# Django imports
from django.db.models import (
    Q,
    OuterRef,
    Func,
    F,
    Case,
    Value,
    CharField,
    When,
    Exists,
    Max,
)
from django.utils.decorators import method_decorator
from django.views.decorators.gzip import gzip_page
from django.contrib.postgres.aggregates import ArrayAgg
from django.contrib.postgres.fields import ArrayField
from django.db.models import Value, UUIDField
from django.db.models.functions import Coalesce
from django.contrib.postgres.aggregates import ArrayAgg
from django.contrib.postgres.fields import ArrayField
from django.db.models import Value, UUIDField

# Third party imports
from rest_framework.response import Response
from rest_framework import status

# Module imports
from . import BaseViewSet
from plane.app.serializers import (
    IssueViewSerializer,
    IssueSerializer,
    IssueViewFavoriteSerializer,
)
from plane.app.permissions import (
    WorkspaceEntityPermission,
    ProjectEntityPermission,
)
from plane.db.models import (
    Workspace,
    IssueView,
    Issue,
    IssueViewFavorite,
    IssueLink,
    IssueAttachment,
)
from plane.utils.issue_filters import issue_filters


class GlobalViewViewSet(BaseViewSet):
    serializer_class = IssueViewSerializer
    model = IssueView
    permission_classes = [
        WorkspaceEntityPermission,
    ]

    def perform_create(self, serializer):
        workspace = Workspace.objects.get(slug=self.kwargs.get("slug"))
        serializer.save(workspace_id=workspace.id)

    def get_queryset(self):
        return self.filter_queryset(
            super()
            .get_queryset()
            .filter(workspace__slug=self.kwargs.get("slug"))
            .filter(project__isnull=True)
            .select_related("workspace")
            .order_by(self.request.GET.get("order_by", "-created_at"))
            .distinct()
        )


class GlobalViewIssuesViewSet(BaseViewSet):
    permission_classes = [
        WorkspaceEntityPermission,
    ]

    def get_queryset(self):
        return (
            Issue.issue_objects.annotate(
                sub_issues_count=Issue.issue_objects.filter(
                    parent=OuterRef("id")
                )
                .order_by()
                .annotate(count=Func(F("id"), function="Count"))
                .values("count")
            )
            .filter(workspace__slug=self.kwargs.get("slug"))
            .filter(
                project__project_projectmember__member=self.request.user,
                project__project_projectmember__is_active=True,
            )
            .select_related("workspace", "project", "state", "parent")
            .prefetch_related("assignees", "labels", "issue_module__module")
            .annotate(cycle_id=F("issue_cycle__cycle_id"))
            .annotate(
                link_count=IssueLink.objects.filter(issue=OuterRef("id"))
                .order_by()
                .annotate(count=Func(F("id"), function="Count"))
                .values("count")
            )
            .annotate(
                attachment_count=IssueAttachment.objects.filter(
                    issue=OuterRef("id")
                )
                .order_by()
                .annotate(count=Func(F("id"), function="Count"))
                .values("count")
            )
            .annotate(
                sub_issues_count=Issue.issue_objects.filter(
                    parent=OuterRef("id")
                )
                .order_by()
                .annotate(count=Func(F("id"), function="Count"))
                .values("count")
            )
            .annotate(
                label_ids=Coalesce(
                    ArrayAgg(
                        "labels__id",
                        distinct=True,
                        filter=~Q(labels__id__isnull=True),
                    ),
                    Value([], output_field=ArrayField(UUIDField())),
                ),
                assignee_ids=Coalesce(
                    ArrayAgg(
                        "assignees__id",
                        distinct=True,
                        filter=~Q(assignees__id__isnull=True),
                    ),
                    Value([], output_field=ArrayField(UUIDField())),
                ),
                module_ids=Coalesce(
                    ArrayAgg(
                        "issue_module__module_id",
                        distinct=True,
                        filter=~Q(issue_module__module_id__isnull=True),
                    ),
                    Value([], output_field=ArrayField(UUIDField())),
                ),
            )
        )

    @method_decorator(gzip_page)
    def list(self, request, slug):
        filters = issue_filters(request.query_params, "GET")
        fields = [
            field
            for field in request.GET.get("fields", "").split(",")
            if field
        ]

        # Custom ordering for priority and state
        priority_order = ["urgent", "high", "medium", "low", "none"]
        state_order = [
            "backlog",
            "unstarted",
            "started",
            "completed",
            "cancelled",
        ]

        order_by_param = request.GET.get("order_by", "-created_at")

        issue_queryset = (
            self.get_queryset()
            .filter(**filters)
            .annotate(cycle_id=F("issue_cycle__cycle_id"))
        )

