# 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 ick2


def wrap(kind, name, as_dict):
    return {
        'kind': kind,
        'name': name,
        'res': copy.deepcopy(as_dict),
    }


def unwrap(obj):
    return obj['kind'], obj['name'], copy.deepcopy(obj['res'])


def find_by_name(store, token, kind, name):
    rids = store.search(token, None)  # FIXME for real searches
    for rid in rids:
        obj, rev = store.show(token, rid)
        if obj is not None:
            okind, oname, as_dict = unwrap(obj)
            if okind == kind and oname == name:
                return as_dict, rid, rev

    raise ick2.NotFound(kind=kind, name=name)


def find_names_by_kind(store, token, kind):
    rids = store.search(token, None)  # FIXME for real searches
    for rid in rids:
        obj, rev = store.show(token, rid)
        if obj is not None:
            okind, oname, as_dict = unwrap(obj)
            if okind == kind:
                yield oname


class TransactionalResource:

    def __init__(self, new, token, store, kind, name):
        self.token = token
        self.store = store
        self.kind = kind
        self.name = name

        self.rid = None
        self.rev = None
        self.resource = None

        if new:
            try:
                find_by_name(self.store, token, kind, name)
            except ick2.NotFound:
                as_dict = {}
            else:
                raise ick2.ExistsAlready(name)
        else:
            try:
                as_dict, self.rid, self.rev = find_by_name(
                    self.store, token, kind, name)
            except ick2.NotFound:
                raise

        self.resource = ick2.resource_from_dict(as_dict)
        assert ((new and self.rid is None) or
                (not new and self.rid is not None))

        methods = [
            'as_dict',
            '__getitem__',
            '__setitem__',
            '__contains__',
            '__len__',
        ]
        for method in methods:
            setattr(self, method, getattr(self.resource, method))

    def __enter__(self):
        return self.resource

    def __exit__(self, exc_type, value, traceback):
        if exc_type is None:
            as_dict = self.resource.as_dict()
            obj = wrap(self.kind, self.name, as_dict)
            if self.rid is None:
                self.store.create(self.token, obj)
            else:
                self.store.update(self.token, self.rid, obj, self.rev)


class TransactionalState:

    def __init__(self, state):
        self.state = state

    def new(self, token, kind, name):
        return TransactionalResource(True, token, self.state, kind, name)

    def modify(self, token, kind, name):
        return TransactionalResource(False, token, self.state, kind, name)

    def get_resource(self, token, kind, name):
        as_dict, rid, rev = find_by_name(self.state, token, kind, name)
        return ick2.resource_from_dict(as_dict)

    def get_resources(self, token, kind):
        return [
            self.get_resource(token, kind, name)
            for name in find_names_by_kind(self.state, token, kind)
        ]

    def remove_resource(self, token, kind, name):
        as_dict, rid, rev = find_by_name(self.state, token, kind, name)
        self.state.delete(token, rid)