#
# This file is part of pretix (Community Edition).
#
# Copyright (C) 2014-2020  Raphael Michel and contributors
# Copyright (C) 2020-today pretix GmbH and contributors
#
# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
# Public License as published by the Free Software Foundation in version 3 of the License.
#
# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
# this file, see <https://pretix.eu/about/en/license>.
#
# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
# <https://www.gnu.org/licenses/>.
#
import json
from contextlib import contextmanager

from django.conf import settings
from django.contrib import messages
from django.contrib.auth import (
    BACKEND_SESSION_KEY, get_user_model, load_backend, login,
)
from django.contrib.auth.mixins import LoginRequiredMixin
from django.db import transaction
from django.shortcuts import get_object_or_404, redirect
from django.urls import reverse
from django.utils.crypto import get_random_string
from django.utils.functional import cached_property
from django.utils.translation import gettext_lazy as _
from django.views import View
from django.views.generic import ListView, TemplateView
from django_otp.plugins.otp_static.models import StaticDevice
from hijack import signals

from pretix.base.auth import get_auth_backends
from pretix.base.models import User
from pretix.base.services.mail import SendMailException
from pretix.control.forms.filter import UserFilterForm
from pretix.control.forms.users import UserEditForm
from pretix.control.permissions import AdministratorPermissionRequiredMixin
from pretix.control.views import CreateView, UpdateView
from pretix.control.views.user import RecentAuthenticationRequiredMixin


def get_used_backend(request):
    # vendored from hijack/views.py
    backend_str = request.session[BACKEND_SESSION_KEY]
    backend = load_backend(backend_str)
    return backend


@contextmanager
def keep_session_age(session):
    # vendored from hijack/views.py
    try:
        session_expiry = session["_session_expiry"]
    except KeyError:
        yield
    else:
        yield
        session["_session_expiry"] = session_expiry


class UserListView(AdministratorPermissionRequiredMixin, ListView):
    template_name = 'pretixcontrol/users/index.html'
    context_object_name = 'users'
    paginate_by = 30

    def get_queryset(self):
        qs = User.objects.all()
        if self.filter_form.is_valid():
            qs = self.filter_form.filter_qs(qs)
        return qs

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['filter_form'] = self.filter_form
        return ctx

    @cached_property
    def filter_form(self):
        return UserFilterForm(data=self.request.GET)


class UserEditView(AdministratorPermissionRequiredMixin, RecentAuthenticationRequiredMixin, UpdateView):
    template_name = 'pretixcontrol/users/form.html'
    context_object_name = 'user'
    form_class = UserEditForm

    def get_object(self, queryset=None):
        return get_object_or_404(User, pk=self.kwargs.get("id"))

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['teams'] = self.object.teams.select_related('organizer')
        b = get_auth_backends()
        ctx['backend'] = (
            b[self.object.auth_backend].verbose_name if self.object.auth_backend in b else self.object.auth_backend
        )
        return ctx

    def get_success_url(self):
        return reverse('control:users.edit', kwargs=self.kwargs)

    @transaction.atomic
    def form_valid(self, form):
        messages.success(self.request, _('Your changes have been saved.'))

        data = {}
        for k in form.changed_data:
            if k != 'new_pw_repeat':
                if 'new_pw' == k:
                    data['new_pw'] = True
                else:
                    data[k] = form.cleaned_data[k]

        sup = super().form_valid(form)

        if 'require_2fa' in form.changed_data and form.cleaned_data['require_2fa']:
            self.object.log_action('pretix.user.settings.2fa.enabled', user=self.request.user)
        elif 'require_2fa' in form.changed_data and not form.cleaned_data['require_2fa']:
            self.object.log_action('pretix.user.settings.2fa.disabled', user=self.request.user)
        self.object.log_action('pretix.user.settings.changed', user=self.request.user, data=data)

        return sup


class UserResetView(AdministratorPermissionRequiredMixin, RecentAuthenticationRequiredMixin, View):

    def get(self, request, *args, **kwargs):
        return redirect(reverse('control:users.edit', kwargs=self.kwargs))

    def post(self, request, *args, **kwargs):
        self.object = get_object_or_404(User, pk=self.kwargs.get("id"))
        try:
            self.object.send_password_reset()
        except SendMailException:
            messages.error(request, _('There was an error sending the mail. Please try again later.'))
            return redirect(self.get_success_url())

        self.object.log_action('pretix.control.auth.user.forgot_password.mail_sent',
                               user=request.user)
        messages.success(request, _('We sent out an email containing further instructions.'))
        return redirect(self.get_success_url())

    def get_success_url(self):
        return reverse('control:users.edit', kwargs=self.kwargs)


class UserEmergencyTokenView(AdministratorPermissionRequiredMixin, RecentAuthenticationRequiredMixin, View):

    def get(self, request, *args, **kwargs):
        return redirect(reverse('control:users.edit', kwargs=self.kwargs))

    def post(self, request, *args, **kwargs):
        self.object = get_object_or_404(User, pk=self.kwargs.get("id"))

