eccodes/tools/grib_to_json.cc

/*
 * (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"

typedef void (*getproc)(FILE*, grib_handle*, const char*, const char*);

static void get_long(FILE* f, grib_handle* h, const char* name, const char* arg)
{
    const char* key = arg ? arg : name;
    long value;
    GRIB_CHECK(grib_get_long(h, key, &value), key);
    fprintf(f, "\"%s\":%ld\n", name, value);
}

static void get_param(FILE* f, grib_handle* h, const char* name, const char* arg)
{
    const char* key = "indicatorOfParameter";
    long value;
    GRIB_CHECK(grib_get_long(h, key, &value), key);
    fprintf(f, "\"%s\":%ld\n", name, value - 131 + 2);
}

static void get_iso_ref_date(FILE* f, grib_handle* h, const char* name, const char* arg)
{
    long year;
    long month;
    long day;
    long hour;
    long minute;
    long second;

    GRIB_CHECK(grib_get_long(h, "year", &year), "year");
    GRIB_CHECK(grib_get_long(h, "month", &month), "month");
    GRIB_CHECK(grib_get_long(h, "day", &day), "day");
    GRIB_CHECK(grib_get_long(h, "hour", &hour), "hour");
    GRIB_CHECK(grib_get_long(h, "minute", &minute), "minute");
    GRIB_CHECK(grib_get_long(h, "second", &second), "second");

    fprintf(f, "\"%s\":\"%04ld-%02ld-%02ldT%02ld:%02ld:%02ld.000Z\"", name, year, month, day, hour, minute, second);
}

typedef struct header_keys
{
    const char* name;
    getproc proc;
    const char* arg;

} header_keys;

/*
{
 *         "header": {
 *           "refTime": "2013-11-30T18:00:00.000Z",
 *           "parameterNumber": 2,



 *         },
 */
header_keys header[] = {

    {
        "scanMode",
        &get_long,
        "scanningMode",
    },
    {
        "la1",
        &get_long,
        "latitudeOfFirstGridPointInDegrees",
    },
    {
        "lo1",
        &get_long,
        "longitudeOfFirstGridPointInDegrees",
    },

    {
        "la2",
        &get_long,
        "latitudeOfLastGridPointInDegrees",
    },
    {
        "lo2",
        &get_long,
        "longitudeOfLastGridPointInDegrees",
    },

    {
        "forecastTime",
        &get_long,
        "step",
    },

    {
        "nx",
        &get_long,
        "Nx",
    },
    {
        "ny",
        &get_long,
        "Ny",
    },

    {
        "dx",
        &get_long,
        "DxInDegrees",
    },
    {
        "dy",
        &get_long,
        "DyInDegrees",
    },

    {
        "parameterNumber",
        &get_param,
        "indicatorOfParameter",
    },
    {
        "refTime",
        &get_iso_ref_date,
        NULL,
    },

    {
        NULL,
        NULL,
        NULL,
    }
};

int main(int argc, char* argv[])
{
    grib_handle* h = NULL;
    FILE* f        = NULL;
    size_t i, j = 0;
    int err = 0;
    double* values;
    size_t size, count;
    size_t n = 0;

    printf("[");

    for (i = 1; i < (size_t)argc; i++) {
        f = fopen(argv[i], "r");
        if (!f) {
            perror(argv[i]);
            exit(1);
        }

        while ((h = grib_handle_new_from_file(0, f, &err)) != NULL) {
            if (++n > 1) {
                printf(",");
            }

            printf("{");
            printf("\"header\":{\n");

            j = 0;
            while (header[j].name) {
                if (j)
                    printf(",");
                header[j].proc(stdout, h, header[j].name, header[j].arg);
                j++;
            }

            printf("},\n");
            printf("\"meta\":{\n");
            printf("},\n");
            /*========== data *============*/
            size = 0;
            GRIB_CHECK(grib_get_size(h, "values", &size), 0);
            values = (double*)malloc(sizeof(double) * size);

            if (!values) {
                fprintf(stderr, "%s: out of memory\n", argv[0]);
                exit(1);
            }
            count = size;
            GRIB_CHECK(grib_get_double_array(h, "values", values, &count), 0);
            if (count != size) {
                fprintf(stderr, "%s: wrong values count %zu %zu\n", argv[0], count, size);
                exit(1);
            }
            printf("\"data\":[\n");

            for (j = 0; j < count; j++) {
                if (j)
                    printf(",");
                printf("%g", (long)(values[j] * 10 + 0.5) / 10.0);
                if (((j + 1) % 20) == 0) {
                    printf("\n");
                }
            }
            free(values);

            printf("]");

            printf("}\n");

            grib_handle_delete(h);
        }
        fclose(f);
        if (err) {
            fprintf(stderr, "%s\n", grib_get_error_message(err));
            exit(1);
        }
    }
    printf("]\n");
    return 0;
}