# Python imports
import json

# Django imports
from django.db.models import (
    Func,
    F,
    Q,
    Exists,
    OuterRef,
    Count,
    Prefetch,
    Sum,
)
from django.core import serializers
from django.utils import timezone
from django.utils.decorators import method_decorator
from django.views.decorators.gzip import gzip_page

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

# Module imports
from . import BaseViewSet, BaseAPIView, WebhookMixin
from plane.app.serializers import (
    CycleSerializer,
    CycleIssueSerializer,
    CycleFavoriteSerializer,
    IssueStateSerializer,
    CycleWriteSerializer,
)
from plane.app.permissions import ProjectEntityPermission
from plane.db.models import (
    User,
    Cycle,
    CycleIssue,
    Issue,
    CycleFavorite,
    IssueLink,
    IssueAttachment,
    Label,
)
from plane.bgtasks.issue_activites_task import issue_activity
from plane.utils.grouper import group_results
from plane.utils.issue_filters import issue_filters
from plane.utils.analytics_plot import burndown_plot


class CycleViewSet(WebhookMixin, BaseViewSet):
    serializer_class = CycleSerializer
    model = Cycle
    webhook_event = "cycle"
    permission_classes = [
        ProjectEntityPermission,
    ]

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

    def get_queryset(self):
        subquery = CycleFavorite.objects.filter(
            user=self.request.user,
            cycle_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)
            .select_related("project")
            .select_related("workspace")
            .select_related("owned_by")
            .annotate(is_favorite=Exists(subquery))
            .annotate(
                total_issues=Count(
                    "issue_cycle",
                    filter=Q(
                        issue_cycle__issue__archived_at__isnull=True,
                        issue_cycle__issue__is_draft=False,
                    ),
                )
            )
            .annotate(
                completed_issues=Count(
                    "issue_cycle__issue__state__group",
                    filter=Q(
                        issue_cycle__issue__state__group="completed",
                        issue_cycle__issue__archived_at__isnull=True,
                        issue_cycle__issue__is_draft=False,
                    ),
                )
            )
            .annotate(
                cancelled_issues=Count(
                    "issue_cycle__issue__state__group",
                    filter=Q(
                        issue_cycle__issue__state__group="cancelled",
                        issue_cycle__issue__archived_at__isnull=True,
                        issue_cycle__issue__is_draft=False,
                    ),
                )
            )
            .annotate(
                started_issues=Count(
                    "issue_cycle__issue__state__group",
                    filter=Q(
                        issue_cycle__issue__state__group="started",
                        issue_cycle__issue__archived_at__isnull=True,
                        issue_cycle__issue__is_draft=False,
                    ),
                )
            )
            .annotate(
                unstarted_issues=Count(
                    "issue_cycle__issue__state__group",
                    filter=Q(
                        issue_cycle__issue__state__group="unstarted",
                        issue_cycle__issue__archived_at__isnull=True,
                        issue_cycle__issue__is_draft=False,
                    ),
                )
            )
            .annotate(
                backlog_issues=Count(
                    "issue_cycle__issue__state__group",
                    filter=Q(
                        issue_cycle__issue__state__group="backlog",
                        issue_cycle__issue__archived_at__isnull=True,
                        issue_cycle__issue__is_draft=False,
                    ),
                )
            )
            .annotate(total_estimates=Sum("issue_cycle__issue__estimate_point"))
            .annotate(
                completed_estimates=Sum(
                    "issue_cycle__issue__estimate_point",
                    filter=Q(
                        issue_cycle__issue__state__group="completed",
                        issue_cycle__issue__archived_at__isnull=True,
                        issue_cycle__issue__is_draft=False,
                    ),
                )
            )
            .annotate(
                started_estimates=Sum(
                    "issue_cycle__issue__estimate_point",
                    filter=Q(
                        issue_cycle__issue__state__group="started",
                        issue_cycle__issue__archived_at__isnull=True,
                        issue_cycle__issue__is_draft=False,
                    ),
                )
            )
            .prefetch_related(
                Prefetch(
                    "issue_cycle__issue__assignees",
                    queryset=User.objects.only("avatar", "first_name", "id").distinct(),
                )
            )
            .prefetch_related(
                Prefetch(
                    "issue_cycle__issue__labels",
                    queryset=Label.objects.only("name", "color", "id").distinct(),
                )
            )
            .order_by("-is_favorite", "name")
            .distinct()
        )

    def list(self, request, slug, project_id):
        queryset = self.get_queryset()
        cycle_view = request.GET.get("cycle_view", "all")

        queryset = queryset.order_by("-is_favorite","-created_at")

