"""
Views for the core application. These are mainly shared, common views
used by multiple applications.

"""
import json

from django.contrib.auth.models import User
from django.http import HttpResponse
from django.shortcuts import render
from django.contrib.auth.decorators import login_required
from django.views.decorators.http import require_GET
from django.views.generic import TemplateView


@login_required
@require_GET
def markdown_help(request):
    """
    This view provides the Markdown help cheat sheet. It is expected
    to be called via AJAX.

    """
    return render(request, 'core/markdown_help.html')


def ajax_users(request):
    """
    If the user is authenticated, return a JSON array of strings of usernames
    whose names start with the 'q' GET parameter, limited by the 'limit' GET
    parameter. Only active usernames are returned.
    If the user is not authenticated, return an empty array.

    """
    q = request.GET.get('q', None)
    if q is None or not request.user.is_authenticated():
        return HttpResponse(json.dumps([]), content_type='application/json')

    limit = int(request.GET.get('limit', 10))
    users = User.objects.filter(is_active=True,
            username__istartswith=q).values_list('username', flat=True)[:limit]
    return HttpResponse(json.dumps(list(users)), content_type='application/json')


class FixedView(TemplateView):
    """
    For displaying our "fixed" views generated with the custom command
    make_fixed_page.

    """
    template_name = 'fixed/base.html'
    title = ''
    content_template = ''

    def get_context_data(self, **kwargs):
        context = super(FixedView, self).get_context_data(**kwargs)
        context['title'] = self.title
        context['content_template'] = self.content_template
        return context