/* Convert OpenEXR to VIPS
 *
 * 1/5/06
 * 	- from im_png2vips.c
 * 17/5/06
 * 	- oops, buffer calcs were wrong
 * 19/5/06
 * 	- added tiled read, with a separate cache
 * 	- removed *255 we had before, better to do something clever with
 * 	  chromaticities
 * 4/2/10
 * 	- gtkdoc
 * 12/12/11
 * 	- redo as a set of fns ready for wrapping in a new-style class
 * 17/9/16
 * 	- tag output as scRGB
 * 16/8/18
 * 	- shut down the input file as soon as we can [kleisauke]
 */

/*

  TODO

	- colour management
	- attributes
	- more of OpenEXR's pixel formats
	- more than just RGBA channels
	- turn alpha to vips 0 - 255 from exr 0 - 1

	the openexr C API is very limited ... it seems RGBA half pixels is
	all you can do

	openexr lets you have different formats in different channels :-(

	there's no API to read the "chromaticities" attribute :-(

	best redo with the C++ API now we support C++ operations

 */

/*

	This file is part of VIPS.

	VIPS is free software; you can redistribute it and/or modify
	it under the terms of the GNU Lesser 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 Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser 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

 */

/*

	These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk

 */

/*
#define DEBUG
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>

#ifdef HAVE_OPENEXR

#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include <vips/vips.h>
#include <vips/thread.h>
#include <vips/internal.h>

#include <ImfCRgbaFile.h>

#include "pforeign.h"

/* What we track during a OpenEXR read.
 */
typedef struct {
	char *filename;
	VipsImage *out;

	ImfTiledInputFile *tiles;
	ImfInputFile *lines;
	const ImfHeader *header;
	VipsRect window;
	int tile_width;
	int tile_height;
} Read;

gboolean
vips__openexr_isexr(const char *filename)
{
	unsigned char buf[4];

	if (vips__get_bytes(filename, buf, 4) == 4)
		if (buf[0] == 0x76 && buf[1] == 0x2f &&
			buf[2] == 0x31 && buf[3] == 0x01)
			return TRUE;

	return FALSE;
}

static void
get_imf_error(void)
{
	vips_error("exr2vips", _("EXR error: %s"), ImfErrorMessage());
}

static void
read_close(Read *read)
{
	VIPS_FREEF(ImfCloseTiledInputFile, read->tiles);
	VIPS_FREEF(ImfCloseInputFile, read->lines);
}

static void
read_destroy(VipsImage *out, Read *read)
{
	VIPS_FREE(read->filename);

	read_close(read);

	g_free(read);
}

static Read *
read_new(const char *filename, VipsImage *out)
{
	Read *read;
	int xmin, ymin;
	int xmax, ymax;

	if (!(read = VIPS_NEW(NULL, Read)))
		return NULL;
	read->filename = vips_strdup(NULL, filename);
	read->out = out;
	read->tiles = NULL;
	read->lines = NULL;
	if (out)
		g_signal_connect(out, "close",
			G_CALLBACK(read_destroy), read);

	/* Try to open tiled first ... if that fails, fall back to scanlines.

		FIXME ... seems a bit ugly, but how else can you spot a tiled
		EXR image?

	 */
	if (!(read->tiles = ImfOpenTiledInputFile(read->filename))) {
		if (!(read->lines = ImfOpenInputFile(read->filename))) {
			get_imf_error();
			return NULL;
		}
	}

#ifdef DEBUG
	if (read->tiles)
		printf("exr2vips: opening in tiled mode\n");
	else
		printf("exr2vips: opening in scanline mode\n");
#endif /*DEBUG*/

	if (read->tiles) {
		read->header = ImfTiledInputHeader(read->tiles);
		read->tile_width = ImfTiledInputTileXSize(read->tiles);
		read->tile_height = ImfTiledInputTileYSize(read->tiles);
	}
	else
		read->header = ImfInputHeader(read->lines);

	ImfHeaderDataWindow(read->header, &xmin, &ymin, &xmax, &ymax);
	read->window.left = xmin;
	read->window.top = ymin;
	read->window.width = xmax - xmin + 1;
	read->window.height = ymax - ymin + 1;

	return read;
}

gboolean
vips__openexr_istiled(const char *filename)
{
	Read *read;
	gboolean tiled;

	if (!(read = read_new(filename, NULL)))
		return FALSE;
	tiled = read->tiles != NULL;
	read_destroy(NULL, read);

	return tiled;
}

/* Read a OpenEXR file (header) into a VIPS (header).
 */
static void
read_header(Read *read, VipsImage *out)
{
	VipsDemandStyle hint;

	/*

	   FIXME ... not really scRGB, you should get the chromaticities
	   from the header and transform

