Exercise feature in video lessons

Exercise is same as quiz except for following differences:
- no time limit
- no marks weightage
- no instruction page
- skip denied for a particular time

An attribute 'is_exercise' in Quiz determines whether the quiz is
exercise or not.
Questions contains 'min_time' attribute.
For an exercise a question cannot be skipped for an allotted minimum
time, after which either django or JavaScript makes Next button
available.

Implementation is as such due to complexity of our existing views and
templates.
Also, after min_time, same question with Next button is available to
move on, assuming that solution is present in the video.

1 files changed, 108 insertions, 22 deletions

diff --git a/yaksh/views.py b/yaksh/views.py
index 483b87c..302ef9e 100644
--- a/yaksh/views.py
+++ b/yaksh/views.py
@@ -46,7 +46,7 @@ from yaksh.forms import (
     UserRegisterForm, UserLoginForm, QuizForm, QuestionForm,
     RandomQuestionForm, QuestionFilterForm, CourseForm, ProfileForm,
     UploadFileForm, get_object_form, FileForm, QuestionPaperForm, LessonForm,
-    LessonFileForm, LearningModuleForm
+    LessonFileForm, LearningModuleForm, ExerciseForm
 )
 from .settings import URL_ROOT
 from .file_utils import extract_files, is_csv
@@ -327,6 +327,56 @@ def add_quiz(request, quiz_id=None, course_id=None):
 
 
 @login_required
+@email_verified
+def add_exercise(request, quiz_id=None, course_id=None):
+    user = request.user
+    ci = RequestContext(request)
+    if not is_moderator(user):
+        raise Http404('You are not allowed to view this course !')
+    if quiz_id:
+        quiz = get_object_or_404(Quiz, pk=quiz_id)
+        if quiz.creator != user and not course_id:
+            raise Http404('This quiz does not belong to you')
+    else:
+        quiz = None
+    if course_id:
+        course = get_object_or_404(Course, pk=course_id)
+        if not course.is_creator(user) and not course.is_teacher(user):
+            raise Http404('This quiz does not belong to you')
+
+    context = {}
+    if request.method == "POST":
+        form = ExerciseForm(request.POST, instance=quiz)
+        if form.is_valid():
+            if quiz is None:
+                form.instance.creator = user
+            quiz = form.save(commit=False)
+            quiz.is_exercise = True
+            quiz.time_between_attempts = 0
+            quiz.weightage = 0
+            quiz.allow_skip = False
+            quiz.attempts_allowed = -1
+            quiz.duration = 1000
+            quiz.pass_criteria = 0
+            quiz.save()
+
+            if not course_id:
+                return my_redirect("/exam/manage/courses/all_quizzes/")
+            else:
+                return my_redirect("/exam/manage/courses/")
+
+    else:
+        quiz = Quiz.objects.get(id=quiz_id) if quiz_id else None
+        form = ExerciseForm(instance=quiz)
+        context["quiz_id"] = quiz_id
+        context["course_id"] = course_id
+    context["form"] = form
+    return my_render_to_response(
+        'yaksh/add_exercise.html', context, context_instance=ci
+    )
+
+
+@login_required
 @has_profile
 @email_verified
 def prof_manage(request, msg=None):
@@ -460,7 +510,8 @@ def start(request, questionpaper_id=None, attempt_num=None, course_id=None,
     if last_attempt and last_attempt.is_attempt_inprogress():
         return show_question(
             request, last_attempt.current_question(), last_attempt,
-            course_id=course_id, module_id=module_id
+            course_id=course_id, module_id=module_id,
+            previous_question=last_attempt.current_question()
         )
     # allowed to start
     if not quest_paper.can_attempt_now(user, course_id):
@@ -474,7 +525,7 @@ def start(request, questionpaper_id=None, attempt_num=None, course_id=None,
         attempt_number = 1
     else:
         attempt_number = last_attempt.attempt_number + 1
-    if attempt_num is None:
+    if attempt_num is None and not quest_paper.quiz.is_exercise:
         context = {
             'user': user,
             'questionpaper': quest_paper,
@@ -496,7 +547,7 @@ def start(request, questionpaper_id=None, attempt_num=None, course_id=None,
         if new_paper.status ==  'inprogress':
             return show_question(request, new_paper.current_question(),
                                  new_paper, course_id=course_id,
-                                 module_id=module_id
+                                 module_id=module_id, previous_question=None
                                  )
         else:
             msg = 'You have already finished the quiz!'
@@ -505,27 +556,42 @@ def start(request, questionpaper_id=None, attempt_num=None, course_id=None,
 @login_required
 @email_verified
 def show_question(request, question, paper, error_message=None, notification=None,
-                  course_id=None, module_id=None):
+                  course_id=None, module_id=None, previous_question=None):
     """Show a question if possible."""
     user = request.user
+    quiz = paper.question_paper.quiz
+    quiz_type = 'Exam'
+    can_skip = False
+    if previous_question:
+        delay_time = paper.time_left_on_question(previous_question)
+    else:
+        delay_time = paper.time_left_on_question(question)
+
+    if previous_question and quiz.is_exercise:
+        if delay_time <= 0:
+            can_skip = True
+        question = previous_question
     if not question:
         msg = 'Congratulations!  You have successfully completed the quiz.'
         return complete(
             request, msg, paper.attempt_number, paper.question_paper.id,
             course_id=course_id, module_id=module_id
         )
-    if not paper.question_paper.quiz.active:
+    if not quiz.active:
         reason = 'The quiz has been deactivated!'
         return complete(
             request, reason, paper.attempt_number, paper.question_paper.id,
             module_id=module_id
         )
-    if paper.time_left() <= 0:
-        reason = 'Your time is up!'
-        return complete(
-            request, reason, paper.attempt_number, paper.question_paper.id,
-            course_id, module_id=module_id
-        )
+    if not quiz.is_exercise:
+        if paper.time_left() <= 0:
+            reason = 'Your time is up!'
+            return complete(
+                request, reason, paper.attempt_number, paper.question_paper.id,
+                course_id, module_id=module_id
+            )
+    else:
+        quiz_type = 'Exercise'
     if question in paper.questions_answered.all():
         notification = (
             'You have already attempted this question successfully'
@@ -539,13 +605,17 @@ def show_question(request, question, paper, error_message=None, notification=Non
     context = {
         'question': question,
         'paper': paper,
+        'quiz': quiz,
         'error_message': error_message,
         'test_cases': test_cases,
         'files': files,
         'notification': notification,
         'last_attempt': question.snippet.encode('unicode-escape'),
         'course': course,
-        'module': module
+        'module': module,
+        'can_skip': can_skip,
+        'delay_time': delay_time,
+        'quiz_type': quiz_type
     }
     answers = paper.get_previous_answers(question)
     if answers:
@@ -568,6 +638,11 @@ def skip(request, q_id, next_q=None, attempt_num=None, questionpaper_id=None,
     )
     question = get_object_or_404(Question, pk=q_id)
 