        # Current Cycle
        if cycle_view == "current":
            queryset = queryset.filter(
                start_date__lte=timezone.now(),
                end_date__gte=timezone.now(),
            )

            data = CycleSerializer(queryset, many=True).data

            if len(data):
                assignee_distribution = (
                    Issue.objects.filter(
                        issue_cycle__cycle_id=data[0]["id"],
                        workspace__slug=slug,
                        project_id=project_id,
                    )
                    .annotate(display_name=F("assignees__display_name"))
                    .annotate(assignee_id=F("assignees__id"))
                    .annotate(avatar=F("assignees__avatar"))
                    .values("display_name", "assignee_id", "avatar")
                    .annotate(
                        total_issues=Count(
                            "assignee_id",
                            filter=Q(archived_at__isnull=True, is_draft=False),
                        ),
                    )
                    .annotate(
                        completed_issues=Count(
                            "assignee_id",
                            filter=Q(
                                completed_at__isnull=False,
                                archived_at__isnull=True,
                                is_draft=False,
                            ),
                        )
                    )
                    .annotate(
                        pending_issues=Count(
                            "assignee_id",
                            filter=Q(
                                completed_at__isnull=True,
                                archived_at__isnull=True,
                                is_draft=False,
                            ),
                        )
                    )
                    .order_by("display_name")
                )

                label_distribution = (
                    Issue.objects.filter(
                        issue_cycle__cycle_id=data[0]["id"],
                        workspace__slug=slug,
                        project_id=project_id,
                    )
                    .annotate(label_name=F("labels__name"))
                    .annotate(color=F("labels__color"))
                    .annotate(label_id=F("labels__id"))
                    .values("label_name", "color", "label_id")
                    .annotate(
                        total_issues=Count(
                            "label_id",
                            filter=Q(archived_at__isnull=True, is_draft=False),
                        )
                    )
                    .annotate(
                        completed_issues=Count(
                            "label_id",
                            filter=Q(
                                completed_at__isnull=False,
                                archived_at__isnull=True,
                                is_draft=False,
                            ),
                        )
                    )
                    .annotate(
                        pending_issues=Count(
                            "label_id",
                            filter=Q(
                                completed_at__isnull=True,
                                archived_at__isnull=True,
                                is_draft=False,
                            ),
                        )
                    )
                    .order_by("label_name")
                )
                data[0]["distribution"] = {
                    "assignees": assignee_distribution,
                    "labels": label_distribution,
                    "completion_chart": {},
                }
                if data[0]["start_date"] and data[0]["end_date"]:
                    data[0]["distribution"]["completion_chart"] = burndown_plot(
                        queryset=queryset.first(),
                        slug=slug,
                        project_id=project_id,
                        cycle_id=data[0]["id"],
                    )

            return Response(data, status=status.HTTP_200_OK)

        # Upcoming Cycles
        if cycle_view == "upcoming":
            queryset = queryset.filter(start_date__gt=timezone.now())
            return Response(
                CycleSerializer(queryset, many=True).data, status=status.HTTP_200_OK
            )

        # Completed Cycles
        if cycle_view == "completed":
            queryset = queryset.filter(end_date__lt=timezone.now())
            return Response(
                CycleSerializer(queryset, many=True).data, status=status.HTTP_200_OK
            )

        # Draft Cycles
        if cycle_view == "draft":
            queryset = queryset.filter(
                end_date=None,
                start_date=None,
            )

            return Response(
                CycleSerializer(queryset, many=True).data, status=status.HTTP_200_OK
            )

        # Incomplete Cycles
        if cycle_view == "incomplete":
            queryset = queryset.filter(
                Q(end_date__gte=timezone.now().date()) | Q(end_date__isnull=True),
            )
            return Response(
                CycleSerializer(queryset, many=True).data, status=status.HTTP_200_OK
            )

