/*
    Stolen from http://cvs.php.net/viewcvs.cgi/gd/playground/gdbmp/
*/

/*
	gd_bmp.c

	Bitmap format support for libgd

	* Written 2007, Scott MacVicar
	---------------------------------------------------------------------------

	Todo:

	Bitfield encoding

	----------------------------------------------------------------------------
 */
/* $Id$ */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

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

extern void* gdCalloc (size_t nmemb, size_t size);

static int bmp_read_header(gdIOCtxPtr infile, bmp_hdr_t *hdr);
static int bmp_read_info(gdIOCtxPtr infile, bmp_info_t *info);
static int bmp_read_windows_v3_info(gdIOCtxPtr infile, bmp_info_t *info);
static int bmp_read_os2_v1_info(gdIOCtxPtr infile, bmp_info_t *info);
static int bmp_read_os2_v2_info(gdIOCtxPtr infile, bmp_info_t *info);

static int bmp_read_direct(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header);
static int bmp_read_1bit(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header);
static int bmp_read_4bit(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header);
static int bmp_read_8bit(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header);
static int bmp_read_rle(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info);

#if GD_MAJOR_VERSION == 2 && GD_MINOR_VERSION < 1
/* Byte helper functions, since added to GD 2.1 */
static int gdGetIntLSB(signed int *result, gdIOCtx * ctx);
static int gdGetWordLSB(signed short int *result, gdIOCtx * ctx);
#endif

#define BMP_DEBUG(s)

gdImagePtr gdImageCreateFromBmpCtx(gdIOCtxPtr infile);

gdImagePtr gdImageCreateFromBmp(FILE * inFile)
{
	gdImagePtr im = 0;
	gdIOCtx *in = gdNewFileCtx(inFile);
	im = gdImageCreateFromBmpCtx(in);
	in->gd_free(in);
	return im;
}

gdImagePtr gdImageCreateFromBmpPtr(int size, void *data)
{
	gdImagePtr im;
	gdIOCtx *in = gdNewDynamicCtxEx(size, data, 0);
	im = gdImageCreateFromBmpCtx(in);
	in->gd_free(in);
	return im;
}

gdImagePtr gdImageCreateFromBmpCtx(gdIOCtxPtr infile)
{
	bmp_hdr_t *hdr;
	bmp_info_t *info;
	gdImagePtr im = NULL;
	int error = 0;

	if (!(hdr= (bmp_hdr_t *)gdCalloc(1, sizeof(bmp_hdr_t)))) {
		return NULL;
	}

	if (bmp_read_header(infile, hdr)) {
		gdFree(hdr);
		return NULL;
	}

	if (hdr->magic != 0x4d42) {
		gdFree(hdr);
		return NULL;
	}

	if (!(info = (bmp_info_t *)gdCalloc(1, sizeof(bmp_info_t)))) {
		gdFree(hdr);
		return NULL;
	}

	if (bmp_read_info(infile, info)) {
		gdFree(hdr);
		gdFree(info);
		return NULL;
	}

	BMP_DEBUG(printf("Numcolours: %d\n", info->numcolors));
	BMP_DEBUG(printf("Width: %d\n", info->width));
	BMP_DEBUG(printf("Height: %d\n", info->height));
	BMP_DEBUG(printf("Planes: %d\n", info->numplanes));
	BMP_DEBUG(printf("Depth: %d\n", info->depth));
	BMP_DEBUG(printf("Offset: %d\n", hdr->off));

	if (info->depth >= 16) {
		im = gdImageCreateTrueColor(info->width, info->height);
	} else {
		im = gdImageCreate(info->width, info->height);
	}

	if (!im) {
		gdFree(hdr);
		gdFree(info);
		return NULL;
	}

	switch (info->depth) {
		case 1:
			BMP_DEBUG(printf("1-bit image\n"));
			error = bmp_read_1bit(im, infile, info, hdr);
		break;
		case 4:
			BMP_DEBUG(printf("4-bit image\n"));
			error = bmp_read_4bit(im, infile, info, hdr);
		break;
		case 8:
			BMP_DEBUG(printf("8-bit image\n"));
			error = bmp_read_8bit(im, infile, info, hdr);
		break;
		case 16:
		case 24:
		case 32:
			BMP_DEBUG(printf("Direct BMP image\n"));
			error = bmp_read_direct(im, infile, info, hdr);
		break;
		default:
			BMP_DEBUG(printf("Unknown bit count\n"));
			error = 1;
	}

	gdFree(hdr);
	gdFree(info);