+    if paper.question_paper.quiz.is_exercise:
+        if paper.time_left_on_question(question) <= 0:
+            paper.start_time = timezone.now()
+            paper.save()
+
     if request.method == 'POST' and question.type == 'code':
         if not paper.answers.filter(question=question, correct=True).exists():
             user_code = request.POST.get('answer')
@@ -612,7 +687,8 @@ def check(request, q_id, attempt_num=None, questionpaper_id=None,
                 msg = "Please enter an Integer Value"
                 return show_question(
                     request, current_question, paper, notification=msg,
-                    course_id=course_id, module_id=module_id
+                    course_id=course_id, module_id=module_id,
+                    previous_question=current_question
                 )
         elif current_question.type == 'float':
             try:
@@ -621,7 +697,8 @@ def check(request, q_id, attempt_num=None, questionpaper_id=None,
                 msg = "Please enter a Float Value"
                 return show_question(request, current_question,
                                      paper, notification=msg,
-                                     course_id=course_id, module_id=module_id)
+                                     course_id=course_id, module_id=module_id,
+                                     previous_question=current_question)
         elif current_question.type == 'string':
             user_answer = str(request.POST.get('answer'))
 
@@ -635,7 +712,8 @@ def check(request, q_id, attempt_num=None, questionpaper_id=None,
                 msg = "Please upload assignment file"
                 return show_question(
                     request, current_question, paper, notification=msg,
-                    course_id=course_id, module_id=module_id
+                    course_id=course_id, module_id=module_id,
+                    previous_question=current_question
                 )
             for fname in assignment_filename:
                 assignment_files = AssignmentUpload.objects.filter(
@@ -663,14 +741,16 @@ def check(request, q_id, attempt_num=None, questionpaper_id=None,
                 paper.answers.add(new_answer)
                 next_q = paper.add_completed_question(current_question.id)
                 return show_question(request, next_q, paper,
-                                     course_id=course_id, module_id=module_id)
+                                     course_id=course_id, module_id=module_id,
+                                     previous_question=current_question)
         else:
             user_answer = request.POST.get('answer')
         if not user_answer:
             msg = "Please submit a valid answer."
             return show_question(
                 request, current_question, paper, notification=msg,
-                course_id=course_id, module_id=module_id
+                course_id=course_id, module_id=module_id,
+                previous_question=current_question
             )
         if current_question in paper.get_questions_answered()\
          and current_question.type not in ['code', 'upload']:
@@ -703,16 +783,19 @@ def check(request, q_id, attempt_num=None, questionpaper_id=None,
                         result)
                 return show_question(request, next_question, paper,
                                      error_message, course_id=course_id,
-                                     module_id=module_id)
+                                     module_id=module_id,
+                                     previous_question=current_question)
             else:
                 return JsonResponse(result)
         else:
             next_question, error_message, paper = _update_paper(request, uid, result)
             return show_question(request, next_question, paper, error_message,
-                                 course_id=course_id, module_id=module_id)
+                                 course_id=course_id, module_id=module_id,
+                                 previous_question=current_question)
     else:
         return show_question(request, current_question, paper,
-                             course_id=course_id, module_id=module_id)
+                             course_id=course_id, module_id=module_id,
+                             previous_question=current_question)
 
 
 @csrf_exempt
@@ -731,9 +814,12 @@ def get_result(request, uid, course_id, module_id):
         next_question, error_message, paper = _update_paper(request, uid,
                                                             result
                                                             )
+        answer = Answer.objects.get(id=uid)
+        current_question = answer.question
         if result.get('success'):
             return show_question(request, next_question, paper, error_message,
-                                 course_id=course_id, module_id=module_id)
+                                 course_id=course_id, module_id=module_id,
+                                 previous_question=current_question)
         else:
             with open(template_path) as f:
                 template_data = f.read()