/**
 * File: GD IO
 *
 * Read and write GD images.
 *
 * The GD image format is a proprietary image format of libgd. *It has to be*
 * *regarded as being obsolete, and should only be used for development and*
 * *testing purposes.*
 *
 * Structure of a GD image file:
 *  - file header
 *  - color header (either truecolor or palette)
 *  - image data
 *
 * All numbers are stored in big-endian format.
 *
 * File header structure:
 *  signature     - 1 word ("\xFF\xFE" for truecolor, "\xFF\xFF" for palette)
 *  width         - 1 word
 *  height        - 1 word
 *
 * Truecolor image color header:
 *  truecolor   - 1 byte (always "\001")
 *  transparent - 1 dword (ARGB color)
 *
 * Palette image color header:
 *  truecolor   - 1 byte (always "\0")
 *  count       - 1 word (the number of used palette colors)
 *  transparent - 1 dword (ARGB color)
 *  palette     - 256 dwords (RGBA colors)
 *
 * Image data:
 *  Sequential pixel data; row-major from top to bottom, left to right:
 *   - 1 byte per pixel for palette images
 *   - 1 dword (ARGB) per pixel for truecolor images
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include "gd.h"

#define TRUE 1
#define FALSE 0

/* Use this for commenting out debug-print statements. */
/* Just use the first '#define' to allow all the prints... */
/*#define GD2_DBG(s) (s) */
#define GD2_DBG(s)

/* */
/* Shared code to read color tables from gd file. */
/* */
int
_gdGetColors (gdIOCtx * in, gdImagePtr im, int gd2xFlag)
{
	int i;
	if (gd2xFlag) {
		int trueColorFlag;
		if (!gdGetByte (&trueColorFlag, in)) {
			goto fail1;
		}
		/* 2.0.12: detect bad truecolor .gd files created by pre-2.0.12.
		   Beginning in 2.0.12 truecolor is indicated by the initial 2-byte
		   signature. */
		if (trueColorFlag != im->trueColor) {
			goto fail1;
		}
		/* This should have been a word all along */
		if (!im->trueColor) {
			if (!gdGetWord (&im->colorsTotal, in)) {
				goto fail1;
			}
			if (im->colorsTotal > gdMaxColors) {
				goto fail1;
			}
		}
		/* Int to accommodate truecolor single-color transparency */
		if (!gdGetInt (&im->transparent, in)) {
			goto fail1;
		}
	} else {
		if (!gdGetByte (&im->colorsTotal, in)) {
			goto fail1;
		}
		if (!gdGetWord (&im->transparent, in)) {
			goto fail1;
		}
		if (im->transparent == 257) {
			im->transparent = (-1);
		}
	}
	GD2_DBG (printf
	         ("Palette had %d colours (T=%d)\n", im->colorsTotal,
	          im->transparent));
	if (im->trueColor) {
		return TRUE;
	}
	for (i = 0; (i < gdMaxColors); i++) {
		if (!gdGetByte (&im->red[i], in)) {
			goto fail1;
		}
		if (!gdGetByte (&im->green[i], in)) {
			goto fail1;
		}
		if (!gdGetByte (&im->blue[i], in)) {
			goto fail1;
		}
		if (gd2xFlag) {
			if (!gdGetByte (&im->alpha[i], in)) {
				goto fail1;
			}
		}
	}

	for (i = 0; (i < im->colorsTotal); i++) {
		im->open[i] = 0;
	};

	return TRUE;
fail1:
	return FALSE;
}

/* */
/* Use the common basic header info to make the image object. */
/* */
static gdImagePtr
_gdCreateFromFile (gdIOCtx * in, int *sx, int *sy)
{
	gdImagePtr im;
	int gd2xFlag = 0;
	int trueColorFlag = 0;
	if (!gdGetWord (sx, in)) {
		goto fail1;
	}
	if ((*sx == 65535) || (*sx == 65534)) {
		/* This is a gd 2.0 .gd file */
		gd2xFlag = 1;
		/* 2.0.12: 65534 signals a truecolor .gd file.
		   There is a slight redundancy here but we can
		   live with it. */
		if (*sx == 65534) {
			trueColorFlag = 1;
		}
		if (!gdGetWord (sx, in)) {
			goto fail1;
		}
	}
	if (!gdGetWord (sy, in)) {
		goto fail1;
	}

	GD2_DBG (printf ("Image is %dx%d\n", *sx, *sy));
	if (trueColorFlag) {
		im = gdImageCreateTrueColor (*sx, *sy);
	} else {
		im = gdImageCreate (*sx, *sy);
	}
	if (!im) {
		goto fail1;
	}
	if (!_gdGetColors (in, im, gd2xFlag)) {
		goto fail2;
	}

	return im;
fail2:
	gdImageDestroy (im);
fail1:
	return 0;
}

/*
  Function: gdImageCreateFromGd

    <gdImageCreateFromGd> is called to load images from gd format
    files. Invoke <gdImageCreateFromGd> with an already opened pointer
    to a file containing the desired image in the gd file format,
    which is specific to gd and intended for very fast loading. (It is
    not intended for compression; for compression, use PNG or JPEG.)

    <gdImageCreateFromGd> returns a <gdImagePtr> to the new image, or
    NULL if unable to load the image (most often because the file is
    corrupt or does not contain a gd format
    image). <gdImageCreateFromGd> does not close the file. You can
    inspect the sx and sy members of the image to determine its
    size. The image must eventually be destroyed using
    <gdImageDestroy>.

