/* Copyright (C) 2010 Nick Bowler
 *
 * License WTFPL2: Do What The Fuck You Want To Public License, version 2.
 * This is free software: you are free to do what the fuck you want to.
 * There is NO WARRANTY, to the extent permitted by law.
 *
 * In case the above is not acceptable, you may alternately choose the terms
 * of the MIT license: http://opensource.org/licenses/mit-license.php.
 */

#include <stdio.h>
#include <stdarg.h>

#include <GL/glew.h>
#include <GL/glut.h>

unsigned create_shader(int type, const char *text)
{
	GLuint shader;
	GLint status;

	shader = glCreateShader(type);
	if (!shader)
		return 0;

	glShaderSource(shader, 1, &text, NULL);
	glCompileShader(shader);
	glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
	if (!status) {
		GLint size;
		glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &size);

		char log[size];
		glGetShaderInfoLog(shader, size, NULL, log);
		fprintf(stderr, "failed to compile shader:\n%s", log);
		glDeleteShader(shader);
		return 0;
	}

	return shader;
}

unsigned create_program(unsigned num, ...)
{
	GLuint program;
	GLint status;
	va_list ap;

	program = glCreateProgram();

	va_start(ap, num);
	for (unsigned i = 0; i < num; i++) {
		glAttachShader(program, va_arg(ap, unsigned));
	}
	va_end(ap);

	glLinkProgram(program);
	glGetProgramiv(program, GL_LINK_STATUS, &status);
	if (!status) {
		GLint size;
		glGetProgramiv(program, GL_INFO_LOG_LENGTH, &size);

		char log[size];
		glGetShaderInfoLog(program, size, NULL, log);
		fprintf(stderr, "failed to link shader:\n%s", log);
		glDeleteProgram(program);
		return 0;
	}

	return program;
}

int main(int argc, char **argv)
{
	const char *glsl_vertex, *glsl_fragment;
	int vertex, fragment;
	GLenum err;
	int window;

	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);

	window = glutCreateWindow("listconfuse");
	if (window == 0)
		return EXIT_FAILURE;
	glutSetWindow(window);

	err = glewInit();
	if (err != GLEW_OK) {
		fprintf(stderr, "glewInit: %s\n", glewGetErrorString(err));
		return EXIT_FAILURE;
	}

	glsl_vertex =
"varying float v;"
"void main(void)"
"{"
"	gl_Position = ftransform();"
"	v = 0.0;"
"}";

	vertex = create_shader(GL_VERTEX_SHADER, glsl_vertex);
	create_program(1, vertex);

	return EXIT_SUCCESS;
}