#include <stdio.h>
#include <string.h>
#include <math.h>
#include <grass/gis.h>
#include <grass/raster.h>
#include <grass/glocale.h>
#include "local_proto.h"

#define DOT        "." /* for determining data type -tw */
#define INT        "int"
#define FLOAT      "float"
#define DOUBLE     "double"
#define TMPBUFSIZE 8192

static int missing(int, char *);
static int extract(int, char *, char *, void *, int,
                   int (*)(const char *, double *, int));
static int scan_int(const char *, double *, int);

const char gs_ascii_flag[5] = {"DSAA"};

int getgrdhead(FILE *fd, struct Cell_head *cellhd)
{
    char grd_flag[6];
    int nc, nr;
    float xmin, xmax, ymin, ymax, zmin, zmax;

    /* make sure the input file is positioned at the beginning */
    rewind(fd);

    /* read and check the flag on the first line */
    if (fgets(grd_flag, sizeof(grd_flag), fd) == NULL) {
        G_warning(_("failed to read the input file"));
        return 0;
    }
    if (strncmp(gs_ascii_flag, grd_flag, strlen(gs_ascii_flag))) {
        G_warning(_("input file is not a Surfer ascii grid file"));
        return 0;
    }

    /* read the row and column dimensions */
    if (fscanf(fd, "%d %d \n", &nc, &nr) != 2) {
        G_warning(_("error reading the column and row dimension from the "
                    "Surfer grid file"));
        return 0;
    }

    /* read the range of x values */
    if (fscanf(fd, "%f %f \n", &xmin, &xmax) != 2) {
        G_warning(_("error reading the X range from the Surfer grid file"));
        return 0;
    }

    /* read the range of y values */
    if (fscanf(fd, "%f %f \n", &ymin, &ymax) != 2) {
        G_warning(_("error reading the Y range from the Surfer grid file"));
        return 0;
    }

    /* read the range of z values (not used) */
    if (fscanf(fd, "%f %f \n", &zmin, &zmax) != 2) {
        G_warning(_("error reading the Z range from the Surfer grid file"));
        return 0;
    }

    /* initialize the cell header */
    cellhd->zone = G_zone();
    cellhd->proj = G_projection();
    cellhd->rows = nr;
    cellhd->cols = nc;

    cellhd->ew_res = (double)(xmax - xmin) / (nc - 1);
    cellhd->ns_res = (double)(ymax - ymin) / (nr - 1);
    /* the Surfer grid specifies x,y locations of gridded points.  The GRASS
       raster specifies an area covered by rectangular cells centered at gridded
       points. That difference requires an adjustment */
    cellhd->north = ymax + cellhd->ns_res / 2.;
    cellhd->south = ymin - cellhd->ns_res / 2.;
    cellhd->east = xmax + cellhd->ew_res / 2.;
    cellhd->west = xmin - cellhd->ew_res / 2.;

    return 1;
}

int gethead(FILE *fd, struct Cell_head *cellhd, RASTER_MAP_TYPE *d_type,
            DCELL *mult, char **nval)
{
    int n, s, e, w, r, c;
    char label[100], value[100];
    char buf[1024];
    int ret;

    /* rsb fix */
    fpos_t p;

    n = s = e = w = r = c = 0;

    cellhd->zone = G_zone();
    cellhd->proj = G_projection();

    /*      while (n == 0 || s== 0 || e == 0 || w == 0 || r == 0 || c == 0) */

    while (1) {
        /* rsb fix */
        if (fgetpos(fd, &p) != 0)
            G_fatal_error(_("error getting file position"));

        if (!G_getl2(buf, sizeof(buf), fd))
            break;

        *label = *value = '\0';
        if (NULL == strstr(buf, ":"))
            break;
        if (sscanf(buf, "%[^:]:%s", label, value) != 2)
            break;
        if (*label == '\0')
            continue; /* ignore blank lines */

        if (strcmp(label, "north") == 0) {
            extract(n++, label, value, &cellhd->north, cellhd->proj,
                    G_scan_northing);
            continue;
        }

        if (strcmp(label, "south") == 0) {
            extract(s++, label, value, &cellhd->south, cellhd->proj,
                    G_scan_northing);
            continue;
        }

        if (strcmp(label, "east") == 0) {
            extract(e++, label, value, &cellhd->east, cellhd->proj,
                    G_scan_easting);
            continue;
        }

