/*!
  \file lib/raster/gdal.c
  
  \brief Raster Library - Utilization of GDAL library.
  
  (C) 2010 by the GRASS Development Team
  
  This program is free software under the GNU General Public License
  (>=v2). Read the file COPYING that comes with GRASS for details.
  
  \author Glynn Clements
*/

#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <grass/config.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/gprojects.h>
#include <grass/glocale.h>

#include "R.h"

#ifndef HAVE_GDAL
#undef GDAL_LINK
#endif

#ifdef GDAL_LINK
#include <gdal.h>
#endif

/*!
  \brief Initialization

  Register all GDAL drivers.
*/
void Rast_init_gdal(void)
{
#ifdef GDAL_LINK
    static int initialized;

    if (G_is_initialized(&initialized))
        return;

    GDALAllRegister();
    G_initialize_done(&initialized);
#endif
}

/*!
  \brief Get GDAL link settings for given raster map

  \param name map name
  \param mapset name of mapset

  \return pointer to GDAL_link structure
  \return NULL if link not found
*/
struct GDAL_link *Rast_get_gdal_link(const char *name, const char *mapset)
{
#ifdef GDAL_LINK
    GDALDatasetH data;
    GDALRasterBandH band;
    GDALDataType type;
    RASTER_MAP_TYPE req_type;
#endif
    const char *filename;
    int band_num;
    struct GDAL_link *gdal;
    RASTER_MAP_TYPE map_type;
    FILE *fp;
    struct Key_Value *key_val;
    const char *p;
    DCELL null_val;
    int hflip, vflip;

    if (!G_find_raster2(name, mapset))
        return NULL;

    map_type = Rast_map_type(name, mapset);
    if (map_type < 0)
        return NULL;

    fp = G_fopen_old_misc("cell_misc", "gdal", name, mapset);
    if (!fp)
        return NULL;
    key_val = G_fread_key_value(fp);
    fclose(fp);

    if (!key_val)
        return NULL;

    filename = G_find_key_value("file", key_val);
    if (!filename)
        return NULL;

    p = G_find_key_value("band", key_val);
    if (!p)
        return NULL;
    band_num = atoi(p);
    if (!band_num)
        return NULL;

    p = G_find_key_value("null", key_val);
    if (!p)
        return NULL;
    /* atof on windows can not read "nan" and returns 0 instead */
    if (strcmp(p, "none") == 0 ||
        G_strcasecmp(p, "nan") == 0 || G_strcasecmp(p, "-nan") == 0) {
        Rast_set_d_null_value(&null_val, 1);
    }
    else
        null_val = atof(p);

    hflip = G_find_key_value("hflip", key_val) ? 1 : 0;
    vflip = G_find_key_value("vflip", key_val) ? 1 : 0;

#ifdef GDAL_LINK
    p = G_find_key_value("type", key_val);
    if (!p)
        return NULL;
    type = atoi(p);

    switch (type) {
    case GDT_Byte:
    case GDT_Int16:
    case GDT_UInt16:
    case GDT_Int32:
    case GDT_UInt32:
        req_type = CELL_TYPE;
        break;
    case GDT_Float32:
        req_type = FCELL_TYPE;
        break;
    case GDT_Float64:
        req_type = DCELL_TYPE;
        break;
    default:
        return NULL;
    }

    if (req_type != map_type)
        return NULL;

    Rast_init_gdal();

    data = GDALOpen(filename, GA_ReadOnly);
    if (!data)
        return NULL;

    band = GDALGetRasterBand(data, band_num);
    if (!band) {
        GDALClose(data);
        return NULL;
    }
#endif

    gdal = G_calloc(1, sizeof(struct GDAL_link));

    gdal->filename = G_store(filename);
    gdal->band_num = band_num;
    gdal->null_val = null_val;
    gdal->hflip = hflip;
    gdal->vflip = vflip;
#ifdef GDAL_LINK
    gdal->data = data;
    gdal->band = band;
    gdal->type = type;
#endif

    return gdal;
}

struct GDAL_Options
{
    const char *dir;
    const char *ext;
    const char *format;
    char **options;
};

static struct state
{
    int initialized;
    struct GDAL_Options opts;
    struct Key_Value *projinfo, *projunits, *projepsg;
    char *srswkt;
} state;

static struct state *st = &state;

static void read_gdal_options(void)
{
    FILE *fp;
    struct Key_Value *key_val;
    const char *p;

    fp = G_fopen_old("", "GDAL", G_mapset());
    if (!fp)
        G_fatal_error(_("Unable to open GDAL file"));
    key_val = G_fread_key_value(fp);
    fclose(fp);

    p = G_find_key_value("directory", key_val);
    if (!p)
        p = "gdal";
    if (*p == '/') {
        st->opts.dir = G_store(p);
    }
    else {
        char path[GPATH_MAX];

