from collections import OrderedDict
from operator import attrgetter
from typing import Any, Dict, List, Set

from django.apps import AppConfig
from django.conf import settings
from django.core.exceptions import ImproperlyConfigured
from django.db.models.signals import post_migrate
from django.db.utils import OperationalError, ProgrammingError

from ..utils.projector import register_projector_elements


class CoreAppConfig(AppConfig):
    name = 'openslides.core'
    verbose_name = 'OpenSlides Core'
    angular_site_module = True
    angular_projector_module = True

    def ready(self):
        # Import all required stuff.
        from .config import config
        from ..utils.rest_api import router
        from ..utils.cache import element_cache
        from .projector import get_projector_elements
        from .signals import (
            delete_django_app_permissions,
            get_permission_change_data,
            permission_change,
            post_permission_creation,
        )
        from .views import (
            ChatMessageViewSet,
            ConfigViewSet,
            CountdownViewSet,
            ProjectorMessageViewSet,
            ProjectorViewSet,
            TagViewSet,
        )
        from ..utils.constants import set_constants, get_constants_from_apps
        from .websocket import (
            NotifyWebsocketClientMessage,
            ConstantsWebsocketClientMessage,
            GetElementsWebsocketClientMessage,
            AutoupdateWebsocketClientMessage,
        )
        from ..utils.websocket import register_client_message
        from ..utils.access_permissions import required_user

        # Collect all config variables before getting the constants.
        config.collect_config_variables_from_apps()

        # Set constants
        try:
            set_constants(get_constants_from_apps())
        except (ImproperlyConfigured, OperationalError, ProgrammingError):
            # Database is not loaded. This happens in tests and migrations.
            pass

        # Define projector elements.
        register_projector_elements(get_projector_elements())

        # Connect signals.
        post_permission_creation.connect(
            delete_django_app_permissions,
            dispatch_uid='delete_django_app_permissions')
        permission_change.connect(
            get_permission_change_data,
            dispatch_uid='core_get_permission_change_data')

        post_migrate.connect(call_save_default_values, sender=self, dispatch_uid='core_save_config_default_values')

        # Register viewsets.
        router.register(self.get_model('Projector').get_collection_string(), ProjectorViewSet)
        router.register(self.get_model('ChatMessage').get_collection_string(), ChatMessageViewSet)
        router.register(self.get_model('Tag').get_collection_string(), TagViewSet)
        router.register(self.get_model('ConfigStore').get_collection_string(), ConfigViewSet, 'config')
        router.register(self.get_model('ProjectorMessage').get_collection_string(), ProjectorMessageViewSet)
        router.register(self.get_model('Countdown').get_collection_string(), CountdownViewSet)

        # Sets the cache
        try:
            element_cache.ensure_cache()
        except (ImproperlyConfigured, OperationalError, ProgrammingError):
            # This happens in the tests or in migrations. Do nothing
            pass

        # Register client messages
        register_client_message(NotifyWebsocketClientMessage())
        register_client_message(ConstantsWebsocketClientMessage())
        register_client_message(GetElementsWebsocketClientMessage())
        register_client_message(AutoupdateWebsocketClientMessage())

        # register required_users
        required_user.add_collection_string(self.get_model('ChatMessage').get_collection_string(), required_users)

    def get_config_variables(self):
        from .config_variables import get_config_variables
        return get_config_variables()

    def get_startup_elements(self):
        """
        Yields all Cachables required on startup i. e. opening the websocket
        connection.
        """
        for model_name in ('Projector', 'ChatMessage', 'Tag', 'ProjectorMessage', 'Countdown', 'ConfigStore'):
            yield self.get_model(model_name)

    def get_angular_constants(self):
        from .config import config

        constants: Dict[str, Any] = {}

        # Client settings
        client_settings_keys = [
            'MOTION_IDENTIFIER_MIN_DIGITS',
            'MOTION_IDENTIFIER_WITHOUT_BLANKS',
            'MOTIONS_ALLOW_AMENDMENTS_OF_AMENDMENTS'
        ]
        client_settings_dict = {}
        for key in client_settings_keys:
            try:
                client_settings_dict[key] = getattr(settings, key)
            except AttributeError:
                # Settings key does not exist. Do nothing. The client will
                # treat this as undefined.
                pass
        constants['OpenSlidesSettings'] = client_settings_dict

        # Config variables
        config_groups: List[Any] = []
        for config_variable in sorted(config.config_variables.values(), key=attrgetter('weight')):
            if config_variable.is_hidden():
                # Skip hidden config variables. Do not even check groups and subgroups.
                continue
            if not config_groups or config_groups[-1]['name'] != config_variable.group:
                # Add new group.
                config_groups.append(OrderedDict(
                    name=config_variable.group,
                    subgroups=[]))
            if not config_groups[-1]['subgroups'] or config_groups[-1]['subgroups'][-1]['name'] != config_variable.subgroup:
                # Add new subgroup.
                config_groups[-1]['subgroups'].append(OrderedDict(
                    name=config_variable.subgroup,
                    items=[]))
            # Add the config variable to the current group and subgroup.
            config_groups[-1]['subgroups'][-1]['items'].append(config_variable.data)
        constants['OpenSlidesConfigVariables'] = config_groups

        return constants


def call_save_default_values(**kwargs):
    from .config import config
    config.save_default_values()


def required_users(element: Dict[str, Any]) -> Set[int]:
    """
    Returns all user ids that are displayed as chatters.
    """
    return set(element['user_id'])