''' Endpoints for RSForm. '''
import json
from typing import Union, cast

import pyconcept
from django.db import transaction
from django.http import HttpResponse
from drf_spectacular.utils import extend_schema, extend_schema_view
from rest_framework import generics
from rest_framework import status as c
from rest_framework import views, viewsets
from rest_framework.decorators import action, api_view
from rest_framework.request import Request
from rest_framework.response import Response

from apps.library.models import AccessPolicy, LibraryItem, LibraryItemType, LocationHead
from apps.library.serializers import LibraryItemSerializer
from apps.users.models import User
from shared import messages as msg
from shared import permissions, utility

from .. import models as m
from .. import serializers as s
from .. import utils


@extend_schema(tags=['RSForm'])
@extend_schema_view()
class RSFormViewSet(viewsets.GenericViewSet, generics.ListAPIView, generics.RetrieveAPIView):
    ''' Endpoint: RSForm operations. '''
    queryset = LibraryItem.objects.filter(item_type=LibraryItemType.RSFORM)
    serializer_class = LibraryItemSerializer

    def _get_item(self) -> LibraryItem:
        return cast(LibraryItem, self.get_object())

    def get_permissions(self):
        ''' Determine permission class. '''
        if self.action in [
            'load_trs',
            'create_cst',
            'delete_multiple_cst',
            'rename_cst',
            'move_cst',
            'substitute',
            'restore_order',
            'reset_aliases',
            'produce_structure'
        ]:
            permission_list = [permissions.ItemEditor]
        elif self.action in [
            'contents',
            'details',
            'export_trs',
            'resolve',
            'check'
        ]:
            permission_list = [permissions.ItemAnyone]
        else:
            permission_list = [permissions.Anyone]
        return [permission() for permission in permission_list]

    @extend_schema(
        summary='create constituenta',
        tags=['Constituenta'],
        request=s.CstCreateSerializer,
        responses={
            c.HTTP_201_CREATED: s.NewCstResponse,
            c.HTTP_400_BAD_REQUEST: None,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['post'], url_path='create-cst')
    def create_cst(self, request: Request, pk):
        ''' Create new constituenta. '''
        schema = self._get_item()
        serializer = s.CstCreateSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        data = serializer.validated_data
        if 'insert_after' in data and data['insert_after'] is not None:
            try:
                insert_after = m.Constituenta.objects.get(pk=data['insert_after'])
            except LibraryItem.DoesNotExist:
                return Response(status=c.HTTP_404_NOT_FOUND)
        else:
            insert_after = None
        new_cst = m.RSForm(schema).create_cst(data, insert_after)

        schema.refresh_from_db()
        response = Response(
            status=c.HTTP_201_CREATED,
            data={
                'new_cst': s.CstSerializer(new_cst).data,
                'schema': s.RSFormParseSerializer(schema).data
            }
        )
        response['Location'] = new_cst.get_absolute_url()
        return response

    @extend_schema(
        summary='produce the structure of a given constituenta',
        tags=['RSForm'],
        request=s.CstTargetSerializer,
        responses={
            c.HTTP_200_OK: s.NewMultiCstResponse,
            c.HTTP_400_BAD_REQUEST: None,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['patch'], url_path='produce-structure')
    def produce_structure(self, request: Request, pk):
        ''' Produce a term for every element of the target constituenta typification. '''
        schema = self._get_item()

        serializer = s.CstTargetSerializer(data=request.data, context={'schema': schema})
        serializer.is_valid(raise_exception=True)
        cst = cast(m.Constituenta, serializer.validated_data['target'])

        schema_details = s.RSFormParseSerializer(schema).data['items']
        cst_parse = next(item for item in schema_details if item['id'] == cst.id)['parse']
        if not cst_parse['typification']:
            return Response(
                status=c.HTTP_400_BAD_REQUEST,
                data={f'{cst.id}': msg.constituentaNoStructure()}
            )

        result = m.RSForm(schema).produce_structure(cst, cst_parse)
        return Response(
            status=c.HTTP_200_OK,
            data={
                'cst_list': result,
                'schema': s.RSFormParseSerializer(schema).data
            }
        )

