"""
Types for objects parsed from the configuration.
"""
from __future__ import absolute_import
from __future__ import unicode_literals

from collections import namedtuple

from compose.config.errors import ConfigurationError


class VolumeFromSpec(namedtuple('_VolumeFromSpec', 'source mode')):

    @classmethod
    def parse(cls, volume_from_config):
        parts = volume_from_config.split(':')
        if len(parts) > 2:
            raise ConfigurationError(
                "volume_from {} has incorrect format, should be "
                "service[:mode]".format(volume_from_config))

        if len(parts) == 1:
            source = parts[0]
            mode = 'rw'
        else:
            source, mode = parts

        return cls(source, mode)