"""Read representation for documents."""

from django.urls import reverse
from drf_spectacular.utils import extend_schema_field
from rest_framework import serializers

from documents.models import (
    Document,
    DocumentAcknowledgement,
    DocumentDisplayState,
)

from ...employees.serializers import EmployeeBriefSerializer
from .common import DepartmentBriefSerializer, FolderBriefSerializer
from .tags import DocumentTagSerializer


class DocumentReadSerializer(serializers.ModelSerializer):
    """Сериализатор для чтения документа.

    Включает список получателей и флаг, ознакомился ли текущий пользователь.
    """

    created_by = EmployeeBriefSerializer(read_only=True)
    uploaded_by = EmployeeBriefSerializer(read_only=True)
    modified_by = EmployeeBriefSerializer(read_only=True)
    recipients = EmployeeBriefSerializer(many=True, read_only=True)
    departments = DepartmentBriefSerializer(many=True, read_only=True)
    acknowledgement_recipients = EmployeeBriefSerializer(many=True, read_only=True)
    acknowledgement_departments = DepartmentBriefSerializer(many=True, read_only=True)
    folder = FolderBriefSerializer(read_only=True)
    folder_path = serializers.CharField(read_only=True)
    tags = DocumentTagSerializer(many=True, read_only=True)
    created_at = serializers.DateTimeField(read_only=True)
    file_url = serializers.SerializerMethodField()
    file_name = serializers.CharField(
        source="file.name", read_only=True, allow_null=True
    )
    file_size = serializers.IntegerField(
        source="file.size", read_only=True, allow_null=True
    )
    is_acknowledged = serializers.SerializerMethodField()
    is_maximally_hidden = serializers.SerializerMethodField()
    acknowledgement_required_for_user = serializers.SerializerMethodField()
    acknowledged_count = serializers.SerializerMethodField()
    acknowledgement_total = serializers.SerializerMethodField()
    comments_count = serializers.SerializerMethodField()
    linked_tasks = serializers.SerializerMethodField()

    class Meta:
        model = Document
        fields = (
            "id",
            "title",
            "description",
            "extracted_text",  # Для полнотекстового поиска
            "folder",  # Папка документа
            "folder_path",  # Полный путь папки
            "tags",  # Теги
            "created_by",  # Создатель документа
            "created_at",  # Дата создания
            "uploaded_by",
            "uploaded_at",
            "modified_by",
            "modified_at",
            "sent_to_all",
            "is_regulation",
            "acknowledgement_required",  # Требуется ли ознакомление
            "acknowledgement_for_all",
            "acknowledgement_required_for_user",
            "acknowledged_count",
            "acknowledgement_total",
            "comments_count",
            "departments",
            "recipients",
            "acknowledgement_departments",
            "acknowledgement_recipients",
            "file_url",
            "file_name",
            "file_size",
            "is_acknowledged",
            "is_maximally_hidden",
            "linked_tasks",
        )

    def get_file_url(self, obj: Document) -> str | None:
        if not obj.file_id:
            return None
        url = reverse("api:v1:documents-download", kwargs={"pk": obj.pk})
        # Replacing an attachment changes the URL so open previews reload it.
        url = f"{url}?version={obj.file_id}"
        request = self.context.get("request")
        return request.build_absolute_uri(url) if request else url

    def get_is_acknowledged(self, obj: Document) -> bool:
        """Возвращает флаг ознакомления текущего пользователя.

        Args:
            obj (Document): Документ.

        Returns:
            bool: True, если текущий пользователь уже ознакомился.
        """
        annotated = getattr(obj, "_is_acknowledged", None)
        if annotated is not None:
            return bool(annotated)

        request = self.context.get("request")
        if not request or not request.user.is_authenticated:
            return False
        return DocumentAcknowledgement.objects.filter(
            document=obj, user=request.user
        ).exists()

    def get_is_maximally_hidden(self, obj: Document) -> bool:
        """Максимально ли скрыта карточка для текущего пользователя."""
        annotated = getattr(obj, "_is_maximally_hidden", None)
        if annotated is not None:
            return bool(annotated)

        request = self.context.get("request")
        if not request or not request.user.is_authenticated:
            return False
        return DocumentDisplayState.objects.filter(
            document=obj,
            user=request.user,
            is_maximally_hidden=True,
        ).exists()

    def get_acknowledgement_required_for_user(self, obj: Document) -> bool:
        """Нужно ли текущему сотруднику подтверждать ознакомление."""
        request = self.context.get("request")
        if not request or not request.user.is_authenticated:
            return False

        audience_ids = getattr(obj, "_acknowledgement_user_ids", None)
        if audience_ids is not None:
            return request.user.pk in audience_ids

        from documents.audience import user_requires_document_acknowledgement

        return user_requires_document_acknowledgement(obj, request.user)

    def get_acknowledged_count(self, obj: Document) -> int:
        """Количество сотрудников из аудитории, уже ознакомившихся."""
        attached = getattr(obj, "_acknowledged_count", None)
        if attached is not None:
            return int(attached)

        from documents.audience import document_acknowledgement_audience

        audience = document_acknowledgement_audience(obj)
        return obj.acknowledgements.filter(user__in=audience).count()

    def get_acknowledgement_total(self, obj: Document) -> int:
        """Размер аудитории обязательного ознакомления."""
        attached = getattr(obj, "_acknowledgement_total", None)
        if attached is not None:
            return int(attached)

        from documents.audience import document_acknowledgement_audience

        return document_acknowledgement_audience(obj).count()

    def get_comments_count(self, obj: Document) -> int:
        """Количество неудалённых комментариев документа."""
        attached = getattr(obj, "_comments_count", None)
        if attached is not None:
            return int(attached)

        from communications.comments_helpers import get_comment_count

        return get_comment_count(obj)

    @extend_schema_field(serializers.ListField(child=serializers.DictField()))
    def get_linked_tasks(self, obj: Document) -> list[dict]:
        prefetched = getattr(obj, "_linked_task_payloads", None)
        if prefetched is not None:
            return prefetched

        request = self.context.get("request")
        user = getattr(request, "user", None)
        if not user or not getattr(user, "is_authenticated", False):
            return []

        from tasks.models import TaskLinkedObjectKind
        from tasks.presentation import linked_task_badges_for_object

        return linked_task_badges_for_object(
            obj=obj,
            kind=TaskLinkedObjectKind.DOCUMENT,
            user=user,
        )