/*
 * radiance_hdr.c
 *
 * $Id$
 *
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
*/

/* ----------------------------------------------------------------------
  Radiance High Dynamic Range image file IO
  For description and code for reading/writing of radiance hdr files 
	by Greg Ward, refer to:
  http://radsite.lbl.gov/radiance/refer/Notes/picture_format.html
----------------------------------------------------------------------
*/

#ifdef WIN32
#include <io.h>
#endif
#include "BLI_blenlib.h"

#include "imbuf.h"
#include "imbuf_patch.h"

#include "IMB_imbuf_types.h"
#include "IMB_imbuf.h"

#include "IMB_allocimbuf.h"
#include "IMB_cmap.h"
#include "IMB_radiance_hdr.h"

/* needed constants */
#define MINELEN 8
#define MAXELEN 0x7fff
#define MINRUN	4	/* minimum run length */
#define RED 0
#define GRN 1
#define BLU 2
#define EXP 3
#define COLXS 128
#define STR_MAX 540
typedef unsigned char RGBE[4];
typedef float fCOLOR[3];
/* copy source -> dest */
#define copy_rgbe(c1, c2) (c2[RED]=c1[RED], c2[GRN]=c1[GRN], c2[BLU]=c1[BLU], c2[EXP]=c1[EXP])
#define copy_fcol(f1, f2) (f2[RED]=f1[RED], f2[GRN]=f1[GRN], f2[BLU]=f1[BLU])

/* read routines */
static unsigned char* oldreadcolrs(RGBE *scan, unsigned char *mem, int xmax)
{
	int i, rshift = 0, len = xmax;
	while (len > 0) {
		scan[0][RED] = *mem++;
		scan[0][GRN] = *mem++;
		scan[0][BLU] = *mem++;
		scan[0][EXP] = *mem++;
		if (scan[0][RED] == 1 && scan[0][GRN] == 1 && scan[0][BLU] == 1) {
			for (i=scan[0][EXP]<<rshift;i>0;i--) {
				copy_rgbe(scan[-1], scan[0]);
				scan++;
				len--;
			}
			rshift += 8;
		}
		else {
			scan++;
			len--;
			rshift = 0;
		}
	}
	return mem;
}

static unsigned char* freadcolrs(RGBE *scan, unsigned char* mem, int xmax)
{
	int i, j, code, val;

	if ((xmax < MINELEN) | (xmax > MAXELEN)) return oldreadcolrs(scan, mem, xmax);

	i = *mem++;
	if (i != 2) return oldreadcolrs(scan, mem-1, xmax);

	scan[0][GRN] = *mem++;
	scan[0][BLU] = *mem++;

	i = *mem++;
	if (((scan[0][BLU] << 8) | i) != xmax) return NULL;

	for (i=0;i<4;i++)
		for (j=0;j<xmax;) {
			code = *mem++;
			if (code > 128) {
				code &= 127;
				val = *mem++;
				while (code--)
					scan[j++][i] = (unsigned char)val;
			}
			else
				while (code--)
					scan[j++][i] = *mem++;
		}
	return mem;
}

/* helper functions */

/* rgbe -> float color */
static void RGBE2FLOAT(RGBE rgbe, fCOLOR fcol)
{
	if (rgbe[EXP]==0) {
		fcol[RED] = fcol[GRN] = fcol[BLU] = 0;
	}
	else {
		float f = ldexp(1.0, rgbe[EXP]-(COLXS+8));
		fcol[RED] = f*(rgbe[RED] + 0.5f);
		fcol[GRN] = f*(rgbe[GRN] + 0.5f);
		fcol[BLU] = f*(rgbe[BLU] + 0.5f);
	}
}

