"""
RESTful view classes for presenting Deis API objects.
"""
# pylint: disable=R0901,R0904

from __future__ import unicode_literals
import json

from Crypto.PublicKey import RSA
from django.contrib.auth.models import AnonymousUser, User
from django.db.utils import IntegrityError
from django.utils import timezone
from rest_framework import permissions, status, viewsets
from rest_framework.authentication import BaseAuthentication
from rest_framework.generics import get_object_or_404
from rest_framework.response import Response
from rest_framework.status import HTTP_201_CREATED, HTTP_400_BAD_REQUEST

from api import models
from api import serializers


class AnonymousAuthentication(BaseAuthentication):

    def authenticate(self, request):
        """
        Authenticate the request and return a two-tuple of (user, token).
        """
        user = AnonymousUser()
        return user, None


class IsAnonymous(permissions.BasePermission):
    """
    Object-level permission to allow anonymous users.
    """

    def has_permission(self, request, view):
        """
        Return `True` if permission is granted, `False` otherwise.
        """
        if type(request.user) == AnonymousUser:
            return True
        return False


class IsOwner(permissions.BasePermission):
    """
    Object-level permission to allow only owners of an object to access it.
    Assumes the model instance has an `owner` attribute.
    """

    def has_object_permission(self, request, view, obj):
        if hasattr(obj, 'owner'):
            return obj.owner == request.user
        elif hasattr(obj, 'formation'):
            return obj.formation.owner == request.user
        else:
            return False


class UserRegistrationView(viewsets.GenericViewSet,
                           viewsets.mixins.CreateModelMixin):

    model = User

    authentication_classes = (AnonymousAuthentication,)
    permission_classes = (IsAnonymous,)
    serializer_class = serializers.UserSerializer

    def post_save(self, user, created=False):
        """Seed both `Providers` and `Flavors` after registration."""
        if created:
            models.Provider.objects.seed(user)
            models.Flavor.objects.seed(user)

    def pre_save(self, obj):
        """Replicate UserManager.create_user functionality."""
        now = timezone.now()
        obj.last_login = now
        obj.date_joined = now
        obj.email = User.objects.normalize_email(obj.email)
        obj.set_password(obj.password)


class OwnerViewSet(viewsets.ModelViewSet):
    """Scope views to an `owner` attribute."""

    permission_classes = (permissions.IsAuthenticated, IsOwner)

    def pre_save(self, obj):
        obj.owner = self.request.user

    def get_queryset(self, **kwargs):
        """Filter all querysets by an `owner` attribute.
        """
        return self.model.objects.filter(owner=self.request.user)


class KeyViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Key`."""

    model = models.Key
    serializer_class = serializers.KeySerializer
    lookup_field = 'id'

    def post_save(self, obj, created=False, **kwargs):
        """Publish all Formations when a Key is saved so gitosis stays updated.
        """
        models.Formation.objects.publish()

    def destroy(self, request, **kwargs):
        """Publish all Formations when a Key is destroyed so gitosis
        stays updated.
        """
        resp = super(KeyViewSet, self).destroy(self, request, **kwargs)
        models.Formation.objects.publish()
        return resp


class ProviderViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Provider`."""

    model = models.Provider
    serializer_class = serializers.ProviderSerializer
    lookup_field = 'id'


class FlavorViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Flavor`."""

    model = models.Flavor
    serializer_class = serializers.FlavorSerializer
    lookup_field = 'id'

    def create(self, request, **kwargs):
        request._data = request.DATA.copy()
        # set default cloud-init configuration
        if not 'init' in request.DATA:
            request.DATA['init'] = models.FlavorManager().load_cloud_config_base()
        return viewsets.ModelViewSet.create(self, request, **kwargs)


class FormationViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Formtion`."""

