(*

 *  This file deines the objects and operations
 *  of a Graded Item
 *)

obj GradedItem is name:Title and we:Weight and al:Access and pt:Points 
    and lp:LatePolicy and par:Parent and nts:Notes and chi:Children;

obj Title is string;

obj Weight is integer;

obj Access is string;

obj Points is integer;

obj Parent is string;

obj  Priority is integer;

obj Children is GradedItem*;

obj GradedItemList is GradedItem*;



operation newGradedItem is
	description:
		(*
		 * This operation creates a new GradedItem in the current class
		 * and adds it to the GradedItemList.
		 *);

	inputs: gi:GradedItem, gil:GradedItemList;
	outputs: gil':GradedItemList;

	
	precondition:
		(*
		 * The GradedItemList must not already contain a GradedItem with the same Title
		 * and the GradedItem must have a Title and Access
		 *)

		not(
		     exists (g:GradedItem)
			exists(g in gil')
				g.name =gi.name
		   )
		and

		gi.name != nil

		and

		gi.al != nil;


				

	postcondition:
		(*
		 * The new GradedItem must exist in the GradedItemList
		 *)

		exists (g:GradedItem)
		   exists(g in gil')
			g.name = gi.name;
		
		
end newGradedItem;



operation delGradedItem is

	description:
		(*
		 * This removes a graded item from the current classes GradedItemList.
		 *);

	inputs: gil:GradedItemList, gi:GradedItem;
	outputs: gil':GradedItemList;


	precondition:
		(*
		 * The GradedItem must already exist in the list
		 *)

		exists(g:GradedItem)
			exists(g in gil')
			g.name = gi.name;

	postcondition:
		(*
		 * The GradedItem must no longer exist in the list
		 *)
		
		not(
			exists (g:GradedItem)
			   exists(g in gil')
				g.name = gi.name)
		   ;
end delGradedItem;


(*
 * Individual Item options
 *)

operation setParentItem is
	description:
		(*
		 * Sets the parent item of a GradedItem
		 *);

	inputs: pgi:GradedItem, gi:GradedItem;
	outputs: gi':GradedItem, pgi':GradedItem;

	precondition:
		(*
		 * Both the parent and the child items must exist and have (unique) titles
		 *)
		
		pgi != nil and gi != nil

		and
		
		pgi.name != gi.name;

	postcondition:
		(*
		 * The child's parent must be the parent item
		 * and the parent must have the child 
		 *)

		gi'.par = pgi'.name

		and
		
		exists(g:GradedItem)
			exists(g in pgi'.chi)
			g.name = gi'.name;

		
end setParentItem;


operation setWeight is
	description:
		(*
		 * Sets the weight in a GradedItem
		 *);

	inputs: gi:GradedItem, w:Weight;
	outputs: gi':GradedItem;

	precondition:
		(*
		 * The GradedItem must exist, and the weight must exist
		 *)
	
		gi != nil and w != nil;

	postcondition:
		(*
		 * The GradedItem must contain the new weight.
		 *)

		gi'.we = w;

end setWeight;


operation setAccess is
	description:
		(*
		 * Sets the access level of a GradedItem
		 *);

	inputs: gi:GradedItem, acl:Access;
	outputs: gi':GradedItem;

	precondition:
		(*
		 * The GradedItem and Access must both exist
		 *)
		
		gi != nil and acl != nil;

	postcondition:
		(*
		 * The GradedItem must contain the correct Access
		 *)

		gi'.al = acl;

end setAccess;
	


operation setLatePolicy is
	description:
		(*
		 * Sets the LatePolicy for a graded item
		 *);
	inputs: gi:GradedItem, lap:LatePolicy;
	outputs: gi':GradedItem;

	precondition:
		(*
		 * Both the GradedItem and LatePolicy must exist
		 *)

		gi != nil and lap != nil;

	postcondition:
		(*
		 * The GradedItem must containt the correct late policy
		 *)

		gi'.lp = lap;

end setLatePolicy;



operation setNotes is
	description:
		(*
		 * Sets the notes field of a GradedItem
		 *);

	inputs: gi:GradedItem, n:Notes;
	outputs: gi':GradedItem;

	precondition:
		(*
		 * Both the GradedItem and notes must exist
		 *)
		
		gi != nil and n != nil;


	postcondition:
		(*
		 * The GradedItem must containt the correct notes
		 *)

		gi'.nts = n;

end setNotes;