# Copyright (C) 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 uuid


import ick2


class StoreInterface:  # pragma: no cover

    def create(self, token, obj):
        raise NotImplementedError()

    def update(self, token, rid, obj, revision):
        raise NotImplementedError()

    def show(self, token, rid):
        raise NotImplementedError()

    def delete(self, token, rid):
        raise NotImplementedError()

    def search(self, token, cond):
        raise NotImplementedError()


class MemoryStore(StoreInterface):

    def __init__(self):
        self._objs = {}

    def search(self, token, cond):
        return list(self._objs.keys())

    def _new_id(self):
        return str(uuid.uuid4())

    def _set(self, rid, rev, obj):
        self._objs[rid] = (rev, copy.deepcopy(obj))

    def create(self, token, obj):
        rid = self._new_id()
        rev = self._new_id()
        self._set(rid, rev, obj)
        return rid, rev

    def show(self, token, rid):
        if rid not in self._objs:
            raise ick2.NotFound('unknown.type', rid)
        rev, obj = self._objs[rid]
        return copy.deepcopy(obj), rev

    def update(self, token, rid, obj, revision):
        old_obj, old_rev = self.show(token, rid)
        if old_rev != revision:
            raise Conflict(rid, old_rev, revision)
        new_rev = self._new_id()
        self._set(rid, new_rev, obj)
        return new_rev

    def delete(self, token, rid):
        del self._objs[rid]


class Conflict(Exception):

    def __init__(self, rid, expected, got):
        super().__init__(
            'Update conflict for {}: expected revision {}, got {}'.format(
                rid, expected, got))