;; pong.scm                         Daniel Azus                         11-13-2006

;; This program uses the world teachpack

;; Controls:
;; W = Up for left paddle
;; S = Down for left paddle
;; Up arrow = Up for right paddle
;; Down arrow = Down for right paddle

;; Constants
(define WindowWidth 900)            ;; The width of the window
(define WindowHeight 600)           ;; The height of the window
(define FrameRate 100)               ;; The rate the window is updated per second
(define FrameDelay (/ 1 FrameRate)) ;; The delay between frames, based on the frame rate

;; Constants
;; Default values for variables
(define CircleStartX (/ WindowWidth 2))  ;; The starting x position for the ball, and used when the balls is reset
(define CircleStartY (/ WindowHeight 2)) ;; The starting y position for the ball, and used when the balls is reset
(define CircleRadius 30)                 ;; Radius of the ball
(define CircleSpeedStartX -15)           ;; The x velocity of the ball
(define CircleSpeedStartY -7)           ;; The y velocity of the ball

(define Paddle1Width 10)   ;; Width of the left paddle
(define Paddle1Height 100) ;; Height of the left paddle
(define Paddle2Width 10)   ;; Width of the right paddle
(define Paddle2Height 100) ;; Height of the right paddle

(define P1X 20)     ;; Starting x position for the left paddle
(define P1Y 100)    ;; Starting y position for the left paddle
(define P1Speed 50) ;; Speed the left paddle moves at

(define P2X (- WindowWidth 20)) ;; Starting x position for the right paddle
(define P2Y 0)                  ;; Starting y position for the right paddle
(define P2Speed 50)             ;; Speed the right paddle moves at

(define P1Score 0) ;; The starting score for the left paddle
(define P2Score 0) ;; The starting score for the right paddle


;; Defining the world
;; World variables
;; Frame = Frames since the program started
;; P1X = Left paddle x position
;; P1Y = Left paddle y position
;; P2X = Right paddle x position
;; P2Y = Right paddle y position
;; CircleX = The ball's x position
;; CircleY = The ball's y position
;; CircleSpeedX = The ball's x velocity
;; CircleSpeedY = The ball's y velocity
;; P1Score = Left paddle's score
;; P2Score = Right paddle's score
;; Paused = If the world is paused
(define-struct World [Frame P1X P1Y P2X P2Y CircleX CircleY CircleSpeedX CircleSpeedY P1Score P2Score Paused])

;; The first world that starts with the default values
(define InitialWorld (make-World 0 P1X P1Y P2X P2Y CircleStartX CircleStartY CircleSpeedStartX CircleSpeedStartY P1Score P2Score false))

;; Used when drawing images in a world
(define (PutImage image x y image2)
  (place-image image (+ x (/ (image-width image) 2)) (- (+ y (/ (image-height image) 2)) 1) image2)
)

;; Used when drawing images in a world with out offset
(define (PutImageNorm image x y image2)
  (place-image image x y image2)
)

;; Used when drawing text in a world
(define (PutText Text TextColor x y image2)
  (PutImageNorm (text Text 12 TextColor) x y image2)
)

;; Used when drawing text in a world with a font size
(define (PutTextSized Text TextColor fontsize x y image2)
  (PutImageNorm (text Text fontsize TextColor) x y image2)
)

;; Constant drawing colors
(define ColorWhite (make-color 0 0 0))
(define ColorBlack (make-color 0 0 0))
(define ColorRed (make-color 255 0 0))
(define ColorGreen (make-color 0 255 0))
(define ColorBlue (make-color 0 0 255))
(define ColorDarkGrey (make-color 100 100 100))

;; Constants for drawing
(define PaddleRed (rectangle Paddle1Width Paddle1Height 'solid ColorRed))
(define PaddleBlue (rectangle Paddle2Width Paddle2Height 'solid ColorBlue))
(define BallGreen (circle CircleRadius 'solid ColorGreen))
(define Background (rectangle WindowWidth WindowHeight 'solid ColorDarkGrey))