        # Priority Ordering
        if order_by_param == "priority" or order_by_param == "-priority":
            priority_order = (
                priority_order
                if order_by_param == "priority"
                else priority_order[::-1]
            )
            issue_queryset = issue_queryset.annotate(
                priority_order=Case(
                    *[
                        When(priority=p, then=Value(i))
                        for i, p in enumerate(priority_order)
                    ],
                    output_field=CharField(),
                )
            ).order_by("priority_order")

        # State Ordering
        elif order_by_param in [
            "state__name",
            "state__group",
            "-state__name",
            "-state__group",
        ]:
            state_order = (
                state_order
                if order_by_param in ["state__name", "state__group"]
                else state_order[::-1]
            )
            issue_queryset = issue_queryset.annotate(
                state_order=Case(
                    *[
                        When(state__group=state_group, then=Value(i))
                        for i, state_group in enumerate(state_order)
                    ],
                    default=Value(len(state_order)),
                    output_field=CharField(),
                )
            ).order_by("state_order")
        # assignee and label ordering
        elif order_by_param in [
            "labels__name",
            "-labels__name",
            "assignees__first_name",
            "-assignees__first_name",
        ]:
            issue_queryset = issue_queryset.annotate(
                max_values=Max(
                    order_by_param[1::]
                    if order_by_param.startswith("-")
                    else order_by_param
                )
            ).order_by(
                "-max_values"
                if order_by_param.startswith("-")
                else "max_values"
            )
        else:
            issue_queryset = issue_queryset.order_by(order_by_param)

        if self.fields:
            issues = IssueSerializer(
                issue_queryset, many=True, fields=self.fields
            ).data
        else:
            issues = issue_queryset.values(
                "id",
                "name",
                "state_id",
                "sort_order",
                "completed_at",
                "estimate_point",
                "priority",
                "start_date",
                "target_date",
                "sequence_id",
                "project_id",
                "parent_id",
                "cycle_id",
                "module_ids",
                "label_ids",
                "assignee_ids",
                "sub_issues_count",
                "created_at",
                "updated_at",
                "created_by",
                "updated_by",
                "attachment_count",
                "link_count",
                "is_draft",
                "archived_at",
            )
        return Response(issues, status=status.HTTP_200_OK)


class IssueViewViewSet(BaseViewSet):
    serializer_class = IssueViewSerializer
    model = IssueView
    permission_classes = [
        ProjectEntityPermission,
    ]

    def perform_create(self, serializer):
        serializer.save(project_id=self.kwargs.get("project_id"))

    def get_queryset(self):
        subquery = IssueViewFavorite.objects.filter(
            user=self.request.user,
            view_id=OuterRef("pk"),
            project_id=self.kwargs.get("project_id"),
            workspace__slug=self.kwargs.get("slug"),
        )
        return self.filter_queryset(
            super()
            .get_queryset()
            .filter(workspace__slug=self.kwargs.get("slug"))
            .filter(project_id=self.kwargs.get("project_id"))
            .filter(
                project__project_projectmember__member=self.request.user,
                project__project_projectmember__is_active=True,
            )
            .select_related("project")
            .select_related("workspace")
            .annotate(is_favorite=Exists(subquery))
            .order_by("-is_favorite", "name")
            .distinct()
        )

    def list(self, request, slug, project_id):
        queryset = self.get_queryset()
        fields = [
            field
            for field in request.GET.get("fields", "").split(",")
            if field
        ]
        views = IssueViewSerializer(
            queryset, many=True, fields=fields if fields else None
        ).data
        return Response(views, status=status.HTTP_200_OK)


class IssueViewFavoriteViewSet(BaseViewSet):
    serializer_class = IssueViewFavoriteSerializer
    model = IssueViewFavorite

    def get_queryset(self):
        return self.filter_queryset(
            super()
            .get_queryset()
            .filter(workspace__slug=self.kwargs.get("slug"))
            .filter(user=self.request.user)
            .select_related("view")
        )

    def create(self, request, slug, project_id):
        serializer = IssueViewFavoriteSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save(user=request.user, project_id=project_id)
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    def destroy(self, request, slug, project_id, view_id):
        view_favourite = IssueViewFavorite.objects.get(
            project=project_id,
            user=request.user,
            workspace__slug=slug,
            view_id=view_id,
        )
        view_favourite.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)