# System library imports.
from os.path import basename

# Django imports.
from django.core.management.base import BaseCommand

# Local imports.
from exam.models import Question

def clear_questions():
    """Delete all questions from the database."""
    for question in Question.objects.all():
        question.delete()

def load_questions(filename):
    """Load questions from the given Python file.  The Python file should
    declare a list of name "questions" which define all the questions in pure 
    Python.
    """
    # Simply exec the given file and we are done.
    exec(open(filename).read())
    
    if 'questions' not in locals():
        msg = 'No variable named "questions" with the Questions in file.'
        raise NameError(msg)
    
    for question in questions:
        question.save()
    
class Command(BaseCommand):
    args = '<q_file1.py q_file2.py>'
    help = '''loads the questions from given Python files which declare the 
              questions in a list called "questions".'''
    
    def handle(self, *args, **options):
        """Handle the command."""
        # Delete existing stuff.
        clear_questions()
        
        # Load from files.
        for fname in args:
            self.stdout.write('Importing from {0} ... '.format(basename(fname)))
            load_questions(fname)
            self.stdout.write('Done\n')