import itertools
import json
from datetime import datetime
from operator import itemgetter

from django.conf import settings
from django.contrib.auth import logout as auth_logout
from django.contrib.auth.decorators import login_required
from django.contrib.auth.models import Permission
from django.contrib.auth.views import redirect_to_login
from django.contrib.contenttypes.models import ContentType
from django.db import transaction
from django.db.models import Count, Max, Min
from django.db.models.fields import DateField
from django.db.models.functions import Cast, ExtractYear
from django.http import Http404, HttpResponseRedirect, JsonResponse
from django.shortcuts import get_object_or_404, render
from django.urls import reverse
from django.utils import timezone
from django.utils.formats import date_format
from django.utils.functional import cached_property
from django.utils.safestring import mark_safe
from django.utils.translation import gettext as _, gettext_lazy
from django.views.generic import DetailView, ListView, TemplateView
from reversion import revisions

from judge.forms import ProfileForm, newsletter_id
from judge.models import Profile, Rating, Submission, Friend
from judge.performance_points import get_pp_breakdown
from judge.ratings import rating_class, rating_progress
from judge.utils.problems import contest_completed_ids, user_completed_ids
from judge.utils.ranker import ranker
from judge.utils.subscription import Subscription
from judge.utils.unicode import utf8text
from judge.utils.views import DiggPaginatorMixin, QueryStringSortMixin, TitleMixin, generic_message
from .contests import ContestRanking

__all__ = ['UserPage', 'UserAboutPage', 'UserProblemsPage', 'users', 'edit_profile']


def remap_keys(iterable, mapping):
    return [dict((mapping.get(k, k), v) for k, v in item.items()) for item in iterable]


class UserMixin(object):
    model = Profile
    slug_field = 'user__username'
    slug_url_kwarg = 'user'
    context_object_name = 'user'

    def render_to_response(self, context, **response_kwargs):
        return super(UserMixin, self).render_to_response(context, **response_kwargs)


class UserPage(TitleMixin, UserMixin, DetailView):
    template_name = 'user/user-base.html'

    def get_object(self, queryset=None):
        if self.kwargs.get(self.slug_url_kwarg, None) is None:
            return self.request.profile
        return super(UserPage, self).get_object(queryset)

    def dispatch(self, request, *args, **kwargs):
        if self.kwargs.get(self.slug_url_kwarg, None) is None:
            if not self.request.user.is_authenticated:
                return redirect_to_login(self.request.get_full_path())
        try:
            return super(UserPage, self).dispatch(request, *args, **kwargs)
        except Http404:
            return generic_message(request, _('No such user'), _('No user handle "%s".') %
                                   self.kwargs.get(self.slug_url_kwarg, None))

    def get_title(self):
        return (_('My account') if self.request.user == self.object.user else
                _('User %s') % self.object.user.username)

    def get_content_title(self):
        username = self.object.user.username
        css_class = self.object.css_class
        return mark_safe(f'<span class="{css_class}">{username}</span>')

    # TODO: the same code exists in problem.py, maybe move to problems.py?
    @cached_property
    def profile(self):
        if not self.request.user.is_authenticated:
            return None
        return self.request.profile

    @cached_property
    def in_contest(self):
        return self.profile is not None and self.profile.current_contest is not None

    def get_completed_problems(self):
        if self.in_contest:
            return contest_completed_ids(self.profile.current_contest)
        else:
            return user_completed_ids(self.profile) if self.profile is not None else ()

    def get_context_data(self, **kwargs):
        context = super(UserPage, self).get_context_data(**kwargs)

        context['followed'] = Friend.is_friend(self.request.profile, self.object)
        context['hide_solved'] = int(self.hide_solved)
        context['authored'] = self.object.authored_problems.filter(is_public=True, is_organization_private=False) \
                                  .order_by('code')

        rating = self.object.ratings.order_by('-contest__end_time')[:1]
        context['rating'] = rating[0] if rating else None

        context['rank'] = Profile.objects.filter(
            is_unlisted=False, performance_points__gt=self.object.performance_points,
        ).count() + 1

        if rating:
            context['rating_rank'] = Profile.objects.filter(
                is_unlisted=False, rating__gt=self.object.rating,
            ).count() + 1
            context['rated_users'] = Profile.objects.filter(is_unlisted=False, rating__isnull=False).count()
        context.update(self.object.ratings.aggregate(min_rating=Min('rating'), max_rating=Max('rating'),
                                                     contests=Count('contest')))
        return context

    def get(self, request, *args, **kwargs):
        self.hide_solved = request.GET.get('hide_solved') == '1' if 'hide_solved' in request.GET else False
        return super(UserPage, self).get(request, *args, **kwargs)


