer;
    size_t length;
    size_t offset;
} png_read_callback_data;

static void png_read_callback(png_structp png, png_bytep data, png_size_t length)
{
    png_read_callback_data* p = (png_read_callback_data*)png_get_io_ptr(png);
    Assert(p->offset + length <= p->length);
    memcpy(data, p->buffer + p->offset, length);
    p->offset += length;
}

static void png_write_callback(png_structp png, png_bytep data, png_size_t length)
{
    png_read_callback_data* p = (png_read_callback_data*)png_get_io_ptr(png);
    Assert(p->offset + length <= p->length);
    memcpy(p->buffer + p->offset, data, length);
    p->offset += length;
}

static void png_flush_callback(png_structp png)
{
    /* Empty */
}


static int unpack_double(grib_accessor* a, double* val, size_t* len)
{
    grib_accessor_data_png_packing* self = (grib_accessor_data_png_packing*)a;

    int err = GRIB_SUCCESS;
    int i, j;
    size_t buflen = grib_byte_count(a);

    double bscale      = 0;
    double dscale      = 0;
    unsigned char* buf = NULL;
    size_t n_vals      = 0;

    long binary_scale_factor  = 0;
    long decimal_scale_factor = 0;
    double reference_value    = 0;
    long bits_per_value       = 0;
    long bits8;
    long nn = 0;

    png_structp png = 0;
    png_infop info = 0, theEnd = 0;
    png_bytepp rows = 0;
    int interlace = 0, colour = 0, compression = 0, filter = 0, depth = 0;

    png_uint_32 width = 0, height = 0;

    png_read_callback_data callback_data;

    self->dirty = 0;

    err    = grib_value_count(a, &nn);
    n_vals = nn;
    if (err)
        return err;

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->bits_per_value, &bits_per_value)) != GRIB_SUCCESS)
        return err;
    if ((err = grib_get_double_internal(grib_handle_of_accessor(a), self->reference_value, &reference_value)) != GRIB_SUCCESS)
        return err;
    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->binary_scale_factor, &binary_scale_factor)) != GRIB_SUCCESS)
        return err;
    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->decimal_scale_factor, &decimal_scale_factor)) != GRIB_SUCCESS)
        return err;

    bscale = grib_power(binary_scale_factor, 2);
    dscale = grib_power(-decimal_scale_factor, 10);

    /* TODO: This should be called upstream */
    if (*len < n_vals)
        return GRIB_ARRAY_TOO_SMALL;

    /* Special case */

    if (bits_per_value == 0) {
        for (i = 0; i < n_vals; i++)
            val[i] = reference_value;
        *len = n_vals;
        return GRIB_SUCCESS;
    }

    buf = (unsigned char*)grib_handle_of_accessor(a)->buffer->data;
    buf += grib_byte_offset(a);


    if (png_sig_cmp(buf, 0, 8) != 0)
        return GRIB_INVALID_MESSAGE;


    png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL,
                                 NULL, NULL);
    if (!png) {
        err = GRIB_DECODING_ERROR;
        goto cleanup;
    }

    info = png_create_info_struct(png);
    if (!info) {
        err = GRIB_DECODING_ERROR;
        goto cleanup;
    }

    theEnd = png_create_info_struct(png);
    if (!theEnd) {
        err = GRIB_DECODING_ERROR;
        goto cleanup;
    }

    if (setjmp(png_jmpbuf(png))) {
        err = GRIB_DECODING_ERROR;
        goto cleanup;
    }

    callback_data.buffer = buf;
    callback_data.offset = 0;
    callback_data.length = buflen;

    /* printf("buflen=%d\n",buflen); */

    png_set_read_fn(png, &callback_data, png_read_callback);
    png_read_png(png, info, PNG_TRANSFORM_IDENTITY, NULL);

    Assert(callback_data.offset == callback_data.length);


    rows = png_get_rows(png, info);

    png_get_IHDR(png, info,
                 &width, &height,
                 &depth, &colour,
                 &interlace,
                 &compression,
                 &filter);


    if (colour == PNG_COLOR_TYPE_RGB)
        depth = 24;
    if (colour == PNG_COLOR_TYPE_RGB_ALPHA)
        depth = 32;
    bits8 = ((bits_per_value + 7) / 8) * 8;

#ifdef PNG_ANYBITS
    Assert(depth == bits8);
#else
    Assert(bits_per_value % 8 == 0);
#endif

    i = 0;

