import datetime
import os
from typing import Any, Dict

from django.conf import settings
from django.contrib.staticfiles import finders
from django.contrib.staticfiles.views import serve
from django.db.models import F
from django.http import Http404, HttpResponse
from django.utils.timezone import now
from django.views import static
from django.views.generic.base import View

from .. import __license__ as license, __url__ as url, __version__ as version
from ..users.models import User
from ..utils import views as utils_views
from ..utils.arguments import arguments
from ..utils.auth import GROUP_ADMIN_PK, anonymous_is_enabled, has_perm, in_some_groups
from ..utils.autoupdate import inform_changed_data, inform_deleted_data
from ..utils.plugins import (
    get_plugin_description,
    get_plugin_license,
    get_plugin_url,
    get_plugin_verbose_name,
    get_plugin_version,
)
from ..utils.rest_api import (
    GenericViewSet,
    ListModelMixin,
    ModelViewSet,
    Response,
    RetrieveModelMixin,
    ValidationError,
    detail_route,
    list_route,
)
from .access_permissions import (
    ChatMessageAccessPermissions,
    ConfigAccessPermissions,
    CountdownAccessPermissions,
    HistoryAccessPermissions,
    ProjectionDefaultAccessPermissions,
    ProjectorAccessPermissions,
    ProjectorMessageAccessPermissions,
    TagAccessPermissions,
)
from .config import config
from .exceptions import ConfigError, ConfigNotFound
from .models import (
    ChatMessage,
    ConfigStore,
    Countdown,
    History,
    HistoryData,
    ProjectionDefault,
    Projector,
    ProjectorMessage,
    Tag,
)
from .serializers import elements_array_validator, elements_validator


# Special Django views


class IndexView(View):
    """
    The primary view for the OpenSlides client. Serves static files. If a file
    does not exist or a directory is requested, the index.html is delivered instead.
    """

    cache: Dict[str, str] = {}
    """
    Saves the path to the index.html.

    May be extended later to cache every template.
    """

    def __init__(self, *args: Any, **kwargs: Any) -> None:
        super().__init__(*args, **kwargs)

        no_caching = arguments.get("no_template_caching", False)
        if "index" not in self.cache or no_caching:
            self.cache["index"] = finders.find("index.html")

        self.index_document_root, self.index_path = os.path.split(self.cache["index"])

    def get(self, request, path, **kwargs) -> HttpResponse:
        """
        Tries to serve the requested file. If it is not found or a directory is
        requested, the index.html is delivered.
        """
        try:
            response = serve(request, path, insecure=True, **kwargs)
        except Http404:
            response = static.serve(
                request,
                self.index_path,
                document_root=self.index_document_root,
                **kwargs,
            )
        return response


# Viewsets for the REST API


class ProjectorViewSet(ModelViewSet):
    """
    API endpoint for the projector slide info.

    There are the following views: See strings in check_view_permissions().
    """

    access_permissions = ProjectorAccessPermissions()
    queryset = Projector.objects.all()

    def check_view_permissions(self):
        """
        Returns True if the user has required permissions.
        """
        if self.action in ("list", "retrieve"):
            result = self.get_access_permissions().check_permissions(self.request.user)
        elif self.action == "metadata":
            result = has_perm(self.request.user, "core.can_see_projector")
        elif self.action in (
            "create",
            "update",
            "partial_update",
            "destroy",
            "control_view",
            "set_scroll",
            "set_projectiondefault",
            "project",
        ):
            result = has_perm(self.request.user, "core.can_see_projector") and has_perm(
                self.request.user, "core.can_manage_projector"
            )
        else:
            result = False
        return result

    def perform_create(self, serializer):
        projector = serializer.save()
        projector.elements = [{"name": "core/clock", "stable": True}]
        projector.save()

    def destroy(self, *args, **kwargs):
        """
        REST API operation for DELETE requests.

        Assigns all ProjectionDefault objects from this projector to the
        first projector found.
        """
        if len(Projector.objects.all()) <= 1:
            raise ValidationError({"detail": "You can't delete the last projector."})
        projector_instance = self.get_object()
        new_projector_id = (
            Projector.objects.exclude(pk=projector_instance.pk).first().pk
        )

        for projection_default in ProjectionDefault.objects.all():
            if projection_default.projector.id == projector_instance.id:
                projection_default.projector_id = new_projector_id
                projection_default.save()
        return super(ProjectorViewSet, self).destroy(*args, **kwargs)

    @detail_route(methods=["post"])
    def project(self, request, pk):
        """
        Sets the `elements` and `elements_preview` and adds one item to the
        `elements_history`.