	if (error) {
		gdImageDestroy(im);
		return NULL;
	}

	return im;
}

static int bmp_read_header(gdIOCtx *infile, bmp_hdr_t *hdr)
{
	if(
	!gdGetWordLSB(&hdr->magic, infile) ||
	!gdGetIntLSB(&hdr->size, infile) ||
	!gdGetWordLSB(&hdr->reserved1, infile) ||
	!gdGetWordLSB(&hdr->reserved2 , infile) ||
	!gdGetIntLSB(&hdr->off , infile)
	) {
		return 1;
	}
	return 0;
}

static int bmp_read_info(gdIOCtx *infile, bmp_info_t *info)
{
	/* read BMP length so we can work out the version */
	if (!gdGetIntLSB(&info->len, infile)) {
		return 1;
	}

	switch (info->len) {
		/* For now treat Windows v4 + v5 as v3 */
		case BMP_WINDOWS_V3:
		case BMP_WINDOWS_V4:
		case BMP_WINDOWS_V5:
			BMP_DEBUG(printf("Reading Windows Header\n"));
			if (bmp_read_windows_v3_info(infile, info)) {
				return 1;
			}
		break;
		case BMP_OS2_V1:
			if (bmp_read_os2_v1_info(infile, info)) {
				return 1;
			}
		break;
		case BMP_OS2_V2:
			if (bmp_read_os2_v2_info(infile, info)) {
				return 1;
			}
		break;
		default:
			BMP_DEBUG(printf("Unhandled bitmap\n"));
			return 1;
	}
	return 0;
}

static int bmp_read_windows_v3_info(gdIOCtxPtr infile, bmp_info_t *info)
{
	if (
		!gdGetIntLSB(&info->width, infile) ||
		!gdGetIntLSB(&info->height, infile) ||
		!gdGetWordLSB(&info->numplanes, infile) ||
		!gdGetWordLSB(&info->depth, infile) ||
		!gdGetIntLSB(&info->enctype, infile) ||
		!gdGetIntLSB(&info->size, infile) ||
		!gdGetIntLSB(&info->hres, infile) ||
		!gdGetIntLSB(&info->vres, infile) ||
		!gdGetIntLSB(&info->numcolors, infile) ||
		!gdGetIntLSB(&info->mincolors, infile)
	) {
		return 1;
	}

	if (info->height < 0) {
		info->topdown = 1;
		info->height = -info->height;
	} else {
		info->topdown = 0;
	}

	info->type = BMP_PALETTE_4;

	if (info->width <= 0 || info->height <= 0 || info->numplanes <= 0 ||
	  info->depth <= 0  || info->numcolors < 0 || info->mincolors < 0) {
		return 1;
	}

	return 0;
}

static int bmp_read_os2_v1_info(gdIOCtxPtr infile, bmp_info_t *info)
{
	if (
		!gdGetWordLSB((signed short int *)&info->width, infile) ||
		!gdGetWordLSB((signed short int *)&info->height, infile) ||
		!gdGetWordLSB(&info->numplanes, infile) ||
		!gdGetWordLSB(&info->depth, infile)
	) {
		return 1;
	}

	/* OS2 v1 doesn't support topdown */
	info->topdown = 0;

	info->numcolors = 1 << info->depth;
	info->type = BMP_PALETTE_3;

	if (info->width <= 0 || info->height <= 0 || info->numplanes <= 0 ||
	  info->depth <= 0 || info->numcolors < 0) {
		return 1;
	}

	return 0;
}

static int bmp_read_os2_v2_info(gdIOCtxPtr infile, bmp_info_t *info)
{
	char useless_bytes[24];
	if (
		!gdGetIntLSB(&info->width, infile) ||
		!gdGetIntLSB(&info->height, infile) ||
		!gdGetWordLSB(&info->numplanes, infile) ||
		!gdGetWordLSB(&info->depth, infile) ||
		!gdGetIntLSB(&info->enctype, infile) ||
		!gdGetIntLSB(&info->size, infile) ||
		!gdGetIntLSB(&info->hres, infile) ||
		!gdGetIntLSB(&info->vres, infile) ||
		!gdGetIntLSB(&info->numcolors, infile) ||
		!gdGetIntLSB(&info->mincolors, infile)
	) {
		return 1;
	}