    /* printf("bscale=%g dscale=%g reference_value=%g\n",bscale,dscale,reference_value); */

    for (j = 0; j < height; j++) {
        png_byte* row = rows[j];
        long pos      = 0;
        int k;
        for (k = 0; k < width; k++)
            val[i++] = (double)(((grib_decode_unsigned_long(row, &pos, bits8) * bscale) + reference_value) * dscale);
    }
    /*-------------------------------------------*/
    *len = n_vals;

cleanup:
    if (png)
        png_destroy_read_struct(&png, info ? &info : NULL, theEnd ? &theEnd : NULL);
    return err;
}

static int is_constant(const double* values, size_t n_vals)
{
    int isConstant = 1;
    double v = 0;
    size_t i;
    for (i = 0; i < n_vals; i++) {
        if (i == 0) v = values[i];
        else if (v != values[i]) {
            isConstant = 0;
            break;
        }
    }
    return isConstant;
}

static int pack_double(grib_accessor* a, const double* val, size_t* len)
{
    grib_accessor_data_png_packing* self = (grib_accessor_data_png_packing*)a;

    int err = GRIB_SUCCESS, is_constant_field = 0;
    int i, j;
    size_t buflen = 0;

    unsigned char* buf     = NULL;
    unsigned char* encoded = NULL;
    size_t n_vals          = 0;

    long binary_scale_factor  = 0;
    long decimal_scale_factor = 0;
    double reference_value    = 0;
    long bits8;
    long bits_per_value = 0;
    double max, min;
    long bytes;
    double d;

    png_structp png = 0;
    png_infop info  = 0;
    png_bytepp rows = 0;
    int colour = 0, depth = 0;

    png_uint_32 width = 0, height = 0;
    unsigned char* p;
    double divisor;

    png_read_callback_data callback_data;
    long ni, nj;
    long scanning_mode;
    long list_defining_points;
    long number_of_data_points;

    self->dirty = 1;

    n_vals = *len;

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->bits_per_value, &bits_per_value)) != GRIB_SUCCESS)
        return err;
    if ((err = grib_get_double_internal(grib_handle_of_accessor(a), self->reference_value, &reference_value)) != GRIB_SUCCESS)
        return err;
    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->binary_scale_factor, &binary_scale_factor)) != GRIB_SUCCESS)
        return err;
    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->decimal_scale_factor, &decimal_scale_factor)) != GRIB_SUCCESS)
        return err;

    /* Special case */

    if (*len == 0) {
        grib_buffer_replace(a, NULL, 0, 1, 1);
        return GRIB_SUCCESS;
    }

    is_constant_field = is_constant(val, n_vals);
    if (!is_constant_field && bits_per_value==0) {
        /* A non-constant field with bitsPerValue==0! */
        bits_per_value = 24; /* Set sane value */
    }

    if (is_constant_field) {
#ifdef DEBUG
        for (i = 1; i < n_vals; i++) {
            Assert(val[i] == val[0]);
        }
#endif
        if ((err = grib_set_double_internal(grib_handle_of_accessor(a), self->reference_value, val[0])) != GRIB_SUCCESS)
            return err;
        {
            /* Make sure we can decode it again */
            double ref = 1e-100;
            grib_get_double_internal(grib_handle_of_accessor(a), self->reference_value, &ref);
            /*printf("%g %g %g\n", reference_value, ref, reference_value - ref);*/
            Assert(ref == reference_value);
        }

        if ((err = grib_set_long_internal(grib_handle_of_accessor(a), self->number_of_values, n_vals)) != GRIB_SUCCESS)
            return err;

        grib_buffer_replace(a, NULL, 0, 1, 1);

        return GRIB_SUCCESS;
    }

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->ni, &ni)) != GRIB_SUCCESS)
        return err;

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->nj, &nj)) != GRIB_SUCCESS)
        return err;

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->scanning_mode, &scanning_mode)) != GRIB_SUCCESS)
        return err;

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->list_defining_points, &list_defining_points)) != GRIB_SUCCESS)
        return err;

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->number_of_data_points, &number_of_data_points)) != GRIB_SUCCESS)
        return err;

    width  = ni;
    height = nj;

    if ((scanning_mode & (1 << 5)) != 0) {
        long tmp = width;
        width    = height;
        height   = tmp;
    }

    /* The grid is not regular */
    if (list_defining_points != 0) {
        width  = *len;
        height = 1;
    }

    /* There is a bitmap */
    if (*len != number_of_data_points) {
        width  = *len;
        height = 1;
    }

    if (width * height != *len) {
        fprintf(stderr, "width=%ld height=%ld len=%ld\n", (long)width, (long)height, (long)(*len));
        Assert(width * height == *len);
    }

    d = grib_power(decimal_scale_factor, 10);

    max = val[0];
    min = max;
    for (i = 1; i < n_vals; i++) {
        if (val[i] > max)      max = val[i];
        else if (val[i] < min) min = val[i];
    }
    min *= d;
    max *= d;

    if (grib_get_nearest_smaller_value(grib_handle_of_accessor(a), self->reference_value, min, &reference_value) != GRIB_SUCCESS) {
        grib_context_log(a->context, GRIB_LOG_ERROR,
                         "unable to find nearest_smaller_value of %g for %s", min, self->reference_value);
        return GRIB_INTERNAL_ERROR;
    }

    if (reference_value > min) {
        fprintf(stderr, "reference_value=%g min_value=%g diff=%g\n", reference_value, min, reference_value - min);
        Assert(reference_value <= min);
    }

    binary_scale_factor = grib_get_binary_scale_fact(max, reference_value, bits_per_value, &err);
    divisor             = grib_power(-binary_scale_factor, 2);

