/*
 *      Gem-graph OpenGL experiments
 *
 *      Desc: OpenGL utils header
 *
 *  Copyright (C) 2023 Jean Sirmai <jean@a-lec.org>
 *
 *  This file is part of Gem-graph.
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#pragma once
#include "base.h"
#include <unistd.h>
#include <stdbool.h>
#include <epoxy/gl.h>
#include <GL/glu.h>
#include <GL/glext.h>

/*
 * Initializes the shaders of a gl_area and link them to a program
 *
 * @param   gl_area, ptr to the gl_area widget
 *
 * @return  true if initialized
 */
bool graphics_init_shaders(const void *gl_area);

/*
 * Created and compile a shader
 *
 * @param   type, shader type
 *          src, source code of shader
 *
 * @return  shader id
 */
static inline GLuint create_shader(int type, const char *src)
{
    GLuint shader;
    int status;

    shader = glCreateShader(type);
    glShaderSource(shader, 1, &src, NULL);
    glCompileShader(shader);

    glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
    if(status == GL_FALSE) {
        int log_len;
        char *buffer;

        glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &log_len);

        buffer = g_malloc(log_len + 1);
        assert (buffer);
        glGetShaderInfoLog(shader, log_len, NULL, buffer);

        g_warning("Compile failure in %s shader:\n%s",
                             type == GL_VERTEX_SHADER ? "vertex" : "fragment",
                             buffer);

        g_free(buffer);

        glDeleteShader(shader);

        return 0;
     }

    return shader;
}

/*
 * Find the gl_area_entry size
 *
 * @param   void
 *
 * @return  size of array
 */
// extern struct gl_area_entry **gl_area_array;
// static inline short gl_area_size(void)
// {
//     struct gl_area_entry **cur;
//     short size;

    // Check uninitialized and quit
//     if (gl_area_array == NULL) return 0;

//     cur = gl_area_array;
//     while(*cur) {
//         cur++;
//         size++;
//     }

//     return size;
// }

/*** TEST ***/

// void main_test_graphics (void);