import logging
from django.db.models import Q
from django.shortcuts import get_object_or_404
from django.utils.translation import gettext_lazy as _
from rest_framework import status
from rest_framework.generics import GenericAPIView
from rest_framework.parsers import MultiPartParser, FormParser, JSONParser
from rest_framework.permissions import AllowAny, IsAuthenticated
from rest_framework.response import Response
from drf_spectacular.utils import extend_schema, OpenApiParameter, OpenApiResponse

from apps.projects.models.project import (
    Project,
    KanbanColumn,
    KanbanTask,
    ProjectDocument,
)
from apps.projects.permissions import IsProjectParticipantOrReadOnly, CanCreateProject
from apps.projects.serializers import (
    ProjectListSerializer,
    ProjectDetailSerializer,
    ProjectCreateUpdateSerializer,
    KanbanColumnSerializer,
    KanbanTaskSerializer,
    KanbanTaskCreateUpdateSerializer,
    ProjectDocumentSerializer,
)
from utils.pagination import StandardResultsSetPagination

logger = logging.getLogger(__name__)


def get_project_by_id_or_slug(lookup_val):
    if str(lookup_val).isdigit():
        return get_object_or_404(Project, id=int(lookup_val))
    return get_object_or_404(Project, slug=lookup_val)


class ProjectListCreateView(GenericAPIView):
    serializer_class = ProjectListSerializer
    pagination_class = StandardResultsSetPagination
    queryset = Project.objects.all().select_related('owner_institution').prefetch_related('collaborating_institutions', 'tasks')

    def get_permissions(self):
        if self.request.method == 'POST':
            return [IsAuthenticated(), CanCreateProject()]
        return [AllowAny()]

    def get_queryset(self):
        if getattr(self, 'swagger_fake_view', False):
            return Project.objects.none()

        qs = Project.objects.all().select_related('owner_institution').prefetch_related('collaborating_institutions', 'tasks')

        # Filters
        status_param = self.request.query_params.get('status')
        if status_param:
            qs = qs.filter(status=status_param)

        category = self.request.query_params.get('category')
        if category:
            qs = qs.filter(category__iexact=category)

        institution_id = self.request.query_params.get('institution_id')
        if institution_id:
            qs = qs.filter(
                Q(owner_institution_id=institution_id) |
                Q(collaborating_institutions__id=institution_id)
            ).distinct()

        owner_id = self.request.query_params.get('owner_institution_id')
        if owner_id:
            qs = qs.filter(owner_institution_id=owner_id)

        search = self.request.query_params.get('search')
        if search:
            qs = qs.filter(
                Q(title__icontains=search) |
                Q(description__icontains=search) |
                Q(category__icontains=search)
            )

        return qs.order_by('-created_at')

    @extend_schema(
        summary="List collaborative projects",
        description="Returns a paginated list of collaborative projects with filtering by institution, category, and status.",
        parameters=[
            OpenApiParameter('status', str, description='Filter by project status (active, completed, on_hold, planning)'),
            OpenApiParameter('category', str, description='Filter by category name'),
            OpenApiParameter('institution_id', int, description='Filter by owner or collaborating institution ID'),
            OpenApiParameter('owner_institution_id', int, description='Filter specifically by owner institution ID'),
            OpenApiParameter('search', str, description='Search query across title and description'),
        ],
        responses={200: ProjectListSerializer(many=True)},
        tags=["Collaborative Projects & Kanban"],
    )
    def get(self, request, *args, **kwargs):
        queryset = self.filter_queryset(self.get_queryset())
        page = self.paginate_queryset(queryset)
        if page is not None:
            serializer = self.get_serializer(page, many=True, context={'request': request})
            return self.get_paginated_response(serializer.data)

        serializer = self.get_serializer(queryset, many=True, context={'request': request})
        return Response(serializer.data, status=status.HTTP_200_OK)