;; This takes care of making sure everything gets drawn
(define (Draw-Window aworld)
  (PutTextSized (number->string (World-P1Score aworld)) ColorRed 25 (/ WindowWidth 3) 0
  (PutTextSized (number->string (World-P2Score aworld)) ColorBlue 25 (* (/ WindowWidth 3) 2) 0
  (PutImageNorm BallGreen (World-CircleX aworld) (World-CircleY aworld)
  (PutImage PaddleRed (World-P1X aworld) (World-P1Y aworld)
  (PutImage PaddleBlue (World-P2X aworld) (World-P2Y aworld)
  (PutImage Background 0 0
  (empty-scene WindowWidth WindowHeight)
  ))))))
)

;; Takes care of updating all the world variables of the current world
(define (UpdateWorld aworld)
  (cond
    [(World-Paused aworld) aworld] ;; Check if this world is paused
    [else
  (make-World
    (+ (World-Frame aworld) 1) ;; Increment the frame count
    (World-P1X aworld) ;; Do not change the left paddle's x position
    (World-P1Y aworld) ;; Do not change the left paddle's y position
    (World-P2X aworld) ;; Do not change the right paddle's x position
    (World-P2Y aworld) ;; Do not change the right paddle's y position
    (cond ;; CircleX
      [(<= (+ (World-CircleX aworld) CircleRadius) 0) CircleStartX]
      [(>= (- (World-CircleX aworld) CircleRadius) WindowWidth) CircleStartX]
      [else (+ (World-CircleX aworld) (World-CircleSpeedX aworld))]
    )
    (cond ;; CircleY
      [(<= (+ (World-CircleX aworld) CircleRadius) 0) CircleStartY]
      [(>= (- (World-CircleX aworld) CircleRadius) WindowWidth) CircleStartY]
      [else (+ (World-CircleY aworld) (World-CircleSpeedY aworld))]
    )
    (cond ;; CircleSpeedX, checks for boundries and paddles
      [(and (<= (- (World-CircleX aworld) CircleRadius) (+ (World-P1X aworld) Paddle1Width)) (>= (+ (World-CircleX aworld) CircleRadius) (World-P1X aworld))
            (>= (+ (World-CircleY aworld) CircleRadius) (World-P1Y aworld)) (<= (- (World-CircleY aworld) CircleRadius) (+ (World-P1Y aworld) Paddle1Height)))
        (cond [(< (World-CircleSpeedX aworld) 0) (- (World-CircleSpeedX aworld))] [else (World-CircleSpeedX aworld)])]
      [(and (<= (- (World-CircleX aworld) CircleRadius) (+ (World-P2X aworld) Paddle2Width)) (>= (+ (World-CircleX aworld) CircleRadius) (World-P2X aworld))
               (>= (+ (World-CircleY aworld) CircleRadius) (World-P2Y aworld)) (<= (- (World-CircleY aworld) CircleRadius) (+ (World-P2Y aworld) Paddle2Height)))
        (cond [(> (World-CircleSpeedX aworld) 0) (- (World-CircleSpeedX aworld))] [else (World-CircleSpeedX aworld)])]
      [else (World-CircleSpeedX aworld)]
    )
    (cond ;; CircleSpeedY, checks for boundries and bouces off the top and bottom
      [(<= (- (World-CircleY aworld) CircleRadius) 0)
       (- CircleSpeedStartY)]
      [(>= (+ (World-CircleY aworld) CircleRadius) WindowHeight)
       CircleSpeedStartY]
      [else (World-CircleSpeedY aworld)]
    )
    (cond ;; P1Score, increase when the ball is in a goal
      [(>= (- (World-CircleX aworld) CircleRadius) WindowWidth) (+ (World-P1Score aworld) 1)]
      [else (World-P1Score aworld)]
    )
    (cond ;; P2Score, increase when the ball is in a goal
      [(<= (+ (World-CircleX aworld) CircleRadius) 0) (+ (World-P2Score aworld) 1)]
      [else (World-P2Score aworld)]
    )
    false ;; This code will not be reached if the world is paused, so it is ok to use a constant value.
  )
  ])
)