    model = models.Formation
    serializer_class = serializers.FormationSerializer
    lookup_field = 'id'

    def create(self, request, **kwargs):
        request._data = request.DATA.copy()
        try:
            return OwnerViewSet.create(self, request, **kwargs)
        except IntegrityError:
            return Response('Formation with this Id already exists.',
                            status=HTTP_400_BAD_REQUEST)

    def post_save(self, formation, created=False, **kwargs):
        if created:
            config = models.Config.objects.create(
                version=1, owner=formation.owner, formation=formation, values={})
            models.Release.objects.create(
                version=1, owner=formation.owner, formation=formation, config=config)
        # update gitosis
        models.Formation.objects.publish()

    def scale_layers(self, request, **kwargs):
        new_structure = {}
        try:
            for target, count in request.DATA.items():
                new_structure[target] = int(count)
        except ValueError:
            return Response('Invalid scaling format', status=HTTP_400_BAD_REQUEST)
        # check for empty credentials
        for p in models.Provider.objects.filter(owner=request.user):
            if p.creds:
                break
        else:
            return Response('No provider credentials available', status=HTTP_400_BAD_REQUEST)
        formation = self.get_object()
        formation.layers.update(new_structure)
        try:
            databag = formation.scale_layers()
        except models.ScalingError as e:
            return Response(str(e), status=status.HTTP_400_BAD_REQUEST)
        except models.Layer.DoesNotExist as e:
            return Response(str(e), status=status.HTTP_400_BAD_REQUEST)
        return Response(databag, status=status.HTTP_200_OK,
                        content_type='application/json')

    def scale_containers(self, request, **kwargs):
        new_structure = {}
        try:
            for target, count in request.DATA.items():
                new_structure[target] = int(count)
        except ValueError:
            return Response('Invalid scaling format', status=HTTP_400_BAD_REQUEST)
        formation = self.get_object()
        formation.containers.update(new_structure)
        try:
            databag = formation.scale_containers()
        except models.ScalingError as e:
            return Response(str(e), status=status.HTTP_400_BAD_REQUEST)
        return Response(databag, status=status.HTTP_200_OK,
                        content_type='application/json')

    def balance(self, request, **kwargs):
        formation = self.get_object()
        databag = formation.balance()
        return Response(databag, status=status.HTTP_200_OK,
                        content_type='application/json')

    def calculate(self, request, **kwargs):
        formation = self.get_object()
        databag = formation.calculate()
        return Response(databag, status=status.HTTP_200_OK,
                        content_type='application/json')

    def converge(self, request, **kwargs):
        formation = self.get_object()
        databag = formation.converge(formation.calculate())
        return Response(databag, status=status.HTTP_200_OK,
                        content_type='application/json')

    def destroy(self, request, **kwargs):
        formation = self.get_object()
        formation.destroy()
        formation.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class FormationLayerViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Layer`."""

    model = models.Layer
    serializer_class = serializers.LayerSerializer

    def get_queryset(self, **kwargs):
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        return self.model.objects.filter(owner=self.request.user, formation=formation)

    def get_object(self, *args, **kwargs):
        qs = self.get_queryset(**kwargs)
        obj = get_object_or_404(qs, id=self.kwargs['layer'])
        return obj

    def create(self, request, **kwargs):
        request._data = request.DATA.copy()
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        request.DATA['formation'] = formation.id
        if not 'ssh_private_key' in request.DATA and not 'ssh_public_key' in request.DATA:
            # SECURITY: figure out best way to get keys with proper entropy
            key = RSA.generate(2048)
            request.DATA['ssh_private_key'] = key.exportKey('PEM')
            request.DATA['ssh_public_key'] = key.exportKey('OpenSSH')
        try:
            return OwnerViewSet.create(self, request, **kwargs)
        except IntegrityError:
            return Response("Layer with this Id already exists.",
                            status=HTTP_400_BAD_REQUEST)

    def post_save(self, layer, created=False, **kwargs):
        if created:
            layer.build()

    def destroy(self, request, **kwargs):
        layer = self.get_object()
        layer.destroy()
        layer.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class FormationNodeViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Node`."""