        # If no matching view is found return all cycles
        return Response(
            CycleSerializer(queryset, many=True).data, status=status.HTTP_200_OK
        )

    def create(self, request, slug, project_id):
        if (
            request.data.get("start_date", None) is None
            and request.data.get("end_date", None) is None
        ) or (
            request.data.get("start_date", None) is not None
            and request.data.get("end_date", None) is not None
        ):
            serializer = CycleSerializer(data=request.data)
            if serializer.is_valid():
                serializer.save(
                    project_id=project_id,
                    owned_by=request.user,
                )
                return Response(serializer.data, status=status.HTTP_201_CREATED)
            return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)
        else:
            return Response(
                {
                    "error": "Both start date and end date are either required or are to be null"
                },
                status=status.HTTP_400_BAD_REQUEST,
            )

    def partial_update(self, request, slug, project_id, pk):
        cycle = Cycle.objects.get(workspace__slug=slug, project_id=project_id, pk=pk)

        request_data = request.data

        if cycle.end_date is not None and cycle.end_date < timezone.now().date():
            if "sort_order" in request_data:
                # Can only change sort order
                request_data = {
                    "sort_order": request_data.get("sort_order", cycle.sort_order)
                }
            else:
                return Response(
                    {
                        "error": "The Cycle has already been completed so it cannot be edited"
                    },
                    status=status.HTTP_400_BAD_REQUEST,
                )

        serializer = CycleWriteSerializer(cycle, data=request.data, partial=True)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_200_OK)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    def retrieve(self, request, slug, project_id, pk):
        queryset = self.get_queryset().get(pk=pk)

        # Assignee Distribution
        assignee_distribution = (
            Issue.objects.filter(
                issue_cycle__cycle_id=pk,
                workspace__slug=slug,
                project_id=project_id,
            )
            .annotate(first_name=F("assignees__first_name"))
            .annotate(last_name=F("assignees__last_name"))
            .annotate(assignee_id=F("assignees__id"))
            .annotate(avatar=F("assignees__avatar"))
            .annotate(display_name=F("assignees__display_name"))
            .values("first_name", "last_name", "assignee_id", "avatar", "display_name")
            .annotate(
                total_issues=Count(
                    "assignee_id",
                    filter=Q(archived_at__isnull=True, is_draft=False),
                ),
            )
            .annotate(
                completed_issues=Count(
                    "assignee_id",
                    filter=Q(
                        completed_at__isnull=False,
                        archived_at__isnull=True,
                        is_draft=False,
                    ),
                )
            )
            .annotate(
                pending_issues=Count(
                    "assignee_id",
                    filter=Q(
                        completed_at__isnull=True,
                        archived_at__isnull=True,
                        is_draft=False,
                    ),
                )
            )
            .order_by("first_name", "last_name")
        )

        # Label Distribution
        label_distribution = (
            Issue.objects.filter(
                issue_cycle__cycle_id=pk,
                workspace__slug=slug,
                project_id=project_id,
            )
            .annotate(label_name=F("labels__name"))
            .annotate(color=F("labels__color"))
            .annotate(label_id=F("labels__id"))
            .values("label_name", "color", "label_id")
            .annotate(
                total_issues=Count(
                    "label_id",
                    filter=Q(archived_at__isnull=True, is_draft=False),
                ),
            )
            .annotate(
                completed_issues=Count(
                    "label_id",
                    filter=Q(
                        completed_at__isnull=False,
                        archived_at__isnull=True,
                        is_draft=False,
                    ),
                )
            )
            .annotate(
                pending_issues=Count(
                    "label_id",
                    filter=Q(
                        completed_at__isnull=True,
                        archived_at__isnull=True,
                        is_draft=False,
                    ),
                )
            )
            .order_by("label_name")
        )

        data = CycleSerializer(queryset).data
        data["distribution"] = {
            "assignees": assignee_distribution,
            "labels": label_distribution,
            "completion_chart": {},
        }

        if queryset.start_date and queryset.end_date:
            data["distribution"]["completion_chart"] = burndown_plot(
                queryset=queryset, slug=slug, project_id=project_id, cycle_id=pk
            )

        return Response(
            data,
            status=status.HTTP_200_OK,
        )

    def destroy(self, request, slug, project_id, pk):
        cycle_issues = list(
            CycleIssue.objects.filter(cycle_id=self.kwargs.get("pk")).values_list(
                "issue", flat=True
            )
        )
        cycle = Cycle.objects.get(workspace__slug=slug, project_id=project_id, pk=pk)

        issue_activity.delay(
            type="cycle.activity.deleted",
            requested_data=json.dumps(
                {
                    "cycle_id": str(pk),
                    "cycle_name": str(cycle.name),
                    "issues": [str(issue_id) for issue_id in cycle_issues],
                }
            ),
            actor_id=str(request.user.id),
            issue_id=str(pk),
            project_id=str(project_id),
            current_instance=None,
            epoch=int(timezone.now().timestamp()),
        )
        # Delete the cycle
        cycle.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class CycleIssueViewSet(WebhookMixin, BaseViewSet):
    serializer_class = CycleIssueSerializer
    model = CycleIssue

