# RhodeCode VCSServer provides access to different vcs backends via network.
# Copyright (C) 2014-2023 RhodeCode GmbH
#
# 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, write to the Free Software Foundation,
# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA

import logging
import threading

from dogpile.cache import register_backend

from . import region_meta
from .utils import (
    backend_key_generator,
    clear_cache_namespace,
    get_default_cache_settings,
    get_or_create_region,
    make_region,
    str2bool,
)

module_name = 'vcsserver'

register_backend(
    "dogpile.cache.rc.memory_lru", f"{module_name}.lib.rc_cache.backends",
    "LRUMemoryBackend")

register_backend(
    "dogpile.cache.rc.file_namespace", f"{module_name}.lib.rc_cache.backends",
    "FileNamespaceBackend")

register_backend(
    "dogpile.cache.rc.redis", f"{module_name}.lib.rc_cache.backends",
    "RedisPickleBackend")

register_backend(
    "dogpile.cache.rc.redis_msgpack", f"{module_name}.lib.rc_cache.backends",
    "RedisMsgPackBackend")


log = logging.getLogger(__name__)


CACHE_OBJ_CACHE_VER = 'v2'

CLEAR_DELETE = 'delete'
CLEAR_INVALIDATE = 'invalidate'


def async_creation_runner(cache, somekey, creator, mutex):

    def runner():
        try:
            value = creator()
            cache.set(somekey, value)
        finally:
            mutex.release()

    thread = threading.Thread(target=runner)
    thread.start()


def configure_dogpile_cache(settings):
    cache_dir = settings.get('cache_dir')
    if cache_dir:
        region_meta.dogpile_config_defaults['cache_dir'] = cache_dir

    rc_cache_data = get_default_cache_settings(settings, prefixes=['rc_cache.'])

    # inspect available namespaces
    avail_regions = set()
    for key in rc_cache_data.keys():
        namespace_name = key.split('.', 1)[0]
        if namespace_name in avail_regions:
            continue

        avail_regions.add(namespace_name)
        log.debug('dogpile: found following cache regions: %s', namespace_name)

        new_region = make_region(
            name=namespace_name,
            function_key_generator=None,
            async_creation_runner=None
        )

        new_region.configure_from_config(settings, f'rc_cache.{namespace_name}.')
        new_region.function_key_generator = backend_key_generator(new_region.actual_backend)

        async_creator = str2bool(settings.pop(f'rc_cache.{namespace_name}.async_creator', 'false'))
        if async_creator:
            log.debug('configuring region %s with async creator', new_region)
            new_region.async_creation_runner = async_creation_runner

        if log.isEnabledFor(logging.DEBUG):
            region_args = dict(backend=new_region.actual_backend,
                               region_invalidator=new_region.region_invalidator.__class__)
            log.debug('dogpile: registering a new region key=`%s` args=%s', namespace_name, region_args)

        region_meta.dogpile_cache_regions[namespace_name] = new_region


def includeme(config):
    configure_dogpile_cache(config.registry.settings)