# Copyright 2014  Lars Wirzenius
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# =*= License: GPL-3+ =*=


import StringIO

import yaml

import distixlib


class MetadataSerialiser(object):

    def serialise(self, metadata):
        obj = self._create_python_object(metadata)
        return self._create_yaml_text(obj)

    def _create_python_object(self, metadata):
        obj = {}
        for key in metadata.keys():
            obj[key] = sorted(metadata.get_all_values(key))
        return obj

    def _create_yaml_text(self, obj):
        return yaml.safe_dump(obj, default_flow_style=False, indent=4)

    def deserialise(self, text):
        obj = self._parse_yaml_text(text)
        return self._create_metadata(obj)

    def _parse_yaml_text(self, text):
        return yaml.safe_load(StringIO.StringIO(text))

    def _create_metadata(self, obj):
        metadata = distixlib.Metadata()
        if obj:
            for key in obj:
                for value in obj[key]:
                    metadata.add(key, value)
        return metadata