        `request.data` can have three arguments: `append_to_history`, `elements`
        and `preview`. Non of them is required.

        `append_to_history` adds one element to the end of the history_elements.
        `elements` and `preview` preplaces the coresponding fields in the
        database.

        If `delete_last_history_element` is True, the last element is deleted.
        Note: You cannot give `append_to_history` and `delete_last_history_element`
        at the same time.
        """
        projector = self.get_object()
        elements = request.data.get("elements")
        preview = request.data.get("preview")
        history_element = request.data.get("append_to_history")
        delete_last_history_element = request.data.get(
            "delete_last_history_element", False
        )

        if elements is not None:
            elements_validator(elements)
            projector.elements = elements

        if preview is not None:
            elements_validator(preview)
            projector.elements_preview = preview

        elements_history = None
        if history_element is not None and delete_last_history_element is False:
            elements_history = projector.elements_history + [history_element]
        if history_element is None and delete_last_history_element is True:
            elements_history = projector.elements_history[:-1]
        if elements_history is not None:
            elements_array_validator(elements_history)
            projector.elements_history = elements_history

        projector.save()
        return Response()

    @detail_route(methods=["post"])
    def control_view(self, request, pk):
        """
        REST API operation to control the projector view, i. e. scale and
        scroll the projector.

        It expects a POST request to
        /rest/core/projector/<pk>/control_view/ with a dictionary with an
        action ('scale' or 'scroll') and a direction ('up', 'down' or
        'reset'). An optional 'step' can be given to control the amount
        of scrolling and scaling. The default is 1.

        Example:

        {
            "action": "scale",
            "direction": "up"
        }
        """
        if not isinstance(request.data, dict):
            raise ValidationError({"detail": "Data must be a dictionary."})
        if request.data.get("action") not in ("scale", "scroll") or request.data.get(
            "direction"
        ) not in ("up", "down", "reset"):
            raise ValidationError(
                {
                    "detail": "Data must be a dictionary with an action ('scale' or 'scroll') "
                    "and a direction ('up', 'down' or 'reset')."
                }
            )

        projector_instance = self.get_object()
        step = request.data.get("step", 1)
        if step < 1:
            step = 1

        if request.data["action"] == "scale":
            if request.data["direction"] == "up":
                projector_instance.scale = F("scale") + step
            elif request.data["direction"] == "down":
                projector_instance.scale = F("scale") - step
            else:
                # request.data['direction'] == 'reset'
                projector_instance.scale = 0
        else:
            # request.data['action'] == 'scroll'
            if request.data["direction"] == "up":
                projector_instance.scroll = F("scroll") + step
            elif request.data["direction"] == "down":
                projector_instance.scroll = F("scroll") - step
            else:
                # request.data['direction'] == 'reset'
                projector_instance.scroll = 0

        projector_instance.save(skip_autoupdate=True)
        projector_instance.refresh_from_db()
        inform_changed_data(projector_instance)
        return Response()

    @detail_route(methods=["post"])
    def set_scroll(self, request, pk):
        """
        REST API operation to scroll the projector.

        It expects a POST request to
        /rest/core/projector/<pk>/set_scroll/ with a new value for scroll.
        """
        if not isinstance(request.data, int):
            raise ValidationError({"detail": "Data must be an int."})

        projector_instance = self.get_object()
        projector_instance.scroll = request.data

        projector_instance.save()
        message = f"Setting scroll to {request.data} was successful."
        return Response({"detail": message})


class ProjectionDefaultViewSet(ListModelMixin, RetrieveModelMixin, GenericViewSet):
    """
    API endpoint for projection defaults.

    There are the following views: list, and retrieve. Assigning projection defaults
    to projectors can be done by updating the projector.
    """

    access_permissions = ProjectionDefaultAccessPermissions()
    queryset = ProjectionDefault.objects.all()

    def check_view_permissions(self):
        """
        Returns True if the user has required permissions.
        """
        if self.action in ("list", "retrieve"):
            result = self.get_access_permissions().check_permissions(self.request.user)
        else:
            result = False
        return result


class TagViewSet(ModelViewSet):
    """
    API endpoint for tags.