    webhook_event = "cycle_issue"
    bulk = True

    permission_classes = [
        ProjectEntityPermission,
    ]

    filterset_fields = [
        "issue__labels__id",
        "issue__assignees__id",
    ]

    def get_queryset(self):
        return self.filter_queryset(
            super()
            .get_queryset()
            .annotate(
                sub_issues_count=Issue.issue_objects.filter(parent=OuterRef("issue_id"))
                .order_by()
                .annotate(count=Func(F("id"), function="Count"))
                .values("count")
            )
            .filter(workspace__slug=self.kwargs.get("slug"))
            .filter(project_id=self.kwargs.get("project_id"))
            .filter(project__project_projectmember__member=self.request.user)
            .filter(cycle_id=self.kwargs.get("cycle_id"))
            .select_related("project")
            .select_related("workspace")
            .select_related("cycle")
            .select_related("issue", "issue__state", "issue__project")
            .prefetch_related("issue__assignees", "issue__labels")
            .distinct()
        )

    @method_decorator(gzip_page)
    def list(self, request, slug, project_id, cycle_id):
        fields = [field for field in request.GET.get("fields", "").split(",") if field]
        order_by = request.GET.get("order_by", "created_at")
        filters = issue_filters(request.query_params, "GET")
        issues = (
            Issue.issue_objects.filter(issue_cycle__cycle_id=cycle_id)
            .annotate(
                sub_issues_count=Issue.issue_objects.filter(parent=OuterRef("id"))
                .order_by()
                .annotate(count=Func(F("id"), function="Count"))
                .values("count")
            )
            .annotate(bridge_id=F("issue_cycle__id"))
            .filter(project_id=project_id)
            .filter(workspace__slug=slug)
            .select_related("project")
            .select_related("workspace")
            .select_related("state")
            .select_related("parent")
            .prefetch_related("assignees")
            .prefetch_related("labels")
            .order_by(order_by)
            .filter(**filters)
            .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")
            )
        )

        issues = IssueStateSerializer(issues, many=True, fields=fields if fields else None).data
        issue_dict = {str(issue["id"]): issue for issue in issues}
        return Response(issue_dict, status=status.HTTP_200_OK)

    def create(self, request, slug, project_id, cycle_id):
        issues = request.data.get("issues", [])

        if not len(issues):
            return Response(
                {"error": "Issues are required"}, status=status.HTTP_400_BAD_REQUEST
            )

        cycle = Cycle.objects.get(
            workspace__slug=slug, project_id=project_id, pk=cycle_id
        )

        if cycle.end_date is not None and cycle.end_date < timezone.now().date():
            return Response(
                {
                    "error": "The Cycle has already been completed so no new issues can be added"
                },
                status=status.HTTP_400_BAD_REQUEST,
            )

        # Get all CycleIssues already created
        cycle_issues = list(CycleIssue.objects.filter(issue_id__in=issues))
        update_cycle_issue_activity = []
        record_to_create = []
        records_to_update = []

        for issue in issues:
            cycle_issue = [
                cycle_issue
                for cycle_issue in cycle_issues
                if str(cycle_issue.issue_id) in issues
            ]
            # Update only when cycle changes
            if len(cycle_issue):
                if cycle_issue[0].cycle_id != cycle_id:
                    update_cycle_issue_activity.append(
                        {
                            "old_cycle_id": str(cycle_issue[0].cycle_id),
                            "new_cycle_id": str(cycle_id),
                            "issue_id": str(cycle_issue[0].issue_id),
                        }
                    )
                    cycle_issue[0].cycle_id = cycle_id
                    records_to_update.append(cycle_issue[0])
            else:
                record_to_create.append(
                    CycleIssue(
                        project_id=project_id,
                        workspace=cycle.workspace,
                        created_by=request.user,
                        updated_by=request.user,
                        cycle=cycle,
                        issue_id=issue,
                    )
                )

        CycleIssue.objects.bulk_create(
            record_to_create,
            batch_size=10,
            ignore_conflicts=True,
        )
        CycleIssue.objects.bulk_update(
            records_to_update,
            ["cycle"],
            batch_size=10,
        )

