import logging

from django.urls import re_path
from django.contrib.auth.decorators import permission_required
from rest_framework import routers, viewsets, serializers, status
from rest_framework.decorators import api_view, permission_classes
from rest_framework.permissions import IsAuthenticated
from rest_framework.response import Response
from asgiref.sync import async_to_sync
from channels.layers import get_channel_layer

from core.settings import MAIL_DOMAIN
from mail.api_v2 import AttachmentSerializer
from mail.models import Email
from mail.protocol import send_smtp, make_reply, collect_references
from notify_sessions.models import SystemEvent
from tickets.models import IssueThread, Comment, STATE_CHOICES


class IssueSerializer(serializers.ModelSerializer):
    timeline = serializers.SerializerMethodField()
    last_activity = serializers.SerializerMethodField()

    class Meta:
        model = IssueThread
        fields = ('id', 'timeline', 'name', 'state', 'assigned_to', 'last_activity', 'uuid')
        read_only_fields = ('id', 'timeline', 'last_activity', 'uuid')

    def to_internal_value(self, data):
        ret = super().to_internal_value(data)
        if 'state' in data:
            ret['state'] = data['state']
        return ret

    def validate(self, attrs):
        if 'state' in attrs:
            if attrs['state'] not in [x[0] for x in STATE_CHOICES]:
                raise serializers.ValidationError('invalid state')
        return attrs

    @staticmethod
    def get_last_activity(self):
        try:
            last_state_change = self.state_changes.order_by('-timestamp').first().timestamp \
                if self.state_changes.count() > 0 else None
            last_comment = self.comments.order_by('-timestamp').first().timestamp if self.comments.count() > 0 else None
            last_mail = self.emails.order_by('-timestamp').first().timestamp if self.emails.count() > 0 else None
            args = [x for x in [last_state_change, last_comment, last_mail] if x is not None]
            return max(args)
        except AttributeError:
            return None

    @staticmethod
    def get_timeline(obj):
        timeline = []
        for comment in obj.comments.all():
            timeline.append({
                'type': 'comment',
                'id': comment.id,
                'timestamp': comment.timestamp,
                'comment': comment.comment,
            })
        for state_change in obj.state_changes.all():
            timeline.append({
                'type': 'state',
                'id': state_change.id,
                'timestamp': state_change.timestamp,
                'state': state_change.state,
            })
        for email in obj.emails.all():
            timeline.append({
                'type': 'mail',
                'id': email.id,
                'timestamp': email.timestamp,
                'sender': email.sender,
                'recipient': email.recipient,
                'subject': email.subject,
                'body': email.body,
                'attachments': AttachmentSerializer(email.attachments.all(), many=True).data,
            })
        return sorted(timeline, key=lambda x: x['timestamp'])

    def get_queryset(self):
        return IssueThread.objects.all().order_by('-last_activity')


class IssueViewSet(viewsets.ModelViewSet):
    serializer_class = IssueSerializer
    queryset = IssueThread.objects.all()


class CommentSerializer(serializers.ModelSerializer):

    def validate(self, attrs):
        if 'comment' not in attrs or attrs['comment'] == '':
            raise serializers.ValidationError('comment cannot be empty')
        return attrs

    class Meta:
        model = Comment
        fields = ('id', 'comment', 'timestamp', 'issue_thread')


class CommentViewSet(viewsets.ModelViewSet):
    serializer_class = CommentSerializer
    queryset = Comment.objects.all()


@api_view(['POST'])
@permission_classes([IsAuthenticated])
@permission_required('tickets.add_issuethread', raise_exception=True)
def reply(request, pk):
    issue = IssueThread.objects.get(pk=pk)
    # email = issue.reply(request.data['body']) # TODO evaluate if this is a useful abstraction
    references = collect_references(issue)
    first_mail = Email.objects.filter(issue_thread=issue, recipient__endswith='@' + MAIL_DOMAIN).order_by(
        'timestamp').first()
    if not first_mail:
        return Response({'status': 'error', 'message': 'no previous mail found, reply would not make sense.'}, status=status.HTTP_400_BAD_REQUEST)
    mail = Email.objects.create(
        issue_thread=issue,
        sender=first_mail.recipient,
        recipient=first_mail.sender,
        subject=f'Re: {issue.name} [#{issue.short_uuid()}]',
        body=request.data['message'],
        in_reply_to=first_mail.reference,
    )
    log = logging.getLogger('mail.log')
    async_to_sync(send_smtp)(make_reply(mail, references), log)

    return Response({'status': 'ok'}, status=status.HTTP_201_CREATED)