/* float color -> rgbe */
static void FLOAT2RGBE(fCOLOR fcol, RGBE rgbe)
{
	int e;
	float d = (fcol[RED]>fcol[GRN]) ? fcol[RED] : fcol[GRN];
	if (fcol[BLU]>d) d = fcol[BLU];
	if (d <= 1e-32f)
		rgbe[RED] = rgbe[GRN] = rgbe[BLU] = rgbe[EXP] = 0;
	else {
		d = frexp(d, &e) * 256.f / d;
		rgbe[RED] = (unsigned char)(fcol[RED] * d);
		rgbe[GRN] = (unsigned char)(fcol[GRN] * d);
		rgbe[BLU] = (unsigned char)(fcol[BLU] * d);
		rgbe[EXP] = (unsigned char)(e + COLXS);
	}
}

/* ImBuf read */

int imb_is_a_hdr(void *buf)
{
	// For recognition, Blender only loads first 32 bytes, so use #?RADIANCE id instead
	// update: actually, the 'RADIANCE' part is just an optional program name, the magic word is really only the '#?' part
	//if (strstr((char*)buf, "#?RADIANCE")) return 1;
	if (strstr((char*)buf, "#?")) return 1;
	// if (strstr((char*)buf, "32-bit_rle_rgbe")) return 1;
	return 0;
}

struct ImBuf *imb_loadhdr(unsigned char *mem, int size, int flags)
{
	struct ImBuf* ibuf;
	RGBE* sline;
	fCOLOR fcol;
	float* rect_float;
	int found=0;
	int width=0, height=0;
	int x, y;
	unsigned char* ptr;
	char oriY[80], oriX[80];

	if (imb_is_a_hdr((void*)mem))
	{
		/* find empty line, next line is resolution info */
		for (x=1;x<size;x++) {
			if ((mem[x-1]=='\n') && (mem[x]=='\n')) {
				found = 1;
				break;
			}
		}
		if (found && (x<(size + 2))) {
			if (sscanf((char *)&mem[x+1], "%79s %d %79s %d", (char*)&oriY, &height, 
				(char*)&oriX, &width) != 4) return NULL;

			/* find end of this line, data right behind it */
			ptr = (unsigned char *)strchr((char*)&mem[x+1], '\n');
			ptr++;

			if (flags & IB_test) ibuf = IMB_allocImBuf(width, height, 32, 0, 0);
			else ibuf = IMB_allocImBuf(width, height, 32, (flags & IB_rect)|IB_rectfloat, 0);

			if (ibuf==NULL) return NULL;
			ibuf->ftype = RADHDR;
			ibuf->profile = IB_PROFILE_LINEAR_RGB;
			ibuf->xorig = ibuf->yorig = 0;

			if (flags & IB_test) return ibuf;

			/* read in and decode the actual data */
			sline = (RGBE*)MEM_mallocN(sizeof(RGBE)*width, "radhdr_read_tmpscan");
			rect_float = (float *)ibuf->rect_float;
			
			for (y=0;y<height;y++) {
				ptr = freadcolrs(sline, ptr, width);
				if (ptr==NULL) {
					printf("HDR decode error\n");
					MEM_freeN(sline);
					return ibuf;
				}
				for (x=0;x<width;x++) {
					/* convert to ldr */
					RGBE2FLOAT(sline[x], fcol);
					*rect_float++ = fcol[RED];
					*rect_float++ = fcol[GRN];
					*rect_float++ = fcol[BLU];
					*rect_float++ = 1.0f;
				}
			}
			MEM_freeN(sline);
			if (oriY[0]=='-') IMB_flipy(ibuf);
			
			if (flags & IB_rect) {
				IMB_rect_from_float(ibuf);
			}
			
			return ibuf;
		}
		//else printf("Data not found!\n");
	}
	//else printf("Not a valid radiance HDR file!\n");

	return NULL;
}

/* ImBuf write */
static int fwritecolrs(FILE* file, int width, int channels, unsigned char* ibufscan, float* fpscan)
{
	int x, i, j, beg, c2, cnt=0;
	fCOLOR fcol;
	RGBE rgbe, *rgbe_scan;

	if ((ibufscan==NULL) && (fpscan==NULL)) return 0;

	rgbe_scan = (RGBE*)MEM_mallocN(sizeof(RGBE)*width, "radhdr_write_tmpscan");

