/*
 *  Copyright (C) 2018  Vito Caputo - <vcaputo@pengaru.com>
 *
 *  This program is free software: you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License version 3 as published
 *  by the Free Software Foundation.
 *
 *  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, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>	/* this is needed by cairo headers of all things */
#include <cairo.h>
#ifdef HAVE_SVG_CAIRO
#include <svg-cairo.h>
#else
#include <librsvg/rsvg.h>
#endif

#include "macros.h"

typedef struct whale_svg_t {
#ifdef HAVE_SVG_CAIRO
	svg_cairo_t		*cairo_svg;
	unsigned		width, height;
#else
	RsvgHandle		*rsvg;
	RsvgDimensionData	dimensions;
#endif
} whale_svg_t;


whale_svg_t * whale_svg_new_file(const char *file)
{
	whale_svg_t	*svg;

	svg = calloc(1, sizeof(whale_svg_t));
	fatal_if(!svg, "Unable to create svg");

#ifdef HAVE_SVG_CAIRO
	fatal_if(svg_cairo_create(&svg->cairo_svg) != 0,
		"Unable to create svg-cairo context");
	fatal_if(svg_cairo_parse(svg->cairo_svg, file) != 0,
		"Unable to parse \"%s\"", file);
	svg_cairo_get_size(svg->cairo_svg, &svg->width, &svg->height);
#else
	//rsvg_init();
	svg->rsvg = rsvg_handle_new_from_file(file, NULL);
	fatal_if(!svg->rsvg,
		"Unable to create rsvg handle from file \"%s\"", file);
	rsvg_handle_get_dimensions(svg->rsvg, &svg->dimensions);
#endif

	return svg;
}


whale_svg_t * whale_svg_new_buffer(const char *buf, size_t count)
{
	whale_svg_t	*svg;

	svg = calloc(1, sizeof(whale_svg_t));
	fatal_if(!svg, "Unable to create svg");

#ifdef HAVE_SVG_CAIRO
	fatal_if(svg_cairo_create(&svg->cairo_svg) != 0,
		"Unable to create svg-cairo context");
	fatal_if(svg_cairo_parse_buffer(svg->cairo_svg, buf, count) != 0,
		"Unable to parse svg buffer");
	svg_cairo_get_size(svg->cairo_svg, &svg->width, &svg->height);
#else
	//rsvg_init();
	svg->rsvg = rsvg_handle_new_from_data(buf, count, NULL);
	fatal_if(!svg->rsvg,
		"Unable to create rsvg handle from buffer");
	rsvg_handle_get_dimensions(svg->rsvg, &svg->dimensions);
#endif

	return svg;
}



SDL_Surface * whale_svg_render(whale_svg_t *svg, int width, int height)
{
	cairo_surface_t	*cairo_surface;
	SDL_Surface	*sdl_surface;
	cairo_t		*cairo;
	double		xscale, yscale, scale, tx, ty, svg_width, svg_height;

#ifdef HAVE_SVG_CAIRO
	svg_width = svg->width;
	svg_height = svg->height;
#else
	svg_width = svg->dimensions.width;
	svg_height = svg->dimensions.height;
#endif

	/* cached size is different so redo the costly SVG render */
	sdl_surface = SDL_CreateRGBSurfaceWithFormat(0, width, height, 32, SDL_PIXELFORMAT_ARGB8888);
	fatal_if(!sdl_surface, "Unable to create sdl surface");

	cairo_surface = cairo_image_surface_create_for_data(sdl_surface->pixels,
				CAIRO_FORMAT_ARGB32,
				width,
				height,
				sdl_surface->pitch);
	fatal_if(!cairo_surface, "Unable to create cairo surface");

#if 0
	/* useful for debugging */
	SDL_FillRect(sdl_surface, NULL, 0xffff0000);
#endif

	cairo = cairo_create(cairo_surface);
	fatal_if(!cairo, "Unable to create cairo target");

	/* XXX: this scaling attempts to preserve the svg's aspect ratio,
	 * while filling the destination surface
	 */
	xscale = (double)width / svg_width;
	yscale = (double)height / svg_height;
	scale = xscale < yscale ? xscale : yscale;

	/* if we have a mismatch between the desired width/height aspect ratio,
	 * and the svg's aspect ratio, we need to translate to center the rendering
	 * in the resulting surface
	 */
	tx = scale * svg_width;
	ty = scale * svg_height;

	if ((int)((double)tx + 0.5) < width)
		tx = ((double)width - tx + 0.5) / 2.0;
	else
		tx = 0;

	if ((int)((double)ty + 0.5) < height)
		ty = ((double)height - ty + 0.5) / 2.0;
	else
		ty = 0;

	cairo_translate(cairo, tx, ty);
	cairo_scale(cairo, scale, scale);

#ifdef HAVE_SVG_CAIRO
	svg_cairo_render(svg->cairo_svg, cairo);
#else
	rsvg_handle_render_cairo(svg->rsvg, cairo);
#endif
	cairo_surface_flush(cairo_surface);
	cairo_surface_destroy(cairo_surface);
	cairo_destroy(cairo);

	return sdl_surface;
}


void whale_svg_free(whale_svg_t *svg)
{
#ifdef HAVE_SVG_CAIRO
	svg_cairo_destroy(svg->cairo_svg);
#else
	rsvg_handle_free(svg->rsvg);
#endif
	free(svg);
}