import atexit
from irods.session import iRODSSession
import irods
import storage.exceptions as StorageException
from storage.storage import BaseStorage
import logging
logger = logging.getLogger(__name__)


# iRods support - https://pypi.org/project/python-irodsclient/


class iRODSStorage(BaseStorage):

    TYPE = 'irods'

    def __init__(self, url=None, username=None, password=None, source=None, destination=None, encryption_key=None, sender_name=None, sender_email=None):
        # The iRODS zone is added to the url parameter. Use a '#' as seperator. This needs to be an Existing iRODS zone
        # Ex: rdms-prod-icat.data.rug.nl#rug
        (url, self.irods_zone) = url.split('#')
        if destination:
            destination = destination.strip('/')

        super().__init__(url, username, password, source, destination, encryption_key, sender_name, sender_email)

        # We need to clean up the iRODS session. Using atexit is the easiest way.
        atexit.register(self.__close)

    def __connect(self):
        try:
            assert(self.client)
        except AttributeError:
            # Connect to the iRODS server
            self.client = None
            try:
                self.client = iRODSSession(host=self.url, port=1247, user=self.username, password=self.password, zone=self.irods_zone)
                # Need to make a call to validate the authentication. So by checking the version, we know if we can authenticate...
                logger.debug(f'iRODS {self.client.server_version} connection through *native* authentication')
            except irods.exception.CAT_INVALID_AUTHENTICATION:
                # Authentication scheme is not native (default), so we try PAM here
                try:
                    self.client = iRODSSession(host=self.url, port=1247, user=self.username, password=self.password, zone=self.irods_zone, irods_authentication_scheme='pam')
                    logger.debug(f'iRODS {self.client.server_version} connection through *PAM* authentication')
                except irods.exception.CAT_INVALID_AUTHENTICATION:
                    # Authentication scheme is not PAM either last try: GIS
                    try:
                        self.client = iRODSSession(host=self.url, port=1247, user=self.username, password=self.password, zone=self.irods_zone, irods_authentication_scheme='gis')
                        logger.debug(f'iRODS {self.client.server_version} connection through *GIS* authentication')
                    except irods.exception.CAT_INVALID_AUTHENTICATION:
                        pass

            if self.client is None:
                logger.error('Unable to login to the iRODS instance. Please check username and password combination!')
                raise StorageException.InvalidAuthentication(self.username)

            logger.info('Created iRODS connection')

    def __close(self):
        logger.debug('Closing iRODS storage connection and clean up')
        self.client.cleanup()

    def _file_exists_action(self, path):
        self.__connect()
        try:
            self.client.data_objects.get(f'/{self.irods_zone}/home/{self.username}/{path}')
        except irods.exception.DataObjectDoesNotExist:
            logger.debug(f'File \'{path}\' does NOT exists on the iRODS server')
            return False
        except irods.exception.CollectionDoesNotExist:
            logger.debug(f'Parent folder of file \'{path}\' does NOT exists on the iRODS server')
            return False

        return True

    def _directory_exists_action(self, path):
        self.__connect()
        try:
            self.client.collections.get(f'/{self.irods_zone}/home/{self.username}/{path}')
            logger.debug(f'Folder \'{path}\' exists on the iRODS server')
        except irods.exception.CollectionDoesNotExist:
            logger.debug(f'Folder \'{path}\' does NOT exists on the iRODS server')
            return False

        return True

    def _make_folder_action(self, path):
        self.__connect()
        try:
            self.client.collections.create(f'/{self.irods_zone}/home/{self.username}/{path}')
        except irods.exception.CollectionDoesNotExist:
            logger.debug(f'Parent folder of file \'{path}\' does NOT exists on the iRODS server')
            return False

        return True

    def _upload_file_action(self, source, destination):
        self.__connect()
        # The upload path consists of a zone, username and path
        destination = f'/{self.irods_zone}/home/{self.username}/{destination}'
        logger.debug(f'Uploading to file: \'{destination}\'')
        try:
            obj = self.client.data_objects.create(destination)
            logger.debug(f'Created file: \'{destination}\'')
            # Open 'both' files and copy 4K data each time.
            with obj.open('w') as irods_file, open(source, 'rb') as source_file_binary:
                while True:
                    buf = source_file_binary.read(4096)
                    if buf:
                        irods_file.write(buf)
                    else:
                        break

            obj.metadata.add('source', f'Upload from VRE DataDropOff\n Added file: {destination} uploaded by: {self.sender_name}({self.sender_email})')

        except irods.exception.OVERWRITE_WITHOUT_FORCE_FLAG:
            logger.warning('The uploaded file already exists. So we did NOT upload the new file!')
            return False

        return True

    def _download_file_action(self, source, destination):
        self.__connect()
        logger.debug(f'Downloading file: \'{source}\' to \'{destination}\'')
        try:
            obj = self.client.data_objects.get(f'/{self.irods_zone}/home/{self.username}/{source}')
            # Open 'both' files and copy 4K data each time.
            with obj.open('r') as irods_source_file, open(destination, 'wb') as local_destination_file:
                while True:
                    buf = irods_source_file.read(4096)
                    if buf:
                        local_destination_file.write(buf)
                    else:
                        break

        except irods.exception.DataObjectDoesNotExist:
            logger.error(f'File: \'{source}\' does not exists on the iRODS server')
            return False

        return True