        # Capture Issue Activity
        issue_activity.delay(
            type="cycle.activity.created",
            requested_data=json.dumps({"cycles_list": issues}),
            actor_id=str(self.request.user.id),
            issue_id=None,
            project_id=str(self.kwargs.get("project_id", None)),
            current_instance=json.dumps(
                {
                    "updated_cycle_issues": update_cycle_issue_activity,
                    "created_cycle_issues": serializers.serialize(
                        "json", record_to_create
                    ),
                }
            ),
            epoch=int(timezone.now().timestamp()),
        )

        # Return all Cycle Issues
        return Response(
            CycleIssueSerializer(self.get_queryset(), many=True).data,
            status=status.HTTP_200_OK,
        )

    def destroy(self, request, slug, project_id, cycle_id, pk):
        cycle_issue = CycleIssue.objects.get(
            pk=pk, workspace__slug=slug, project_id=project_id, cycle_id=cycle_id
        )
        issue_id = cycle_issue.issue_id
        issue_activity.delay(
            type="cycle.activity.deleted",
            requested_data=json.dumps(
                {
                    "cycle_id": str(self.kwargs.get("cycle_id")),
                    "issues": [str(issue_id)],
                }
            ),
            actor_id=str(self.request.user.id),
            issue_id=str(cycle_issue.issue_id),
            project_id=str(self.kwargs.get("project_id", None)),
            current_instance=None,
            epoch=int(timezone.now().timestamp()),
        )
        cycle_issue.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class CycleDateCheckEndpoint(BaseAPIView):
    permission_classes = [
        ProjectEntityPermission,
    ]

    def post(self, request, slug, project_id):
        start_date = request.data.get("start_date", False)
        end_date = request.data.get("end_date", False)
        cycle_id = request.data.get("cycle_id")
        if not start_date or not end_date:
            return Response(
                {"error": "Start date and end date both are required"},
                status=status.HTTP_400_BAD_REQUEST,
            )

        cycles = Cycle.objects.filter(
            Q(workspace__slug=slug)
            & Q(project_id=project_id)
            & (
                Q(start_date__lte=start_date, end_date__gte=start_date)
                | Q(start_date__lte=end_date, end_date__gte=end_date)
                | Q(start_date__gte=start_date, end_date__lte=end_date)
            )
        ).exclude(pk=cycle_id)

        if cycles.exists():
            return Response(
                {
                    "error": "You have a cycle already on the given dates, if you want to create a draft cycle you can do that by removing dates",
                    "status": False,
                }
            )
        else:
            return Response({"status": True}, status=status.HTTP_200_OK)


class CycleFavoriteViewSet(BaseViewSet):
    serializer_class = CycleFavoriteSerializer
    model = CycleFavorite

    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("cycle", "cycle__owned_by")
        )

    def create(self, request, slug, project_id):
        serializer = CycleFavoriteSerializer(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, cycle_id):
        cycle_favorite = CycleFavorite.objects.get(
            project=project_id,
            user=request.user,
            workspace__slug=slug,
            cycle_id=cycle_id,
        )
        cycle_favorite.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)


class TransferCycleIssueEndpoint(BaseAPIView):
    permission_classes = [
        ProjectEntityPermission,
    ]

    def post(self, request, slug, project_id, cycle_id):
        new_cycle_id = request.data.get("new_cycle_id", False)

        if not new_cycle_id:
            return Response(
                {"error": "New Cycle Id is required"},
                status=status.HTTP_400_BAD_REQUEST,
            )

        new_cycle = Cycle.objects.get(
            workspace__slug=slug, project_id=project_id, pk=new_cycle_id
        )

        if (
            new_cycle.end_date is not None
            and new_cycle.end_date < timezone.now().date()
        ):
            return Response(
                {
                    "error": "The cycle where the issues are transferred is already completed"
                },
                status=status.HTTP_400_BAD_REQUEST,
            )

        cycle_issues = CycleIssue.objects.filter(
            cycle_id=cycle_id,
            project_id=project_id,
            workspace__slug=slug,
            issue__state__group__in=["backlog", "unstarted", "started"],
        )

        updated_cycles = []
        for cycle_issue in cycle_issues:
            cycle_issue.cycle_id = new_cycle_id
            updated_cycles.append(cycle_issue)

        cycle_issues = CycleIssue.objects.bulk_update(
            updated_cycles, ["cycle_id"], batch_size=100
        )

        return Response({"message": "Success"}, status=status.HTTP_200_OK)