        G_file_name(path, p, "", G_mapset());
        st->opts.dir = G_store(path);
        if (access(path, 0) != 0)
            G_make_mapset_object_group(p);
    }

    p = G_find_key_value("extension", key_val);
    st->opts.ext = G_store(p ? p : "");

    p = G_find_key_value("format", key_val);
    st->opts.format = G_store(p ? p : "GTiff");

    p = G_find_key_value("options", key_val);
    st->opts.options = p ? G_tokenize(p, ",") : NULL;

    G_free_key_value(key_val);
}

/*!
  \brief Create GDAL settings for given raster map

  \param name map name
  \param map_type map type (CELL, FCELL, DCELL)

  \return pointer to allocated GDAL_link structure
  \return NULL on error
*/
struct GDAL_link *Rast_create_gdal_link(const char *name,
                                        RASTER_MAP_TYPE map_type)
{
#ifdef GDAL_LINK
    char path[GPATH_MAX];
    GDALDriverH driver;
    double transform[6];
    struct GDAL_link *gdal;
    FILE *fp;
    struct Key_Value *key_val;
    char buf[32];

    Rast__init_window();

    Rast_init_gdal();

    if (!G_is_initialized(&st->initialized)) {
        read_gdal_options();
        st->projinfo = G_get_projinfo();
        st->projunits = G_get_projunits();
        st->projepsg = G_get_projepsg();
        if (st->projinfo && st->projunits)
            st->srswkt = GPJ_grass_to_wkt2(st->projinfo, st->projunits,
                                           st->projepsg, 0, 0);
        G_initialize_done(&st->initialized);
    }

    gdal = G_calloc(1, sizeof(struct GDAL_link));

    sprintf(path, "%s/%s%s", st->opts.dir, name, st->opts.ext);
    gdal->filename = G_store(path);
    gdal->band_num = 1;
    gdal->hflip = 0;
    gdal->vflip = 0;

    switch (map_type) {
    case CELL_TYPE:
        switch (R__.nbytes) {
        case 1:
            gdal->type = GDT_Byte;
            gdal->null_val = (DCELL) 0xFF;
            break;
        case 2:
            gdal->type = GDT_UInt16;
            gdal->null_val = (DCELL) 0xFFFF;
            break;
        case 3:
        case 4:
            gdal->type = GDT_Int32;
            gdal->null_val = (DCELL) 0x80000000U;
            break;
        }
        break;
    case FCELL_TYPE:
        gdal->type = GDT_Float32;
        Rast_set_d_null_value(&gdal->null_val, 1);
        break;
    case DCELL_TYPE:
        gdal->type = GDT_Float64;
        Rast_set_d_null_value(&gdal->null_val, 1);
        break;
    default:
        G_fatal_error(_("Invalid map type <%d>"), map_type);
        break;
    }

    driver = GDALGetDriverByName(st->opts.format);
    if (!driver)
        G_fatal_error(_("Unable to get <%s> driver"), st->opts.format);

    /* Does driver support GDALCreate ? */
    if (GDALGetMetadataItem(driver, GDAL_DCAP_CREATE, NULL)) {
        gdal->data =
            GDALCreate(driver, gdal->filename,
                       R__.wr_window.cols, R__.wr_window.rows,
                       1, gdal->type, st->opts.options);
        if (!gdal->data)
            G_fatal_error(_("Unable to create <%s> dataset using <%s> driver"),
                          name, st->opts.format);
    }
    /* If not - create MEM driver for intermediate dataset. 
     * Check if raster can be created at all (with GDALCreateCopy) */
    else if (GDALGetMetadataItem(driver, GDAL_DCAP_CREATECOPY, NULL)) {
        GDALDriverH mem_driver;