    There are the following views: metadata, list, retrieve, create,
    partial_update, update and destroy.
    """

    access_permissions = TagAccessPermissions()
    queryset = Tag.objects.all()

    def check_view_permissions(self):
        """
        Returns True if the user has required permissions.
        """
        if self.action in ("list", "retrieve"):
            result = self.get_access_permissions().check_permissions(self.request.user)
        elif self.action == "metadata":
            # Every authenticated user can see the metadata.
            # Anonymous users can do so if they are enabled.
            result = self.request.user.is_authenticated or anonymous_is_enabled()
        elif self.action in ("create", "partial_update", "update", "destroy"):
            result = has_perm(self.request.user, "core.can_manage_tags")
        else:
            result = False
        return result


class ConfigViewSet(ModelViewSet):
    """
    API endpoint for the config.

    There are the following views: metadata, list, retrieve, update and
    partial_update.
    """

    access_permissions = ConfigAccessPermissions()
    queryset = ConfigStore.objects.all()

    def check_view_permissions(self):
        """
        Returns True if the user has required permissions.
        """
        if self.action in ("list", "retrieve"):
            result = self.get_access_permissions().check_permissions(self.request.user)
        elif self.action == "metadata":
            # Every authenticated user can see the metadata and list or
            # retrieve the config. Anonymous users can do so if they are
            # enabled.
            result = self.request.user.is_authenticated or anonymous_is_enabled()
        elif self.action in ("partial_update", "update"):
            # The user needs 'core.can_manage_logos_and_fonts' for all config values
            # starting with 'logo' and 'font'. For all other config values th euser needs
            # the default permissions 'core.can_manage_config'.
            pk = self.kwargs["pk"]
            if pk.startswith("logo") or pk.startswith("font"):
                result = has_perm(self.request.user, "core.can_manage_logos_and_fonts")
            else:
                result = has_perm(self.request.user, "core.can_manage_config")
        else:
            result = False
        return result

    def update(self, request, *args, **kwargs):
        """
        Updates a config variable. Only managers can do this.

        Example: {"value": 42}
        """
        key = kwargs["pk"]
        value = request.data.get("value")
        if value is None:
            raise ValidationError({"detail": "Invalid input. Config value is missing."})

        # Validate and change value.
        try:
            config[key] = value
        except ConfigNotFound:
            raise Http404
        except ConfigError as err:
            raise ValidationError({"detail": str(err)})

        # Return response.
        return Response({"key": key, "value": value})


class ChatMessageViewSet(ModelViewSet):
    """
    API endpoint for chat messages.

    There are the following views: metadata, list, retrieve and create.
    The views partial_update, update and destroy are disabled.
    """

    access_permissions = ChatMessageAccessPermissions()
    queryset = ChatMessage.objects.all()

    def check_view_permissions(self):
        """
        Returns True if the user has required permissions.
        """
        if self.action in ("list", "retrieve"):
            result = self.get_access_permissions().check_permissions(self.request.user)
        elif self.action in ("metadata", "create"):
            # We do not want anonymous users to use the chat even the anonymous
            # group has the permission core.can_use_chat.
            result = self.request.user.is_authenticated and has_perm(
                self.request.user, "core.can_use_chat"
            )
        elif self.action == "clear":
            result = has_perm(self.request.user, "core.can_use_chat") and has_perm(
                self.request.user, "core.can_manage_chat"
            )
        else:
            result = False
        return result

    def perform_create(self, serializer):
        """
        Customized method to inject the request.user into serializer's save
        method so that the request.user can be saved into the model field.
        """
        serializer.save(user=self.request.user)
        # Send chatter via autoupdate because users without permission
        # to see users may not have it but can get it now.
        inform_changed_data([self.request.user])

    @list_route(methods=["post"])
    def clear(self, request):
        """
        Deletes all chat messages.
        """
        # Collect all chat messages with their collection_string and id
        chatmessages = ChatMessage.objects.all()
        args = []
        for chatmessage in chatmessages:
            args.append((chatmessage.get_collection_string(), chatmessage.pk))
        chatmessages.delete()
        # Trigger autoupdate and setup response.
        if args:
            inform_deleted_data(args)
        return Response({"detail": "All chat messages deleted successfully."})


class ProjectorMessageViewSet(ModelViewSet):
    """
    API endpoint for messages.

