from collections import defaultdict
import json
import logging
import urllib
import itertools

from functools import partial

from functools import partial

from django.conf import settings
from django.core.context_processors import csrf
from django.core.urlresolvers import reverse
from django.contrib.auth.models import User
from django.contrib.auth.decorators import login_required
from django.http import Http404, HttpResponse
from django.shortcuts import redirect
from mitxmako.shortcuts import render_to_response, render_to_string
#from django.views.decorators.csrf import ensure_csrf_cookie
from django_future.csrf import ensure_csrf_cookie
from django.views.decorators.cache import cache_control

from module_render import toc_for_course, get_module, get_section
from models import StudentModuleCache
from student.models import UserProfile

from multicourse import multicourse_settings

from django_comment_client.utils import get_discussion_title

from xmodule.modulestore import Location
from xmodule.modulestore.search import path_to_location
from xmodule.modulestore.exceptions import InvalidLocationError, ItemNotFoundError, NoPathToItem
from xmodule.modulestore.django import modulestore
from xmodule.course_module import CourseDescriptor

from util.cache import cache, cache_if_anonymous
from student.models import UserTestGroup, CourseEnrollment
from courseware import grades
from courseware.courses import check_course


import comment_client




log = logging.getLogger("mitx.courseware")

template_imports = {'urllib': urllib}


def user_groups(user):
    if not user.is_authenticated():
        return []

    # TODO: Rewrite in Django
    key = 'user_group_names_{user.id}'.format(user=user)
    cache_expiration = 60 * 60  # one hour

    # Kill caching on dev machines -- we switch groups a lot
    group_names = cache.get(key)

    if group_names is None:
        group_names = [u.name for u in UserTestGroup.objects.filter(users=user)]
        cache.set(key, group_names, cache_expiration)

    return group_names


def format_url_params(params):
    return [urllib.quote(string.replace(' ', '_'))
            if string is not None else None
            for string in params]


@ensure_csrf_cookie
@cache_if_anonymous
def courses(request):
    # TODO: Clean up how 'error' is done.

    # filter out any courses that errored.
    courses = [c for c in modulestore().get_courses()
               if isinstance(c, CourseDescriptor)]
    courses = sorted(courses, key=lambda course: course.number)
    universities = defaultdict(list)
    for course in courses:
        universities[course.org].append(course)

    return render_to_response("courses.html", {'universities': universities})


@cache_control(no_cache=True, no_store=True, must_revalidate=True)
def gradebook(request, course_id):
    if 'course_admin' not in user_groups(request.user):
        raise Http404
    course = check_course(course_id)

    student_objects = User.objects.all()[:100]
    student_info = []

    for student in student_objects:
        student_module_cache = StudentModuleCache(student, course)
        course, _, _, _ = get_module(request.user, request, course.location, student_module_cache)
        student_info.append({
            'username': student.username,
            'id': student.id,
            'email': student.email,
            'grade_info': grades.grade_sheet(student, course, student_module_cache),
            'realname': UserProfile.objects.get(user=student).name
        })

    return render_to_response('gradebook.html', {'students': student_info, 'course': course})


@login_required
@cache_control(no_cache=True, no_store=True, must_revalidate=True)
def profile(request, course_id, student_id=None):
    ''' User profile. Show username, location, etc, as well as grades .
        We need to allow the user to change some of these settings .'''
    course = check_course(course_id)

    if student_id is None:
        student = request.user
    else:
        if 'course_admin' not in user_groups(request.user):
            raise Http404
        student = User.objects.get(id=int(student_id))

    user_info = UserProfile.objects.get(user=student)

    student_module_cache = StudentModuleCache(request.user, course)
    course_module, _, _, _ = get_module(request.user, request, course.location, student_module_cache)

    context = {'name': user_info.name,
               'username': student.username,
               'location': user_info.location,
               'language': user_info.language,
               'email': student.email,
               'course': course,
               'format_url_params': format_url_params,
               'csrf': csrf(request)['csrf_token']
               }
    context.update(grades.grade_sheet(student, course_module, course.grader, student_module_cache))

    return render_to_response('profile.html', context)


def render_accordion(request, course, chapter, section):
    ''' Draws navigation bar. Takes current position in accordion as
        parameter.

        If chapter and section are '' or None, renders a default accordion.

        Returns (initialization_javascript, content)'''

    # TODO (cpennington): do the right thing with courses
    toc = toc_for_course(request.user, request, course, chapter, section)

    active_chapter = 1
    for i in range(len(toc)):
        if toc[i]['active']:
            active_chapter = i

    context = dict([('active_chapter', active_chapter),
                    ('toc', toc),
                    ('course_name', course.title),
                    ('course_id', course.id),
                    ('format_url_params', format_url_params),
                    ('csrf', csrf(request)['csrf_token'])] + template_imports.items())
    return render_to_string('accordion.html', context)


@ensure_csrf_cookie
@cache_control(no_cache=True, no_store=True, must_revalidate=True)
def index(request, course_id, chapter=None, section=None,
          position=None):
    ''' Displays courseware accordion, and any associated content.
    If course, chapter, and section aren't all specified, just returns
    the accordion.  If they are specified, returns an error if they don't
    point to a valid module.