	 */
	vips_image_init_fields(out,
		read->window.width, read->window.height, 4,
		VIPS_FORMAT_FLOAT,
		VIPS_CODING_NONE, VIPS_INTERPRETATION_scRGB, 1.0, 1.0);

	if (read->tiles)
		/* Even though this is a tiled reader, we hint thinstrip
		 * since with the cache we are quite happy serving that if
		 * anything downstream would like it.
		 */
		hint = VIPS_DEMAND_STYLE_THINSTRIP;
	else
		hint = VIPS_DEMAND_STYLE_FATSTRIP;
	(void) vips_image_pipelinev(out, hint, NULL);
}

int
vips__openexr_read_header(const char *filename, VipsImage *out)
{
	Read *read;

	if (!(read = read_new(filename, out)))
		return -1;
	read_header(read, out);
	read_close(read);

	return 0;
}

/* Allocate a tile buffer.
 */
static void *
vips__openexr_start(VipsImage *out, void *a, void *b)
{
	Read *read = (Read *) a;
	ImfRgba *imf_buffer;

	if (!(imf_buffer = VIPS_ARRAY(out,
			  read->tile_width * read->tile_height, ImfRgba)))
		return NULL;

	return imf_buffer;
}

static int
vips__openexr_generate(VipsRegion *out,
	void *seq, void *a, void *b, gboolean *top)
{
	ImfRgba *imf_buffer = (ImfRgba *) seq;
	Read *read = (Read *) a;
	VipsRect *r = &out->valid;

	const int tw = read->tile_width;
	const int th = read->tile_height;

	/* Find top left of tiles we need.
	 */
	const int xs = (r->left / tw) * tw;
	const int ys = (r->top / th) * th;

	int x, y, z;
	VipsRect image;

	/* Area of image.
	 */
	image.left = 0;
	image.top = 0;
	image.width = read->out->Xsize;
	image.height = read->out->Ysize;

	for (y = ys; y < VIPS_RECT_BOTTOM(r); y += th)
		for (x = xs; x < VIPS_RECT_RIGHT(r); x += tw) {
			VipsRect tile;
			VipsRect hit;
			int result;

			if (!ImfTiledInputSetFrameBuffer(read->tiles,
					imf_buffer -
						(read->window.left + x) -
						(read->window.top + y) * tw,
					1, tw)) {
				vips_foreign_load_invalidate(read->out);
				get_imf_error();
				return -1;
			}

#ifdef DEBUG
			printf("exr2vips: requesting tile %d x %d\n",
				x / tw, y / th);
#endif /*DEBUG*/

			result = ImfTiledInputReadTile(read->tiles,
				x / tw, y / th, 0, 0);

			if (!result) {
				get_imf_error();
				return -1;
			}

			/* The tile in the file, in VIPS coordinates.
			 */
			tile.left = x;
			tile.top = y;
			tile.width = tw;
			tile.height = th;
			vips_rect_intersectrect(&tile, &image, &tile);

			/* The part of this tile that hits the region.
			 */
			vips_rect_intersectrect(&tile, r, &hit);

			/* Convert to float and write to the region.
			 */
			for (z = 0; z < hit.height; z++) {
				ImfRgba *p = imf_buffer +
					(hit.left - tile.left) +
					(hit.top - tile.top + z) * tw;
				float *q = (float *) VIPS_REGION_ADDR(out,
					hit.left, hit.top + z);

				ImfHalfToFloatArray(4 * hit.width,
					(ImfHalf *) p, q);
			}
		}

	return 0;
}

int
vips__openexr_read(const char *filename, VipsImage *out)
{
	Read *read;

	if (!(read = read_new(filename, out)))
		return -1;

	if (read->tiles) {
		VipsImage *raw;
		VipsImage *t;

		/* Tile cache: keep enough for two complete rows of tiles,
		 * plus 50%.
		 */
		raw = vips_image_new();
		vips_object_local(out, raw);

		read_header(read, raw);

		if (vips_image_generate(raw,
				vips__openexr_start, vips__openexr_generate, NULL,
				read, NULL))
			return -1;

		if (vips_tilecache(raw, &t,
				"tile_width", read->tile_width,
				"tile_height", read->tile_height,
				"max_tiles", (int) (2.5 * (1 + raw->Xsize / read->tile_width)),
				NULL))
			return -1;
		if (vips_image_write(t, out)) {
			g_object_unref(t);
			return -1;
		}
		g_object_unref(t);
	}
	else {
		const int left = read->window.left;
		const int top = read->window.top;
		const int width = read->window.width;
		const int height = read->window.height;

		ImfRgba *imf_buffer;
		float *vips_buffer;
		int y;

		if (!(imf_buffer = VIPS_ARRAY(out, width, ImfRgba)) ||
			!(vips_buffer = VIPS_ARRAY(out, 4 * width, float)))
			return -1;

		read_header(read, out);

		for (y = 0; y < height; y++) {
			if (!ImfInputSetFrameBuffer(read->lines,
					imf_buffer - left - (top + y) * width,
					1, width)) {
				get_imf_error();
				return -1;
			}
			if (!ImfInputReadPixels(read->lines,
					top + y, top + y)) {
				get_imf_error();
				return -1;
			}

			ImfHalfToFloatArray(4 * width,
				(ImfHalf *) imf_buffer, vips_buffer);

			if (vips_image_write_line(out, y,
					(VipsPel *) vips_buffer))
				return -1;
		}

		read_close(read);
	}

	return 0;
}

#endif /*HAVE_OPENEXR*/