    @extend_schema(
        summary="Create collaborative project",
        description="Creates a new multi-institution collaborative project with default Kanban columns.",
        request=ProjectCreateUpdateSerializer,
        responses={
            201: ProjectDetailSerializer,
            400: OpenApiResponse(description="Validation error"),
            401: OpenApiResponse(description="Authentication required"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def post(self, request, *args, **kwargs):
        serializer = ProjectCreateUpdateSerializer(data=request.data, context={'request': request})
        serializer.is_valid(raise_exception=True)
        project = serializer.save()

        response_serializer = ProjectDetailSerializer(project, context={'request': request})
        return Response(response_serializer.data, status=status.HTTP_201_CREATED)


class ProjectDetailView(GenericAPIView):
    serializer_class = ProjectDetailSerializer
    queryset = Project.objects.all()

    def get_permissions(self):
        if self.request.method in ['PATCH', 'PUT', 'DELETE']:
            return [IsAuthenticated(), IsProjectParticipantOrReadOnly()]
        return [AllowAny()]

    def get_object(self):
        lookup = self.kwargs.get('pk_or_slug')
        project = get_project_by_id_or_slug(lookup)
        self.check_object_permissions(self.request, project)
        return project

    @extend_schema(
        summary="Get project details",
        description="Retrieves full project details, collaborating institutions, and Kanban boards.",
        responses={
            200: ProjectDetailSerializer,
            404: OpenApiResponse(description="Project not found"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def get(self, request, pk_or_slug, *args, **kwargs):
        project = self.get_object()
        serializer = ProjectDetailSerializer(project, context={'request': request})
        return Response(serializer.data, status=status.HTTP_200_OK)

    @extend_schema(
        summary="Update project",
        description="Updates project status, progress percentage, or details. Permitted for owner and collaborating editors.",
        request=ProjectCreateUpdateSerializer,
        responses={
            200: ProjectDetailSerializer,
            403: OpenApiResponse(description="Permission denied"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def patch(self, request, pk_or_slug, *args, **kwargs):
        project = self.get_object()
        serializer = ProjectCreateUpdateSerializer(
            project,
            data=request.data,
            partial=True,
            context={'request': request}
        )
        serializer.is_valid(raise_exception=True)
        serializer.save()

        response_serializer = ProjectDetailSerializer(project, context={'request': request})
        return Response(response_serializer.data, status=status.HTTP_200_OK)

    @extend_schema(
        summary="Delete project",
        description="Removes a collaborative project and associated Kanban boards.",
        responses={
            204: OpenApiResponse(description="Project deleted successfully"),
            403: OpenApiResponse(description="Permission denied"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def delete(self, request, pk_or_slug, *args, **kwargs):
        project = self.get_object()
        project.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class ProjectKanbanBoardView(GenericAPIView):
    serializer_class = KanbanColumnSerializer
    queryset = KanbanColumn.objects.all()

    def get_permissions(self):
        return [AllowAny()]

    @extend_schema(
        summary="Get project Kanban board hierarchy",
        description="Returns hierarchical Kanban columns with nested task lists for drag-and-drop board interfaces.",
        responses={200: KanbanColumnSerializer(many=True)},
        tags=["Collaborative Projects & Kanban"],
    )
    def get(self, request, pk_or_slug, *args, **kwargs):
        project = get_project_by_id_or_slug(pk_or_slug)
        columns = project.columns.all().order_by('order', 'id')
        serializer = KanbanColumnSerializer(columns, many=True, context={'request': request})
        return Response(serializer.data, status=status.HTTP_200_OK)


class KanbanTaskCreateView(GenericAPIView):
    serializer_class = KanbanTaskCreateUpdateSerializer
    permission_classes = [IsAuthenticated, IsProjectParticipantOrReadOnly]
    queryset = KanbanTask.objects.all()

    @extend_schema(
        summary="Create Kanban task",
        description="Adds a new task under a specific column of the project.",
        request=KanbanTaskCreateUpdateSerializer,
        responses={
            201: KanbanTaskSerializer,
            400: OpenApiResponse(description="Validation error"),
            403: OpenApiResponse(description="Permission denied"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def post(self, request, pk_or_slug, *args, **kwargs):
        project = get_project_by_id_or_slug(pk_or_slug)
        self.check_object_permissions(request, project)

        serializer = KanbanTaskCreateUpdateSerializer(
            data=request.data,
            context={'project': project, 'request': request}
        )
        serializer.is_valid(raise_exception=True)
        task = serializer.save(project=project)

        response_serializer = KanbanTaskSerializer(task, context={'request': request})
        return Response(response_serializer.data, status=status.HTTP_201_CREATED)


class KanbanTaskDetailView(GenericAPIView):
    serializer_class = KanbanTaskCreateUpdateSerializer
    permission_classes = [IsAuthenticated, IsProjectParticipantOrReadOnly]
    queryset = KanbanTask.objects.all()