@api_view(['POST'])
@permission_classes([IsAuthenticated])
@permission_required('tickets.add_issuethread_manual', raise_exception=True)
def manual_ticket(request):
    if 'name' not in request.data:
        return Response({'status': 'error', 'message': 'missing name'}, status=status.HTTP_400_BAD_REQUEST)
    if 'sender' not in request.data:
        return Response({'status': 'error', 'message': 'missing sender'}, status=status.HTTP_400_BAD_REQUEST)
    if 'recipient' not in request.data:
        return Response({'status': 'error', 'message': 'missing recipient'}, status=status.HTTP_400_BAD_REQUEST)
    if 'body' not in request.data:
        return Response({'status': 'error', 'message': 'missing body'}, status=status.HTTP_400_BAD_REQUEST)

    issue = IssueThread.objects.create(
        name=request.data['name'],
        manually_created=True,
    )
    email = Email.objects.create(
        issue_thread=issue,
        sender=request.data['sender'],
        recipient=request.data['recipient'],
        subject=request.data['name'],
        body=request.data['body'],
    )
    systemevent = SystemEvent.objects.create(type='email received', reference=email.id)
    channel_layer = get_channel_layer()
    async_to_sync(channel_layer.group_send)(
        'general', {"type": "generic.event", "name": "send_message_to_frontend", "event_id": systemevent.id,
                    "message": "email received"}
    )

    return Response(IssueSerializer(issue).data, status=status.HTTP_201_CREATED)


class StateSerializer(serializers.Serializer):
    text = serializers.SerializerMethodField()
    value = serializers.SerializerMethodField()

    def get_text(self, obj):
        return obj['text']

    def get_value(self, obj):
        return obj['value']


@api_view(['GET'])
@permission_classes([IsAuthenticated])
def get_available_states(request):
    def get_state_choices():
        for state in STATE_CHOICES:
            yield {'value': list(state)[0], 'text': list(state)[1]}

    return Response(get_state_choices())


@api_view(['POST'])
@permission_classes([IsAuthenticated])
@permission_required('tickets.add_comment', raise_exception=True)
def add_comment(request, pk):
    issue = IssueThread.objects.get(pk=pk)
    if 'comment' not in request.data or request.data['comment'] == '':
        return Response({'status': 'error', 'message': 'missing comment'}, status=status.HTTP_400_BAD_REQUEST)
    comment = Comment.objects.create(
        issue_thread=issue,
        comment=request.data['comment'],
    )
    systemevent = SystemEvent.objects.create(type='comment added', reference=comment.id)
    channel_layer = get_channel_layer()
    async_to_sync(channel_layer.group_send)(
        'general', {"type": "generic.event", "name": "send_message_to_frontend", "event_id": systemevent.id,
                    "message": "comment added"}
    )
    return Response(CommentSerializer(comment).data, status=status.HTTP_201_CREATED)


router = routers.SimpleRouter()
router.register(r'tickets', IssueViewSet, basename='issues')
router.register(r'comments', CommentViewSet, basename='comments')

urlpatterns = ([
                   re_path(r'^tickets/(?P<pk>\d+)/reply/$', reply, name='reply'),
                   re_path(r'^tickets/(?P<pk>\d+)/comment/$', add_comment, name='add_comment'),
                   re_path(r'^tickets/manual/$', manual_ticket, name='manual_ticket'),
                   re_path(r'^tickets/states/$', get_available_states, name='get_available_states'),
               ] + router.urls)