    model = models.Node
    serializer_class = serializers.NodeSerializer

    def get_queryset(self, **kwargs):
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        return self.model.objects.filter(owner=self.request.user,
                                         formation=formation)

    def get_object(self, *args, **kwargs):
        qs = self.get_queryset(**kwargs)
        obj = get_object_or_404(qs, id=self.kwargs['node'])
        return obj

    def destroy(self, request, **kwargs):
        node = self.get_object()
        node.destroy()
        node.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class FormationContainerViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Container`."""

    model = models.Container
    serializer_class = serializers.ContainerSerializer

    def get_queryset(self, **kwargs):
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        return self.model.objects.filter(owner=self.request.user,
                                         formation=formation)

    def get_object(self, *args, **kwargs):
        qs = self.get_queryset(**kwargs)
        obj = qs.get(pk=self.kwargs['container'])
        return obj


class FormationImageViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Image`."""

    model = models.Release
    serializer_class = serializers.ReleaseSerializer

    def get_queryset(self, **kwargs):
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        return self.model.objects.filter(owner=self.request.user,
                                         formation=formation)

    def get_object(self, *args, **kwargs):
        qs = self.get_queryset(**kwargs)
        obj = qs.get(pk=self.kwargs['id'])
        return obj

    def reset_image(self, request, *args, **kwargs):
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        models.release_signal.send(sender=self, image=request.DATA['image'],
                                   formation=formation, user=self.request.user)
        return Response(status=HTTP_201_CREATED)


class FormationConfigViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Config`."""

    model = models.Config
    serializer_class = serializers.ConfigSerializer

    def get_queryset(self, **kwargs):
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        return self.model.objects.filter(owner=self.request.user,
                                         formation=formation)

    def get_object(self, *args, **kwargs):
        formation = models.Formation.objects.get(id=self.kwargs['id'])
        config = self.model.objects.filter(
            formation=formation).order_by('-created')[0]
        return config

    def post_save(self, obj, created=False):
        if created:
            models.release_signal.send(
                sender=self, config=obj, formation=obj.formation,
                user=self.request.user)
            # recalculate and converge after each config update
            databag = obj.formation.calculate()
            obj.formation.converge(databag)

    def create(self, request, *args, **kwargs):
        request._data = request.DATA.copy()
        # assume an existing config object exists
        obj = self.get_object()
        # increment version and use the same formation
        request.DATA['version'] = obj.version + 1
        request.DATA['formation'] = obj.formation
        # merge config values
        values = obj.values.copy()
        provided = json.loads(request.DATA['values'])
        values.update(provided)
        # remove config keys if we provided a null value
        [values.pop(k) for k, v in provided.items() if v is None]
        request.DATA['values'] = values
        return super(OwnerViewSet, self).create(request, *args, **kwargs)


class FormationBuildViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Build`."""

    model = models.Build
    serializer_class = serializers.BuildSerializer

    def get_queryset(self, **kwargs):
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        return self.model.objects.filter(owner=self.request.user,
                                         formation=formation)

    def get_object(self, *args, **kwargs):
        qs = self.get_queryset().order_by('-created')
        build = get_object_or_404(qs)
        return build

    def post_save(self, obj, created=False):
        if created:
            models.release_signal.send(
                sender=self, build=obj, formation=obj.formation,
                user=self.request.user)

    def create(self, request, *args, **kwargs):
        request._data = request.DATA.copy()
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        request.DATA['formation'] = formation
        return super(OwnerViewSet, self).create(request, *args, **kwargs)


class FormationReleaseViewSet(OwnerViewSet):
    """RESTful views for :class:`~api.models.Release`."""

    model = models.Release
    serializer_class = serializers.ReleaseSerializer

    def get_queryset(self, **kwargs):
        formation = models.Formation.objects.get(
            owner=self.request.user, id=self.kwargs['id'])
        return self.model.objects.filter(owner=self.request.user,
                                         formation=formation)

    def get_object(self, *args, **kwargs):
        formation = models.Formation.objects.get(id=self.kwargs['id'])
        release = self.model.objects.filter(
            formation=formation).order_by('-created')[0]
        return release