    There are the following views: list, retrieve, create, update,
    partial_update and destroy.
    """

    access_permissions = ProjectorMessageAccessPermissions()
    queryset = ProjectorMessage.objects.all()

    def check_view_permissions(self):
        """
        Returns True if the user has required permissions.
        """
        if self.action in ("list", "retrieve"):
            result = self.get_access_permissions().check_permissions(self.request.user)
        elif self.action in ("create", "partial_update", "update", "destroy"):
            result = has_perm(self.request.user, "core.can_manage_projector")
        else:
            result = False
        return result


class CountdownViewSet(ModelViewSet):
    """
    API endpoint for Countdown.

    There are the following views: list, retrieve, create, update,
    partial_update and destroy.
    """

    access_permissions = CountdownAccessPermissions()
    queryset = Countdown.objects.all()

    def check_view_permissions(self):
        """
        Returns True if the user has required permissions.
        """
        if self.action in ("list", "retrieve"):
            result = self.get_access_permissions().check_permissions(self.request.user)
        elif self.action in ("create", "partial_update", "update", "destroy"):
            result = has_perm(self.request.user, "core.can_manage_projector")
        else:
            result = False
        return result


class HistoryViewSet(ListModelMixin, RetrieveModelMixin, GenericViewSet):
    """
    API endpoint for History.

    There are the following views: list, retrieve, clear_history.
    """

    access_permissions = HistoryAccessPermissions()
    queryset = History.objects.all()

    def check_view_permissions(self):
        """
        Returns True if the user has required permissions.
        """
        if self.action in ("list", "retrieve"):
            result = self.get_access_permissions().check_permissions(self.request.user)
        elif self.action == "clear_history":
            result = in_some_groups(self.request.user.pk or 0, [GROUP_ADMIN_PK])
        else:
            result = False
        return result

    @list_route(methods=["post"])
    def clear_history(self, request):
        """
        Deletes and rebuilds the history.
        """
        # Collect all history objects with their collection_string and id.
        args = []
        for history_obj in History.objects.all():
            args.append((history_obj.get_collection_string(), history_obj.pk))

        # Delete history data and history (via CASCADE)
        HistoryData.objects.all().delete()

        # Trigger autoupdate.
        if args:
            inform_deleted_data(args)

        # Rebuild history.
        history_instances = History.objects.build_history()
        inform_changed_data(history_instances)

        # Setup response.
        return Response({"detail": "History was deleted successfully."})


# Special API views


class ServerTime(utils_views.APIView):
    """
    Returns the server time as UNIX timestamp.
    """

    http_method_names = ["get"]

    def get_context_data(self, **context):
        return now().timestamp()


class VersionView(utils_views.APIView):
    """
    Returns a dictionary with the OpenSlides version and the version of all
    plugins.
    """

    http_method_names = ["get"]

    def get_context_data(self, **context):
        result: Dict[str, Any] = {
            "openslides_version": version,
            "openslides_license": license,
            "openslides_url": url,
            "plugins": [],
            "no_name_yet_users": User.objects.filter(last_login__isnull=False).count(),
        }
        # Versions of plugins.
        for plugin in settings.INSTALLED_PLUGINS:
            result["plugins"].append(
                {
                    "verbose_name": get_plugin_verbose_name(plugin),
                    "description": get_plugin_description(plugin),
                    "version": get_plugin_version(plugin),
                    "license": get_plugin_license(plugin),
                    "url": get_plugin_url(plugin),
                }
            )
        return result


class HistoryView(utils_views.APIView):
    """
    View to retrieve the history data of OpenSlides.

    Use query paramter timestamp (UNIX timestamp) to get all elements from begin
    until (including) this timestamp.
    """

    http_method_names = ["get"]

    def get_context_data(self, **context):
        """
        Checks if user is in admin group. If yes all history data until
        (including) timestamp are added to the response data.
        """
        if not in_some_groups(self.request.user.pk or 0, [GROUP_ADMIN_PK]):
            self.permission_denied(self.request)
        try:
            timestamp = int(self.request.query_params.get("timestamp", 0))
        except ValueError:
            raise ValidationError(
                {"detail": "Invalid input. Timestamp  should be an integer."}
            )
        data = []
        queryset = History.objects.select_related("full_data")
        if timestamp:
            queryset = queryset.filter(
                now__lte=datetime.datetime.fromtimestamp(timestamp)
            )
        for instance in queryset:
            data.append(
                {
                    "full_data": instance.full_data.full_data,
                    "element_id": instance.element_id,
                    "timestamp": instance.now.timestamp(),
                    "information": instance.information,
                    "user_id": instance.user.pk if instance.user else None,
                }
            )
        return data