#
# This file is part of FreedomBox.
#
# 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, either version 3 of the
# License, or (at your option) any later version.
#
# 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 <http://www.gnu.org/licenses/>.
#
"""
Main FreedomBox views.
"""

import time

from django.contrib import messages
from django.core.exceptions import ImproperlyConfigured
from django.http import Http404, HttpResponseRedirect
from django.template.response import TemplateResponse
from django.urls import reverse
from django.utils.http import is_safe_url
from django.utils.translation import ugettext as _
from django.views.generic import TemplateView
from django.views.generic.edit import FormView
from stronghold.decorators import public

from plinth import package
from plinth.app import App
from plinth.daemon import app_is_running
from plinth.modules.config import get_advanced_mode
from plinth.translation import get_language_from_request, set_language

from . import forms, frontpage

REDIRECT_FIELD_NAME = 'next'


def _get_redirect_url_from_param(request):
    """Return the redirect URL from 'next' GET/POST param."""
    redirect_to = request.GET.get(REDIRECT_FIELD_NAME, '')
    redirect_to = request.POST.get(REDIRECT_FIELD_NAME, redirect_to)
    if is_safe_url(url=redirect_to, allowed_hosts={request.get_host()}):
        return redirect_to

    return reverse('index')


@public
def index(request):
    """Serve the main index page."""
    username = str(request.user) if request.user.is_authenticated else None
    shortcuts = frontpage.Shortcut.list(username)
    selected = request.GET.get('selected')

    selected_shortcut = [
        shortcut for shortcut in shortcuts if shortcut.component_id == selected
    ]
    selected_shortcut = selected_shortcut[0] if selected_shortcut else None

    return TemplateResponse(
        request, 'index.html', {
            'title': _('FreedomBox'),
            'shortcuts': shortcuts,
            'selected_shortcut': selected_shortcut,
        })


class AppsIndexView(TemplateView):
    """View for apps index"""
    template_name = 'apps.html'

    def get_context_data(self, *args, **kwargs):
        context = super().get_context_data(*args, **kwargs)
        context['show_disabled'] = True
        context['advanced_mode'] = get_advanced_mode()
        return context


def system_index(request):
    """Serve the system index page."""
    return TemplateResponse(request, 'system.html',
                            {'advanced_mode': get_advanced_mode()})


class LanguageSelectionView(FormView):
    """View for language selection"""
    form_class = forms.LanguageSelectionForm
    template_name = 'language-selection.html'

    def get_initial(self):
        """Return the initial values for the form."""
        return {'language': get_language_from_request(self.request)}

    def form_valid(self, form):
        """Set or reset the current language."""
        response = super().form_valid(form)
        set_language(self.request, response, form.cleaned_data['language'])
        return response

    def get_success_url(self):
        """Return the URL in the next parameter or home page."""
        return _get_redirect_url_from_param(self.request)


class AppView(FormView):
    """A generic view for configuring simple apps."""
    clients = []
    name = None
    # List of paragraphs describing the service
    description = ""
    form_class = forms.AppForm
    # Display the 'status' block of the app.html template
    # This block uses information from service.is_running. This method is
    # optional, so allow not showing this block here.
    show_status_block = True
    app_id = None
    template_name = 'app.html'
    manual_page = ''
    port_forwarding_info = None
    icon_filename = ''

    def __init__(self, *args, **kwargs):
        """Initialize the view."""
        super().__init__(*args, **kwargs)
        self._common_status = None

        if not self.name:
            raise ImproperlyConfigured('Missing name attribute')

    @property
    def success_url(self):
        return self.request.path

    @property
    def app(self):
        """Return the app for which this view is configured."""
        if not self.app_id:
            raise ImproperlyConfigured('Missing attribute: app_id')

        return App.get(self.app_id)

    def _get_common_status(self):
        """Return the status needed for form and template.

        Avoid multiple queries to expensive operations such as
        app.is_enabled().

        """
        if self._common_status:
            return self._common_status

        self._common_status = {'is_enabled': self.app.is_enabled()}
        return self._common_status

    def get_initial(self):
        """Return the status of the app to fill in the form."""
        return self._get_common_status()

    def form_valid(self, form):
        """Enable/disable a service and set messages."""
        old_status = form.initial
        new_status = form.cleaned_data

        if old_status['is_enabled'] == new_status['is_enabled']:
            # TODO: find a more reliable/official way to check whether the
            # request has messages attached.
            if not self.request._messages._queued_messages:
                messages.info(self.request, _('Setting unchanged'))
        else:
            if new_status['is_enabled']:
                self.app.enable()
                messages.success(self.request, _('Application enabled'))
            else:
                self.app.disable()
                messages.success(self.request, _('Application disabled'))

        return super().form_valid(form)

    def get_context_data(self, *args, **kwargs):
        """Add service to the context data."""
        context = super().get_context_data(*args, **kwargs)
        context.update(self._get_common_status())
        context['app'] = self.app
        context['app_id'] = self.app.app_id
        context['is_running'] = app_is_running(self.app)
        context['clients'] = self.clients
        context['name'] = self.name
        context['description'] = self.description
        context['has_diagnostics'] = self.app.has_diagnostics()
        context['show_status_block'] = self.show_status_block
        context['manual_page'] = self.manual_page
        context['port_forwarding_info'] = self.port_forwarding_info
        context['icon_filename'] = self.icon_filename

        from plinth.modules.firewall.components import Firewall
        context['firewall'] = self.app.get_components_of_type(Firewall)

        return context


class SetupView(TemplateView):
    """View to prompt and setup applications."""
    template_name = 'setup.html'
    name = 'None'
    # List of paragraphs describing the service
    description = []

    def get_context_data(self, **kwargs):
        """Return the context data rendering the template."""
        context = super(SetupView, self).get_context_data(**kwargs)
        setup_helper = self.kwargs['setup_helper']
        context['setup_helper'] = setup_helper

        # Reuse the value of setup_state throughout the view for consistency.
        context['setup_state'] = setup_helper.get_state()
        context['setup_current_operation'] = setup_helper.current_operation

        # Perform expensive operation only if needed
        if not context['setup_current_operation']:
            context[
                'package_manager_is_busy'] = package.is_package_manager_busy()

        context['name'] = self.name
        context['description'] = self.description

        return context

    def dispatch(self, request, *args, **kwargs):
        if request.method == 'POST':
            if 'install' in request.POST:
                # Handle installing/upgrading applications.
                # Start the application setup, and refresh the page every few
                # seconds to keep displaying the status.
                self.kwargs['setup_helper'].run_in_thread()

                # Give a moment for the setup process to start and show
                # meaningful status.
                time.sleep(1)
                response = self.render_to_response(self.get_context_data())
                # Post/Response/Get pattern for reloads
                response.status_code = 303
                return response

            if 'refresh-packages' in request.POST:
                # Refresh apt package lists
                package.refresh_package_lists()
                return self.render_to_response(self.get_context_data())

        return super(SetupView, self).dispatch(request, *args, **kwargs)


def notification_dismiss(request, id):
    """Dismiss a notification."""
    from .notification import Notification
    notes = Notification.list(key=id, user=request.user)
    if not notes:
        raise Http404

    notes[0].dismiss()

    return HttpResponseRedirect(_get_redirect_url_from_param(request))