EPOCH = datetime(1970, 1, 1, tzinfo=timezone.utc)


class UserAboutPage(UserPage):
    template_name = 'user/user-about.html'

    def get_awards(self, ratings):
        result = {}

        sorted_ratings = sorted(ratings,
            key=lambda x: (x.rank, -x.contest.end_time.timestamp()))

        result['medals'] = [{
            'label': rating.contest.name,
            'ranking': rating.rank,
            'link': reverse('contest_ranking', args=(rating.contest.key,)) + '#!' + self.object.username,
            'date': date_format(rating.contest.end_time, _('M j, Y')),
        } for rating in sorted_ratings if rating.rank <= 3]

        num_awards = 0
        for i in result:
            num_awards += len(result[i])

        if num_awards == 0:
            result = None

        return result

    def get_context_data(self, **kwargs):
        context = super(UserAboutPage, self).get_context_data(**kwargs)
        ratings = context['ratings'] = self.object.ratings.order_by('-contest__end_time').select_related('contest') \
            .defer('contest__description')

        context['rating_data'] = mark_safe(json.dumps([{
            'label': rating.contest.name,
            'rating': rating.rating,
            'ranking': rating.rank,
            'link': reverse('contest_ranking', args=(rating.contest.key,)),
            'timestamp': (rating.contest.end_time - EPOCH).total_seconds() * 1000,
            'date': date_format(rating.contest.end_time, _('M j, Y, G:i')),
            'class': rating_class(rating.rating),
            'height': '%.3fem' % rating_progress(rating.rating),
        } for rating in ratings]))

        context['awards'] = self.get_awards(ratings)

        if ratings:
            user_data = self.object.ratings.aggregate(Min('rating'), Max('rating'))
            global_data = Rating.objects.aggregate(Min('rating'), Max('rating'))
            min_ever, max_ever = global_data['rating__min'], global_data['rating__max']
            min_user, max_user = user_data['rating__min'], user_data['rating__max']
            delta = max_user - min_user
            ratio = (max_ever - max_user) / (max_ever - min_ever) if max_ever != min_ever else 1.0
            context['max_graph'] = max_user + ratio * delta
            context['min_graph'] = min_user + ratio * delta - delta


        submissions = (
            self.object.submission_set
            .annotate(date_only=Cast('date', DateField()))
            .values('date_only').annotate(cnt=Count('id'))
        )

        context['submission_data'] = mark_safe(json.dumps({
            date_counts['date_only'].isoformat(): date_counts['cnt'] for date_counts in submissions
        }))
        context['submission_metadata'] = mark_safe(json.dumps({
            'min_year': (
                self.object.submission_set
                .annotate(year_only=ExtractYear('date'))
                .aggregate(min_year=Min('year_only'))['min_year']
            ),
        }))
        
        return context

    # follow/unfollow user
    def post(self, request, user, *args, **kwargs):
        try:
            if not request.profile:
                raise Exception('You have to login')
            if (request.profile.username == user):
                raise Exception('Cannot make friend with yourself')
            
            following_profile = Profile.objects.get(user__username=user)
            Friend.toggle_friend(request.profile, following_profile)
        finally:
            return HttpResponseRedirect(request.path_info)


class UserProblemsPage(UserPage):
    template_name = 'user/user-problems.html'

    def get_context_data(self, **kwargs):
        context = super(UserProblemsPage, self).get_context_data(**kwargs)

        result = Submission.objects.filter(user=self.object, points__gt=0, problem__is_public=True,
                                           problem__is_organization_private=False) \
            .exclude(problem__in=self.get_completed_problems() if self.hide_solved else []) \
            .values('problem__id', 'problem__code', 'problem__name', 'problem__points', 'problem__group__full_name') \
            .distinct().annotate(points=Max('points')).order_by('problem__group__full_name', 'problem__code')

        def process_group(group, problems_iter):
            problems = list(problems_iter)
            points = sum(map(itemgetter('points'), problems))
            return {'name': group, 'problems': problems, 'points': points}

        context['best_submissions'] = [
            process_group(group, problems) for group, problems in itertools.groupby(
                remap_keys(result, {
                    'problem__code': 'code', 'problem__name': 'name', 'problem__points': 'total',
                    'problem__group__full_name': 'group',
                }), itemgetter('group'))
        ]
        breakdown, has_more = get_pp_breakdown(self.object, start=0, end=10)
        context['pp_breakdown'] = breakdown
        context['pp_has_more'] = has_more

        return context


class UserPerformancePointsAjax(UserProblemsPage):
    template_name = 'user/pp-table-body.html'

    def get_context_data(self, **kwargs):
        context = super(UserPerformancePointsAjax, self).get_context_data(**kwargs)
        try:
            start = int(self.request.GET.get('start', 0))
            end = int(self.request.GET.get('end', settings.DMOJ_PP_ENTRIES))
            if start < 0 or end < 0 or start > end:
                raise ValueError
        except ValueError:
            start, end = 0, 100
        breakdown, self.has_more = get_pp_breakdown(self.object, start=start, end=end)
        context['pp_breakdown'] = breakdown
        return context

    def get(self, request, *args, **kwargs):
        httpresp = super(UserPerformancePointsAjax, self).get(request, *args, **kwargs)
        httpresp.render()

        return JsonResponse({
            'results': utf8text(httpresp.content),
            'has_more': self.has_more,
        })


