webapp/app/services/seaweedfs_service.py

import os
import httpx
from fastapi import UploadFile
from app.core.biz_exception import BizLogicError
from app.core.logger import logger

class SeaweedFSService:
    # 1. 优先读取环境变量，默认使用 Docker 内部网络的服务名
    # 只要后端和 SeaweedFS 在同一个 Docker 网络 (visafly-net)，这个地址就是通的
    MASTER_URL = os.getenv("SEAWEEDFS_MASTER_URL", "http://seaweedfs-master:9333")
    
    # 文件下载的公网入口（经过你的 Nginx + Backend 代理）
    DOWNLOAD_GATEWAY = "https://visafly.top/api/resource/download_file"

    @classmethod
    async def upload(cls, file: UploadFile):
        """
        上传文件到 SeaweedFS
        """
        try:
            async with httpx.AsyncClient(timeout=10.0) as client:
                # 1️⃣ 向 Master 申请 fid
                # logger.info(f"Connecting to SeaweedFS Master: {cls.MASTER_URL}")
                try:
                    assign_resp = await client.get(f"{cls.MASTER_URL}/dir/assign")
                    assign_resp.raise_for_status()
                except Exception as e:
                    logger.error(f"Failed to connect to Master at {cls.MASTER_URL}. Error: {e}")
                    raise BizLogicError("Storage service unavailable")

                assign_data = assign_resp.json()
                fid = assign_data.get("fid")
                
                # 2️⃣ 获取上传地址
                # 在 Docker 共享网络模式下，Master 返回的 publicUrl 就是 "seaweedfs-volume:8080"
                # 后端可以直接解析并访问这个地址，无需任何修改
                public_url = assign_data.get("publicUrl")
                
                if not public_url:
                    raise BizLogicError("No volume server available")

                upload_url = f"http://{public_url}/{fid}"
                download_url = f"{cls.DOWNLOAD_GATEWAY}?fid={fid}"

                # 3️⃣ 上传文件数据
                # 读取文件内容
                file_content = await file.read()
                files = {
                    "file": (
                        file.filename,
                        file_content,
                        file.content_type or "application/octet-stream",
                    )
                }

                # logger.info(f"Uploading to Volume Node: {upload_url}")
                upload_resp = await client.post(upload_url, files=files)

                if upload_resp.status_code == 201:
                    return {
                        "fid": fid,
                        "url": download_url,
                        "size": len(file_content)
                    }

                logger.error(f"Upload failed. Status: {upload_resp.status_code}, Body: {upload_resp.text}")
                raise BizLogicError(f"Storage upload error: {upload_resp.text}")

        except BizLogicError as e:
            raise e
        except Exception as e:
            logger.exception("SeaweedFS upload unexpected error")
            raise BizLogicError(f"Upload exception: {str(e)}")

    @classmethod
    async def get(cls, fid: str):
        """
        根据 fid 读取文件流
        """
        try:
            if not fid:
                return None
                
            # fid 格式通常是 "3,016a..."，逗号前是 volumeId
            volume_id = fid.split(",")[0]

            async with httpx.AsyncClient(timeout=10.0) as client:
                # 1️⃣ 查询文件位置
                lookup_resp = await client.get(
                    f"{cls.MASTER_URL}/dir/lookup",
                    params={"volumeId": volume_id},
                )
                
                if lookup_resp.status_code != 200:
                    logger.warning(f"Lookup failed for fid {fid}: {lookup_resp.text}")
                    return None
                    
                data = lookup_resp.json()
                locations = data.get("locations")

                if not locations:
                    return None

                # 2️⃣ 直接请求 Volume Server
                # 同样直接使用 Docker 内部地址
                public_url = locations[0]["publicUrl"]
                file_url = f"http://{public_url}/{fid}"

                file_resp = await client.get(file_url)
                
                if file_resp.status_code == 200:
                    return (
                        file_resp.content,
                        file_resp.headers.get("Content-Type", "application/octet-stream"),
                    )

                return None

        except Exception as e:
            logger.exception(f"SeaweedFS get failed for fid {fid}")
            return None

    @classmethod
    async def delete(cls, fid: str) -> bool:
        """
        删除文件
        """
        try:
            if not fid:
                return False

            volume_id = fid.split(",")[0]

            async with httpx.AsyncClient(timeout=5.0) as client:
                # 1️⃣ 查找位置
                lookup_resp = await client.get(
                    f"{cls.MASTER_URL}/dir/lookup",
                    params={"volumeId": volume_id},
                )
                
                if lookup_resp.status_code != 200:
                    return False
                    
                data = lookup_resp.json()
                locations = data.get("locations")

                if not locations:
                    return False

                # 2️⃣ 发送删除请求
                public_url = locations[0]["publicUrl"]
                delete_url = f"http://{public_url}/{fid}"

                del_resp = await client.delete(delete_url)
                
                # SeaweedFS 删除成功通常返回 200 或 202
                return del_resp.status_code in [200, 202]

        except Exception as e:
            logger.error(f"SeaweedFS delete failed for fid {fid}: {e}")
            return False