#include <iostream>
#include <cmath>
#include <ctime>
#include <raylib-cpp.hpp>
#include "paddle.hpp"
#include "ball.hpp"
#include "math-helpers.hpp"

/* Global variables used to instantiate structs */
const int WIDTH = 1500;
const int HEIGHT = 600;
const int RECT_H = HEIGHT / 3;
const int RECT_W = 30;
const int PADDLE_SPEED = 8;
const int CIRC_RAD = 10;
const float BASE_BOUNCE_DEG = 60;
const float BASE_BOUNCE_RAD = (BASE_BOUNCE_DEG / 180.0) * M_PI;
const float BASE_SPEED_COMPONENTS = 15;
const float BASE_SPEED = sqrt(powf(BASE_SPEED_COMPONENTS, 2) * 2);

raylib::Vector2 changeVelocityAfterCollision(Paddle paddle, Ball ball) {
	float paddle_mid_y = (paddle.getRect().y + paddle.getRect().GetHeight()) / 2.0; /* Middle y value of rectangle */
	float  ball_y = ball.pos.y; /* Y co-ordinate of ball */

	float offset = paddle_mid_y - ball_y; /* Subtracting the ball coordinate will give us a value between -paddle_mid_y (represents bottom of paddle) and +paddle_mid_y (represents top of paddle) */
	offset /= (paddle.getRect().GetHeight()); /* Normalize the value, by dividing it by its maximum magnitude. It is now a value between -1 and 1. */

	offset *= 0.8 + (float)(std::rand()) / (float) (RAND_MAX / ( 1.2 - 0.8)); // Generate a random float from 0.8 to 1.2

	float bounce_angle = offset * BASE_BOUNCE_RAD; /* Calculate the actual bounce angle from the base bounce angle. */

	/* Calculate new velocities as multiples of the original velocity. I use sine and cosine, because when the ball hits the paddle
	perpendicular to it (bounce angle is 0), the y_velocity should be 0 (i.e. It should bounce straight back). The sin function does
	this for us. A similar reasoning was employed for the use of cosine */
	float new_x_vel = abs(BASE_SPEED * cosf(bounce_angle)) * (-1 * signum(ball.vel.x)); /* Reverse the sign of the x-velocity */
	float new_y_vel = abs(BASE_SPEED * sinf(bounce_angle)) * signum(ball.vel.y); /* Keep the sign of the y-velocity */

	return raylib::Vector2(new_x_vel, new_y_vel);
}

int main() {
	/* Initialize window and other variables */
	raylib::Window window = raylib::Window(WIDTH, HEIGHT, "Pong");
	SetTraceLogLevel(LOG_INFO);
	window.ClearBackground(BLACK);
	SetTargetFPS(60);
	SetExitKey(KEY_Q);
	std::string points_str = std::string("0\t\t0");
	bool game_started = false;
	srand(std::time(NULL));

	/* Instantiate Paddle and Ball objects */
	Paddle pad1 = Paddle(10, (HEIGHT / 2) - (RECT_H / 2), RECT_W, RECT_H);
	Paddle pad2 = Paddle(window.GetWidth() - RECT_W - 10, (HEIGHT / 2) - (RECT_H / 2), RECT_W, RECT_H);
	Ball ball = Ball(window.GetWidth()/2, window.GetHeight()/2, CIRC_RAD, BASE_SPEED, 0);

	window.BeginDrawing();
		pad1.draw();
		pad2.draw();
		ball.draw();
	window.EndDrawing();

	/* Main loop */
	while (!window.ShouldClose()) {

		if (!game_started) {
			if (IsKeyDown(KEY_SPACE)) {
				game_started = true;
			}
		}

		if (game_started) {
			/* Update paddle velocity */
			if (IsKeyPressed(KEY_S)) {
				pad1.velocity.y = PADDLE_SPEED; /* Set positive (downward) velocity, since (0,0) is top-left */
			}
			if (IsKeyPressed(KEY_W)) {
				pad1.velocity.y = (-1) * PADDLE_SPEED; /* Set negative (upward) velocity */
			}

			if (IsKeyReleased(KEY_S) || IsKeyReleased(KEY_W)) {
				pad1.velocity.y = 0;
			}

			if (IsKeyPressed(KEY_UP)) {
				pad2.velocity.y = (-1) * PADDLE_SPEED;
			}
			if (IsKeyPressed(KEY_DOWN)) {
				pad2.velocity.y = PADDLE_SPEED;
			}
			if (IsKeyReleased(KEY_UP) || IsKeyReleased(KEY_DOWN)) {
				pad2.velocity.y = 0;
			}

			/* Update ball velocity based on collision detection */
			if (pad1.getRect().CheckCollision(ball.pos, ball.radius)) { /* Collision with paddle 1 */
				ball.pos.x = pad1.getRect().x + pad1.getRect().GetWidth() + ball.radius + 1; /* Ensuring that the ball doesn't get stuck inside the paddle */
				ball.vel = changeVelocityAfterCollision(pad1, ball);
			}
			if (pad2.getRect().CheckCollision(ball.pos, ball.radius)) { /* Collision with paddle 2 */
				ball.pos.x = pad2.getRect().x - ball.radius - 1;
				ball.vel = changeVelocityAfterCollision(pad2, ball);
			}

			if (ball.pos.x + ball.radius >= window.GetWidth()) { /* Collision with right wall */
				pad1.incrementPoints();
				game_started = false;
				ball.reset();
				pad1.reset();
				pad2.reset();
			}
			if (ball.pos.x - ball.radius <= 0) { /* Collision with left wall */
				pad2.incrementPoints();
				game_started = false;
				ball.reset();
				pad1.reset();
				pad2.reset();
			}
			if (ball.pos.y - ball.radius <= 0) { /* Collision with top wall */
				ball.pos.y = ball.radius + 1;
				ball.vel.y = ball.vel.y * -1;
			}

			if (ball.pos.y + ball.radius >= window.GetHeight()) { /* Collision with bottom wall */
				ball.pos.y = HEIGHT - ball.radius - 1;
				ball.vel.y = ball.vel.y * -1;
			}

			/* Update positions based on velocities */
			pad1.updatePosition();
			pad2.updatePosition();
			ball.updatePosition();

		}

		/* Draw objects */
		window.BeginDrawing();
			window.ClearBackground(BLACK);
			points_str = std::to_string(pad1.getPoints()) + "\t\t" + std::to_string(pad2.getPoints());
			raylib::Text::Draw( points_str, (WIDTH / 2) - 30, HEIGHT / 10, 30, raylib::Color::White() );
			pad1.draw();
			pad2.draw();
			ball.draw();
		window.EndDrawing();
	}

	window.Close();

	return 0;
}