;; This takes care of making sure everything gets updated
(define (Update aworld)
  (cond
    [(World-Paused aworld) aworld] ; If world is paused nothing changes
    [else (UpdateWorld aworld)]
  )
)

;; This is called when a mouse button is pressed.
;; It is unable to tell which button.
(define (Mouse-Button-Down x y aworld)
  aworld
)

;; This is called when a mouse button is released.
;; It is unable to tell which button.
(define (Mouse-Button-Released x y aworld)
  aworld
)

;; This is called when the mouse is moved.
;; It is unable to tell which button.
(define (Mouse-Move x y aworld)
  aworld
)

;; This is called when the mouse is dragged.
;; It is unable to tell which button.
(define (Mouse-Drag x y aworld)
  aworld
)

;; This is called anytime the mouse changes.
;; It is unable to tell which button is pressed or released.
(define (Handle-Mouse a b c d)
  (cond
    [(eqv? d 'button-down) (Mouse-Button-Down b c a)]
    [(eqv? d 'button-up) (Mouse-Button-Released b c a)]
    [(eqv? d 'drag) (Mouse-Drag b c a)]
    [(eqv? d 'move) (Mouse-Move b c a)]
    [else a]
  )
)

;; The up arrow key was pressed
(define (Key-UpArrow aworld)
  (make-World
   (World-Frame aworld)
   (World-P1X aworld)
   (World-P1Y aworld)
   (World-P2X aworld)
   (- (World-P2Y aworld) P2Speed)
   (World-CircleX aworld)
   (World-CircleY aworld)
   (World-CircleSpeedX aworld)
   (World-CircleSpeedY aworld)
   (World-P1Score aworld)
   (World-P2Score aworld)
   (World-Paused aworld)
  )
)

;; The down arrow key was pressed
(define (Key-DownArrow aworld)
  (make-World
   (World-Frame aworld)
   (World-P1X aworld)
   (World-P1Y aworld)
   (World-P2X aworld)
   (+ (World-P2Y aworld) P2Speed)
   (World-CircleX aworld)
   (World-CircleY aworld)
   (World-CircleSpeedX aworld)
   (World-CircleSpeedY aworld)
   (World-P1Score aworld)
   (World-P2Score aworld)
   (World-Paused aworld)
  )
)

;; The W key was pressed
(define (Key-W aworld)
  (make-World
   (World-Frame aworld)
   (World-P1X aworld)
   (- (World-P1Y aworld) P1Speed)
   (World-P2X aworld)
   (World-P2Y aworld)
   (World-CircleX aworld)
   (World-CircleY aworld)
   (World-CircleSpeedX aworld)
   (World-CircleSpeedY aworld)
   (World-P1Score aworld)
   (World-P2Score aworld)
   (World-Paused aworld)
  )
)

;; The S key was pressed
(define (Key-S aworld)
  (make-World
   (World-Frame aworld)
   (World-P1X aworld)
   (+ (World-P1Y aworld) P1Speed)
   (World-P2X aworld)
   (World-P2Y aworld)
   (World-CircleX aworld)
   (World-CircleY aworld)
   (World-CircleSpeedX aworld)
   (World-CircleSpeedY aworld)
   (World-P1Score aworld)
   (World-P2Score aworld)
   (World-Paused aworld)
  )
)

;; This is called anytime a key to pressed or released.
;; It is unable to tell if a key is still pressed or which key was released.
;; If a key is held down then the function will get called multiple times.
(define (Handle-Keys a b)
  (cond
    [(eqv? b 'up) (Key-UpArrow a)]
    [(eqv? b 'down) (Key-DownArrow a)]
    [(eqv? b #\w) (Key-W a)]
    [(eqv? b #\s) (Key-S a)]
    [else a]
  )
)

;; Creates the window
(big-bang WindowWidth WindowHeight FrameDelay InitialWorld)

;; Set the drawing function
(on-redraw Draw-Window)

;; Set the updating function
(on-tick-event Update)

;; Set the key press function
(on-key-event Handle-Keys)

;; Set the mouse handler function
(on-mouse-event Handle-Mouse)