"""
对象存储服务（腾讯云 COS）

支持两种认证模式：
1. CVM 角色认证：通过元数据服务自动获取临时凭证（推荐，Docker 需配置 iptables 转发）
2. 密钥认证：通过 COS_SECRET_ID / COS_SECRET_KEY 环境变量（备选）
"""
import os
import time
import uuid
from datetime import datetime, timezone
from typing import Optional
from pathlib import Path

from app.config import settings
from app.utils.logger import logger


# 按需导入 COS SDK
_cos_client = None
_cos_available = False

try:
    from qcloud_cos import CosConfig, CosS3Client
    _cos_available = True
except ImportError:
    _cos_available = False


class CosStorageError(Exception):
    """COS 存储操作异常"""
    pass


class CvmRoleCredential:
    """CVM 角色凭证提供者，从元数据服务自动获取和刷新临时凭证"""

    def __init__(self, role_name: str):
        self._role_name = role_name
        self._expired_time = 0
        self._secret_id = ""
        self._secret_key = ""
        self._token = ""
        self._refresh()

    def _refresh(self):
        """从元数据服务获取临时凭证（提前5分钟刷新）"""
        if time.time() < self._expired_time - 300:
            return
        import requests
        url = f"http://metadata.tencentyun.com/latest/meta-data/cam/security-credentials/{self._role_name}"
        resp = requests.get(url, timeout=5)
        resp.raise_for_status()
        data = resp.json()
        if data.get("Code") != "Success":
            raise CosStorageError(f"获取 CVM 角色凭证失败: {data}")
        self._secret_id = data["TmpSecretId"]
        self._secret_key = data["TmpSecretKey"]
        self._token = data["Token"]
        self._expired_time = data["ExpiredTime"]
        logger.info(f"CVM 角色凭证已刷新，过期时间: {datetime.fromtimestamp(self._expired_time)}")

    @property
    def secret_id(self):
        self._refresh()
        return self._secret_id

    @property
    def secret_key(self):
        self._refresh()
        return self._secret_key

    @property
    def token(self):
        self._refresh()
        return self._token


def _discover_cvm_role() -> Optional[str]:
    """自动发现 CVM 绑定的角色名"""
    import requests
    try:
        resp = requests.get(
            "http://metadata.tencentyun.com/latest/meta-data/cam/security-credentials/",
            timeout=3,
        )
        if resp.status_code == 200 and resp.text.strip():
            return resp.text.strip()
    except Exception:
        pass
    return None


def _get_cos_client():
    """懒加载 COS 客户端单例"""
    global _cos_client
    if _cos_client is not None:
        return _cos_client

    if not _cos_available:
        raise CosStorageError("qcloud_cos 未安装，请运行: pip install cos-python-sdk-v5")

    cfg = settings.cos
    if not cfg.enabled:
        return None
    if not cfg.bucket:
        raise CosStorageError("COS_BUCKET 未配置")

    secret_id = os.getenv("COS_SECRET_ID", "")
    secret_key = os.getenv("COS_SECRET_KEY", "")

    try:
        if secret_id and secret_key:
            # 模式1：密钥认证
            cos_config = CosConfig(
                Region=cfg.region,
                SecretId=secret_id,
                SecretKey=secret_key,
                Scheme="https",
            )
            logger.info(f"COS 客户端初始化成功 (密钥模式): bucket={cfg.bucket}")
        else:
            # 模式2：CVM 角色认证（通过元数据服务获取临时凭证）
            role_name = _discover_cvm_role()
            if not role_name:
                raise CosStorageError(
                    "COS 认证失败: 未设置 COS_SECRET_ID/COS_SECRET_KEY，"
                    "且无法访问 CVM 元数据服务。请检查 iptables 转发规则或配置密钥。"
                )
            credential = CvmRoleCredential(role_name)
            cos_config = CosConfig(
                Region=cfg.region,
                CredentialInstance=credential,
                Scheme="https",
            )
            logger.info(f"COS 客户端初始化成功 (CVM角色: {role_name}): bucket={cfg.bucket}")

