import hashlib
import logging
import os
import sys
from collections import OrderedDict
from operator import attrgetter
from typing import Any, Dict, List

from django.apps import AppConfig
from django.conf import settings
from django.db.models import Max
from django.db.models.signals import post_migrate, pre_delete


logger = logging.getLogger("openslides.core")


class CoreAppConfig(AppConfig):
    name = "openslides.core"
    verbose_name = "OpenSlides Core"

    def ready(self):
        # Import all required stuff.
        from .config import config
        from .projector import register_projector_slides
        from . import serializers  # noqa
        from .signals import (
            autoupdate_for_many_to_many_relations,
            cleanup_unused_permissions,
            delete_django_app_permissions,
            get_permission_change_data,
            permission_change,
            post_permission_creation,
        )
        from .views import (
            ConfigViewSet,
            CountdownViewSet,
            ProjectorMessageViewSet,
            ProjectorViewSet,
            ProjectionDefaultViewSet,
            TagViewSet,
        )
        from .websocket import (
            NotifyWebsocketClientMessage,
            ConstantsWebsocketClientMessage,
            GetElementsWebsocketClientMessage,
            AutoupdateWebsocketClientMessage,
            ListenToProjectors,
            PingPong,
        )
        from ..utils.rest_api import router
        from ..utils.websocket import register_client_message

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

        # Define projector elements.
        register_projector_slides()

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

        post_migrate.connect(
            manage_config, sender=self, dispatch_uid="core_manage_config"
        )
        pre_delete.connect(
            autoupdate_for_many_to_many_relations,
            dispatch_uid="core_autoupdate_for_many_to_many_relations",
        )

        # Register viewsets.
        router.register(
            self.get_model("Projector").get_collection_string(), ProjectorViewSet
        )
        router.register(
            self.get_model("Projectiondefault").get_collection_string(),
            ProjectionDefaultViewSet,
        )
        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
        )

        if "runserver" in sys.argv or "changeconfig" in sys.argv:
            startup()

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

    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",
            "ProjectionDefault",
            "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",
            "PRIORITIZED_GROUP_IDS",
            "PING_INTERVAL",
            "PING_TIMEOUT",
        ]
        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["Settings"] = 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["ConfigVariables"] = config_groups

        # get max migration id -> the "version" of the DB
        from django.db.migrations.recorder import MigrationRecorder

        migration_version = MigrationRecorder.Migration.objects.aggregate(Max("id"))[
            "id__max"
        ]
        config_version = config["config_version"]
        hash = hashlib.sha1(
            f"{migration_version}#{config_version}".encode()
        ).hexdigest()
        constants["DbSchemaVersion"] = hash
        logger.info(f"DbSchemaVersion={hash}")

        return constants


def manage_config(**kwargs):
    """
    Should be run after every migration. Saves default values
    of all non db-existing config objects into the db. Deletes all
    unnecessary old config values, e.g. all db entries, that does
    not have a config_variable anymore. Increments the config version,
    if at least one of the operations altered some data.
    """
    from .config import config

    altered = config.save_default_values()
    altered = config.cleanup_old_config_values() or altered
    if altered:
        config.increment_version()


def startup():
    """
    Runs commands that are needed at startup.

    Sets the cache, constants and startup history
    """
    if os.environ.get("NO_STARTUP"):
        return

    from openslides.utils.constants import set_constants, get_constants_from_apps
    from openslides.utils.cache import element_cache
    from openslides.core.models import History

    element_cache.ensure_cache()
    set_constants(get_constants_from_apps())
    History.objects.build_history()