/*

Minceraft

By CobaltXII

*/

#include "main.hpp"

// The entry point.

int main(int argc, char** argv)
{
	// Initialize SDL.

	if (SDL_Init(SDL_INIT_EVERYTHING))
	{
		std::cout << "Could not initialize SDL." << std::endl;

		exit(1);
	}

	// The dimensions of the SDL_Window*.

	int sdl_x_res = 840;
	int sdl_y_res = 525;

	// Create the SDL_Window*.

	SDL_Window* sdl_window = SDL_CreateWindow
	(
		"Minceraft 0.0.0",

		SDL_WINDOWPOS_UNDEFINED,
		SDL_WINDOWPOS_UNDEFINED,

		sdl_x_res,
		sdl_y_res,

		SDL_WINDOW_ALLOW_HIGHDPI | SDL_WINDOW_OPENGL
	);

	// Make sure the SDL_Window* was created successfully.

	if (!sdl_window)
	{
		std::cout << "Could not create the SDL_Window*." << std::endl;

		exit(2);
	}

	// Request OpenGL 3.3 (core profile).

	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);

	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);

	// Request double-buffering.

	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);

	// Request a 24-bit depth buffer. 24-bit depth buffers are supported on
	// most modern hardware. Having a floating-point precision of lower than
	// 24-bits will cause graphical issues.

	SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);

	// Enable vertical retrace synchronization. If this is not enabled, a
	// phenomenon known as tearing occurs, which causes half of the screen to
	// retain the contents of the last frame instead of the entire screen 
	// updating immediately.

	SDL_GL_SetSwapInterval(1);

	// Create the SDL_GLContext.

	SDL_GLContext gl_context = SDL_GL_CreateContext(sdl_window);

	if (!gl_context)
	{
		std::cout << "Could not create the SDL_GLContext." << std::endl;

		exit(3);
	}

	// Load all OpenGL 3.3 (core profile) functions using GLAD.

	if (!gladLoadGLLoader(SDL_GL_GetProcAddress)) 
	{
        std::cout << "Could not load OpenGL functions using GLAD." << std::endl;

        exit(4);
    }

    // Make sure the OpenGL version that was provided is greater than or equal
    // to OpenGL 3.3.

    if (GLVersion.major * 10 + GLVersion.minor < 33)
    {
    	std::cout << "Could not load OpenGL 3.3 using GLAD. Received OpenGL " << GLVersion.major << "." << GLVersion.minor << " instead." << std::endl;

        exit(5);
    }

    // Load the block texture array.

    GLuint block_texture_array = mc_load_block_texture_array();

    // Load the block shader program.

    GLuint block_shader_program = mc_load_program("../glsl/block_vertex.glsl", "../glsl/block_fragment.glsl");

    // Create variables to represent the position of the mouse pointer, and
    // state of the mouse buttons.

    int sdl_mouse_x = 0;
    int sdl_mouse_y = 0;

    bool sdl_mouse_l = false;
    bool sdl_mouse_r = false;

    // Enter the main loop.

    bool sdl_running = true;

    unsigned long long sdl_iteration = 0;

    while (sdl_running)
    {
    	// Remember the time at the start of the frame. At the end of the 
    	// frame, this timestamp will be used to cap the framerate.

    	auto frame_start_time = std::chrono::high_resolution_clock::now();

    	// Poll events.

    	SDL_Event e;

    	while (SDL_PollEvent(&e))
		{
			if (e.type == SDL_QUIT)
			{
				// The application was quit.

				sdl_running = false;
			}
			else if (e.type == SDL_MOUSEMOTION)
			{
				// The mouse moved.

				sdl_mouse_x = e.motion.x;
				sdl_mouse_y = e.motion.y;
			}
			else if (e.type == SDL_MOUSEBUTTONDOWN)
			{
				// A mouse button was pressed.

				if (e.button.button == SDL_BUTTON_LEFT)
				{
					sdl_mouse_l = true;
				}
				else if (e.button.button == SDL_BUTTON_RIGHT)
				{
					sdl_mouse_r = true;
				}
			}
			else if (e.type == SDL_MOUSEBUTTONUP)
			{
				// A mouse button was released.

				if (e.button.button == SDL_BUTTON_LEFT)
				{
					sdl_mouse_l = false;
				}
				else if (e.button.button == SDL_BUTTON_RIGHT)
				{
					sdl_mouse_r = false;
				}
			}
			else if (e.type == SDL_KEYDOWN)
			{
				// A key was pressed.

				SDL_Keycode key = e.key.keysym.sym;

				if (key == SDLK_ESCAPE)
				{
					sdl_running = false;
				}
			}
		}

		// Clear the OpenGL context.

		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);

		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		// Swap the back buffer to the front, so that the last frame will 
		// appear on the screen.

		SDL_GL_SwapWindow(sdl_window);

		// Cap the framerate to 60 Hz.

		float frame_elapsed_time = std::chrono::duration<float, std::milli>(std::chrono::high_resolution_clock::now() - frame_start_time).count();

		if (frame_elapsed_time < 1000.0f / 60.0f)
		{
			int frame_sleep_time = round(1000.0f / 60.0f - frame_elapsed_time);

			std::this_thread::sleep_for(std::chrono::milliseconds(frame_sleep_time));
		}

		// Increment the iteration counter. Do not use the iteration counter
		// as a precise time measurement!

		sdl_iteration++;

		if (sdl_iteration % 60 == 0)
		{
			std::cout << "Running at " << 1000.0f / frame_elapsed_time << " Hz" << std::endl;
		}
    }

    // Destroy all OpenGL related objects.

    SDL_GL_DeleteContext(gl_context);

    // Destroy all SDL related objects.

    SDL_DestroyWindow(sdl_window);

    SDL_Quit();

    // Exit cleanly.

    exit(EXIT_SUCCESS);
}