        _cos_client = CosS3Client(cos_config)
        return _cos_client
    except CosStorageError:
        raise
    except Exception as e:
        raise CosStorageError(f"COS 客户端初始化失败: {e}")


def _generate_object_key(prefix: str = "", ext: str = ".jpg") -> str:
    """
    生成对象存储 Key
    格式: {prefix}/{YYYY}/{MM}/{DD}/{YYYYMMDDHHmmss}_{uuid8}{ext}
    """
    now = datetime.now(timezone.utc)
    date_path = now.strftime("%Y/%m/%d")
    timestamp = now.strftime("%Y%m%d%H%M%S")
    unique_id = uuid.uuid4().hex[:8].upper()
    prefix = prefix.strip("/") if prefix else settings.cos.upload_prefix
    return f"{prefix}/{date_path}/{timestamp}_{unique_id}{ext}"


class COSStorage:
    """
    对象存储接口（纯 COS 模式）

    COS_ENABLED=true: 使用腾讯云 COS，上传失败直接报错
    COS_ENABLED=false: 未启用，调用上传方法时报错
    """

    def __init__(self):
        self._client = None
        self._enabled = False
        self._init()

    def _init(self):
        """初始化 COS 客户端"""
        if not settings.cos.enabled:
            logger.info("COS 未启用 (COS_ENABLED=false)")
            return

        self._client = _get_cos_client()
        if self._client:
            self._enabled = True

    @property
    def is_cos_mode(self) -> bool:
        return self._enabled and self._client is not None

    def _require_cos(self):
        """检查 COS 是否可用，不可用则抛出异常"""
        if not self._enabled or self._client is None:
            raise CosStorageError("COS 未启用或初始化失败，请检查 COS_ENABLED 和 CVM 角色绑定")

    # ======================== 上传 ========================

    def upload_image(self, image_data: bytes, filename: Optional[str] = None) -> str:
        """上传图片到 COS，返回 object_key"""
        self._require_cos()
        object_key = filename or _generate_object_key(ext=".jpg")
        try:
            self._client.put_object(
                Bucket=settings.cos.bucket,
                Body=image_data,
                Key=object_key,
                ContentType="image/jpeg",
            )
            logger.info(f"COS 上传成功: {object_key}")
            return object_key
        except Exception as e:
            raise CosStorageError(f"COS 图片上传失败: {e}")

    def upload_file(self, file_data: bytes, object_key: str, content_type: str = "application/octet-stream") -> str:
        """上传任意文件到 COS"""
        self._require_cos()
        try:
            self._client.put_object(
                Bucket=settings.cos.bucket,
                Body=file_data,
                Key=object_key,
                ContentType=content_type,
            )
            logger.info(f"COS 文件上传成功: {object_key}")
            return object_key
        except Exception as e:
            raise CosStorageError(f"COS 文件上传失败: {e}")

    # ======================== 下载（预签名 URL） ========================

    def get_presigned_url(self, object_key: str, expire: Optional[int] = None) -> str:
        """获取预签名下载 URL"""
        if object_key.startswith("http"):
            return object_key

        if not self._enabled:
            return object_key

        expire = expire or settings.cos.presign_expire
        try:
            url = self._client.get_presigned_download_url(
                Bucket=settings.cos.bucket,
                Key=object_key,
                Expired=expire,
            )
            return url
        except Exception as e:
            logger.error(f"生成预签名 URL 失败: {e}")
            return object_key

    def get_presigned_upload_url(self, object_key: str, expire: Optional[int] = None) -> str:
        """获取预签名上传 URL（供前端直传）"""
        self._require_cos()
        expire = expire or settings.cos.presign_expire
        try:
            url = self._client.get_presigned_url(
                Method="PUT",
                Bucket=settings.cos.bucket,
                Key=object_key,
                Expired=expire,
            )
            return url
        except Exception as e:
            raise CosStorageError(f"生成预签名上传 URL 失败: {e}")

    # ======================== 删除 ========================

    def delete_object(self, object_key: str) -> bool:
        """删除 COS 对象"""
        if not self._enabled:
            return False
        try:
            self._client.delete_object(
                Bucket=settings.cos.bucket,
                Key=object_key,
            )
            logger.info(f"COS 对象已删除: {object_key}")
            return True
        except Exception as e:
            logger.error(f"COS 删除失败: {e}")
            return False

    # ======================== 兼容旧接口 ========================

    def get_url(self, path: str) -> str:
        """获取访问 URL（兼容旧代码调用）"""
        if not path:
            return ""
        if path.startswith("http"):
            return path
        return self.get_presigned_url(path)


# 全局单例
_cos_storage: Optional[COSStorage] = None


def get_oss_storage() -> COSStorage:
    """获取存储服务单例"""
    global _cos_storage
    if _cos_storage is None:
        _cos_storage = COSStorage()
    return _cos_storage