module QuestionDatabase;

	from Question import QuestionDB, Question, TestQuestion, AnsweredQuestion, GradedQuestion, QuestionText, Type, Class, LastUsed, Keywords, Author, Time, Difficulty, AutoGrade, CorrectAnswer, QuestionNumber;
	
	operation SearchQuestionDatabase is
		inputs: qdb:QuestionDB, c:Class;
		outputs: ql:Question*;
		description: (*
			Find a question or questions by class.  If more than one is found, output list is sorted
			by keyword.
		*);
		precondition: (* None *);
		postcondition: 
		(*
		 * The output list consists of all questions of the given class in the input db.
		 *)
		(forall (q:Question)
			(q in ql) iff (q in qdb) and (q.class = c))
			
			and
			
		(* 
		 * The output list is sorted in alphabetical order
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].class < ql[i + 1].class);

	end SearchQuestionDatabase;

	operation SearchQuestionDatabase is
		inputs: qdb:QuestionDB, tp:Type;
		outputs: ql:Question*;
		description: (*
			Find a question or questions by type.  If more than one is found, output list is sorted
			by keyword.
		*);
		precondition: (* None*);
		postcondition: 
		(*
		 * The output list consists of all questions of the given type in the input db.
		 *)
		(forall (q:Question)
			(q in ql) iff (q in qdb) and (q.type = tp))
					
			and
			
		(* 
		 * The output list is sorted in alphabetical order by keyword.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].keywords < ql[i + 1].keywords);

	end SearchQuestionDatabase;

	operation SearchQuestionDatabase is
		inputs: qdb:QuestionDB, tm:Time;
		outputs: ql:Question*;
		description: (*
			Find a question or questions by time.  If more than one is found, output list is sorted
			by keyword.
		*);
		precondition: (* None *);
		postcondition: 
		(*
		 * The output list consists of all questions of the given time in the input db.
		 *)
		(forall (q:Question)
			(q in ql) iff (q in qdb) and (q.time = tm))
								
			and
			
		(* 
		 * The output list is sorted in alphabetical order by keyword.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].keywords < ql[i + 1].keywords);

	end SearchQuestionDatabase;

	operation SearchQuestionDatabase is
		inputs: qdb:QuestionDB, d:Difficulty;
		outputs: ql:Question*;
		description: (*
			Find a question or questions by difficulty.  If more than one is found, output list is sorted
			by keyword.
		*); 
		precondition: (* None *);
		postcondition:  
		(*
		 * The output list consists of all questions of the given difficulty in the input db.
		 *)
		(forall (q:Question)
			(q in ql) iff (q in qdb) and (q.difficulty = d))
											
			and
			
		(* 
		 * The output list is sorted in alphabetical order by keyword.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].keywords < ql[i + 1].keywords);

	end SearchQuestionDatabase;

	operation SearchQuestionDatabase is
		inputs: qdb:QuestionDB, l:LastUsed;
		outputs: ql:Question*;
		description: (*
			Find a question or questions by LastUse.  If more than one is found, output list is sorted
			by keyword.
		*);
		precondition: (* None *);
		postcondition: 
		(*
		 * The output list consists of all questions of the given Last Use in the input db.
		 *)
		(forall (q:Question)
			(q in ql) iff (q in qdb) and (q.lastused = l))
											
			and
			
		(* 
		 * The output list is sorted in alphabetical order by keyword.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].keywords < ql[i + 1].keywords);

	end SearchQuestionDatabase;

	operation SearchQuestionDatabase is
		inputs: qdb:QuestionDB, k:Keywords;
		outputs: ql:Question*;
		description: (*
			Find a question or questions by keyword.  If more than one is found, output list is sorted
			by keyword.
		*);
		precondition: (* None *);
		postcondition:  
		(*
		 * The output list consists of all questions of the given keyword in the input db.
		 *)
		(forall (q:Question)
			(q in ql) iff (q in qdb) and (q.keywords = k))
														
			and
			
		(* 
		 * The output list is sorted in alphabetical order by keyword.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].keywords < ql[i + 1].keywords);

	end SearchQuestionDatabase;

	operation SearchQuestionDatabase is
		inputs: qdb:QuestionDB, a:Author;
		outputs: ql:Question*;
		description: (*
			Find a question or questions by author.  If more than one is found, output list is sorted
			by keyword.
		*);
		precondition: (* None *);
		postcondition:  
		(*
		 * The output list consists of all questions of the given author in the input db.
		 *)
		(forall (q:Question)
			(q in ql) iff (q in qdb) and (q.author = a))
														
			and
			
		(* 
		 * The output list is sorted in alphabetical order by keyword.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].keywords < ql[i + 1].keywords);

	end SearchQuestionDatabase;




	operation SortQuestionDatabase is
		inputs: qdb:QuestionDB;
		outputs: ql:Question*;
		description: (*
			Sorts the column labeled class in alphabetical order.
		*);
		precondition: (* None *);
		postcondition:
		(* 
		 * The output list is sorted in alphabetical order by class.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].class < ql[i + 1].class);
	end SortQuestionDatabase;

	operation SortQuestionDatabase is
		inputs: qdb:QuestionDB;
		outputs: ql:Question*;
		description: (*
			Sorts the column labeled type in alphabetical order.
		*);
		precondition: (* None *);
		postcondition: 
		(* 
		 * The output list is sorted in alphabetical order by type.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].type < ql[i + 1].type);
	end SortQuestionDatabase;

	operation SortQuestionDatabase is
		inputs: qdb:QuestionDB;
		outputs: ql:Question*;
		description: (*
			Sort the column labeled time in descending numerical order.
		*);
		precondition: (* None *);
		postcondition: 
		(* 
		 * The output list is sorted in numerical order by time.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].time < ql[i + 1].time);
	end SortQuestionDatabase;

	operation SortQuestionDatabase is
		inputs: qdb:QuestionDB;
		outputs: ql:Question*;
		description: (*
			Sort the column labeled difficulty in descending numerical order.
		*); 
		precondition: (* None *);
		postcondition: 
		(* 
		 * The output list is sorted in numerical order by difficulty.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].difficulty < ql[i + 1].difficulty);

	end SortQuestionDatabase;

	operation SortQuestionDatabase is
		inputs: qdb:QuestionDB;
		outputs: ql:Question*;
		description: (*
			Sort the column labeled Last Use by date with the most recent at the top.
		*);
		precondition: (* None *);
		postcondition:
		(* 
		 * The output list is sorted in alphabetical order by last use.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].lastused < ql[i + 1].lastused);
	end SortQuestionDatabase;

	operation SortQuestionDatabase is
		inputs: qdb:QuestionDB;
		outputs: ql:Question*;
		description: (*
			Sort the column labeled keyword in alphabetical order.
		*);
		precondition: (* None *);
		postcondition:
		(* 
		 * The output list is sorted in alphabetical order by keyword.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].keywords < ql[i + 1].keywords);
	end SortQuestionDatabase;

	operation SortQuestionDatabase is
		inputs: qdb:QuestionDB;
		outputs: ql:Question*;
		description: (*
			Sort the column labeled author in alphabetical order.
		*);
		precondition: (* None *);
		postcondition:
		(* 
		 * The output list is sorted in alphabetical order by keyword.
		 *)
		(forall (i:integer | (i >= 1) and (i < #ql))
			ql[i].author < ql[i + 1].author);
	end SortQuestionDatabase;
	
end QuestionDatabase;