  Variants:

    <gdImageCreateFromGdPtr> creates an image from GD data (i.e. the
    contents of a GD file) already in memory.

    <gdImageCreateFromGdCtx> reads in an image using the functions in
    a <gdIOCtx> struct.

  Parameters:

    infile - The input FILE pointer

  Returns:

    A pointer to the new image or NULL if an error occurred.

  Example:

    > gdImagePtr im;
    > FILE *in;
    > in = fopen("mygd.gd", "rb");
    > im = gdImageCreateFromGd(in);
    > fclose(in);
    > // ... Use the image ... 
    > gdImageDestroy(im);
*/
BGD_DECLARE(gdImagePtr) gdImageCreateFromGd (FILE * inFile)
{
	gdImagePtr im;
	gdIOCtx *in;

	in = gdNewFileCtx (inFile);
	if (in == NULL) return NULL;
	im = gdImageCreateFromGdCtx (in);

	in->gd_free (in);

	return im;
}

/*
  Function: gdImageCreateFromGdPtr

  Parameters:

    size - size of GD data in bytes.
    data - GD data (i.e. contents of a GIF file).

  Reads in GD data from memory. See <gdImageCreateFromGd>.
*/
BGD_DECLARE(gdImagePtr) gdImageCreateFromGdPtr (int size, void *data)
{
	gdImagePtr im;
	gdIOCtx *in = gdNewDynamicCtxEx (size, data, 0);
	if(!in)
		return 0;
	im = gdImageCreateFromGdCtx (in);
	in->gd_free (in);
	return im;
}

/*
  Function: gdImageCreateFromGdCtx

  Reads in a GD image via a <gdIOCtx> struct.  See
  <gdImageCreateFromGd>.
*/
BGD_DECLARE(gdImagePtr) gdImageCreateFromGdCtx (gdIOCtxPtr in)
{
	int sx, sy;
	int x, y;
	gdImagePtr im;

	/* Read the header */
	im = _gdCreateFromFile (in, &sx, &sy);

	if (im == NULL) {
		goto fail1;
	};

	/* Then the data... */
	/* 2.0.12: support truecolor properly in .gd as well as in .gd2.
	   Problem reported by Andreas Pfaller. */
	if (im->trueColor) {
		for (y = 0; (y < sy); y++) {
			for (x = 0; (x < sx); x++) {
				int pix;
				if (!gdGetInt (&pix, in)) {
					goto fail2;
				}
				im->tpixels[y][x] = pix;
			}
		}
	} else {
		for (y = 0; (y < sy); y++) {
			for (x = 0; (x < sx); x++) {
				int ch;
				ch = gdGetC (in);
				if (ch == EOF) {
					goto fail2;
				}
				/* ROW-MAJOR IN GD 1.3 */
				im->pixels[y][x] = ch;
			}
		}
	}
	return im;

fail2:
	gdImageDestroy (im);
fail1:
	return 0;
}

void
_gdPutColors (gdImagePtr im, gdIOCtx * out)
{
	int i;

	gdPutC (im->trueColor, out);
	if (!im->trueColor) {
		gdPutWord (im->colorsTotal, out);
	}
	gdPutInt (im->transparent, out);
	if (!im->trueColor) {
		for (i = 0; (i < gdMaxColors); i++) {
			gdPutC ((unsigned char) im->red[i], out);
			gdPutC ((unsigned char) im->green[i], out);
			gdPutC ((unsigned char) im->blue[i], out);
			gdPutC ((unsigned char) im->alpha[i], out);
		}
	}
}

static void
_gdPutHeader (gdImagePtr im, gdIOCtx * out)
{
	/* 65535 indicates this is a gd 2.x .gd file.
	   2.0.12: 65534 indicates truecolor. */
	if (im->trueColor) {
		gdPutWord (65534, out);
	} else {
		gdPutWord (65535, out);
	}
	gdPutWord (im->sx, out);
	gdPutWord (im->sy, out);

	_gdPutColors (im, out);

}

static void
_gdImageGd (gdImagePtr im, gdIOCtx * out)
{
	int x, y;

	_gdPutHeader (im, out);

	for (y = 0; (y < im->sy); y++) {
		for (x = 0; (x < im->sx); x++) {
			/* ROW-MAJOR IN GD 1.3 */
			if (im->trueColor) {
				gdPutInt (im->tpixels[y][x], out);
			} else {
				gdPutC ((unsigned char) im->pixels[y][x], out);
			}
		}
	}
}

/*
	Function: gdImageGd
 */
BGD_DECLARE(void) gdImageGd (gdImagePtr im, FILE * outFile)
{
	gdIOCtx *out = gdNewFileCtx (outFile);
	if (out == NULL) return;
	_gdImageGd (im, out);
	out->gd_free (out);
}

/*
	Function: gdImageGdPtr
 */
BGD_DECLARE(void *) gdImageGdPtr (gdImagePtr im, int *size)
{
	void *rv;
	gdIOCtx *out = gdNewDynamicCtx (2048, NULL);
	if (out == NULL) return NULL;
	_gdImageGd (im, out);
	rv = gdDPExtractData (out, size);
	out->gd_free (out);
	return rv;
}