        if (strcmp(label, "west") == 0) {
            extract(w++, label, value, &cellhd->west, cellhd->proj,
                    G_scan_easting);
            continue;
        }

        if (strcmp(label, "rows") == 0) {
            extract(r++, label, value, &cellhd->rows, cellhd->proj, scan_int);
            continue;
        }

        if (strcmp(label, "cols") == 0) {
            extract(c++, label, value, &cellhd->cols, cellhd->proj, scan_int);
            continue;
        }
        /* try to read optional header fields */

        if (strcmp(label, "type") == 0) { /* if not exist then the file scan */
            if (*d_type < 0) { /* if data type not set on command line */
                if (!strncmp(value, INT, strlen(INT)))
                    *d_type = CELL_TYPE;
                else if (!strncmp(value, FLOAT, strlen(FLOAT)))
                    *d_type = FCELL_TYPE;
                else if (!strncmp(value, DOUBLE, strlen(DOUBLE)))
                    *d_type = DCELL_TYPE;
                else {
                    G_warning(_("illegal type field: using type int"));
                    *d_type = CELL_TYPE;
                }
            }
            else
                G_warning(_("ignoring type filed in header, type is set on "
                            "command line"));
            continue;
        }

        if (strcmp(label, "multiplier") == 0) {
            if (Rast_is_d_null_value(
                    mult)) { /* if mult not set on command line */
                if (sscanf(value, "%lf", mult) != 1) {
                    G_warning(_("illegal multiplier field: using 1.0"));
                    *mult = 1.0;
                }
            }
            else
                G_warning(_("ignoring multiplier filed in header, multiplier "
                            "is set on command line"));
            continue;
        }

        if (strcmp(label, "null") == 0) {
            if (!(*nval)) /* if null val string not set on command line */
                *nval = G_store(value);
            else
                G_warning(_("ignoring null filed in header, null string is set "
                            "on command line"));
            continue;
        }

    } /* while */
    /* the line read was not a header line, but actually
       the first data line, so put it back on the stack and break */
    /* rsb fix */
    fsetpos(fd, &p);

    missing(n, "north");
    missing(s, "south");
    missing(e, "east");
    missing(w, "west");
    missing(r, "rows");
    missing(c, "cols");

    if (!(*nval))
        *nval = G_store("*");
    if (Rast_is_d_null_value(mult))
        *mult = 1.0;
    /* if data type is not set, then scan data to find out data type */
    if (*d_type < 0) {
        ret = file_scan(fd);
        if (!ret)
            *d_type = DCELL_TYPE;
        else if (ret == 1)
            *d_type = CELL_TYPE;
        else {
            G_warning(_("error in ascii data format"));
            return 0;
        }
    }

    G_adjust_Cell_head(cellhd, 1, 1);

    return 1;
}

static int scan_int(const char *s, double *i, int proj G_UNUSED)
{
    char dummy[3];
    int *i_loc = (int *)i;

    *dummy = 0;

    if (sscanf(s, "%d%1s", i_loc, dummy) != 1)
        return 0;
    if (*dummy)
        return 0;
    if (*i_loc <= 0)
        return 0;
    return 1;
}

static int extract(int count, char *label, char *value, void *data, int proj,
                   int (*scanner)(const char *, double *, int))
{
    if (count) {
        G_warning(_("Duplicate \"%s\" field in header"), label);
        return 0;
    }
    if (scanner(value, data, proj))
        return 1;
    G_warning(_("Illegal \"%s\" value in header: %s"), label, value);
    return 0;
}

static int missing(int count, char *label)
{
    if (count)
        return 0;
    G_warning(_("\"%s\" field missing from header"), label);
    return 1;
}

/* file_scan(): determine data type in ascii format */
int file_scan(FILE *fd)
{
    long curpos;
    char tmpbuf[TMPBUFSIZE];
    size_t size = TMPBUFSIZE;

    if ((curpos = G_ftell(fd)) == -1)
        return -1;
    while (!feof(fd)) {
        if (size != fread(tmpbuf, sizeof(char), size, fd)) {
            if (!feof(fd))
                return -1;
        }
        if (strstr(tmpbuf, DOT) != NULL) {
            G_fseek(fd, curpos - 1L, SEEK_SET);
            return 0;
        }
    }
    G_fseek(fd, curpos - 1L, SEEK_SET);
    return 1;
}
