#include <SDL/SDL.h>
#include <iostream>

SDL_Rect map_rect(int x, int y, int w, int h) {
  SDL_Rect tmp;
  tmp.x = x;
  tmp.y = y;
  tmp.w = w;
  tmp.h = h;
  return tmp;
}

bool between(int which, int range_a, int range_b) {
  int a = (range_a > range_b) ? range_a : range_b;
  int b = (range_a > range_b) ? range_b : range_a;
  if(which <= a) {
    if(which >= b) {
	  return true;
	}
  }
  return false;
}

int main(int argc, char * argv[]) {
  SDL_Init(SDL_INIT_VIDEO);
  SDL_Surface * screen = SDL_SetVideoMode(640,480,32,SDL_DOUBLEBUF);
  bool done = false;
  SDL_Event event;
  int player1_y = 0;
  int player2_y = 0;
  int player1_score = 0;
  int player2_score = 0;
  int ball_x = 50, ball_y = 50;
  int ballspeed_x = 2, ballspeed_y = 2;
  SDL_Rect destination;
  Uint32 old_ticks = SDL_GetTicks();
  Uint32 new_ticks = old_ticks;
  while(!done) {
	old_ticks = SDL_GetTicks();
    SDL_FillRect(SDL_GetVideoSurface(),NULL,SDL_MapRGB(SDL_GetVideoSurface()->format,0,0,255));
	destination = map_rect(5,player1_y, 10, 50);
	SDL_FillRect(SDL_GetVideoSurface(),&destination, SDL_MapRGB(SDL_GetVideoSurface()->format,0,0,0));	
	destination = map_rect(ball_x,ball_y,5,5);
	SDL_FillRect(SDL_GetVideoSurface(),&destination, SDL_MapRGB(SDL_GetVideoSurface()->format,255,255,255));
	destination = map_rect(screen->w - 15, player2_y, 10, 50);
	SDL_FillRect(SDL_GetVideoSurface(),&destination, SDL_MapRGB(SDL_GetVideoSurface()->format,0,0,0));	
	SDL_Flip(SDL_GetVideoSurface());
	while(SDL_PollEvent(&event)) {
	  if(event.type == SDL_QUIT) {
	    done = true;
	  }
	  if(event.type == SDL_KEYDOWN) {
	    if(event.key.keysym.sym == SDLK_ESCAPE) {
		  done = true;
		}
	  }
	}
	if(SDL_GetKeyState(NULL)[SDLK_DOWN]) {
	  player1_y += 1;
	}
	if(SDL_GetKeyState(NULL)[SDLK_UP]) {
	  player1_y -= 1;
	}
	if(ball_y > player2_y + 25) {
	  player2_y += 1;
	}
	if(ball_y < player2_y + 25) {
	  player2_y -= 1;
	}
	ball_x += ballspeed_x;
	ball_y += ballspeed_y;
	if(ball_y < 0 && ballspeed_y < 0) ballspeed_y *= -1;
	if(ball_y > screen->h && ballspeed_y > 0) ballspeed_y *= -1;
	if(ball_x < 0 && ballspeed_x < 0) {
	  ballspeed_x *= -1;
	  player2_score += 1;
	  std::cout << "They scored! :( They have " << player2_score << " points.\n";
	}
	if(ball_x > screen->w && ballspeed_x > 0) { 
	  ballspeed_x *= -1;
	  player1_score += 1;
	  std::cout << "You scored! You have " << player1_score << " points.\n";
	}
	
	if(ball_x < 15) {
	  if(between(ball_y, player1_y, player1_y+50)) {
	    if(ballspeed_x < 0) {
		  ballspeed_x *= -1;
		}
	  }
	}
	if(ball_x > screen->w - 15) {
	  if(between(ball_y,player2_y, player2_y+50)) {
	    if(ballspeed_x > 0) {
		  ballspeed_x *= -1;
		}
	  }
	}
	new_ticks = SDL_GetTicks();
	if(new_ticks - old_ticks < 17) {
	  SDL_Delay(17 - (new_ticks-old_ticks));
	}
  }
  return 0;
}