module TestPackage;

from Test_Preferences import all;
from QuestionManagement import all;
from TestGeneration import all;
export all;

object Test is
   components: qs:TestQuestion* and tl:TestLength and tt:TestTime and td:TestDifficulty 
      and cl:Class and tkw:TestKeyword* and tpts:TestPoints and tn:TestName and ntf:NumTF
      and nmc:NumMC and ness:NumEssay and ncde:NumCode and nfill:NumFill; 
   description: (*
      A test is composed of zero or more TestQuestions
   *); 
end Test;

object TestKeyword is
   components: string;
   description: (*
      The keywords of a test.
   *);
end TestKeyword;

object TestName is
   components: string;
   description: (*
      The name of a test.
   *);
end TestName;

object TestPoints is
   components: integer;
   description: (*
      A integer that holds the total number of points for a test.
   *);
end TestPoints;

object TestLength is
   components: integer;
   description: (*
      A integer that represents the number of questions on a test.
   *);
end TestLength;

object TestTime is
   components: integer;
   description: (*
      A integer that represents the duration of a test.
   *);
end TestTime;

object TestDifficulty is
   components: integer;
   description: (*
      A integer that represents the difficulty of a test on a 1-10 scale.
   *);
end TestDifficulty;

object TestQuestion inherits from Question is
   components: qn:QuestionNumber and qpts:QuestionPoints;
   description: (*
      A TestQuestion has all the components of a Question, but has an extra
   component that specifies what number in a test it is.
   *);
end TestQuestion;

object QuestionPoints is
   components: integer;
   description: (*
      Points is the point value assigned to a TestQuestion for a test.
   *);
end QuestionPoints;

object QuestionNumber is
   components: integer;
   description: (*
      QuestNumber is the question number assigned a TestQuestion to 
   signify the order in which it appears in a Test.
   *);
end QuestionNumber;

operation AddTestQuestion
   inputs: q:TestQuestion, tst:Test;
   outputs: tst':Test;
   
   precondition:
      (*
       * There is no question in the input Test that is the same as the input
       * question.
       *)
      (not (exists (q' in tst.qs) q' = q)) 

         and

      (*
       * The input question is not empty.
       *)
      (q != nil);

   postcondition:
      (*
       * A Question is only in the output Test if and only if it is the new
       * Question to be added or it is in the input Test. 
       *)
      forall (q':TestQuestion)
         (q' in tst'.qs) iff ((q' = q) or (q' in tst.qs));

   description: (*A Question becomes a TestQuestion and is applied to the
      Test.
   *);
end AddTestQuestion;

operation EditTestQuestion
   inputs: oldQuestion:TestQuestion, newQuestion:TestQuestion, tst:Test;
   outputs: tst':Test;

   precondition:
      (*
       * There is no question in the input Test that is the same as the new
       * question.
       *)
      (not (exists (q' in tst.qs) (q' = newQuestion)))

         and

      (*
       * The old question is in the input test.
       *)
      (exists (q' in tst.qs) (q' = oldQuestion));

   postcondition:
      (*
       * A Question is only in the output Test if and only if it is the new
       * Question to be added or is in the input Test, and it is not the old
       * Question.
       *)
      forall (q':TestQuestion)
         (newQuestion in tst'.qs) iff (((q' = newQuestion) or (q' in tst.qs)) and (q' != oldQuestion));


end EditTestQuestion;

operation DeleteTestQuestion
   inputs: tq:TestQuestion, tst:Test;
   outputs: tst':Test;

   precondition:
      (*
       * The given TestQuestion is in Test
       *)
      tq in tst.qs;

   postcondition:
      (*
       * A TestQuestion is in the output Test if and only if it is not the existing
       * TestQuestion to be deleted and it is in the input Test.
       *)
      forall (tq':TestQuestion)
         (tq' in tst'.qs) iff ((tq' != tq) and (tq' in tst.qs));

   description: (*A TestQuestion is selected and removed from Test.
   *);
end DeleteTestQuestion;

operation ReplaceQuestion
   inputs: tq:TestQuestion, tst:Test, qdb:QuestionDatabase, tp:TestPreferences;
   outputs: tst':Test;

   precondition:
      (*
       * The given TestQuestion is in test
       *)
      tq in tst.qs;

   postcondition:
      (*
       * A TestQuestion is in the output Test if it is not the input 
       * TestQuestion, but it is either in the input Test or has the
       *  same properties as the input question, but is not the input question.
       *)

      forall (tq':TestQuestion)
         if (tq' in tst'.qs) then ((tq' != tq) and ((tq' in tst.qs) or
         (forall (i:integer | i >= 1 and i <= #qdb.qs)
         ((tq'.qt != qdb.qs[i].qt) and (tq'.class = qdb.qs[i].class) and 
         (tq'.author = qdb.qs[i].author) and 
         ((tq'.time + tp.qtv.v >= qdb.qs[i].time) or
         (tq'.time - tp.qtv.v <= qdb.qs[i].time)) and
         ((tq'.diff + tp.df.v >= qdb.qs[i].diff) or 
         (tq'.diff - tp.df.v <= qdb.qs[i].diff)) and
         (tq'.t = qdb.qs[i].t) and
            forall (j:integer | j >= 1 and j <= #tq'.keywords)
			   tq'.keywords[j] in qdb.qs[i].keywords))));

   description: (*A suitable replacement for tq is found in qdb
      and is then applied to Test.
   *);
end ReplaceQuestion;

end TestPackage;