from django.conf import settings

from django.contrib.auth import REDIRECT_FIELD_NAME

from django.contrib.auth.models import Permission

from django.contrib.contenttypes.models import ContentType

from django.shortcuts import get_object_or_404

from django.core.urlresolvers import reverse

from django.http import HttpResponseRedirect

from django.utils.http import urlquote

from django.db.models import Q

from piston.utils import rc

import logging

from django.core.cache import cache

from hashlib import sha1

from cm.models import *

from cm import cm_settings

from cm.exception import UnauthorizedException

from cm.cm_settings import DECORATED_CREATORS

def get_request_user(request):

    if request and request.user and not request.user.is_anonymous():

        user = request.user

    else:

        user = None

    return user

## Permission functions

class FakeRequest(object):

    def __init__(self, user):

        self.user = user

def user_has_perm(user, perm_name, text=None):

    return has_perm(FakeRequest(user),perm_name, text)

def has_perm(request, perm_name, text=None):

    # bypass sec if NO_SECURITY

    if cm_settings.NO_SECURITY:

        return True

    # make sure perm exist

    assert Permission.objects.get(codename=perm_name)

    user = get_request_user(request)

    key = sha1(str((settings.SITE_URL, 'has_perm', (user, myself, text, perm_name)))).hexdigest()

    val = cache.get(key)

    if val != None:

      return val

    if user and user.is_staff:

        cache.set(key, True)

        return True

    if not text:

        ret = UserRole.objects.filter(user=user, text=None).filter(Q(role__permissions__codename__exact=perm_name)).count() != 0

        cache.set(key, ret)

        return ret

    else:

        # local role only ADDS permissions:

        # either a global or a local role with appropriate permissions

        #return UserRole.objects.filter(user=user).filter(Q(text=text) | Q(text=None)).filter(Q(role__permissions__codename__exact=perm_name)).count() != 0

        # local role OVERRIDES global role:

        if UserRole.objects.filter(Q(user=user),Q(text=text),~Q(role=None)): # if non void local role

            ret = UserRole.objects.filter(user=user).filter(text=text).filter(Q(role__permissions__codename__exact=perm_name)).count() != 0

            cache.set(key, ret)

            return ret

        else:

            # local role for anon users

            # OR global role for anon users

            # OR global role for this user

            ret = UserRole.objects.filter(Q(user=user) | Q(user=None)).filter(Q(text=None) | Q(text=text)).filter(Q(role__permissions__codename__exact=perm_name)).count() != 0            

            cache.set(key, ret)

            return ret

            #return UserRole.objects.filter(user=user).filter(text=None).filter(Q(role__permissions__codename__exact=perm_name)).count() != 0

def has_own_perm(request, perm_name, text, comment):

    user = get_request_user(request)

    if not user:

        return False

    # bypass sec if NO_SECURITY

    if cm_settings.NO_SECURITY:

        return True

    # make sure perm exist

    assert Permission.objects.get(codename=perm_name)

    key = sha1(str((settings.SITE_URL, 'has_own_perm', (user, myself, text, comment, perm_name)))).hexdigest()

    val = cache.get(key)

    if val != None:

      return val

    # 2 special cases for comment own edition:

    # 1

    # if perm = can_edit_own_comment and 

    # text is a priori moderated and

    # comment is approved and

    # don't have moderation rights and

    if comment and comment.state == 'approved' and \

       perm_name == 'can_edit_comment_own' and \

       text.last_text_version.mod_posteriori == False and \

       not has_perm(request, 'can_manage_text', text=text):

        cache.set(key, False)

        return False

    # 2       

    # if perm = can_edit_own_comment and and 

    # text is a posteriori moderated and

    # there is a reply

    # don't have moderation rights and

    if comment and comment.state == 'approved' and \

       perm_name == 'can_edit_comment_own' and \

       text.last_text_version.mod_posteriori == True and \

       comment.comment_set.count() != 0 and \

       not has_perm(request, 'can_manage_text', text=text):

        cache.set(key, False)

        return False

    actual_own_user = False

    if comment.user == request.user:

      if DECORATED_CREATORS:

          actual_own_user = True

      else:

        actual_own_user = True

    ret = (actual_own_user and has_perm(request, perm_name, text=text)) 

    cache.set(key, ret)

    return ret

def is_authenticated(request):

    # We customize this to be able to monkey patch it if needed

    return request.user.is_authenticated()

