from urllib.parse import urlsplit

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

from api.v1.employees.serializers import EmployeeBriefSerializer
from tasks.models import (
    TaskActivity,
    TaskAttachment,
    TaskChecklistItem,
    TaskExternalLink,
)


class TaskActivitySerializer(serializers.ModelSerializer):
    actor = EmployeeBriefSerializer(read_only=True)
    action_display = serializers.CharField(source="get_action_display", read_only=True)

    class Meta:
        model = TaskActivity
        fields = [
            "id",
            "action",
            "action_display",
            "actor",
            "object_kind",
            "object_id",
            "metadata",
            "created_at",
        ]
        read_only_fields = fields


class TaskAttachmentSerializer(serializers.ModelSerializer):
    uploaded_by = EmployeeBriefSerializer(read_only=True)
    download_url = serializers.SerializerMethodField()
    thumbnail_url = serializers.SerializerMethodField()

    class Meta:
        model = TaskAttachment
        fields = [
            "id",
            "task",
            "comment",
            "file_name",
            "file_size",
            "mime_type",
            "uploaded_by",
            "created_at",
            "download_url",
            "thumbnail_url",
        ]
        read_only_fields = fields

    @extend_schema_field(serializers.URLField())
    def get_download_url(self, obj):
        url = reverse(
            "api:v1:tasks:task-attachment-download",
            kwargs={"pk": obj.task_id, "attachment_id": obj.id},
        )
        request = self.context.get("request")
        return request.build_absolute_uri(url) if request else url

    @extend_schema_field(serializers.URLField(allow_null=True))
    def get_thumbnail_url(self, obj):
        from tasks.media import task_attachment_media_kind

        if not task_attachment_media_kind(obj):
            return None
        url = reverse(
            "api:v1:tasks:task-attachment-thumbnail",
            kwargs={"pk": obj.task_id, "attachment_id": obj.id},
        )
        request = self.context.get("request")
        return request.build_absolute_uri(url) if request else url


class TaskChecklistItemSerializer(serializers.ModelSerializer):
    created_by = EmployeeBriefSerializer(read_only=True)
    completed_by = EmployeeBriefSerializer(read_only=True)

    class Meta:
        model = TaskChecklistItem
        fields = [
            "id",
            "task",
            "title",
            "position",
            "is_completed",
            "created_by",
            "completed_by",
            "completed_at",
            "created_at",
            "updated_at",
        ]
        read_only_fields = [
            "id",
            "task",
            "created_by",
            "completed_by",
            "completed_at",
            "created_at",
            "updated_at",
        ]

    def validate_title(self, value):
        value = value.strip()
        if not value:
            raise serializers.ValidationError("Введите текст пункта чек-листа.")
        return value


class TaskExternalLinkSerializer(serializers.ModelSerializer):
    created_by = EmployeeBriefSerializer(read_only=True)

    class Meta:
        model = TaskExternalLink
        fields = ["id", "task", "url", "title", "created_by", "created_at"]
        read_only_fields = ["id", "task", "created_by", "created_at"]

    def validate_url(self, value):
        value = value.strip()
        if urlsplit(value).scheme.lower() not in {"http", "https"}:
            raise serializers.ValidationError(
                "Разрешены только ссылки с протоколом http или https."
            )
        return value

    def validate_title(self, value):
        return value.strip()