    @extend_schema(
        summary='rename constituenta',
        tags=['Constituenta'],
        request=s.CstRenameSerializer,
        responses={
            c.HTTP_200_OK: s.NewCstResponse,
            c.HTTP_400_BAD_REQUEST: None,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['patch'], url_path='rename-cst')
    def rename_cst(self, request: Request, pk):
        ''' Rename constituenta possibly changing type. '''
        schema = self._get_item()
        serializer = s.CstRenameSerializer(data=request.data, context={'schema': schema})
        serializer.is_valid(raise_exception=True)

        cst = cast(m.Constituenta, serializer.validated_data['target'])
        old_alias = cst.alias

        cst.alias = serializer.validated_data['alias']
        cst.cst_type = serializer.validated_data['cst_type']

        with transaction.atomic():
            cst.save()
            m.RSForm(schema).apply_mapping(mapping={old_alias: cst.alias}, change_aliases=False)

        schema.refresh_from_db()
        cst.refresh_from_db()
        return Response(
            status=c.HTTP_200_OK,
            data={
                'new_cst': s.CstSerializer(cst).data,
                'schema': s.RSFormParseSerializer(schema).data
            }
        )

    @extend_schema(
        summary='execute substitutions',
        tags=['RSForm'],
        request=s.CstSubstituteSerializer,
        responses={
            c.HTTP_200_OK: s.RSFormParseSerializer,
            c.HTTP_400_BAD_REQUEST: None,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['patch'], url_path='substitute')
    def substitute(self, request: Request, pk):
        ''' Substitute occurrences of constituenta with another one. '''
        schema = self._get_item()
        serializer = s.CstSubstituteSerializer(
            data=request.data,
            context={'schema': schema}
        )
        serializer.is_valid(raise_exception=True)

        with transaction.atomic():
            for substitution in serializer.validated_data['substitutions']:
                original = cast(m.Constituenta, substitution['original'])
                replacement = cast(m.Constituenta, substitution['substitution'])
                m.RSForm(schema).substitute(original, replacement)

        schema.refresh_from_db()
        return Response(
            status=c.HTTP_200_OK,
            data=s.RSFormParseSerializer(schema).data
        )

    @extend_schema(
        summary='delete constituents',
        tags=['RSForm'],
        request=s.CstListSerializer,
        responses={
            c.HTTP_200_OK: s.RSFormParseSerializer,
            c.HTTP_400_BAD_REQUEST: None,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['patch'], url_path='delete-multiple-cst')
    def delete_multiple_cst(self, request: Request, pk):
        ''' Endpoint: Delete multiple constituents. '''
        schema = self._get_item()
        serializer = s.CstListSerializer(
            data=request.data,
            context={'schema': schema}
        )
        serializer.is_valid(raise_exception=True)
        m.RSForm(schema).delete_cst(serializer.validated_data['items'])

        schema.refresh_from_db()
        return Response(
            status=c.HTTP_200_OK,
            data=s.RSFormParseSerializer(schema).data
        )

    @extend_schema(
        summary='move constituenta',
        tags=['RSForm'],
        request=s.CstMoveSerializer,
        responses={
            c.HTTP_200_OK: s.RSFormParseSerializer,
            c.HTTP_400_BAD_REQUEST: None,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['patch'], url_path='move-cst')
    def move_cst(self, request: Request, pk):
        ''' Endpoint: Move multiple constituents. '''
        schema = self._get_item()
        serializer = s.CstMoveSerializer(
            data=request.data,
            context={'schema': schema}
        )
        serializer.is_valid(raise_exception=True)
        m.RSForm(schema).move_cst(
            listCst=serializer.validated_data['items'],
            target=serializer.validated_data['move_to']
        )
        return Response(
            status=c.HTTP_200_OK,
            data=s.RSFormParseSerializer(schema).data
        )

    @extend_schema(
        summary='reset aliases, update expressions and references',
        tags=['RSForm'],
        request=None,
        responses={
            c.HTTP_200_OK: s.RSFormParseSerializer,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['patch'], url_path='reset-aliases')
    def reset_aliases(self, request: Request, pk):
        ''' Endpoint: Recreate all aliases based on order. '''
        schema = self._get_item()
        m.RSForm(schema).reset_aliases()
        return Response(
            status=c.HTTP_200_OK,
            data=s.RSFormParseSerializer(schema).data
        )

