internal inline void monitor_key(GLFWwindow *window, u16 *key_state, i32 glfw_key, Input_Key haru_key) {
	u16& state = key_state[haru_key];
	if (glfwGetKey(window, glfw_key) == GLFW_PRESS) {
		if (!(state & KEY_STATE_IS_DOWN)) state |= KEY_STATE_JUST_PRESSED;
		state |= KEY_STATE_IS_DOWN;
	} else if (glfwGetKey(window, glfw_key) == GLFW_RELEASE) {
		if (state & KEY_STATE_IS_DOWN) state |= KEY_STATE_JUST_RELEASED;
		state &= ~KEY_STATE_IS_DOWN;
	}
}

internal inline void monitor_mouse_btn(GLFWwindow *window, u16 *mouse_btn_state, i32 glfw_btn, Mouse_Button haru_btn) {
	u16& state = mouse_btn_state[haru_btn];
	if (glfwGetMouseButton(window, glfw_btn) == GLFW_PRESS) {
		if (!(state & MOUSE_BTN_STATE_IS_DOWN)) state |= MOUSE_BTN_STATE_JUST_PRESSED;
		state |= MOUSE_BTN_STATE_IS_DOWN;
	} else if (glfwGetMouseButton(window, glfw_btn) == GLFW_RELEASE) {
		if (state & MOUSE_BTN_STATE_IS_DOWN) state |= MOUSE_BTN_STATE_JUST_RELEASED;
		state &= ~MOUSE_BTN_STATE_IS_DOWN;
	}
}

internal void run_main_loop(GLFWwindow *window, Arena *arena, App_State &app)
{
  f32 delta_time;
  chr::time_point last_saved_time = chr::high_resolution_clock::now();
  
  b8 running = true;
  while (running) {
		chr::time_point frame_start = chr::high_resolution_clock::now();
		u64 time_since_prev_frame_us = chr::duration_cast<chr::microseconds>(frame_start - last_saved_time).count();
		delta_time = time_since_prev_frame_us * 0.000'001f;
		last_saved_time = frame_start;

		glfwPollEvents();

		// Update window size
		{
			Window_Data &wdata = app.win_data;

			i32 prev_width = wdata.width;
			i32 prev_height = wdata.height;

			glfwGetWindowSize(window, &wdata.width, &wdata.height);

			wdata.size_just_changed = prev_width != wdata.width || prev_height != wdata.height;
		}

		ImGui_ImplOpenGL3_NewFrame();
		ImGui_ImplGlfw_NewFrame();
		ImGui::NewFrame();

		if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS ||
				glfwWindowShouldClose(window))
		{
			running = false;
			break;
		}

		b32 focused = glfwGetWindowAttrib(window, GLFW_FOCUSED);
		if (focused) {
			// TODO Update keyboard / mouse
			// Update keyboard
			u16 *key_state = app.user_input.key_state;
			monitor_key(window, key_state, GLFW_KEY_Q, KEY_Q);
			monitor_key(window, key_state, GLFW_KEY_UP, KEY_UP);
			monitor_key(window, key_state, GLFW_KEY_DOWN, KEY_DOWN);
			monitor_key(window, key_state, GLFW_KEY_LEFT, KEY_LEFT);
			monitor_key(window, key_state, GLFW_KEY_RIGHT, KEY_RIGHT);
			monitor_key(window, key_state, GLFW_KEY_LEFT_ALT, KEY_ALT);
			monitor_key(window, key_state, GLFW_KEY_TAB, KEY_TAB);

			// Update mouse
			f64 mposx, mposy;
			glfwGetCursorPos(window, &mposx, &mposy);

			app.user_input.mouse_pos.x = (i32)mposx;
			app.user_input.mouse_pos.y = (i32)mposy;

			u16 *mouse_btn_state = app.user_input.mouse_btn_state;
			monitor_mouse_btn(window, mouse_btn_state, GLFW_MOUSE_BUTTON_LEFT, MOUSE_BTN_LEFT);
			monitor_mouse_btn(window, mouse_btn_state, GLFW_MOUSE_BUTTON_RIGHT, MOUSE_BTN_RIGHT);
		}

		update_and_render(arena, app, delta_time);

		ImGui::Render();
		ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());

		glfwSwapBuffers(window);
  }  
}