    Arguments:

     - request    : HTTP request
     - course     : coursename (str)
     - chapter    : chapter name (str)
     - section    : section name (str)
     - position   : position in module, eg of <sequential> module (str)

    Returns:

     - HTTPresponse
    '''
    course = check_course(course_id)

    def clean(s):
        ''' Fixes URLs -- we convert spaces to _ in URLs to prevent
        funny encoding characters and keep the URLs readable.  This undoes
        that transformation.
        '''
        return s.replace('_', ' ') if s is not None else None

    chapter = clean(chapter)
    section = clean(section)

    try:
        context = {
            'csrf': csrf(request)['csrf_token'],
            'accordion': render_accordion(request, course, chapter, section),
            'COURSE_TITLE': course.title,
            'course': course,
            'init': '',
            'content': ''
            }

        look_for_module = chapter is not None and section is not None
        if look_for_module:
            # TODO (cpennington): Pass the right course in here

            section_descriptor = get_section(course, chapter, section)
            if section_descriptor is not None:
                student_module_cache = StudentModuleCache(request.user,
                                                          section_descriptor)
                module, _, _, _ = get_module(request.user, request,
                                             section_descriptor.location,
                                             student_module_cache)
                context['content'] = module.get_html()
            else:
                log.warning("Couldn't find a section descriptor for course_id '{0}',"
                            "chapter '{1}', section '{2}'".format(
                                course_id, chapter, section))
        else:
            if request.user.is_staff:
                # Add a list of all the errors...
                context['course_errors'] = modulestore().get_item_errors(course.location)

        result = render_to_response('courseware.html', context)
    except:
        # In production, don't want to let a 500 out for any reason
        if settings.DEBUG:
            raise
        else:
            log.exception("Error in index view: user={user}, course={course},"
                          " chapter={chapter} section={section}"
                          "position={position}".format(
                              user=request.user,
                              course=course,
                              chapter=chapter,
                              section=section,
                              position=position
                              ))
            try:
                result = render_to_response('courseware-error.html', {})
            except:
                result = HttpResponse("There was an unrecoverable error")

    return result


@ensure_csrf_cookie
def jump_to(request, location):
    '''
    Show the page that contains a specific location.

    If the location is invalid, return a 404.

    If the location is valid, but not present in a course, ?

    If the location is valid, but in a course the current user isn't registered for, ?
        TODO -- let the index view deal with it?
    '''
    # Complain if the location isn't valid
    try:
        location = Location(location)
    except InvalidLocationError:
        raise Http404("Invalid location")

    # Complain if there's not data for this location
    try:
        (course_id, chapter, section, position) = path_to_location(modulestore(), location)
    except ItemNotFoundError:
        raise Http404("No data at this location: {0}".format(location))
    except NoPathToItem:
        raise Http404("This location is not in any class: {0}".format(location))

    # Rely on index to do all error handling
    return index(request, course_id, chapter, section, position)

@ensure_csrf_cookie
def course_info(request, course_id):
    '''
    Display the course's info.html, or 404 if there is no such course.

    Assumes the course_id is in a valid format.
    '''
    course = check_course(course_id)

    return render_to_response('info.html', {'course': course})

@ensure_csrf_cookie
@cache_if_anonymous
def course_about(request, course_id):
    def registered_for_course(course, user):
        if user.is_authenticated():
            return CourseEnrollment.objects.filter(user=user, course_id=course.id).exists()
        else:
            return False
    course = check_course(course_id, course_must_be_open=False)
    registered = registered_for_course(course, request.user)
    return render_to_response('portal/course_about.html', {'course': course, 'registered': registered})


@ensure_csrf_cookie
@cache_if_anonymous
def university_profile(request, org_id):
    all_courses = sorted(modulestore().get_courses(), key=lambda course: course.number)
    valid_org_ids = set(c.org for c in all_courses)
    if org_id not in valid_org_ids:
        raise Http404("University Profile not found for {0}".format(org_id))

    # Only grab courses for this org...
    courses = [c for c in all_courses if c.org == org_id]
    context = dict(courses=courses, org_id=org_id)
    template_file = "university_profile/{0}.html".format(org_id).lower()

    return render_to_response(template_file, context)

def render_notifications(request, course, notifications):
    context = {
        'notifications': notifications,
        'get_discussion_title': partial(get_discussion_title, request=request, course=course),
        'course': course,
    }
    return render_to_string('notifications.html', context)

@login_required
def news(request, course_id):
    course = check_course(course_id)

    notifications = comment_client.get_notifications(request.user.id)

    context = {
        'course': course,
        'content': render_notifications(request, course, notifications),
    }

    return render_to_response('news.html', context)
