"""
Fetcher Factory - Backend Version
Currently supports CN market with Tushare
"""
import os


class FetcherFactory:
    """
    数据获取工厂类 (Backend版本)
    
    当前支持的数据源:
    - Tushare: CN (中国A股)
    - iFinD: HK, JP, US, VN
    - Bloomberg: CN, HK, JP, US, VN
    """
    
    @staticmethod
    def get_fetcher(market: str, data_source: str = None, **kwargs):
        """
        获取对应市场和数据源的 Fetcher
        
        Args:
            market: 市场代码 (CN, HK, JP, US, VN)
            data_source: 数据源名称 (iFinD, Tushare, Bloomberg)
            **kwargs: 额外参数（如 API tokens）
        
        Returns:
            Fetcher 实例
        """
        market = market.upper()
        
        # 如果未指定数据源，使用默认值
        if not data_source:
            data_source = FetcherFactory._get_default_source(market)
        
        elif data_source == 'iFinD':
            return FetcherFactory._get_ifind_fetcher(market, **kwargs)
        elif data_source == 'Bloomberg':
            return FetcherFactory._get_bloomberg_fetcher(market, **kwargs)
        else:
            # 其他数据源暂未迁移
            raise NotImplementedError(
                f"Data source '{data_source}' not supported in backend."
            )
    
    @staticmethod
    def _get_default_source(market: str) -> str:
        """获取市场的默认数据源"""
        defaults = {
            'CN': 'Tushare',
            'HK': 'iFinD',
            'JP': 'iFinD',
            'US': 'iFinD',
            'VN': 'iFinD'
        }
        return defaults.get(market, 'iFinD')
    
    @staticmethod
    def _get_tushare_fetcher(market: str, **kwargs):
        """获取 Tushare Fetcher"""
        if market != 'CN':
            raise ValueError("Tushare only supports CN market")
        
        # 获取 Tushare token
        tushare_token = kwargs.get('tushare_token') or os.getenv('TUSHARE_TOKEN')
        
        if not tushare_token:
            raise ValueError("Tushare token is required for CN market")
        
        from app.fetchers.cn_fetcher import CnFetcher
        return CnFetcher(tushare_token)

    @staticmethod
    def _get_ifind_fetcher(market: str, **kwargs):
        """Get iFinD Fetcher"""
        ifind_token = kwargs.get('ifind_token') or os.getenv('IFIND_REFRESH_TOKEN')
        if not ifind_token:
             # Try legacy env var name if needed, but IFIND_REFRESH_TOKEN is standard
             ifind_token = os.getenv('IFIND_REFRESH_TOKEN')

        if not ifind_token:
             raise ValueError("iFinD refresh token is required (IFIND_REFRESH_TOKEN)")

        if market == 'HK':
            from app.fetchers.hk_fetcher import HkFetcher
            return HkFetcher(ifind_token)
        elif market == 'JP':
            from app.fetchers.jp_fetcher import JpFetcher
            return JpFetcher(ifind_token)
        elif market == 'VN':
            from app.fetchers.vn_fetcher import VnFetcher
            return VnFetcher(ifind_token)
        elif market == 'US':
            from app.fetchers.us_fetcher import UsFetcher
            return UsFetcher(ifind_token)
        else:
            raise NotImplementedError(f"iFinD fetcher for market {market} not yet migrated to backend.")

    @staticmethod
    def _get_bloomberg_fetcher(market: str, **kwargs):
        """Get Bloomberg Fetcher"""
        # Bloomberg client typically uses internal auth (password based) or default keys.
        # We can pass kwargs but default init handles env vars.
        from app.fetchers.bloomberg_fetcher import BloombergFetcher
        return BloombergFetcher(market=market)