## Content access functions

def get_texts_with_perm(request, perm_name):

    assert Permission.objects.get(codename=perm_name)

    user = get_request_user(request)

    key = sha1(str((settings.SITE_URL, 'get_texts_with_perm', (user, perm_name)))).hexdigest()

    val = cache.get(key)

    if val != None:

      return val

    if user and user.is_staff:

        ret = Text.objects.all()

        cache.set(key, ret)

        return ret

    # local role only ADDS permissions:

    ## global perm

    # if UserRole.objects.filter(text=None).filter(role__permissions__codename__exact=perm_name).filter(Q(user=user) | Q(user=None) ).count() != 0:

    #    return Text.objects.all().distinct()

    ## only texts with role with perm

    #else:

    #    return Text.objects.filter(Q(userrole__role__permissions__codename__exact=perm_name), Q(userrole__user=user) | Q(userrole__user=None)).distinct()

    # local role OVERRIDES global role:

    texts_with_local_role = Text.objects.filter(userrole__in=UserRole.objects.filter(Q(user=user) | Q(user=None)).filter(~Q(role=None)))

    #Text.objects.filter(Q(userrole__user=user) & ~Q(userrole__role=None))

    texts_without_local_role = Text.objects.exclude(id__in=texts_with_local_role)

    texts_with_local_role_with_perm = Text.objects.filter(id__in=texts_with_local_role).filter(Q(userrole__role__permissions__codename__exact=perm_name), Q(userrole__user=user) | Q(userrole__user=None)).distinct()

    # global perm?

    if UserRole.objects.filter(text=None).filter(role__permissions__codename__exact=perm_name).filter(Q(user=user) | Q(user=None) ).count() != 0:    

        texts_without_local_role_with_perm = Text.objects.filter(id__in=texts_without_local_role)

    else:

        texts_without_local_role_with_perm = []

    ids = set([t.id for t in texts_with_local_role_with_perm]).union(set([t.id for t in texts_without_local_role_with_perm]))

    ret = Text.objects.filter(id__in=ids)

    cache.set(key, ret)

    return ret

def get_viewable_comments(request, comments, text, order_by=('created',)):

    """

    Get comments visibles by user

    comments: queryset

    """

    user = get_request_user(request)

    key = sha1(str((settings.SITE_URL, 'get_viewable_comments', (user, myself, text, comments)))).hexdigest()

    val = cache.get(key)

    if val != None:

      return val

    if user and has_perm(request, 'can_view_unapproved_comment', text=text):

        ret = list(comments.order_by(*order_by))

        cache.set(key, ret)

        return ret

    else:

        # Fetch role_model to process specific behaviour for role_teacher model

        from cm.models import ApplicationConfiguration

        role_model = ApplicationConfiguration.get_key('workspace_role_model')

        if has_perm(request, 'can_view_approved_comment', text=text):

            visible_comments = comments.filter(state = 'approved').order_by(*order_by)

            # filter comments with a non visible (i.e. moderated) comment in the above thread 

            comments_thread_viewable = [c for c in visible_comments if c.is_thread_full_visible()]

            # for role_teacher role model, do not show 'individual student' comments

            if (role_model == 'teacher'):

              unfiltered_comments = list(comments_thread_viewable)

              for c in unfiltered_comments:

                if c.user_id and c.user_id != 1:

                  try:

                    userrole = UserRole.objects.get(user=c.user, text=text)

                  except:

                    userrole = UserRole.objects.get(user=None, text=None)

                  if userrole.role_id == None:

                    role = c.user.get_profile().global_userrole().role

                  else:

                    role = userrole.role

                  if role.name == 'Individual student':

                    comments_thread_viewable.remove(c)

            cache.set(key, comments_thread_viewable)

            return comments_thread_viewable 

        elif user and has_perm(request, 'can_view_comment_own', text=text):

            if DECORATED_CREATORS:

              visible_comments = comments.filter(name=myself).order_by(*order_by)

            else:

              visible_comments = comments.filter(user=user).order_by(*order_by)

            # for role_teacher role model, add 'teacher' comments

            if (role_model == 'teacher'):

              with_teachers = []

              for u in list(User.objects.filter(userrole__role__name = 'Teacher')):

                with_teachers.append(u.id)

              # add admin and current user

              admin =  User.objects.get(id=1)

              with_teachers.append(admin.id)

              if DECORATED_CREATORS:

                visible_comments = comments.filter(Q(user__id__in=with_teachers) | Q(name=myself)).order_by(*order_by)

              else:

                with_teachers.append(user.id)

                visible_comments = comments.filter(user__id__in=with_teachers).order_by(*order_by)

