from __future__ import absolute_import, unicode_literals

from django.conf import settings
from django.contrib import messages
from django.core.exceptions import PermissionDenied
from django.core.urlresolvers import reverse
from django.http import HttpResponseRedirect
from django.shortcuts import get_object_or_404, render_to_response
from django.template import RequestContext
from django.utils.translation import ugettext_lazy as _

from documents.models import Document
from documents.views import DocumentListView

from acls.models import AccessControlList
from common.utils import encapsulate
from common.views import SingleObjectCreateView
from permissions import Permission

from .exceptions import DocumentAlreadyCheckedOut, DocumentNotCheckedOut
from .forms import DocumentCheckoutForm
from .literals import STATE_LABELS
from .models import DocumentCheckout
from .permissions import (
    permission_document_checkin, permission_document_checkin_override,
    permission_document_checkout
)


class CheckoutDocumentView(SingleObjectCreateView):
    form_class = DocumentCheckoutForm

    def dispatch(self, request, *args, **kwargs):
        self.document = get_object_or_404(Document, pk=self.kwargs['pk'])

        try:
            Permission.check_permissions(request.user, [permission_document_checkout])
        except PermissionDenied:
            AccessControlList.objects.check_access(permission_document_checkout, request.user, self.document)

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

    def form_valid(self, form):
        try:
            instance = form.save(commit=False)
            instance.user = self.request.user
            instance.document = self.document
            instance.save()
        except DocumentAlreadyCheckedOut:
            messages.error(self.request, _('Document already checked out.'))
        except Exception as exception:
            messages.error(self.request, _('Error trying to check out document; %s') % exception)
        else:
            messages.success(self.request, _('Document "%s" checked out successfully.') % self.document)

        return HttpResponseRedirect(self.get_success_url())

    def get_extra_context(self):
        return {
            'object': self.document,
            'title': _('Check out document: %s') % self.document
        }

    def get_post_action_redirect(self):
        return reverse('checkouts:checkout_info', args=[self.document.pk])


class CheckoutListView(DocumentListView):
    def get_document_queryset(self):
        return DocumentCheckout.objects.checked_out_documents()

    extra_context = {
        'title': _('Documents checked out'),
        'hide_links': True,
        'extra_columns': [
            {'name': _('User'), 'attribute': encapsulate(lambda document: document.checkout_info().user.get_full_name() or document.checkout_info().user)},
            {'name': _('Checkout time and date'), 'attribute': encapsulate(lambda document: document.checkout_info().checkout_datetime)},
            {'name': _('Checkout expiration'), 'attribute': encapsulate(lambda document: document.checkout_info().expiration_datetime)},
        ],
    }


def checkout_info(request, document_pk):
    document = get_object_or_404(Document, pk=document_pk)
    try:
        Permission.check_permissions(request.user, [permission_document_checkout, permission_document_checkin])
    except PermissionDenied:
        AccessControlList.objects.check_access([permission_document_checkout, permission_document_checkin], request.user, document)

    paragraphs = [_('Document status: %s') % STATE_LABELS[document.checkout_state()]]

    if document.is_checked_out():
        checkout_info = document.checkout_info()
        paragraphs.append(_('User: %s') % (checkout_info.user.get_full_name() or checkout_info.user))
        paragraphs.append(_('Check out time: %s') % checkout_info.checkout_datetime)
        paragraphs.append(_('Check out expiration: %s') % checkout_info.expiration_datetime)
        paragraphs.append(_('New versions allowed: %s') % (_('Yes') if not checkout_info.block_new_version else _('No')))

    return render_to_response('appearance/generic_template.html', {
        'paragraphs': paragraphs,
        'object': document,
        'title': _('Check out details for document: %s') % document
    }, context_instance=RequestContext(request))


def checkin_document(request, document_pk):
    document = get_object_or_404(Document, pk=document_pk)
    post_action_redirect = reverse('checkouts:checkout_info', args=[document.pk])

    previous = request.POST.get('previous', request.GET.get('previous', request.META.get('HTTP_REFERER', reverse(settings.LOGIN_REDIRECT_URL))))
    next = request.POST.get('next', request.GET.get('next', post_action_redirect if post_action_redirect else request.META.get('HTTP_REFERER', reverse(settings.LOGIN_REDIRECT_URL))))

    if not document.is_checked_out():
        messages.error(request, _('Document has not been checked out.'))
        return HttpResponseRedirect(previous)

    # If the user trying to check in the document is the same as the check out
    # user just check for the normal permission otherwise check for the forceful
    # checkin permission
    if document.checkout_info().user == request.user:
        try:
            Permission.check_permissions(request.user, [permission_document_checkin])
        except PermissionDenied:
            AccessControlList.objects.check_access(permission_document_checkin, request.user, document)
    else:
        try:
            Permission.check_permissions(request.user, [permission_document_checkin_override])
        except PermissionDenied:
            AccessControlList.objects.check_access(permission_document_checkin_override, request.user, document)

    if request.method == 'POST':
        try:
            document.check_in(user=request.user)
        except DocumentNotCheckedOut:
            messages.error(request, _('Document has not been checked out.'))
        except Exception as exception:
            messages.error(request, _('Error trying to check in document; %s') % exception)
        else:
            messages.success(request, _('Document "%s" checked in successfully.') % document)
            return HttpResponseRedirect(next)

    context = {
        'delete_view': False,
        'previous': previous,
        'next': next,
        'object': document,
    }

    if document.checkout_info().user != request.user:
        context['title'] = _('You didn\'t originally checked out this document.  Are you sure you wish to forcefully check in document: %s?') % document
    else:
        context['title'] = _('Are you sure you wish to check in document: %s?') % document

    return render_to_response('appearance/generic_confirm.html', context,
                              context_instance=RequestContext(request))