@login_required
def edit_profile(request):
    profile = Profile.objects.get(user=request.user)
    if profile.mute:
        raise Http404()
    if request.method == 'POST':
        form = ProfileForm(request.POST, instance=profile, user=request.user)
        if form.is_valid():
            with transaction.atomic(), revisions.create_revision():
                form.save()
                revisions.set_user(request.user)
                revisions.set_comment(_('Updated on site'))

            if newsletter_id is not None:
                try:
                    subscription = Subscription.objects.get(user=request.user, newsletter_id=newsletter_id)
                except Subscription.DoesNotExist:
                    if form.cleaned_data['newsletter']:
                        Subscription(user=request.user, newsletter_id=newsletter_id, subscribed=True).save()
                else:
                    if subscription.subscribed != form.cleaned_data['newsletter']:
                        subscription.update(('unsubscribe', 'subscribe')[form.cleaned_data['newsletter']])

            perm = Permission.objects.get(codename='test_site', content_type=ContentType.objects.get_for_model(Profile))
            if form.cleaned_data['test_site']:
                request.user.user_permissions.add(perm)
            else:
                request.user.user_permissions.remove(perm)

            return HttpResponseRedirect(request.path)
    else:
        form = ProfileForm(instance=profile, user=request.user)
        if newsletter_id is not None:
            try:
                subscription = Subscription.objects.get(user=request.user, newsletter_id=newsletter_id)
            except Subscription.DoesNotExist:
                form.fields['newsletter'].initial = False
            else:
                form.fields['newsletter'].initial = subscription.subscribed
        form.fields['test_site'].initial = request.user.has_perm('judge.test_site')

    tzmap = settings.TIMEZONE_MAP
    return render(request, 'user/edit-profile.html', {
        'require_staff_2fa': settings.DMOJ_REQUIRE_STAFF_2FA,
        'form': form, 'title': _('Edit profile'), 'profile': profile,
        'has_math_config': bool(settings.MATHOID_URL),
        'TIMEZONE_MAP': tzmap or 'http://momentjs.com/static/img/world.png',
        'TIMEZONE_BG': settings.TIMEZONE_BG if tzmap else '#4E7CAD',
    })


class UserList(QueryStringSortMixin, DiggPaginatorMixin, TitleMixin, ListView):
    model = Profile
    title = gettext_lazy('Leaderboard')
    context_object_name = 'users'
    template_name = 'user/list.html'
    paginate_by = 100
    all_sorts = frozenset(('points', 'problem_count', 'rating', 'performance_points'))
    default_desc = all_sorts
    default_sort = '-performance_points'

    def filter_friend_queryset(self, queryset):
        friends = list(self.request.profile.get_friends())
        ret = queryset.filter(user__username__in=friends)
        return ret

    def get_queryset(self):
        ret = Profile.objects.filter(is_unlisted=False).order_by(self.order, 'id').select_related('user') \
                .only('display_rank', 'user__username', 'points', 'rating', 'performance_points',
                      'problem_count')

        if (self.request.GET.get('friend') == 'true') and self.request.profile:
            ret = self.filter_friend_queryset(ret)
        return ret

    def get_context_data(self, **kwargs):
        context = super(UserList, self).get_context_data(**kwargs)
        context['users'] = ranker(context['users'], rank=self.paginate_by * (context['page_obj'].number - 1))
        context['first_page_href'] = '.'
        context.update(self.get_sort_context())
        context.update(self.get_sort_paginate_context())
        return context


user_list_view = UserList.as_view()


class FixedContestRanking(ContestRanking):
    contest = None

    def get_object(self, queryset=None):
        return self.contest


def users(request):
    if request.user.is_authenticated:
        participation = request.profile.current_contest
        if participation is not None:
            contest = participation.contest
            return FixedContestRanking.as_view(contest=contest)(request, contest=contest.key)
    return user_list_view(request)


def user_ranking_redirect(request):
    try:
        username = request.GET['handle']
    except KeyError:
        raise Http404()
    user = get_object_or_404(Profile, user__username=username)
    rank = Profile.objects.filter(is_unlisted=False, performance_points__gt=user.performance_points).count()
    rank += Profile.objects.filter(
        is_unlisted=False, performance_points__exact=user.performance_points, id__lt=user.id,
    ).count()
    page = rank // UserList.paginate_by
    return HttpResponseRedirect('%s%s#!%s' % (reverse('user_list'), '?page=%d' % (page + 1) if page else '', username))


class UserLogoutView(TitleMixin, TemplateView):
    template_name = 'registration/logout.html'
    title = 'You have been successfully logged out.'

    def post(self, request, *args, **kwargs):
        auth_logout(request)
        return HttpResponseRedirect(request.get_full_path())