/*
 * Copyright © 2009 Eric Anholt
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <err.h>
#include <errno.h>
#include <assert.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <getopt.h>

#include <png.h>

#include "glass.h"

/* libpng sucks and I hope I never have to read this file again. */

GLuint load_texture_rgb(const char *filename)
{
	GLuint tex;
	FILE *f;
	png_uint_32 w, h;
	int depth;
	unsigned char *data;
	png_structp png;
	png_infop png_info;
	int png_type;
	int stride;
	png_bytep *row_pointers;
	int i;
	GLenum format;

	glGenTextures(1, &tex);

	f = fopen(filename, "rb");

	png = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL,
					 NULL);
	assert(png);

	png_info = png_create_info_struct(png);
	assert(png_info);

	if (setjmp(png->jmpbuf)) {
		png_destroy_read_struct(&png, &png_info, NULL);
		abort();
	}

	png_init_io(png, f);
	png_read_info(png, png_info);
	png_get_IHDR(png, png_info, &w, &h, &depth, &png_type,
		     NULL, NULL, NULL);

	/* Give us sensible data.  This API is terrible */
	png_set_expand(png);
	/* No, really.  Sensible data. */
	if (depth == 16)
		png_set_strip_16(png);
	/* Not even kidding. */
	png_set_gray_to_rgb(png);

	png_read_update_info(png, png_info);

	stride = png_get_rowbytes(png, png_info);
	data = malloc(h * stride);
	assert(data);

	/* So, you've told us what the stride needs to be, but you make
	 * us give you pointers to the data?  Brilliant.
	 */
	row_pointers = malloc(sizeof(png_bytep) * h);
	assert(row_pointers);
	for (i = 0; i < h; i++)
		row_pointers[i] = data + i * stride;

	png_read_image(png, row_pointers);

	glBindTexture(GL_TEXTURE_2D, tex);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

	switch (png_info->color_type) {
	case PNG_COLOR_TYPE_RGB:
		format = GL_RGB;
		break;
	case PNG_COLOR_TYPE_RGBA:
		format = GL_RGBA;
		break;
	default:
		abort();
	}
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, w, h, 0,
		     format, GL_UNSIGNED_BYTE, data);

	free(data);
	free(row_pointers);

	png_destroy_read_struct(&png, &png_info, NULL);

	return tex;
}