#include <psemek/app/app.hpp>
#include <psemek/gfx/gl.hpp>
#include <psemek/log/log.hpp>

#include <SDL2/SDL.h>

namespace
{

	[[noreturn]] void sdl_fail(std::string const & message)
	{
		throw std::runtime_error(message + SDL_GetError());
	}

	struct sdl_initializer
	{
		sdl_initializer()
		{
			if (SDL_Init(SDL_INIT_VIDEO) != 0)
				sdl_fail("Failed to initialize SDL2: ");
		}

		~sdl_initializer()
		{
			SDL_Quit();
		}
	};

}

namespace psemek::util::pimpl
{

	template <>
	struct impl<app::app>
	{
		sdl_initializer init;
		SDL_Window * window = nullptr;
		SDL_GLContext gl_context = nullptr;

		bool running = false;

		~impl()
		{
			if (gl_context) SDL_GL_DeleteContext(gl_context);
			if (window) SDL_DestroyWindow(window);
		}
	};

}

namespace psemek::app
{


	app::app(std::string const & name)
	{
		SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
		SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, gl::sys::GetLeastMajorVersion());
		SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, gl::sys::GetLeastMinorVersion());
		SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
		SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
		SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
		SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 8);

		impl().window = SDL_CreateWindow(name.data(), SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, 800, 600, SDL_WINDOW_RESIZABLE | SDL_WINDOW_OPENGL | SDL_WINDOW_MAXIMIZED);
		if (!impl().window)
			sdl_fail("Failed to create window: ");

		impl().gl_context = SDL_GL_CreateContext(impl().window);
		if (!impl().gl_context)
			sdl_fail("Failed to create OpenGL context: ");

		SDL_GL_MakeCurrent(impl().window, impl().gl_context);

		if (!gl::sys::LoadFunctions())
			throw std::runtime_error("Failed to load OpenGL functions");

		log::info() << "Initialized OpenGL " << gl::sys::GetMajorVersion() << '.' << gl::sys::GetMinorVersion();
	}

	app::~app()
	{}

	bool app::running() const
	{
		return impl().running;
	}

	void app::on_resize(int width, int height)
	{
		gl::Viewport(0, 0, width, height);
	}

	void app::on_focus_gained() {}

	void app::on_focus_lost() {}

	void app::on_quit()
	{
		impl().running = false;
	}

	void app::on_mouse_move(int, int) {}

	void app::on_mouse_wheel(int) {}

	void app::on_left_button_down() {}

	void app::on_left_button_up() {}

	void app::on_middle_button_down() {}

	void app::on_middle_button_up() {}

	void app::on_right_button_down() {}

	void app::on_right_button_up() {}

	void app::on_key_down(SDL_Keycode) {}

	void app::on_key_up(SDL_Keycode) {}

	void app::poll_events()
	{
		for (SDL_Event e; SDL_PollEvent(&e);) switch (e.type)
		{
		case SDL_QUIT:
			on_quit();
			break;
		case SDL_WINDOWEVENT: switch (e.window.event)
			{
			case SDL_WINDOWEVENT_RESIZED:
				on_resize(e.window.data1, e.window.data2);
				break;
			case SDL_WINDOWEVENT_FOCUS_GAINED:
				on_focus_gained();
				break;
			case SDL_WINDOWEVENT_FOCUS_LOST:
				on_focus_lost();
				break;
			}
			break;
		case SDL_MOUSEMOTION:
			on_mouse_move(e.motion.x, e.motion.y);
			break;
		case SDL_MOUSEWHEEL:
			on_mouse_wheel(e.wheel.y);
			break;
		case SDL_MOUSEBUTTONDOWN:
			switch (e.button.button)
			{
			case SDL_BUTTON_LEFT:
				on_left_button_down();
				break;
			case SDL_BUTTON_MIDDLE:
				on_middle_button_down();
				break;
			case SDL_BUTTON_RIGHT:
				on_right_button_down();
				break;
			}
			break;
		case SDL_MOUSEBUTTONUP:
			switch (e.button.button)
			{
			case SDL_BUTTON_LEFT:
				on_left_button_up();
				break;
			case SDL_BUTTON_MIDDLE:
				on_middle_button_up();
				break;
			case SDL_BUTTON_RIGHT:
				on_right_button_up();
				break;
			}
			break;
		case SDL_KEYDOWN:
			on_key_down(e.key.keysym.sym);
			break;
		case SDL_KEYUP:
			on_key_up(e.key.keysym.sym);
			break;
		}
	}

	void app::update()
	{}

	void app::draw()
	{
		gl::ClearColor(0.7f, 0.7f, 1.f, 1.f);
		gl::Clear(gl::COLOR_BUFFER_BIT);
	}

	void app::run()
	{
		impl().running = true;
		while (running())
		{
			poll_events();
			if (!running()) break;
			update();
			draw();

			SDL_GL_SwapWindow(impl().window);
		}
	}

	void app::show_cursor(bool show)
	{
		SDL_ShowCursor(show ? SDL_TRUE : SDL_FALSE);
	}

}