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

/* Global variables used to instantiate structs */
const int WIDTH = 1000;
const int HEIGHT = 480;
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 = 30;
const float BASE_BOUNCE_RAD = (BASE_BOUNCE_DEG / 180.0) * M_PI;
const float BASE_SPEED_COMPONENTS = 7;
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() / 2.0); /* Normalize the value, by dividing it by its magnitude. It is now a value between -1 and 1. */
//	offset *= -1; /* Reverse the sign of the offset, so that -1 represents the top, and 1 represents the bottom */

	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 */
	raylib::Window window = raylib::Window(WIDTH, HEIGHT, "Pong");
	SetTraceLogLevel(LOG_INFO);
	window.ClearBackground(BLACK);
	SetTargetFPS(60);
	SetExitKey(KEY_Q);

	/* Instantiate Paddle and Ball objects */
	Paddle pad1 = Paddle(10, 10, RECT_W, RECT_H);
	Paddle pad2 = Paddle(window.GetWidth() - RECT_W - 10, 10, RECT_W, RECT_H);
	Ball ball = Ball(window.GetWidth()/2, window.GetHeight()/2, CIRC_RAD, 5, 5);

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

	/* Main loop */
	while (!window.ShouldClose()) {
		/* 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();
			ball.pos = raylib::Vector2(window.GetWidth() / 2, window.GetHeight() / 2);
		}
		if (ball.pos.x - ball.radius <= 0) { /* Collision with left wall */
			pad2.incrementPoints();
			ball.pos = raylib::Vector2(window.GetWidth() / 2, window.GetHeight() / 2);
		}
		if (ball.pos.y - ball.radius <= 0 || ball.pos.y + ball.radius >= window.GetHeight()) { /* Collision with top and bottom wals */
			ball.vel.y = ball.vel.y * -1;
		}

		/* Draw objects */

		window.BeginDrawing();
			window.ClearBackground(BLACK);
			pad1.draw();
			pad2.draw();
			ball.draw();
		window.EndDrawing();
	}

	window.Close();

	return 0;
}