        G_message(_("Driver <%s> does not support direct writing. "
                    "Using MEM driver for intermediate dataset."),
                  st->opts.format);

        mem_driver = GDALGetDriverByName("MEM");
        if (!mem_driver)
            G_fatal_error(_("Unable to get in-memory raster driver"));

        gdal->data =
            GDALCreate(mem_driver, "",
                       R__.wr_window.cols, R__.wr_window.rows,
                       1, gdal->type, st->opts.options);
        if (!gdal->data)
            G_fatal_error(_("Unable to create <%s> dataset using memory driver"),
                          name);
    }
    else
        G_fatal_error(_("Driver <%s> does not support creating rasters"),
                      st->opts.format);

    gdal->band = GDALGetRasterBand(gdal->data, gdal->band_num);

    GDALSetRasterNoDataValue(gdal->band, gdal->null_val);

    /* Set Geo Transform  */
    transform[0] = R__.wr_window.west;
    transform[1] = R__.wr_window.ew_res;
    transform[2] = 0.0;
    transform[3] = R__.wr_window.north;
    transform[4] = 0.0;
    transform[5] = -R__.wr_window.ns_res;

    if (GDALSetGeoTransform(gdal->data, transform) >= CE_Failure)
        G_warning(_("Unable to set geo transform"));

    if (st->srswkt)
        if (GDALSetProjection(gdal->data, st->srswkt) == CE_Failure)
            G_warning(_("Unable to set projection"));

    fp = G_fopen_new_misc("cell_misc", "gdal", name);
    if (!fp)
        G_fatal_error(_("Unable to create cell_misc/%s/gdal file"), name);

    key_val = G_create_key_value();

    G_set_key_value("file", gdal->filename, key_val);

    sprintf(buf, "%d", gdal->band_num);
    G_set_key_value("band", buf, key_val);

    sprintf(buf, "%.22g", gdal->null_val);
    G_set_key_value("null", buf, key_val);

    sprintf(buf, "%d", gdal->type);
    G_set_key_value("type", buf, key_val);

    if (G_fwrite_key_value(fp, key_val) < 0)
        G_fatal_error(_("Error writing cell_misc/%s/gdal file"), name);

    G_free_key_value(key_val);

    fclose(fp);

    return gdal;
#else
    return NULL;
#endif
}

/*!
  \brief Close existing GDAL link
  
  \param gdal pointer to GDAL_link to be closed
*/
void Rast_close_gdal_link(struct GDAL_link *gdal)
{
#ifdef GDAL_LINK
    GDALClose(gdal->data);
#endif
    G_free(gdal->filename);
    G_free(gdal);
}

/*!
  \brief Close existing GDAL link and write out data

  \param gdal pointer to GDAL_link to be closed

  \return 1 on success
  \return -1 on failure
*/
int Rast_close_gdal_write_link(struct GDAL_link *gdal)
{
    int stat = 1;

#ifdef GDAL_LINK
    GDALDriverH src_drv = GDALGetDatasetDriver(gdal->data);

    if (G_strcasecmp(GDALGetDriverShortName(src_drv), "MEM") == 0) {
        GDALDriverH dst_drv = GDALGetDriverByName(st->opts.format);
        GDALDatasetH dst =
            GDALCreateCopy(dst_drv, gdal->filename, gdal->data, FALSE,
                           st->opts.options, NULL, NULL);

        if (!dst) {
            G_warning(_("Unable to create output file <%s> using driver <%s>"),
                      gdal->filename, st->opts.format);
            stat = -1;
        }
        GDALClose(dst);
    }

    GDALClose(gdal->data);

#endif
    G_free(gdal->filename);
    G_free(gdal);

    return stat;
}

#ifdef GDAL_LINK
/*!
  \brief Input/output function for GDAL links

  See GDAL's RasterIO for details.
*/
CPLErr Rast_gdal_raster_IO(GDALRasterBandH band, GDALRWFlag rw_flag,
                           int x_off, int y_off, int x_size, int y_size,
                           void *buffer, int buf_x_size, int buf_y_size,
                           GDALDataType buf_type, int pixel_size,
                           int line_size)
{
    return GDALRasterIO(band, rw_flag, x_off, y_off, x_size, y_size,
                        buffer, buf_x_size, buf_y_size, buf_type,
                        pixel_size, line_size);
}
#endif