            # filter comments with a non visible (i.e. moderated) comment in the above thread 

            comments_thread_viewable = [c for c in visible_comments if c.is_thread_full_visible(own_user=user)]

            cache.set(key, comments_thread_viewable)

            return comments_thread_viewable                

        else:

            cache.set(key, [])

            return []

def get_viewable_activities(request=None, act_types={}, text=None):

    """

    Get activities user in request is allowed to see

    """

    from cm.security import has_perm, get_texts_with_perm, get_viewable_comments

    selected_activities = reduce(list.__add__,[Activity.VIEWABLE_ACTIVITIES[k] for k in act_types.keys() if act_types[k]], [])

    activities = Activity.objects.filter(type__in=selected_activities)

    if text:

        activities = activities.filter(text=text)

    if not has_perm(request, 'can_manage_workspace'):

        texts = get_texts_with_perm(request, 'can_view_text')

        activities = activities.filter(Q(text__in=texts))

        comments = [] 

        [comments.extend(get_viewable_comments(request, t.last_text_version.comment_set.all(), t)) for t in texts]

        activities = activities.filter(Q(comment__in=comments) | Q(comment=None))

    return activities.order_by('-created')

# won't need to be overridden, should it be moved to another file ? 

def list_viewable_comments(request, comments_list, text):

    ret = []

    for comment in comments_list :

        ret += [comment] + list_viewable_comments(request, get_viewable_comments(request, comment.comment_set, text), text)

    return ret

# decorators (simple wrappers around above functions)

def has_global_perm(perm_name, must_be_logged_in=False, redirect_field_name=REDIRECT_FIELD_NAME):

    def _dec(view_func):

        def _check_global_perm(request, *args, **kwargs):

            if must_be_logged_in and not is_authenticated(request):

                raise UnauthorizedException('Should be logged in')

            if has_perm(request, perm_name, text=None): 

                return view_func(request, *args, **kwargs)

            raise UnauthorizedException('No global perm %s' % perm_name)

        _check_global_perm.__doc__ = view_func.__doc__

        _check_global_perm.__dict__ = view_func.__dict__

        return _check_global_perm

    return _dec    

def has_perm_on_text_api(perm_name, must_be_logged_in=False, redirect_field_name=REDIRECT_FIELD_NAME):    

    return _has_perm_on_text(perm_name, must_be_logged_in, redirect_field_name, api=True)

def has_perm_on_text(perm_name, must_be_logged_in=False, redirect_field_name=REDIRECT_FIELD_NAME, api=False):

    return _has_perm_on_text(perm_name, must_be_logged_in, redirect_field_name, api)

def _has_perm_on_text(perm_name, must_be_logged_in=False, redirect_field_name=REDIRECT_FIELD_NAME, api=False):    

    """

    decorator protection checking for perm for logged in user

    force logged in (i.e. redirect to connection screen if not if must_be_logged_in 

    """    

    def _dec(view_func):

        def _check_local_perm(request, *args, **kwargs):

            if cm_settings.NO_SECURITY:

                return view_func(request, *args, **kwargs)

            if must_be_logged_in and not is_authenticated(request):

                if not api:

                    raise UnauthorizedException('Should be logged in')

                else:

                    return rc.FORBIDDEN

            if 'key' in kwargs: 

                text = get_object_or_404(Text, key=kwargs['key'])                

            else:

                raise Exception('no security check possible')

            # in api, the view has an object as first parameter, request is args[0]

            if not api:                

                req = request

            else:                    

                req = args[0]     

            if has_perm(req, perm_name, text=text): 

                return view_func(request, *args, **kwargs)

            #else:

                # TODO: (? useful ?) if some user have the perm and not logged-in : redirect to login

                #if not request.user.is_authenticated() and number_has_perm_on_text(permission, text_id) > 0:

                #    return HttpResponseRedirect('%s?%s=%s' % (login_url, redirect_field_name, urlquote(request.get_full_path())))                    

            # else : unauthorized

            if not api:

                raise UnauthorizedException('No perm %s' % perm_name)

            else:

                return rc.FORBIDDEN

        _check_local_perm.__doc__ = view_func.__doc__

        _check_local_perm.__dict__ = view_func.__dict__

        return _check_local_perm

    return _dec

def has_perm_on_comment(perm_name):    

    """

    decorator protection checking for perm for logged in user on to comment

    perm_name: 'virtual' permission name 

    """    

    def _dec(view_func):

        def _check_local_perm(request, *args, **kwargs):

            if cm_settings.NO_SECURITY:

                return view_func(request, *args, **kwargs)

            if 'key' in kwargs: 

                text = get_object_or_404(Text, key=kwargs['key'])