#ifndef PNG_ANYBITS
    Assert(bits_per_value % 8 == 0);
#endif
    bits8   = (bits_per_value + 7) / 8 * 8;
    encoded = (unsigned char*)grib_context_buffer_malloc_clear(a->context, bits8 / 8 * n_vals);
    if (!encoded) {
        err = GRIB_OUT_OF_MEMORY;
        goto cleanup;
    }

    buflen = 0;
    p      = encoded;
    for (i = 0; i < n_vals; i++) {
        long blen                  = bits8;
        unsigned long unsigned_val = (unsigned long)((((val[i] * d) - (reference_value)) * divisor) + 0.5);
        while (blen >= 8) {
            blen -= 8;
            *p = (unsigned_val >> blen);
            p++;
            buflen++;
        }
    }
    /* buflen = n_vals*(bits_per_value/8); */
    grib_context_log(a->context, GRIB_LOG_DEBUG,
                     "grib_accessor_data_png_packing : pack_double : packing %s, %d values", a->name, n_vals);
    buf = (unsigned char*)grib_context_buffer_malloc_clear(a->context, buflen);

    if (!buf) {
        err = GRIB_OUT_OF_MEMORY;
        goto cleanup;
    }

    if ((err = grib_set_double_internal(grib_handle_of_accessor(a), self->reference_value, reference_value)) != GRIB_SUCCESS)
        return err;
    {
        /* Make sure we can decode it again */
        double ref = 1e-100;
        grib_get_double_internal(grib_handle_of_accessor(a), self->reference_value, &ref);
        Assert(ref == reference_value);
    }
    if ((err = grib_set_long_internal(grib_handle_of_accessor(a), self->binary_scale_factor, binary_scale_factor)) != GRIB_SUCCESS)
        return err;
    if ((err = grib_set_long_internal(grib_handle_of_accessor(a), self->decimal_scale_factor, decimal_scale_factor)) != GRIB_SUCCESS)
        return err;

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->ni, &ni)) != GRIB_SUCCESS)
        return err;

    if ((err = grib_get_long_internal(grib_handle_of_accessor(a), self->nj, &nj)) != GRIB_SUCCESS)
        return err;

    png = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
    if (!png) {
        err = GRIB_DECODING_ERROR;
        goto cleanup;
    }

    info = png_create_info_struct(png);
    if (!info) {
        err = GRIB_DECODING_ERROR;
        goto cleanup;
    }

    if (setjmp(png_jmpbuf(png))) {
        err = GRIB_DECODING_ERROR;
        goto cleanup;
    }

    callback_data.buffer = buf;
    callback_data.offset = 0;
    callback_data.length = buflen;

    /* printf("buflen=%d\n",buflen); */
    png_set_write_fn(png, &callback_data, png_write_callback, png_flush_callback);

    depth = bits8;

    colour = PNG_COLOR_TYPE_GRAY;
    if (bits8 == 24) {
        depth  = 8;
        colour = PNG_COLOR_TYPE_RGB;
    }

    if (bits8 == 32) {
        depth  = 8;
        colour = PNG_COLOR_TYPE_RGB_ALPHA;
    }

    png_set_IHDR(png, info, width, height,
                 depth, colour, PNG_INTERLACE_NONE,
                 PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);

    /*bytes=bit_depth/8;*/
    bytes = bits8 / 8;

    rows = (png_bytepp)grib_context_buffer_malloc_clear(a->context, sizeof(png_bytep) * height);
    if (!rows) {
        err = GRIB_OUT_OF_MEMORY;
        goto cleanup;
    }

    for (j = 0; j < height; j++)
        rows[j] = &encoded[j * width * bytes];

    png_set_rows(png, info, rows);

    png_write_png(png, info, PNG_TRANSFORM_IDENTITY, NULL);

    Assert(callback_data.offset <= callback_data.length);

    grib_buffer_replace(a, buf, callback_data.offset, 1, 1);

cleanup:
    if (png)
        png_destroy_write_struct(&png, info ? &info : NULL);


    grib_context_buffer_free(a->context, buf);
    grib_context_buffer_free(a->context, encoded);
    grib_context_buffer_free(a->context, rows);

    if (err == GRIB_SUCCESS)
        err = grib_set_long_internal(grib_handle_of_accessor(a), self->number_of_values, *len);

    return err;
}
#else

static int unpack_double(grib_accessor* a, double* val, size_t* len)
{
    grib_context_log(a->context, GRIB_LOG_ERROR,
                     "grib_accessor_data_png_packing: PNG support not enabled. "
                     "Please rebuild with -DENABLE_PNG=ON");
    return GRIB_FUNCTIONALITY_NOT_ENABLED;
}

static int pack_double(grib_accessor* a, const double* val, size_t* len)
{
    grib_context_log(a->context, GRIB_LOG_ERROR,
                     "grib_accessor_data_png_packing: PNG support not enabled. "
                     "Please rebuild with -DENABLE_PNG=ON");
    return GRIB_FUNCTIONALITY_NOT_ENABLED;
}

#endif
