# Copyright (C) 2018  Lars Wirzenius
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero 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 Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


import os

import yaml


class FileStore:

    def __init__(self, dirname):
        self._dirname = dirname

    def _typedir(self, resource_type):
        return os.path.join(self._dirname, resource_type)

    def _filename(self, resource_type, resource_id):
        dirname = self._typedir(resource_type)
        return os.path.join(dirname, resource_id)

    def list(self, resource_type):
        dirname = self._typedir(resource_type)
        if not os.path.isdir(dirname):
            return []
        return [
            x
            for x in sorted(os.listdir(self._typedir(resource_type)))
        ]

    def get(self, resource_type, resource_id):
        filename = self._filename(resource_type, resource_id)
        if os.path.exists(filename):
            with open(filename) as f:
                return yaml.safe_load(f)
        raise ResourceDoesNotExist(resource_type, resource_id)

    def create(self, resource_type, resource_id, resource):
        dirname = self._typedir(resource_type)
        if not os.path.exists(dirname):
            os.mkdir(dirname)

        filename = self._filename(resource_type, resource_id)
        with open(filename, 'w') as f:
            yaml.safe_dump(resource, stream=f)

    def delete(self, resource_type, resource_id):
        filename = self._filename(resource_type, resource_id)
        if os.path.exists(filename):
            os.remove(filename)


class ResourceStoreError(Exception):

    pass


class ResourceDoesNotExist(ResourceStoreError):

    def __init__(self, resource_type, resource_id):
        super().__init__(
            'Resource does not exist: {}:{}'.format(
                resource_type, resource_id))