(* this file must be compiled with gradeditems.rsl at the same time *)

module NewClass;

from GradedItems import Gradebook, total, Item;

export all;

object RawStudent is
	components: name:Name and id:ID and major:Major and email:Email and
	 unix:UNIXLogin;
	description: (* student without classwork attached *);
end RawStudent;

	object Name is
		components: string;
		description: (* name *);
	end Name;
	object ID is
		components: integer;
		description: (* ID *);
	end ID;
	object Major is
		components: string;
		description: (* major *);
	end Major;
	object Email is
		components: string;
		description: (* email *);
	end Email;
	object UNIXLogin is
		components: string;
		description: (* UNIX login *);
	end UNIXLogin;

object Column is
	components: total* or Item*;
	description: (*
		contains total column or Item column for purposes of statistics
		 calculation
	*);
end Column;

object NewClassInfo is
	components: coursename:CourseName and downlod:Download and login:Login
	 and password:Password;
	description: (* info for a new class *);
end NewClassInfo;
	object CourseName is
		components: string;
		description: (* course name *);
	end CourseName;
	object Download is
		components: boolean;
		description: (* whether to download roster from SIS *);
	end Download;
	object Login is
		components: string;
		description: (* instructor's login *);
	end Login;
	object Password is
		components: string;
		description: (* password *);
	end Password;

object Server is
	components: users:Users and db:Database;
	description: (* server info *);
end Server;

object Users is
	components: ur:UserRecord*;
	description: (* users *);
end Users;
object UserRecord is
	components: uid:UserID and password:Password;
	description: (* user record *);
end UserRecord;
object UserID is
	components: string;
	description: (* user id *);
end UserID;
object Database is
	components: ...;
	description: (* server-side student database *);
end Database;

object StatsBar is
	components: Mean and Median and StdDev and Range and DataPoints;
	description: (* statistics bar *);
end StatsBar;
	object Mean is
		components: real;
		description: (* mean *);
	end Mean;
	object Median is
		components: real;
		description: (* median *);
	end Median;
	object StdDev is
		components: real;
		description: (* standard deviation *);
	end StdDev;
	object Range is
		components: real;
		description: (* range *);
	end Range;
	object DataPoints is
		components: integer;
		description: (* number of data points *);
	end DataPoints;

object List is
	components: ListElement*;
	description: (*
		list object for stats operations
	*);
end List;

object ListElement is
	components: real;
	description: (*
		list element object for stats operations
	*);
end ListElement;

operation CreateNewClass is
	inputs: nci:NewClassInfo;
	outputs: g:Gradebook;
	precondition: ;
	postcondition: ;
	description: (*
		creates a new class
	*);
end CreateNewClass;

operation Login
	inputs: s:Server, uid:UserID, passwd:Password;
	outputs: db:Database;
	precondition:
		exists (u:User) u in s.users (u.uid = uid)
		 and (u.passwd = passwd);
	postcondition:
		db = s.db;
	description: (* 
		logs in to the specified server for roster retrieval or
		 gradebook updating
	*);
end Login;

operation AddStudent is
	inputs: s:Student, g:Gradebook;
	outputs: g':Gradebook;
	precondition:
		(not (exists (s':Student) s in g and s'.ID = s.ID)) and
 	         (s.ID != nil) and (#(s.ID) <= 8);
	postcondition:
		forall (s':Student)
		 (s' in g') iff ((s' = s) or (s' in g));
	description: (*
		adds a student to the class
	*);
end AddStudent;

operation EditStudent is
	inputs: g:Gradebook, old_s:Student, new_s:Student;
	outputs:  g':Gradebook;
	precondition:
		(old_s != new_s)
		and
		(old_s in g)
		and
		(not (exists (new_s' in g) new_s'.id = new_s.id))
		and
		(new_s.id != nil) and (#(new_s.id) <= 8)
		and
		(new_s.email != nil);
	postcondition:
		forall (s':Student)
		(s' in g') iff (((s' = new_s) or (s' in g)) and
		 (s' != old_s));
	description: (*
		edits a student already in the class
	*);
end EditUser;

operation DeleteStudent is
	inputs: g:Gradebook, s:Student;
	outputs: g':Gradebook;
	precondition:
		s in g;
	postcondition:
		(forall (s':Student)
		(s' in g') iff ((s' != s) and (s' in g)));
	description: (*
		removes a student from the class
	*);
end DeleteUser;

operation Sum is
	inputs: r:real*;
	outputs: s:real;
	precondition: ;
	postcondition: ;
	description: (*
		adds inputs together and outputs the sum
	*);
end Sum;

operation CalcMean is
	inputs: g:Gradebook, c:Column;
	outputs: m:Mean;
	precondition: ;
	postcondition:
		(* forall (i:integer | (i >= 1) and (i < #c))
		    s:integer = s + c[i];  <-- not sure if this is right 
		                               so i put Sum() in late work *)
		m = Sum(c)/#c;
	description: (*
		calculates mean
	*);
end CalcMean;

operation SortA is
	inputs: l:List;
	outputs: l':List;
	precondition: ;
	postcondition: 
		(forall (i:integer | (i >= 1) and (i < #l))
		 l[i].ListElement < l[i+1].ListElement);
	description: (*
		sorts data in list
	*);
end SortA;

operation CalcMedian is
	inputs: g:Gradebook, c:Column;
	outputs: m:Median;
	precondition: ;
	postcondition: m = SortA(c)[#c/2];
	description: (*
		calculates median
	*);
end CalcMedian;

operation CalcStdDev is
	inputs: g:Gradebook, c:Column;
	outputs: s:StdDev;
	precondition: ;
	postcondition: ;
	description: (*
		calculates standard deviation
	*);
end CalcStdDev;

operation CalcRange is
	inputs: g:Gradebook, c:Column;
	outputs: r:Range;
	precondition: ;
	postcondition:
		r = SortA(c)[#c] - SortA(c)[1];
	description: (*
		calculates range
	*);
end CalcRange;

operation CalcDataPoints is
	inputs: g:Gradebook, c:Column;
	outputs: d:DataPoints;
	precondition: ;
	postcondition:
		d = #c;
	description: (*
		returns number of data points
	*);
end CalcDataPoints;

end NewClass;