    @extend_schema(
        summary='restore order based on types and term graph',
        tags=['RSForm'],
        request=None,
        responses={
            c.HTTP_200_OK: s.RSFormParseSerializer,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['patch'], url_path='restore-order')
    def restore_order(self, request: Request, pk):
        ''' Endpoint: Restore order based on types and term graph. '''
        schema = self._get_item()
        m.RSForm(schema).restore_order()
        return Response(
            status=c.HTTP_200_OK,
            data=s.RSFormParseSerializer(schema).data
        )

    @extend_schema(
        summary='load data from TRS file',
        tags=['RSForm'],
        request=s.RSFormUploadSerializer,
        responses={
            c.HTTP_200_OK: s.RSFormParseSerializer,
            c.HTTP_400_BAD_REQUEST: None,
            c.HTTP_403_FORBIDDEN: None,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['patch'], url_path='load-trs')
    def load_trs(self, request: Request, pk):
        ''' Endpoint: Load data from file and replace current schema. '''
        input_serializer = s.RSFormUploadSerializer(data=request.data)
        input_serializer.is_valid(raise_exception=True)

        schema = self._get_item()
        load_metadata = input_serializer.validated_data['load_metadata']
        data = utility.read_zipped_json(request.FILES['file'].file, utils.EXTEOR_INNER_FILENAME)
        data['id'] = schema.pk

        serializer = s.RSFormTRSSerializer(
            data=data,
            context={'load_meta': load_metadata}
        )
        serializer.is_valid(raise_exception=True)
        result: m.RSForm = serializer.save()
        return Response(
            status=c.HTTP_200_OK,
            data=s.RSFormParseSerializer(result.model).data
        )

    @extend_schema(
        summary='get all constituents data from DB',
        tags=['RSForm'],
        request=None,
        responses={
            c.HTTP_200_OK: s.RSFormSerializer,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['get'], url_path='contents')
    def contents(self, request: Request, pk):
        ''' Endpoint: View schema db contents (including constituents). '''
        serializer = s.RSFormSerializer(self.get_object())
        return Response(
            status=c.HTTP_200_OK,
            data=serializer.data
        )

    @extend_schema(
        summary='get all constituents data and parses',
        tags=['RSForm'],
        request=None,
        responses={
            c.HTTP_200_OK: s.RSFormParseSerializer,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['get'], url_path='details')
    def details(self, request: Request, pk):
        ''' Endpoint: Detailed schema view including statuses and parse. '''
        serializer = s.RSFormParseSerializer(self.get_object())
        return Response(
            status=c.HTTP_200_OK,
            data=serializer.data
        )

    @extend_schema(
        summary='check RSLang expression',
        tags=['RSForm', 'FormalLanguage'],
        request=s.ExpressionSerializer,
        responses={
            c.HTTP_200_OK: s.ExpressionParseSerializer,
            c.HTTP_404_NOT_FOUND: None
        },
    )
    @action(detail=True, methods=['post'], url_path='check')
    def check(self, request: Request, pk):
        ''' Endpoint: Check RSLang expression against schema context. '''
        serializer = s.ExpressionSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        expression = serializer.validated_data['expression']
        pySchema = s.PyConceptAdapter(m.RSForm(self.get_object()))
        result = pyconcept.check_expression(json.dumps(pySchema.data), expression)
        return Response(
            status=c.HTTP_200_OK,
            data=json.loads(result)
        )

    @extend_schema(
        summary='resolve text with references',
        tags=['RSForm', 'NaturalLanguage'],
        request=s.TextSerializer,
        responses={
            c.HTTP_200_OK: s.ResolverSerializer,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['post'], url_path='resolve')
    def resolve(self, request: Request, pk):
        ''' Endpoint: Resolve references in text against schema terms context. '''
        serializer = s.TextSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        text = serializer.validated_data['text']
        resolver = m.RSForm(self.get_object()).resolver()
        resolver.resolve(text)
        return Response(
            status=c.HTTP_200_OK,
            data=s.ResolverSerializer(resolver).data
        )