	/* Lets seek the next 24 pointless bytes, we don't care too much about it */
	if (!gdGetBuf(useless_bytes, 24, infile)) {
		return 1;
	}

	if (info->height < 0) {
		info->topdown = 1;
		info->height = -info->height;
	} else {
		info->topdown = 0;
	}

	info->type = BMP_PALETTE_4;

	if (info->width <= 0 || info->height <= 0 || info->numplanes <= 0 ||
	 info->depth <= 0  || info->numcolors < 0 || info->mincolors < 0) {
		return 1;
	}


	return 0;
}

static int bmp_read_direct(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header)
{
	int ypos = 0, xpos = 0, row = 0;
	int padding = 0, alpha = 0, red = 0, green = 0, blue = 0;
	signed short int data = 0;

	switch(info->enctype) {
		case BMP_BI_RGB:
			/* no-op */
		break;

		case BMP_BI_BITFIELDS:
			if (info->depth == 24) {
				BMP_DEBUG(printf("Bitfield compression isn't supported for 24-bit\n"));
				return 1;
			}
			BMP_DEBUG(printf("Currently no bitfield support\n"));
			return 1;
		break;

		case BMP_BI_RLE8:
			if (info->depth != 8) {
				BMP_DEBUG(printf("RLE is only valid for 8-bit images\n"));
				return 1;
			}
		case BMP_BI_RLE4:
			if (info->depth != 4) {
				BMP_DEBUG(printf("RLE is only valid for 4-bit images\n"));
				return 1;
			}
		case BMP_BI_JPEG:
		case BMP_BI_PNG:
		default:
			BMP_DEBUG(printf("Unsupported BMP compression format\n"));
			return 1;
	}

	/* There is a chance the data isn't until later, would be wierd but it is possible */
	if (gdTell(infile) != header->off) {
		/* Should make sure we don't seek past the file size */
		gdSeek(infile, header->off);
	}

	/* The line must be divisible by 4, else its padded with NULLs */
	padding = ((int)(info->depth / 8) * info->width) % 4;
	if (padding) {
		padding = 4 - padding;
	}


	for (ypos = 0; ypos < info->height; ++ypos) {
		if (info->topdown) {
			row = ypos;
		} else {
			row = info->height - ypos - 1;
		}

		for (xpos = 0; xpos < info->width; xpos++) {
			if (info->depth == 16) {
				if (!gdGetWordLSB(&data, infile)) {
					return 1;
				}
				BMP_DEBUG(printf("Data: %X\n", data));
				red = ((data & 0x7C00) >> 10) << 3;
				green = ((data & 0x3E0) >> 5) << 3;
				blue = (data & 0x1F) << 3;
				BMP_DEBUG(printf("R: %d, G: %d, B: %d\n", red, green, blue));
			} else if (info->depth == 24) {
				if (!gdGetByte(&blue, infile) || !gdGetByte(&green, infile) || !gdGetByte(&red, infile)) {
					return 1;
				}
			} else {
				if (!gdGetByte(&blue, infile) || !gdGetByte(&green, infile) || !gdGetByte(&red, infile) || !gdGetByte(&alpha, infile)) {
					return 1;
				}
			}
			/*alpha = gdAlphaMax - (alpha >> 1);*/
			gdImageSetPixel(im, xpos, row, gdTrueColor(red, green, blue));
		}
		for (xpos = padding; xpos > 0; --xpos) {
			if (!gdGetByte(&red, infile)) {
				return 1;
			}
		}
	}

	return 0;
}

static int bmp_read_palette(gdImagePtr im, gdIOCtxPtr infile, int count, int read_four)
{
	int i;
	int r, g, b, z;

	for (i = 0; i < count; i++) {
		if (
		!gdGetByte(&r, infile) ||
		!gdGetByte(&g, infile) ||
		!gdGetByte(&b, infile) ||
		(read_four && !gdGetByte(&z, infile))
		) {
			return 1;
		}
		im->red[i] = r;
		im->green[i] = g;
		im->blue[i] = b;
		im->open[i] = 1;
	}
	return 0;
}

static int bmp_read_1bit(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header)
{
	int ypos = 0, xpos = 0, row = 0, index = 0;
	int padding = 0, current_byte = 0, bit = 0;

	if (info->enctype != BMP_BI_RGB) {
		return 1;
	}

	if (!info->numcolors) {
		info->numcolors = 2;
	} else if (info->numcolors < 0 || info->numcolors > 2) {
		return 1;
	}

	if (bmp_read_palette(im, infile, info->numcolors, (info->type == BMP_PALETTE_4))) {
		return 1;
	}

	im->colorsTotal = info->numcolors;

	/* There is a chance the data isn't until later, would be wierd but it is possible */
	if (gdTell(infile) != header->off) {
		/* Should make sure we don't seek past the file size */
		gdSeek(infile, header->off);
	}