	/* convert scanline */
		j= 0;
	for (i=0;i<width;i++) {
		if (fpscan) {
			fcol[RED] = fpscan[j];
			fcol[GRN] = (channels >= 2)? fpscan[j+1]: fpscan[j];
			fcol[BLU] = (channels >= 3)? fpscan[j+2]: fpscan[j];
		} else {
			fcol[RED] = (float)ibufscan[j] / 255.f;
			fcol[GRN] = (float)((channels >= 2)? ibufscan[j+1]: ibufscan[j]) / 255.f;
			fcol[BLU] = (float)((channels >= 3)? ibufscan[j+2]: ibufscan[j]) / 255.f;
		}
		FLOAT2RGBE(fcol, rgbe);
		copy_rgbe(rgbe, rgbe_scan[i]);
		j+=channels;
	}

	if ((width < MINELEN) | (width > MAXELEN)) {	/* OOBs, write out flat */
		x=fwrite((char *)rgbe_scan, sizeof(RGBE), width, file) - width;
		MEM_freeN(rgbe_scan);
		return x;
	}
	/* put magic header */
	putc(2, file);
	putc(2, file);
	putc((unsigned char)(width >> 8), file);
	putc((unsigned char)(width & 255), file);
	/* put components separately */
	for (i=0;i<4;i++) {
		for (j=0;j<width;j+=cnt) {	/* find next run */
			for (beg=j;beg<width;beg+=cnt) {
				for (cnt=1;(cnt<127) && ((beg+cnt)<width) && (rgbe_scan[beg+cnt][i] == rgbe_scan[beg][i]); cnt++);
				if (cnt>=MINRUN) break;   /* long enough */
			}
			if (((beg-j)>1) && ((beg-j) < MINRUN)) {
				c2 = j+1;
				while (rgbe_scan[c2++][i] == rgbe_scan[j][i])
					if (c2 == beg) {        /* short run */
						putc((unsigned char)(128+beg-j), file);
						putc((unsigned char)(rgbe_scan[j][i]), file);
						j = beg;
						break;
					}
			}
			while (j < beg) {     /* write out non-run */
				if ((c2 = beg-j) > 128) c2 = 128;
				putc((unsigned char)(c2), file);
				while (c2--) putc(rgbe_scan[j++][i], file);
			}
			if (cnt >= MINRUN) {      /* write out run */
				putc((unsigned char)(128+cnt), file);
				putc(rgbe_scan[beg][i], file);
			}
			else cnt = 0;
		}
	}
	MEM_freeN(rgbe_scan);
	return(ferror(file) ? -1 : 0);
}

static void writeHeader(FILE *file, int width, int height)
{
	fprintf(file, "#?RADIANCE");
	fputc(10, file);
	fprintf(file, "# %s", "Created with Blender");
	fputc(10, file);
	fprintf(file, "EXPOSURE=%25.13f", 1.0);
	fputc(10, file);
	fprintf(file, "FORMAT=32-bit_rle_rgbe");
	fputc(10, file);
	fputc(10, file);
	fprintf(file, "-Y %d +X %d", height, width);
	fputc(10, file);
}

short imb_savehdr(struct ImBuf *ibuf, char *name, int flags)
{
	FILE* file = fopen(name, "wb");
	float *fp= NULL;
	int y, width=ibuf->x, height=ibuf->y;
	unsigned char *cp= NULL;
	
	if (file==NULL) return 0;

	writeHeader(file, width, height);

	if(ibuf->rect)
		cp= (unsigned char *)ibuf->rect + ibuf->channels*(height-1)*width;
	if(ibuf->rect_float)
		fp= ibuf->rect_float + ibuf->channels*(height-1)*width;
	
	for (y=height-1;y>=0;y--) {
		if (fwritecolrs(file, width, ibuf->channels, cp, fp) < 0) {
			fclose(file);
			printf("HDR write error\n");
			return 0;
		}
		if(cp) cp-= ibuf->channels*width;
		if(fp) fp-= ibuf->channels*width;
	}

	fclose(file);
	return 1;
}