dingdanquanliucheng/backend/app/services/file_service.py

"""文件管理服务层。

负责文件上传凭证生成、附件元数据保存、文件类型检测和大小校验等业务逻辑。
依赖 storage_service 进行对象存储交互，依赖 FileRepository 进行附件数据持久化，
依赖 audit_service 记录操作审计日志。
"""

from datetime import datetime

from sqlalchemy.exc import SQLAlchemyError
from sqlalchemy.orm import Session

from backend.app.core.config import get_settings
from backend.app.core.error_codes import ErrorCode
from backend.app.core.exceptions import AppException
from backend.app.repositories.file_repository import FileRepository
from backend.app.services.audit_service import audit_service
from backend.app.services.storage_service import storage_service


class FileService:
    """文件服务，封装上传凭证、附件元数据和文件校验逻辑。

    依赖:
        FileRepository - 附件数据访问
        storage_service - 阿里云 OSS 存储交互
        audit_service - 操作审计日志
        settings - OSS 上传大小限制等配置
    """

    def __init__(self) -> None:
        self.settings = get_settings()
        self.repository = FileRepository()

    def create_upload_token(self, payload: dict, session: Session | None = None) -> dict:
        """生成文件上传凭证。

        校验文件名和业务类型非空，自动检测文件分类和校验文件大小，
        调用 storage_service 生成 OSS 上传凭证。

        Args:
            payload: 包含 file_name、biz_type、file_type、file_size 等的请求体
            session: 数据库会话

        Returns:
            包含上传凭证和 file_category 的字典

        被调用路由: files.py - POST /files/upload-token
        """
        if not payload["file_name"].strip():
            raise AppException(code=ErrorCode.PARAM_ERROR, message="文件名不能为空", status_code=400)
        if not payload["biz_type"].strip():
            raise AppException(code=ErrorCode.PARAM_ERROR, message="业务类型不能为空", status_code=400)

        file_category = self._detect_file_category(payload["file_type"], payload["file_name"])
        self._validate_file_size(file_category, payload["file_size"])
        token_payload = storage_service.create_upload_token(
            payload["biz_type"],
            payload["biz_id"],
            payload["file_name"],
            payload["file_size"],
        )
        token_payload["file_category"] = file_category
        return token_payload

    def save_attachment(self, payload: dict, session: Session | None = None) -> dict:
        """保存附件元数据。

        在文件上传至 OSS 后调用，将文件元信息持久化到数据库。
        自动记录审计日志。

        Args:
            payload: 包含 biz_type、biz_id、file_name、file_url 等的请求体
            session: 数据库会话

        Returns:
            附件元数据字典

        被调用路由: files.py - POST /files/attachment
        """
        if session is None:
            raise AppException(code=ErrorCode.INTERNAL_ERROR, message="数据库连接不可用", status_code=500)
        attachment_payload = self.build_attachment_payload(payload, created_by=payload.get("created_by"))
        try:
            attachment = self.repository.create_attachment(session, attachment_payload)
            audit_service.write_log(
                session,
                {
                    "operate_type": "attachment_create",
                    "biz_type": payload["biz_type"],
                    "biz_id": payload["biz_id"],
                    "before_value": None,
                    "after_value": self._map_attachment(attachment),
                    "remark": f"保存附件 {payload['file_name']}",
                },
            )
            session.commit()
            return self._map_attachment(attachment)
        except AppException:
            session.rollback()
            raise
        except SQLAlchemyError as exc:
            session.rollback()
            raise AppException(code=ErrorCode.INTERNAL_ERROR, message="数据库异常", status_code=500) from exc

    def build_attachment_payload(
        self,
        payload: dict,
        created_by: int | None = None,
        require_file_size: bool = True,
    ) -> dict:
        """构建附件入库的数据载荷。

        校验必填字段，检测文件分类，提取 object_key，验证文件名与地址匹配性。
        供 save_attachment 和 logistics_service._persist_task_attachments 共用。

        Args:
            payload: 包含 biz_type、biz_id、file_name、file_url 等的原始请求体
            created_by: 创建人用户 ID
            require_file_size: 是否要求 file_size 非空（司机任务附件可为 False）

        Returns:
            标准化后的附件入库数据字典
        """
        if not payload["biz_type"].strip():
            raise AppException(code=ErrorCode.PARAM_ERROR, message="业务类型不能为空", status_code=400)
        if not payload["file_name"].strip():
            raise AppException(code=ErrorCode.PARAM_ERROR, message="文件名不能为空", status_code=400)
        if not payload["file_url"].strip():
            raise AppException(code=ErrorCode.PARAM_ERROR, message="文件地址不能为空", status_code=400)

        file_name = payload["file_name"]
        file_url = payload["file_url"]
        file_type = payload.get("file_type") or None
        file_size = payload.get("file_size")
        if require_file_size and (file_size is None or int(file_size) <= 0):
            raise AppException(code=ErrorCode.PARAM_ERROR, message="文件大小不能为空", status_code=400)

        file_category = self._detect_file_category(file_type or "", file_name)
        if file_size is not None and int(file_size) > 0:
            self._validate_file_size(file_category, int(file_size))

        object_key = storage_service.extract_object_key(file_url)
        file_ext = self._extract_file_ext(file_name)
        self._validate_attachment_file(file_name, file_url, object_key)

