import os
import aiohttp
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:
            timeout = aiohttp.ClientTimeout(total=10.0)
            async with aiohttp.ClientSession(timeout=timeout) as client:
                # 1️⃣ 向 Master 申请 fid
                # logger.info(f"Connecting to SeaweedFS Master: {cls.MASTER_URL}")
                try:
                    async with client.get(f"{cls.MASTER_URL}/dir/assign") as assign_resp:
                        if assign_resp.status >= 300:
                            raise BizLogicError("Storage service unavailable")
                        assign_data = await assign_resp.json()
                except Exception as e:
                    logger.error(f"Failed to connect to Master at {cls.MASTER_URL}. Error: {e}")
                    raise BizLogicError("Storage service unavailable")
                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}")
                form = aiohttp.FormData()
                form.add_field(
                    "file",
                    file_content,
                    filename=file.filename,
                    content_type=file.content_type or "application/octet-stream",
                )
                async with client.post(upload_url, data=form) as upload_resp:
                    status = upload_resp.status
                    resp_text = await upload_resp.text()

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

                logger.error(f"Upload failed. Status: {status}, Body: {resp_text}")
                raise BizLogicError(f"Storage upload error: {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]

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

                async with client.get(file_url) as file_resp:
                    if file_resp.status == 200:
                        content = await file_resp.read()
                        return (
                            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]

            timeout = aiohttp.ClientTimeout(total=5.0)
            async with aiohttp.ClientSession(timeout=timeout) as client:
                # 1️⃣ 查找位置
                async with client.get(
                    f"{cls.MASTER_URL}/dir/lookup",
                    params={"volumeId": volume_id},
                ) as lookup_resp:
                    if lookup_resp.status != 200:
                        return False
                    data = await 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}"

                async with client.delete(delete_url) as del_resp:
                    # SeaweedFS 删除成功通常返回 200 或 202
                    return del_resp.status in [200, 202]

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