	/* The line must be divisible by 4, else its padded with NULLs */
	padding = ((int)ceill(0.1 * info->width)) % 4;
	if (padding) {
		padding = 4 - padding;
	}

	for (ypos = 0; ypos < info->height; ++ypos) {
		if (info->topdown) {
			row = ypos;
		} else {
			row = info->height - ypos - 1;
		}

		for (xpos = 0; xpos < info->width; xpos += 8) {
			/* Bitmaps are always aligned in bytes so we'll never overflow */
			if (!gdGetByte(&current_byte, infile)) {
				return 1;
			}

			for (bit = 0; bit < 8; bit++) {
				index = ((current_byte & (0x80 >> bit)) != 0 ? 0x01 : 0x00);
				if (im->open[index]) {
					im->open[index] = 0;
				}
				gdImageSetPixel(im, xpos + bit, row, index);
				/* No need to read anything extra */
				if ((xpos + bit) >= info->width) {
					break;
				}
			}
		}

		for (xpos = padding; xpos > 0; --xpos) {
			if (!gdGetByte(&index, infile)) {
				return 1;
			}
		}
	}
	return 0;
}

static int bmp_read_4bit(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header)
{
	int ypos = 0, xpos = 0, row = 0, index = 0;
	int padding = 0, current_byte = 0;

	if (info->enctype != BMP_BI_RGB && info->enctype != BMP_BI_RLE4) {
		return 1;
	}

	if (!info->numcolors) {
		info->numcolors = 16;
	} else if (info->numcolors < 0 || info->numcolors > 16) {
		return 1;
	}

	if (bmp_read_palette(im, infile, info->numcolors, (info->type == BMP_PALETTE_4))) {
		return 1;
	}

	im->colorsTotal = info->numcolors;

	/* There is a chance the data isn't until later, would be wierd but it is possible */
	if (gdTell(infile) != header->off) {
		/* Should make sure we don't seek past the file size */
		gdSeek(infile, header->off);
	}

	/* The line must be divisible by 4, else its padded with NULLs */
	padding = ((int)ceil(0.5 * info->width)) % 4;
	if (padding) {
		padding = 4 - padding;
	}

	switch (info->enctype) {
		case BMP_BI_RGB:
		for (ypos = 0; ypos < info->height; ++ypos) {
			if (info->topdown) {
				row = ypos;
			} else {
				row = info->height - ypos - 1;
			}

			for (xpos = 0; xpos < info->width; xpos += 2) {
				if (!gdGetByte(&current_byte, infile)) {
					return 1;
				}

				index = (current_byte >> 4) & 0x0f;
				if (im->open[index]) {
					im->open[index] = 0;
				}
				gdImageSetPixel(im, xpos, row, index);

				/* This condition may get called often, potential optimsations */
				if (xpos >= info->width) {
					break;
				}

				index = current_byte & 0x0f;
				if (im->open[index]) {
					im->open[index] = 0;
				}
				gdImageSetPixel(im, xpos + 1, row, index);
			}

			for (xpos = padding; xpos > 0; --xpos) {
				if (!gdGetByte(&index, infile)) {
					return 1;
				}
			}
		}
		break;

		case BMP_BI_RLE4:
		if (bmp_read_rle(im, infile, info)) {
			return 1;
		}
		break;

		default:
			return 1;
	}
	return 0;
}

static int bmp_read_8bit(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info, bmp_hdr_t *header)
{
	int ypos = 0, xpos = 0, row = 0, index = 0;
	int padding = 0;

	if (info->enctype != BMP_BI_RGB && info->enctype != BMP_BI_RLE8) {
		return 1;
	}

	if (!info->numcolors) {
		info->numcolors = 256;
	} else if (info->numcolors < 0 || info->numcolors > 256) {
		return 1;
	}

	if (bmp_read_palette(im, infile, info->numcolors, (info->type == BMP_PALETTE_4))) {
		return 1;
	}

	im->colorsTotal = info->numcolors;

	/* There is a chance the data isn't until later, would be wierd but it is possible */
	if (gdTell(infile) != header->off) {
		/* Should make sure we don't seek past the file size */
		gdSeek(infile, header->off);
	}

