-- AUTHOR: 	E. Burke
-- DATE:	November, 1996
-- PURPOSE: 	Specification for generic boxes and stacks and operations
--		needed to play Box Game
--		Driver program is Boxgame

with TEXT_IO;

generic

  MAX_BOXES	   :   	POSITIVE;
  MAX_STACKS       :    POSITIVE;
  MAX_INPUT        :    POSITIVE;
  SCREEN_WIDTH	   :	POSITIVE;
  SCREEN_HEIGHT    :	POSITIVE;
  
package PLAY_FIELD is

  subtype BOX_ID is NATURAL range 0..MAX_BOXES;
  subtype STACK_ID is POSITIVE range 1..MAX_STACKS;
  subtype BOX_DIM is NATURAL range 0..16;
  subtype FIELD_DIM is POSITIVE range 1..80;

  type BOX_PROP is record
    ID			: BOX_ID;
    Height		: BOX_DIM;
    Radius		: BOX_DIM;
    Color		: CHARACTER;
    Cur_Stack		: STACK_ID;
    Cur_Box_Below	: BOX_ID;
    Cur_Height_Bottom	: FIELD_DIM;
  end record;

  type STACK_PROP is record
    ID			: STACK_ID;
    Center_Pos		: FIELD_DIM;
    Base_Height		: FIELD_DIM;
    Box_Id_Top		: BOX_ID;
  end record;

  type BOXES is array	(1..MAX_BOXES) OF BOX_PROP;
  type STACKS is array (1..MAX_STACKS) OF STACK_PROP;
  type SCREEN_DISPLAY is array (1..SCREEN_HEIGHT, 1..SCREEN_WIDTH)
	of CHARACTER;

  procedure Input	(Play_Box : out BOXES; 
		   	 Play_Stack : out STACKS);
  procedure Move_Box    (Play_Box : in out BOXES; 
		         Play_Stack : in out STACKS;
			 Continue : out BOOLEAN);  
  procedure Place_Box   (Bid : in BOX_ID;
			 Sid : in STACK_ID;
 			 Play_Box : in out BOXES; 
		         Play_Stack : in out STACKS);
  procedure Remove_Box  (Bid : out BOX_ID;
			 Sid : in STACK_ID;
			 Play_Box : in BOXES; 
		         Play_Stack : in out STACKS);
  procedure Display	(Play_Box : in BOXES; 
		         Play_Stack : in STACKS);
  procedure Output	(Bid : in BOX_ID;
			 Play_Box : in BOXES; 
		         Play_Stack : in STACKS;
			 Box_Display : out SCREEN_DISPLAY);
  function Enquire return BOOLEAN;
end PLAY_FIELD;


-- comments by G. Levine
-- Why are you putting all of these operations in the specification?
-- The specification should contain only these capabilities that are
-- to be exported.
-- You might consider including an exception handler here.