#include <GL/gl.h>
#include <GL/glkos.h>
#include <kos.h>
#include <sys/time.h>

#include <algorithm>
#include <cstdio>

const float microSecond = 0.000001f;

float angle = 0;
float deltaTime = 1.0 / 60.0;
float speed = 5.0f;

bool thirtyfps;
uint32 buttonsPressed;

template <typename T>
void pressButton(cont_state_t* controller_state, int button, T&& callback) {
	if (controller_state->buttons & button) {
		if (!(buttonsPressed & button)) {
			buttonsPressed |= button;

			callback();
		}
	} else if ((buttonsPressed & button) &&
			   ~(controller_state->buttons & button)) {
		buttonsPressed &= ~button;
	}
}

void initScreen() {
	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
	glViewport(0, 0, 640, 480);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	glOrtho(0, 640, 0, 480, -100, 100);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
}

void glVertex3fNormalized(float x, float y, float z) {
	int xSize, ySize;
	xSize = 640;
	ySize = 480;

	glVertex3f(x * xSize, y * ySize, z);
}

void displayStuff() {
	glClear(GL_COLOR_BUFFER_BIT);

	// clang-format off
	glPushMatrix();
		glRotatef(angle, 0, 0, 1);
		glColor3f(0.5f, 0.0f, 1.0f);
		glBegin(GL_POLYGON);
			glColor3f(1.0f, 0.0f, 0.0f);
			glVertex3fNormalized(0.25f, 0.25f, 0.0f);

			glColor3f(0.0f, 1.0f, 0.0f);
			glVertex3fNormalized(0.75f, 0.25f, 0.0f);

			glColor3f(0.0f, 0.0f, 1.0f);
			glVertex3fNormalized(0.75f, 0.75f, 0.0f);

			glColor3f(1.0f, 1.0f, 1.0f);
			glVertex3fNormalized(0.25f, 0.75f, 0.0f);
		glEnd();
	glPopMatrix();
	// clang-format on

	if (thirtyfps) {
		vid_waitvbl();
		vid_waitvbl();
	}

	glKosSwapBuffers();
}

void process_input() {
	maple_device_t* controller;
	cont_state_t* controller_state;

	controller = maple_enum_type(0, MAPLE_FUNC_CONTROLLER);

	if (controller) {
		controller_state = (cont_state_t*)maple_dev_status(controller);

		if (!controller_state) {
			printf(
				"An error has occured while trying to read the controller.\n");
		}

		pressButton(controller_state, CONT_DPAD_LEFT, []() { speed -= 1.0f; });
		pressButton(controller_state, CONT_DPAD_RIGHT, []() { speed += 1.0f; });
		pressButton(controller_state, CONT_A, []() { thirtyfps = !thirtyfps; });

		speed = std::clamp(speed, 1.0f, 10.0f);

		angle += (controller_state->joyx / 127.0f) * deltaTime * speed;
	}
}

void printSystemInformation() {
	printf("GL_VENDOR: %s\n", glGetString(GL_VENDOR));
	printf("GL_RENDERER: %s\n", glGetString(GL_RENDERER));
	printf("GL_VERSION: %s\n", glGetString(GL_VERSION));
	printf("GL_EXTENSIONS: %s\n", glGetString(GL_EXTENSIONS));
}

template <typename T>
void deltaTimeLoop(T&& callback, struct timeval& beginningOfFrame,
				   struct timeval& endOfFrame) {
	gettimeofday(&beginningOfFrame, 0);
	callback();
	gettimeofday(&endOfFrame, 0);
	float time = ((float)(endOfFrame.tv_usec) * microSecond) -
				 ((float)(beginningOfFrame.tv_usec) * microSecond);
	if (time > 0.0f) {
		deltaTime = time;
	}
}

void gameLoop() {
	process_input();
	displayStuff();
}

int main() {
	glKosInit();
	initScreen();
	printSystemInformation();
	struct timeval beginningOfFrame, endOfFrame;

	while (1) {
		deltaTimeLoop(gameLoop, beginningOfFrame, endOfFrame);
	}
}