from __future__ import annotations

import os
from typing import Dict, Optional

from flask import current_app

from .interface import StorageInterface
from .local import LocalStorage
from ..enums import StorageTypeEnum


class StorageManager:
    """存储管理器，负责根据类型创建存储实例"""

    _instances: Dict[str, StorageInterface] = {}

    @classmethod
    def get_storage(cls, storage_type: Optional[str] = None) -> StorageInterface:
        """
        获取存储实例（单例模式）
        
        Args:
            storage_type: 存储类型，为None时使用默认类型
            
        Returns:
            存储实例
        """
        config = current_app.config.get("FILE_STORAGE", {})
        default_type = config.get("DEFAULT_STORAGE_TYPE", StorageTypeEnum.LOCAL.value)
        storage_type = storage_type or default_type

        if storage_type not in cls._instances:
            cls._instances[storage_type] = cls._create_storage(storage_type, config)
        return cls._instances[storage_type]

    @staticmethod
    def _create_storage(storage_type: str, config: dict) -> StorageInterface:
        """
        创建存储实例
        
        Args:
            storage_type: 存储类型
            config: 配置字典
            
        Returns:
            存储实例
        """
        if storage_type == StorageTypeEnum.LOCAL.value:
            local_config = config.get("LOCAL", {})
            if not local_config.get("base_path"):
                local_config["base_path"] = os.path.join(
                    current_app.config.get("BASE_DIR", current_app.root_path), "runtime", "uploads"
                )
            return LocalStorage(local_config)
        
        elif storage_type == StorageTypeEnum.ALIYUN_OSS.value:
            from .aliyun_oss import AliyunOSSStorage
            oss_config = config.get("ALIYUN_OSS", {})
            return AliyunOSSStorage(oss_config)
        
        elif storage_type == StorageTypeEnum.TENCENT_COS.value:
            from .tencent_cos import TencentCOSStorage
            cos_config = config.get("TENCENT_COS", {})
            return TencentCOSStorage(cos_config)
        
        elif storage_type == StorageTypeEnum.QINIU_KODO.value:
            from .qiniu_kodo import QiniuKodoStorage
            kodo_config = config.get("QINIU_KODO", {})
            return QiniuKodoStorage(kodo_config)
        
        elif storage_type == StorageTypeEnum.AWS_S3.value:
            # AWS S3 可以后续添加
            raise NotImplementedError("AWS S3 适配器尚未实现")
        
        elif storage_type == StorageTypeEnum.HUAWEI_OBS.value:
            from .huawei_obs import HuaweiOBSStorage
            obs_config = config.get("HUAWEI_OBS", {})
            return HuaweiOBSStorage(obs_config)
        
        elif storage_type == StorageTypeEnum.MINIO.value:
            # MinIO 可以后续添加
            raise NotImplementedError("MinIO 适配器尚未实现")
        
        raise ValueError(f"未支持的存储类型: {storage_type}")