from rest_framework import serializers

from .models import Notification


class NotificationSerializer(serializers.ModelSerializer):
    type = serializers.CharField(source="notification_type", read_only=True)
    unread = serializers.SerializerMethodField()
    project_name = serializers.CharField(source="project.name", read_only=True)
    brief = serializers.SerializerMethodField()
    body = serializers.SerializerMethodField()
    metadata = serializers.SerializerMethodField()

    class Meta:
        model = Notification
        fields = [
            "id",
            "type",
            "notification_type",
            "priority",
            "title",
            "brief",
            "body",
            "source",
            "project",
            "project_name",
            "stage",
            "owner_label",
            "cost_label",
            "related_url",
            "is_read",
            "unread",
            "read_at",
            "archived_at",
            "metadata",
            "created_at",
            "updated_at",
        ]
        read_only_fields = [
            "id",
            "type",
            "project_name",
            "read_at",
            "archived_at",
            "created_at",
            "updated_at",
        ]

    def get_unread(self, obj):
        return not obj.is_read

    def _current_generation_message(self, obj):
        metadata = obj.metadata if isinstance(obj.metadata, dict) else {}
        error = metadata.get("generation_error")
        if not isinstance(error, dict) or error.get("domain") != "generation":
            return ""
        from apps.ai.generation_errors import public_error_for_code

        return public_error_for_code(
            str(error.get("code") or "unknown"),
            operation=str(error.get("operation") or "image_generate"),
            reference_id=str(error.get("reference_id") or "") or None,
        ).fallback_message

    def get_brief(self, obj):
        return self._current_generation_message(obj) or obj.brief or ""

    def get_body(self, obj):
        """兼容早期 AI 失败通知：不再向普通用户回传嵌入正文的上游原始异常。"""
        current = self._current_generation_message(obj)
        if current:
            return current
        body = obj.body or ""
        marker = "—— 第三方服务商 API 返回的原始报错 ——"
        return body.split(marker, 1)[0].strip()

    def get_metadata(self, obj):
        """旧通知的 api_error 也必须从普通用户 API 中移除。"""
        metadata = dict(obj.metadata or {})
        metadata.pop("api_error", None)
        return metadata