    @extend_schema(
        summary="Update or move Kanban task",
        description="Updates task attributes, priority, assignee, or moves task to another column / reorders within column.",
        request=KanbanTaskCreateUpdateSerializer,
        responses={
            200: KanbanTaskSerializer,
            400: OpenApiResponse(description="Validation error"),
            403: OpenApiResponse(description="Permission denied"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def patch(self, request, pk_or_slug, task_id, *args, **kwargs):
        project = get_project_by_id_or_slug(pk_or_slug)
        self.check_object_permissions(request, project)

        task = get_object_or_404(KanbanTask, id=task_id, project=project)
        serializer = KanbanTaskCreateUpdateSerializer(
            task,
            data=request.data,
            partial=True,
            context={'project': project, 'request': request}
        )
        serializer.is_valid(raise_exception=True)
        serializer.save()

        response_serializer = KanbanTaskSerializer(task, context={'request': request})
        return Response(response_serializer.data, status=status.HTTP_200_OK)

    @extend_schema(
        summary="Delete Kanban task",
        description="Removes a task from the project Kanban board.",
        responses={
            204: OpenApiResponse(description="Task deleted successfully"),
            403: OpenApiResponse(description="Permission denied"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def delete(self, request, pk_or_slug, task_id, *args, **kwargs):
        project = get_project_by_id_or_slug(pk_or_slug)
        self.check_object_permissions(request, project)

        task = get_object_or_404(KanbanTask, id=task_id, project=project)
        task.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class ProjectDocumentListView(GenericAPIView):
    serializer_class = ProjectDocumentSerializer
    parser_classes = [MultiPartParser, FormParser, JSONParser]
    queryset = ProjectDocument.objects.all()

    def get_permissions(self):
        if self.request.method == 'POST':
            return [IsAuthenticated(), IsProjectParticipantOrReadOnly()]
        return [AllowAny()]

    @extend_schema(
        summary="List project documents & MOUs",
        description="Returns uploaded agreements, contracts, and progress reports for a project.",
        responses={200: ProjectDocumentSerializer(many=True)},
        tags=["Collaborative Projects & Kanban"],
    )
    def get(self, request, pk_or_slug, *args, **kwargs):
        project = get_project_by_id_or_slug(pk_or_slug)
        docs = project.documents.all().order_by('-uploaded_at')
        serializer = ProjectDocumentSerializer(docs, many=True, context={'request': request})
        return Response(serializer.data, status=status.HTTP_200_OK)

    @extend_schema(
        summary="Upload project document",
        description="Uploads an agreement, contract, or milestone report.",
        request=ProjectDocumentSerializer,
        responses={
            201: ProjectDocumentSerializer,
            400: OpenApiResponse(description="Validation error"),
            403: OpenApiResponse(description="Permission denied"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def post(self, request, pk_or_slug, *args, **kwargs):
        project = get_project_by_id_or_slug(pk_or_slug)
        self.check_object_permissions(request, project)

        serializer = ProjectDocumentSerializer(data=request.data, context={'request': request})
        serializer.is_valid(raise_exception=True)
        doc = serializer.save(project=project)

        return Response(ProjectDocumentSerializer(doc, context={'request': request}).data, status=status.HTTP_201_CREATED)


class ProjectDocumentDetailView(GenericAPIView):
    serializer_class = ProjectDocumentSerializer
    permission_classes = [IsAuthenticated, IsProjectParticipantOrReadOnly]
    queryset = ProjectDocument.objects.all()

    @extend_schema(
        summary="Delete project document",
        description="Removes a document attachment from the project.",
        responses={
            204: OpenApiResponse(description="Document removed successfully"),
            403: OpenApiResponse(description="Permission denied"),
        },
        tags=["Collaborative Projects & Kanban"],
    )
    def delete(self, request, pk_or_slug, doc_id, *args, **kwargs):
        project = get_project_by_id_or_slug(pk_or_slug)
        self.check_object_permissions(request, project)

        doc = get_object_or_404(ProjectDocument, id=doc_id, project=project)
        doc.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)