# Copyright (C) 2012-2020 RhodeCode GmbH
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License, version 3
# (only), as published by the Free Software Foundation.
#
# 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 Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# This program is dual-licensed. If you wish to learn more about the
# RhodeCode Enterprise Edition, including its added features, Support services,
# and proprietary license terms, please see https://rhodecode.com/licenses/

import time
import logging

from pyramid.exceptions import ConfigurationError
from zope.interface import implementer

from rhodecode.authentication.interface import IAuthnPluginRegistry
from rhodecode.model.settings import SettingsModel
from rhodecode.lib.utils2 import safe_str
from rhodecode.lib.statsd_client import StatsdClient
from rhodecode.lib import rc_cache

log = logging.getLogger(__name__)


@implementer(IAuthnPluginRegistry)
class AuthenticationPluginRegistry(object):

    # INI settings key to set a fallback authentication plugin.
    fallback_plugin_key = 'rhodecode.auth_plugin_fallback'

    def __init__(self, settings):
        self._plugins = {}
        self._fallback_plugin = settings.get(self.fallback_plugin_key, None)

    def add_authn_plugin(self, config, plugin):
        plugin_id = plugin.get_id()
        if plugin_id in self._plugins.keys():
            raise ConfigurationError(
                'Cannot register authentication plugin twice: "%s"', plugin_id)
        else:
            log.debug('Register authentication plugin: "%s"', plugin_id)
            self._plugins[plugin_id] = plugin

    def get_plugins(self):
        def sort_key(plugin):
            return str.lower(safe_str(plugin.get_display_name()))

        return sorted(self._plugins.values(), key=sort_key)

    def get_plugin(self, plugin_id):
        return self._plugins.get(plugin_id, None)

    def get_plugin_by_uid(self, plugin_uid):
        for plugin in self._plugins.values():
            if plugin.uid == plugin_uid:
                return plugin

    def get_cache_call_method(self, cache=True):
        region, _ns = self.get_cache_region()

        @region.conditional_cache_on_arguments(condition=cache)
        def _get_auth_plugins(name: str, key: str, fallback_plugin):
            log.debug('auth-plugins: calculating plugins available for authentication')

            _plugins = []
            # Add all enabled and active plugins to the list. We iterate over the
            # auth_plugins setting from DB because it also represents the ordering.
            enabled_plugins = SettingsModel().get_auth_plugins()
            raw_settings = SettingsModel().get_all_settings(cache=False)

            for plugin_id in enabled_plugins:
                plugin = self.get_plugin(plugin_id)
                if plugin is not None and plugin.is_active(
                        plugin_cached_settings=raw_settings):

                    # inject settings into plugin, we can re-use the DB fetched settings here
                    plugin._settings = plugin._propagate_settings(raw_settings)
                    _plugins.append(plugin)

            # Add the fallback plugin from ini file.
            if fallback_plugin:
                log.warning(
                    'Using fallback authentication plugin from INI file: "%s"',
                    fallback_plugin)
                plugin = self.get_plugin(fallback_plugin)
                if plugin is not None and plugin not in _plugins:
                    plugin._settings = plugin._propagate_settings(raw_settings)
                    _plugins.append(plugin)
            return _plugins

        return _get_auth_plugins

    def get_plugins_for_authentication(self, cache=True):
        """
        Returns a list of plugins which should be consulted when authenticating
        a user. It only returns plugins which are enabled and active.
        Additionally, it includes the fallback plugin from the INI file, if
        `rhodecode.auth_plugin_fallback` is set to a plugin ID.
        """

        _get_auth_plugins = self.get_cache_call_method(cache=cache)

        start = time.time()
        plugins = _get_auth_plugins('rhodecode_auth_plugins', 'v1', self._fallback_plugin)

        compute_time = time.time() - start
        log.debug('cached method:%s took %.4fs', _get_auth_plugins.__name__, compute_time)

        statsd = StatsdClient.statsd
        if statsd:
            elapsed_time_ms = round(1000.0 * compute_time)  # use ms only
            statsd.timing("rhodecode_auth_plugins_timing.histogram", elapsed_time_ms,
                          use_decimals=False)

        return plugins

    @classmethod
    def get_cache_region(cls):
        cache_namespace_uid = 'auth_plugins'
        region = rc_cache.get_or_create_region('cache_general', cache_namespace_uid)
        return region, cache_namespace_uid

    @classmethod
    def invalidate_auth_plugins_cache(cls, hard=True):
        region, namespace_key = cls.get_cache_region()
        log.debug('Invalidation cache [%s] region %s for cache_key: %s',
                  'invalidate_auth_plugins_cache', region, namespace_key)

        # we use hard cleanup if invalidation is sent
        rc_cache.clear_cache_namespace(region, namespace_key, method=rc_cache.CLEAR_DELETE)