from six import text_type

from logilab.mtconverter import guess_mimetype_and_encoding

from cubicweb.entities import AnyEntity, fetch_config

class File(AnyEntity):

    """customized class for File entities"""

    __regid__ = 'File'

    fetch_attrs, cw_fetch_order = fetch_config(['data_name', 'title'])

    def set_format_and_encoding(self):

        """try to set format and encoding according to known values (filename,

        file content, format, encoding).

        This method must be called in a before_[add|update]_entity hook else it

        won't have any effect.

        """

        assert 'data' in self.cw_edited, "missing mandatory attribute data"

        if self.cw_edited.get('data'):

            if (hasattr(self.data, 'filename')

                    and not self.cw_edited.get('data_name')):

                self.cw_edited['data_name'] = self.data.filename

        else:

            self.cw_edited['data_format'] = None

            self.cw_edited['data_encoding'] = None

            self.cw_edited['data_name'] = None

            return

        if 'data_format' in self.cw_edited:

            format = self.cw_edited.get('data_format')

        else:

            format = None

        if 'data_encoding' in self.cw_edited:

            encoding = self.cw_edited.get('data_encoding')

        else:

            encoding = None

        if not (format and encoding):

            format, encoding = guess_mimetype_and_encoding(

                data=self.cw_edited.get('data'),

                # use get and not get_value since data has changed, we only

                # want to consider explicitly specified values, not old ones

                filename=self.cw_edited.get('data_name'),

                format=format, encoding=encoding,

                fallbackencoding=self._cw.encoding)

            if format:

                self.cw_edited['data_format'] = text_type(format)

            if encoding:

                self.cw_edited['data_encoding'] = text_type(encoding)

class UnResizeable(Exception):

    pass