	/* The line must be divisible by 4, else its padded with NULLs */
	padding = (1 * info->width) % 4;
	if (padding) {
		padding = 4 - padding;
	}

	switch (info->enctype) {
		case BMP_BI_RGB:
		for (ypos = 0; ypos < info->height; ++ypos) {
			if (info->topdown) {
				row = ypos;
			} else {
				row = info->height - ypos - 1;
			}

			for (xpos = 0; xpos < info->width; ++xpos) {
				if (!gdGetByte(&index, infile)) {
					return 1;
				}

				if (im->open[index]) {
					im->open[index] = 0;
				}
				gdImageSetPixel(im, xpos, row, index);
			}
			/* Could create a new variable, but it isn't really worth it */
			for (xpos = padding; xpos > 0; --xpos) {
				if (!gdGetByte(&index, infile)) {
					return 1;
				}
			}
		}
		break;

		case BMP_BI_RLE8:
		if (bmp_read_rle(im, infile, info)) {
			return 1;
		}
		break;

		default:
			return 1;
	}
	return 0;
}

static int bmp_read_rle(gdImagePtr im, gdIOCtxPtr infile, bmp_info_t *info)
{
	int ypos = 0, xpos = 0, row = 0, index = 0;
	int rle_length = 0, rle_data = 0;
	int padding = 0;
	int i = 0, j = 0;
	int pixels_per_byte = 8 / info->depth;

	for (ypos = 0; ypos < info->height && xpos <= info->width;) {
		if (!gdGetByte(&rle_length, infile) || !gdGetByte(&rle_data, infile)) {
			return 1;
		}
		row = info->height - ypos - 1;

		if (rle_length != BMP_RLE_COMMAND) {
			if (im->open[rle_data]) {
				im->open[rle_data] = 0;
			}

			for (i = 0; (i < rle_length) && (xpos < info->width);) {
				for (j = 1; (j <= pixels_per_byte) && (xpos < info->width) && (i < rle_length); j++, xpos++, i++) {
					index = (rle_data & (((1 << info->depth) - 1) << (8 - (j * info->depth)))) >> (8 - (j * info->depth));
					if (im->open[index]) {
						im->open[index] = 0;
					}
					gdImageSetPixel(im, xpos, row, index);
				}
			}
		} else if (rle_length == BMP_RLE_COMMAND && rle_data > 2) {
			/* Uncompressed RLE needs to be even */
			padding = 0;
			for (i = 0; (i < rle_data) && (xpos < info->width); i += pixels_per_byte) {
				int max_pixels = pixels_per_byte;

				if (!gdGetByte(&index, infile)) {
					return 1;
				}
				padding++;

				if (rle_data - i < max_pixels) {
					max_pixels = rle_data - i;
				}

				for (j = 1; (j <= max_pixels)  && (xpos < info->width); j++, xpos++) {
					int temp = (index >> (8 - (j * info->depth))) & ((1 << info->depth) - 1);
					if (im->open[temp]) {
						im->open[temp] = 0;
					}
					gdImageSetPixel(im, xpos, row, temp);
				}
			}

			/* Make sure the bytes read are even */
			if (padding % 2 && !gdGetByte(&index, infile)) {
				return 1;
			}
		} else if (rle_length == BMP_RLE_COMMAND && rle_data == BMP_RLE_ENDOFLINE) {
			/* Next Line */
			xpos = 0;
			ypos++;
		} else if (rle_length == BMP_RLE_COMMAND && rle_data == BMP_RLE_DELTA) {
			/* Delta Record, used for bmp files that contain other data*/
			if (!gdGetByte(&rle_length, infile) || !gdGetByte(&rle_data, infile)) {
				return 1;
			}
			xpos += rle_length;
			ypos += rle_data;
		} else if (rle_length == BMP_RLE_COMMAND && rle_data == BMP_RLE_ENDOFBITMAP) {
			/* End of bitmap */
			break;
		}
	}
	return 0;
}

#if GD_MAJOR_VERSION == 2 && GD_MINOR_VERSION < 1
static int gdGetWordLSB(signed short int *result, gdIOCtx * ctx)
{
	unsigned int high = 0, low = 0;
	low = (ctx->getC) (ctx);
	if (low == EOF) {
 		return 0;
	}

	high = (ctx->getC) (ctx);
	if (high == EOF) {
 		return 0;
	}

	if (result) {
		*result = (high << 8) | low;
	}

	return 1;
}

static int gdGetIntLSB(signed int *result, gdIOCtx * ctx)
{
	int c = 0;
	unsigned int r = 0;

	c = (ctx->getC) (ctx);
	if (c == EOF) {
 		return 0;
	}
	r |= (c << 24);
	r >>= 8;

	c = (ctx->getC) (ctx);
	if (c == EOF) {
 		return 0;
	}
	r |= (c << 24);
	r >>= 8;

	c = (ctx->getC) (ctx);
	if (c == EOF) {
 		return 0;
	}
	r |= (c << 24);
	r >>= 8;

	c = (ctx->getC) (ctx);
	if (c == EOF) {
 		return 0;
	}
	r |= (c << 24);

	if (result) {
		*result = (signed int)r;
	}

	return 1;
}
#endif