import os
import importlib
import logging

from .errors import *
from .constants import *

log = logging.getLogger('csst')

API_MODULE_PREFIX = "csst_dfs_api_"

class Delegate(object):
    def __init__(self):
        self.mode = os.getenv("CSST_DFS_API_MODE",'local')
        self.check_env()
 
    def check_env(self):
        if self.mode == MODE_LOCAL:
            self.local_path = os.getenv("CSST_LOCAL_FILE_ROOT")
            if not self.local_path:
                log.warn("enviroment variable CSST_DFS_API_MODE is not set, use default: /opt/temp/csst")
                self.local_path = "/opt/temp/csst"
            try:
                from csst_dfs_api_local._version import version  as local_version
            except ImportError:
                raise CSSTFatalException("please install csst_dfs_api_local firstly.")

        if self.mode == MODE_CLUSTER:
            self.config_server = os.getenv("CSST_DFS_CONFIG_SERVER")
            if not self.config_server:
                raise CSSTGenericException("enviroment variable CSST_DFS_CONFIG_SERVER is not set")
            try:
                from csst_dfs_api_cluster._version import version as cluster_version
            except ImportError:
                raise CSSTFatalException("please install csst_dfs_api_cluster firstly.")
    
    def load(self, sub_module):
        return importlib.import_module(f"{API_MODULE_PREFIX}{self.mode}.{sub_module}")