        # 司机任务操作里可能只有文件名和 URL，这里允许 MIME 和大小为空，但仍统一沉淀附件元数据。
        return {
            "biz_type": payload["biz_type"],
            "biz_id": payload["biz_id"],
            "file_name": file_name,
            "file_url": file_url,
            "file_type": file_type,
            "file_size": int(file_size) if file_size is not None else None,
            "created_by": created_by,
            "storage_provider": "aliyun_oss",
            "bucket_name": self.settings.aliyun_oss_bucket,
            "object_key": object_key,
            "content_type": file_type,
            "file_ext": file_ext,
            "file_category": file_category,
        }

    def _validate_attachment_file(self, file_name: str, file_url: str, object_key: str) -> None:
        """校验附件文件名与对象地址的匹配性和 URL 格式。

        防止前端绕过上传凭证直接塞入不匹配的文件。

        Args:
            file_name: 文件名
            file_url: 文件 URL
            object_key: OSS 对象 key

        Raises:
            AppException: 不匹配或格式错误时抛出 FILE_UPLOAD_FAILED
        """
        expected_name = file_name.strip()
        object_name = object_key.rsplit("/", 1)[-1]
        # 保存附件时再次核对 object key 与文件名，避免前端绕过上传凭证直接塞入不匹配文件。
        if expected_name and expected_name not in object_name:
            raise AppException(code=ErrorCode.FILE_UPLOAD_FAILED, message="附件文件名与对象地址不匹配", status_code=400)
        if not file_url.startswith(("http://", "https://")):
            raise AppException(code=ErrorCode.FILE_UPLOAD_FAILED, message="附件地址格式不正确", status_code=400)

    def _detect_file_category(self, file_type: str, file_name: str) -> str:
        """根据 MIME 类型和文件扩展名检测文件分类。

        分类包括: image、video、import（Excel/CSV）、document。

        Args:
            file_type: MIME 类型
            file_name: 文件名

        Returns:
            文件分类字符串
        """
        content_type = (file_type or "").lower()
        suffix = self._extract_file_ext(file_name).lower()
        if content_type.startswith("image/") or suffix in {"jpg", "jpeg", "png", "gif", "webp"}:
            return "image"
        if content_type.startswith("video/") or suffix in {"mp4", "mov", "avi"}:
            return "video"
        if suffix in {"xlsx", "xls", "csv"}:
            return "import"
        return "document"

    def _validate_file_size(self, file_category: str, file_size: int) -> None:
        """校验文件大小是否超出分类对应的限制。

        Args:
            file_category: 文件分类
            file_size: 文件大小（字节）

        Raises:
            AppException: 超出限制时抛出 FILE_UPLOAD_FAILED
        """
        max_mb = (
            self.settings.oss_upload_max_image_mb
            if file_category == "image"
            else self.settings.oss_upload_max_video_mb
            if file_category == "video"
            else max(self.settings.oss_upload_max_image_mb, self.settings.oss_upload_max_video_mb)
        )
        if file_size > max_mb * 1024 * 1024:
            raise AppException(code=ErrorCode.FILE_UPLOAD_FAILED, message="文件大小超出限制", status_code=400)

    def _extract_file_ext(self, file_name: str) -> str:
        """从文件名中提取扩展名。

        Args:
            file_name: 文件名

        Returns:
            扩展名字符串（不含点号），无扩展名时返回空字符串
        """
        parts = file_name.rsplit(".", 1)
        return parts[1] if len(parts) == 2 else ""

    def list_attachments(self, biz_type: str, biz_id: int, session: Session | None = None) -> list[dict]:
        """按业务类型和 ID 查询附件列表。"""
        if session is None:
            return []
        attachments = self.repository.list_attachments(session, biz_type, int(biz_id))
        return [self._map_attachment(a) for a in attachments]

    def _map_attachment(self, attachment) -> dict:
        """将附件 ORM 对象映射为字典格式。

        Args:
            attachment: 附件 ORM 对象

        Returns:
            附件摘要字典
        """
        return {
            "attachment_id": attachment.id,
            "biz_type": attachment.biz_type,
            "biz_id": attachment.biz_id,
            "file_name": attachment.file_name,
            "file_url": attachment.file_url,
            "file_type": attachment.file_type,
            "file_size": attachment.file_size,
            "storage_provider": attachment.storage_provider,
            "bucket_name": attachment.bucket_name,
            "object_key": attachment.object_key,
            "content_type": attachment.content_type,
            "file_ext": attachment.file_ext,
            "file_category": attachment.file_category,
            "created_at": attachment.created_at.strftime("%Y-%m-%d %H:%M:%S") if attachment.created_at else "",
        }


file_service = FileService()