# Copyright (C) 2018-2019  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 copy
import os
import urllib.parse


import yaml


import ick2


class PersistentStateInterface:  # pragma: no cover

    def get_resource_ids(self, kind):
        raise NotImplementedError()

    def has_resource(self, kind, rid):
        raise NotImplementedError()

    def get_resource(self, kind, rid):
        raise NotImplementedError()

    def get_resources(self, kind):
        return [
            self.get_resource(kind, rid)
            for rid in self.get_resource_ids(kind)
        ]

    def write_resource(self, kind, rid, resource):
        raise NotImplementedError()

    def remove_resource(self, kind, rid):
        raise NotImplementedError()


class FilePersistentState(PersistentStateInterface):

    def __init__(self):
        self._dir = None

    def get_directory(self):
        return self._dir

    def set_directory(self, dirname):
        self._dir = dirname

    def _safe(self, name):
        return urllib.parse.quote(name, safe='')

    def _unsafe(self, safe):
        return urllib.parse.unquote(safe)

    def _unsafe_list(self, safe_names):
        return [self._unsafe(safe) for safe in safe_names]

    def _dirname(self, kind):
        return os.path.join(self._dir, self._safe(kind))

    def _filename(self, kind, rid):
        dirname = self._dirname(kind)
        return os.path.join(dirname, self._safe(rid))

    def has_resource(self, kind, rid):
        filename = self._filename(kind, rid)
        return os.path.exists(filename)

    def get_resource_ids(self, kind):
        dirname = self._dirname(kind)
        if os.path.exists(dirname):
            return self._unsafe_list(os.listdir(dirname))
        return []

    def get_resource(self, kind, rid):
        filename = self._filename(kind, rid)
        if not os.path.exists(filename):
            raise ick2.NotFound(kind=kind, rid=rid)
        with open(filename, 'r') as f:
            as_dict = yaml.load(f, Loader=yaml.CSafeLoader)
            return resource_from_dict(as_dict)

    def write_resource(self, kind, rid, resource):
        dirname = self._dirname(kind)
        if not os.path.exists(dirname):
            os.makedirs(dirname)

        filename = self._filename(kind, rid)
        with open(filename, 'w') as f:
            yaml.dump(
                resource.as_dict(), stream=f, Dumper=yaml.CSafeDumper)

    def remove_resource(self, kind, rid):
        filename = self._filename(kind, rid)
        os.remove(filename)


class NotFound(Exception):

    def __init__(self, kind, rid):
        super().__init__(
            'Resource {}:{} not found'.format(
                kind or "unknown", rid or "unknown"))


class Resource:  # pragma: no cover

    def __init__(self, as_dict=None):
        self._dict = copy.deepcopy(as_dict or {})

    def as_dict(self):
        return copy.deepcopy(self._dict)

    def __getitem__(self, key):
        return self._dict[key]

    def __setitem__(self, key, value):
        self._dict[key] = value

    def __contains__(self, key):
        return key in self._dict

    def __len__(self):
        return len(self._dict)

    def get(self, key, default=None):
        return self._dict.get(key, default)

    def from_dict(self, as_dict):
        self._dict.clear()
        for key in as_dict:
            self[key] = as_dict[key]


def resource_from_dict(as_dict):  # pragma: no cover
    return Resource(as_dict)