from hdfswrapper.base_hook import BaseHook

try:
    snakebite_imported = True
    from snakebite.client import Client, HAClient, Namenode
except ImportError:
    snakebite_imported = False


class HDFSHookException(Exception):
    pass


class HDFSHook(BaseHook):
    '''
    Interact with HDFS. This class is a wrapper around the snakebite library.
    '''

    def __init__(self, hdfs_conn_id='hdfs_default', proxy_user=None):
        if not snakebite_imported:
            raise ImportError(
                'This HDFSHook implementation requires snakebite, but '
                'snakebite is not compatible with Python 3 '
                '(as of August 2015). Please use Python 2 if you require '
                'this hook  -- or help by submitting a PR!')
        self.hdfs_conn_id = hdfs_conn_id
        self.proxy_user = proxy_user

    def get_conn(self):
        '''
        Returns a snakebite HDFSClient object.
        '''
        use_sasl = False
        securityConfig = None
        if securityConfig == 'kerberos':  # TODO make confugration file for thiw
            use_sasl = True

        connections = self.get_connections(self.hdfs_conn_id)
        client = None
        # When using HAClient, proxy_user must be the same, so is ok to always take the first
        effective_user = self.proxy_user or connections[0].login
        if len(connections) == 1:
            client = Client(connections[0].host, connections[0].port, use_sasl=use_sasl, effective_user=effective_user)
        elif len(connections) > 1:
            nn = [Namenode(conn.host, conn.port) for conn in connections]
            client = HAClient(nn, use_sasl=use_sasl, effective_user=effective_user)
        else:
            raise HDFSHookException("conn_id doesn't exist in the repository")
        return client

    def test(self):
        try:
            client = self.get_conn()
            print('***' * 30)
            print("\n    Test connection (ls /) \n")
            print('***' * 30)
            print(type(client.count(['/'])))
            print('-' * 40 + '\n')
            return False
        except Exception, e:
            print("     EROOR: connection can not be established: %s \n" % e)
            print('***' * 30)
            return False

    def download_file(self):
        raise NotImplementedError

    def mkdir(self):
        raise NotImplementedError

    def write(self):
        raise NotImplementedError

    def load_file(self):
        raise NotImplementedError

    def check_for_path(self):
        raise NotImplementedError

    def get_cursor(self):
        raise NotImplementedError

    def execute(self, hql):
        raise NotImplementedError