        d, __ = StaticDevice.objects.get_or_create(user=self.object, name='emergency')
        token = d.token_set.create(token=get_random_string(length=12, allowed_chars='1234567890'))
        self.object.log_action('pretix.user.settings.2fa.emergency', user=self.request.user)
        self.object.send_security_notice([
            _('A two-factor emergency code has been generated by a system administrator. This will usually happen '
              'if you lost access to your two-factor credentials and requested a reset of the credentials.')
        ])

        messages.success(request, _(
            'The emergency token for this user is "{token}". It can only be used once. Please make sure to transmit '
            'this code only over an authenticated channel (other than email, if possible). Any previous emergency '
            'tokens for this user remain active.'
        ).format(
            token=token.token
        ))

        return redirect(self.get_success_url())

    def get_success_url(self):
        return reverse('control:users.edit', kwargs=self.kwargs)


class UserAnonymizeView(AdministratorPermissionRequiredMixin, RecentAuthenticationRequiredMixin, TemplateView):
    template_name = "pretixcontrol/users/anonymize.html"

    def get_context_data(self, **kwargs):
        ctx = super().get_context_data(**kwargs)
        ctx['user'] = get_object_or_404(User, pk=self.kwargs.get("id"))
        return ctx

    def post(self, request, *args, **kwargs):
        self.object = get_object_or_404(User, pk=self.kwargs.get("id"))
        self.object.log_action('pretix.user.anonymized',
                               user=request.user)
        self.object.email = "{}.{}@disabled.pretix.eu".format(self.object.pk, self.object.auth_backend)
        self.object.fullname = ""
        self.object.is_active = False
        self.object.notifications_send = False
        self.object.auth_backend = 'anonymized'
        self.object.auth_backend_identifier = None
        self.object.save()
        for le in self.object.all_logentries.filter(action_type="pretix.user.settings.changed"):
            d = le.parsed_data
            if 'email' in d:
                d['email'] = '█'
            if 'fullname' in d:
                d['fullname'] = '█'
            le.data = json.dumps(d)
            le.shredded = True
            le.save(update_fields=['data', 'shredded'])

        return redirect(reverse('control:users.edit', kwargs=self.kwargs))


class UserImpersonateView(AdministratorPermissionRequiredMixin, RecentAuthenticationRequiredMixin, View):

    def get(self, request, *args, **kwargs):
        return redirect(reverse('control:users.edit', kwargs=self.kwargs))

    def post(self, request, *args, **kwargs):
        self.object = get_object_or_404(User, pk=self.kwargs.get("id"))
        self.request.user.log_action('pretix.control.auth.user.impersonated',
                                     user=request.user,
                                     data={
                                         'other': self.kwargs.get("id"),
                                         'other_email': self.object.email
                                     })
        oldkey = request.session.session_key

        hijacker = request.user
        hijacked = self.object

        hijack_history = request.session.get("hijack_history", [])
        hijack_history.append(request.user._meta.pk.value_to_string(hijacker))

        backend = get_used_backend(request)
        backend = f"{backend.__module__}.{backend.__class__.__name__}"

        with signals.no_update_last_login(), keep_session_age(request.session):
            login(request, hijacked, backend=backend)

        request.session["hijack_history"] = hijack_history

        signals.hijack_started.send(
            sender=None,
            request=request,
            hijacker=hijacker,
            hijacked=hijacked,
        )

        request.session['hijacker_session'] = oldkey
        return redirect(reverse('control:index'))


class UserImpersonateStopView(LoginRequiredMixin, View):

    def post(self, request, *args, **kwargs):
        impersonated = request.user

        hijs = request.session['hijacker_session']
        hijack_history = request.session.get("hijack_history", [])
        hijacked = request.user
        user_pk = hijack_history.pop()
        hijacker = get_object_or_404(get_user_model(), pk=user_pk)
        backend = get_used_backend(request)
        backend = f"{backend.__module__}.{backend.__class__.__name__}"
        with signals.no_update_last_login(), keep_session_age(request.session):
            login(request, hijacker, backend=backend)

        request.session["hijack_history"] = hijack_history

        signals.hijack_ended.send(
            sender=None,
            request=request,
            hijacker=hijacker,
            hijacked=hijacked,
        )

        ss = request.user.get_active_staff_session(hijs)
        if ss:
            request.session.save()
            ss.session_key = request.session.session_key
            ss.save()

        request.user.log_action('pretix.control.auth.user.impersonate_stopped',
                                user=request.user,
                                data={
                                    'other': impersonated.pk,
                                    'other_email': impersonated.email
                                })
        return redirect(reverse('control:index'))


class UserCreateView(AdministratorPermissionRequiredMixin, RecentAuthenticationRequiredMixin, CreateView):
    template_name = 'pretixcontrol/users/create.html'
    context_object_name = 'user'
    form_class = UserEditForm

    def get_form(self, form_class=None):
        f = super().get_form(form_class)
        f.fields['new_pw'].required = True
        f.fields['new_pw_repeat'].required = True
        return f

    def get_initial(self):
        i = super().get_initial()
        i['timezone'] = settings.TIME_ZONE
        return i

    def get_success_url(self):
        return reverse('control:users')

    def form_valid(self, form):
        messages.success(self.request, _('The new user has been created.'))
        return super().form_valid(form)