    @extend_schema(
        summary='export as TRS file',
        tags=['RSForm'],
        request=None,
        responses={
            (c.HTTP_200_OK, 'application/zip'): bytes,
            c.HTTP_404_NOT_FOUND: None
        }
    )
    @action(detail=True, methods=['get'], url_path='export-trs')
    def export_trs(self, request: Request, pk):
        ''' Endpoint: Download Exteor compatible file. '''
        schema = self._get_item()
        data = s.RSFormTRSSerializer(m.RSForm(schema)).data
        file = utility.write_zipped_json(data, utils.EXTEOR_INNER_FILENAME)
        filename = utils.filename_for_schema(schema.alias)
        response = HttpResponse(file, content_type='application/zip')
        response['Content-Disposition'] = f'attachment; filename={filename}'
        return response


class TrsImportView(views.APIView):
    ''' Endpoint: Upload RS form in Exteor format. '''
    serializer_class = s.FileSerializer
    permission_classes = [permissions.GlobalUser]

    @extend_schema(
        summary='import TRS file into RSForm',
        tags=['RSForm'],
        request=s.FileSerializer,
        responses={
            c.HTTP_201_CREATED: LibraryItemSerializer,
            c.HTTP_403_FORBIDDEN: None
        }
    )
    def post(self, request: Request):
        data = utility.read_zipped_json(request.FILES['file'].file, utils.EXTEOR_INNER_FILENAME)
        owner = cast(User, self.request.user)
        _prepare_rsform_data(data, request, owner)
        serializer = s.RSFormTRSSerializer(
            data=data,
            context={'load_meta': True}
        )
        serializer.is_valid(raise_exception=True)
        schema: m.RSForm = serializer.save()
        return Response(
            status=c.HTTP_201_CREATED,
            data=LibraryItemSerializer(schema.model).data
        )


@extend_schema(
    summary='create new RSForm empty or from file',
    tags=['RSForm'],
    request=LibraryItemSerializer,
    responses={
        c.HTTP_201_CREATED: LibraryItemSerializer,
        c.HTTP_400_BAD_REQUEST: None,
        c.HTTP_403_FORBIDDEN: None
    }
)
@api_view(['POST'])
def create_rsform(request: Request):
    ''' Endpoint: Create RSForm from user input and/or trs file. '''
    owner = cast(User, request.user) if not request.user.is_anonymous else None
    if 'file' not in request.FILES:
        return Response(
            status=c.HTTP_400_BAD_REQUEST,
            data={'file': msg.missingFile()}
        )

    data = utility.read_zipped_json(request.FILES['file'].file, utils.EXTEOR_INNER_FILENAME)
    _prepare_rsform_data(data, request, owner)
    serializer_rsform = s.RSFormTRSSerializer(data=data, context={'load_meta': True})
    serializer_rsform.is_valid(raise_exception=True)
    schema: m.RSForm = serializer_rsform.save()
    return Response(
        status=c.HTTP_201_CREATED,
        data=LibraryItemSerializer(schema.model).data
    )


def _prepare_rsform_data(data: dict, request: Request, owner: Union[User, None]):
    data['owner'] = owner
    if 'title' in request.data and request.data['title'] != '':
        data['title'] = request.data['title']
    if data['title'] == '':
        data['title'] = 'Без названия ' + request.FILES['file'].fileName
    if 'alias' in request.data and request.data['alias'] != '':
        data['alias'] = request.data['alias']
    if 'comment' in request.data and request.data['comment'] != '':
        data['comment'] = request.data['comment']

    visible = True
    if 'visible' in request.data:
        visible = request.data['visible'] == 'true'
    data['visible'] = visible

    read_only = False
    if 'read_only' in request.data:
        read_only = request.data['read_only'] == 'true'
    data['read_only'] = read_only

    data['access_policy'] = request.data.get('access_policy', AccessPolicy.PUBLIC)
    data['location'] = request.data.get('location', LocationHead.USER)