/*
 * Start up graphics processing.  Anything that needs to be assigned, set up,
 * started-up, or otherwise initialized happens here.  This is called only at
 * the startup of the graphics driver.
 *
 * The external variables define the pixle limits of the graphics surface.  The
 * coordinate system used by the applications programs has the (0,0) origin
 * in the upper left-hand corner.  Hence,
 *    screen_left < screen_right
 *    screen_top  < screen_bottom 
 */

#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef __MINGW32__
#include <windows.h>
#else
#include <sys/mman.h>
#endif

#include <grass/gis.h>
#include <grass/colors.h>
#include <grass/glocale.h>
#include "pngdriver.h"

struct png_state png;

static void map_file(void)
{
    size_t size = HEADER_SIZE + png.width * png.height * sizeof(unsigned int);
    void *ptr;
    int fd;

    fd = open(png.file_name, O_RDWR);
    if (fd < 0)
	return;

#ifdef __MINGW32__
    png.handle = CreateFileMapping((HANDLE) _get_osfhandle(fd),
				   NULL, PAGE_READWRITE,
				   0, size, NULL);
    if (!png.handle)
	return;
    ptr = MapViewOfFile(png.handle, FILE_MAP_WRITE, 0, 0, size);
    if (!ptr)
	return;
#else
    ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, (off_t) 0);
    if (ptr == MAP_FAILED)
	return;
#endif

    if (png.grid)
	G_free(png.grid);
    png.grid = (unsigned int *)((char *) ptr + HEADER_SIZE);

    close(fd);

    png.mapped = 1;
}

int PNG_Graph_set(void)
{
    unsigned int red, grn, blu;
    int do_read = 0;
    int do_map = 0;
    char *p;

    G_gisinit("PNG driver");

    p = getenv("GRASS_PNGFILE");
    if (!p || strlen(p) == 0)
	p = FILE_NAME;

    png.file_name = p;

    p = getenv("GRASS_TRUECOLOR");
    png.true_color = !p || strcmp(p, "FALSE") != 0;

    G_verbose_message(_("png: truecolor status %s"),
		      png.true_color ? _("enabled") : _("disabled"));

    p = getenv("GRASS_PNG_MAPPED");
    do_map = p && strcmp(p, "TRUE") == 0;

    if (do_map) {
	char *ext = png.file_name + strlen(png.file_name) - 4;

	if (G_strcasecmp(ext, ".bmp") != 0)
	    do_map = 0;
    }

    p = getenv("GRASS_PNG_READ");
    do_read = p && strcmp(p, "TRUE") == 0;

    if (do_read && access(png.file_name, 0) != 0)
	do_read = 0;

    png.width = screen_width;
    png.height = screen_height;

    png.clip_top = 0;
    png.clip_bot = png.height;
    png.clip_left = 0;
    png.clip_rite = png.width;

    p = getenv("GRASS_TRANSPARENT");
    png.has_alpha = p && strcmp(p, "TRUE") == 0;

    png_init_color_table();

    p = getenv("GRASS_BACKGROUNDCOLOR");
    if (p && *p && 
	(sscanf(p, "%02x%02x%02x", &red, &grn, &blu) == 3 ||
	 G_str_to_color(p, (int *)&red, (int *)&grn, (int *)&blu) == 1)) {
	png.background = png_get_color(red, grn, blu, png.has_alpha ? 255 : 0);
    }
    else {
	/* 0xffffff = white, 0x000000 = black */
	if (strcmp(DEFAULT_FG_COLOR, "white") == 0)
	    /* foreground: white, background: black */
	    png.background = png_get_color(0, 0, 0, png.has_alpha ? 255 : 0);
	else
	    /* foreground: black, background: white */
	    png.background = png_get_color(255, 255, 255, png.has_alpha ? 255 : 0);
    }
    
    G_verbose_message(_("png: collecting to file '%s'"), png.file_name);
    G_verbose_message(_("png: image size %dx%d"),
		      png.width, png.height);

    if (do_read && do_map)
	map_file();

    if (!png.mapped)
	png.grid = G_malloc(png.width * png.height * sizeof(unsigned int));

    if (!do_read) {
	PNG_Erase();
	png.modified = 1;
    }

    if (do_read && !png.mapped)
	read_image();

    if (do_map && !png.mapped) {
	write_image();
	map_file();
    }

    return 0;
}
