#include <glad/glad.h>
#include <SDL2/SDL.h>
#include <stdbool.h>
#include <linmath.h>

SDL_Window             *window              = NULL;
SDL_GLContext           gl_context;
int                     main_shader         = 0;

float triangle_vertices[9] = {
    0.0f, 0.0f, 0.0f,
    0.0f, 1.0f, 0.0f,
    1.0f, 0.0f, 0.0f
};

typedef struct tc_vec3
{
    float               x;
    float               y;
    float               z;
    
} tc_vec3_s;

typedef struct tc_object
{
    int                 vbo;
    int                 vao;
    
} tc_object_s;

typedef struct tc_block
{
    tc_vec3_s           position;
    tc_object_s         drawing;
    
} tc_block_s;

tc_block_s block;

void render_block(tc_block_s block)
{
    glBindBuffer(GL_ARRAY_BUFFER, block.drawing.vbo);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *) 0);
    glEnableVertexAttribArray(0);
    glUseProgram(main_shader);
    glDrawArrays(GL_TRIANGLES, 0, 3);
}

tc_block_s tc_new_block_at_3f(float x, float y, float z)
{
    tc_block_s          block;
    block.position.x            = x;
    block.position.y            = y;
    block.position.z            = z;
    glGenBuffers(1, &block.drawing.vbo);
    glBindBuffer(GL_ARRAY_BUFFER, block.drawing.vbo);
    glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 9, &triangle_vertices[0], GL_STATIC_DRAW);
    
    return block;
}

char * load_file(char *path, int *out_len)
{
    FILE *file = NULL;
    if((file = fopen(path, "r")) != NULL)
    {
        fseek(file, 0, SEEK_END);
        int length = ftell(file);
        fseek(file, 0, SEEK_SET);
        
        char *content = malloc(length+1);
        fread(content, 1, length, file);
        
        if(out_len != NULL)
        {
            *out_len = length;
        }
        return content;
    }
    
    return NULL;
}

int setup_shaders(char *vertex_path, char *fragment_path)
{
    int         vertex_shader       = glCreateShader(GL_VERTEX_SHADER);
    int         fragment_shader     = glCreateShader(GL_FRAGMENT_SHADER);
    
    int         len_vertex_source   = 0;
    char        *vertex_source      = load_file(vertex_path, &len_vertex_source);
    
    int         len_fragment_source = 0;
    char        *fragment_source    = load_file(fragment_path, &len_fragment_source);
    
    glShaderSource(vertex_shader, 1, &vertex_source, &len_vertex_source);
    glShaderSource(fragment_shader, 1, &fragment_source, &len_fragment_source);
    
    glCompileShader(vertex_shader);
    glCompileShader(fragment_shader);
    
    int         vertex_compile_status = 0;
    glGetShaderiv(vertex_shader, GL_COMPILE_STATUS, &vertex_compile_status);
    
    if(vertex_compile_status != GL_TRUE)
    {
        int         log_length  = 0;
        glGetShaderiv(vertex_shader, GL_INFO_LOG_LENGTH, &log_length);
        
        char       *info_log    = malloc(log_length+1);
        
        glGetShaderInfoLog(vertex_shader, log_length, &log_length, info_log);
        
        printf("VERTEX SHADER FAILED COMPILING! ERROR: %s\n", info_log);
        return -1;
    }
    
    int         fragment_compile_status = 0;
    glGetShaderiv(fragment_shader, GL_COMPILE_STATUS, &fragment_compile_status);
    
    if(fragment_compile_status != GL_TRUE)
    {
        int         log_length  = 0;
        glGetShaderiv(fragment_shader, GL_INFO_LOG_LENGTH, &log_length);
        
        char       *info_log    = malloc(log_length+1);
        
        glGetShaderInfoLog(fragment_shader, log_length, &log_length, info_log);
        
        printf("FRAGMENT SHADER FAILED COMPILING! ERROR: %s\n", info_log);
        return -1;
    }
    
    int         program             = glCreateProgram();
    glAttachShader(program, vertex_shader);
    glAttachShader(program, fragment_shader);
    glLinkProgram(program);
    
    return program;
}

void cleanup()
{
    SDL_GL_DeleteContext(gl_context);
    SDL_DestroyWindow(window);
}

void render()
{
    float           color[4] = { 0.0f, 1.0f, 0.0f, 1.0f };
    glClearBufferfv(GL_COLOR, 0, color);
    
    render_block(block);
    
    SDL_GL_SwapWindow(window);
}

int main(int argc, char **argv)
{
    SDL_Init(SDL_INIT_EVERYTHING);
    
    window                      = SDL_CreateWindow(
        "Techneck",
        SDL_WINDOWPOS_CENTERED,
        SDL_WINDOWPOS_CENTERED,
        1200,
        800,
        SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE
    );
    
    gl_context                  = SDL_GL_CreateContext(window);
    gladLoadGLLoader(&SDL_GL_GetProcAddress);
    gladLoadGL();
    
    main_shader                 = setup_shaders("vertex_shader.glsl", "fragment_shader.glsl");
    
    block    = tc_new_block_at_3f(0.0, 0.0, 0.0);
    
    int64_t                 frame_index         = 1;
    while(frame_index > 0)
    {
        SDL_Event               event;
        while(SDL_PollEvent(&event))
        {
            switch(event.type)
            {
                case SDL_QUIT:
                    SDL_HideWindow(window);
                    frame_index = -1;
                    break;
                break;
                
                case SDL_WINDOWEVENT:
                {
                    if(event.window.event == SDL_WINDOWEVENT_RESIZED)
                    {
                        puts("RESIZED");
                    }
                } break;
            }
        }
        
        render();
        
        if(frame_index == 1)
        {
            SDL_ShowWindow(window);
        }
        
        ++frame_index;
        SDL_Delay(1000/60);
    }
    
    cleanup();
    SDL_Quit();
    
    return 0;
}