from typing import Iterable

from asgiref.sync import async_to_sync
from django.conf import settings
from django.db import models, transaction
from django.utils.timezone import now
from jsonfield import JSONField

from openslides.utils.autoupdate import AutoupdateElement
from openslides.utils.cache import element_cache, get_element_id
from openslides.utils.locking import locking
from openslides.utils.manager import BaseManager
from openslides.utils.models import SET_NULL_AND_AUTOUPDATE, RESTModelMixin
from openslides.utils.postgres import is_postgres


class ProjectorManager(BaseManager):
    """
    Customized model manager to support our get_prefetched_queryset method.
    """

    def get_prefetched_queryset(self, *args, **kwargs):
        """
        Returns the normal queryset with all projectors. In the background
        projector defaults are prefetched from the database.
        """
        return (
            super()
            .get_prefetched_queryset(*args, **kwargs)
            .prefetch_related("projectiondefaults")
        )


class Projector(RESTModelMixin, models.Model):
    """
    Model for all projectors.

    The elements field contains a list. Every element must have at least the
    property "name".

    Example:
    [
        {
            "name": "topics/topic",
            "id": 1,
        },
        {
            "name": "core/countdown",
            "id": 1,
        },
        {
            "name": "core/clock",
            "id": 1,
        },
    ]

    If the config field is empty or invalid the projector shows a default
    slide.

    There are two additional fields to control the behavior of the projector
    view itself: scale and scroll.

    The projector can be controlled using the REST API with POST requests
    on e. g. the URL /rest/core/projector/1/activate_elements/.
    """

    objects = ProjectorManager()

    elements = JSONField(default=list)
    elements_preview = JSONField(default=list)
    elements_history = JSONField(default=list)

    scale = models.IntegerField(default=0)
    scroll = models.IntegerField(default=0)

    width = models.PositiveIntegerField(default=1200)
    aspect_ratio_numerator = models.PositiveIntegerField(default=16)
    aspect_ratio_denominator = models.PositiveIntegerField(default=9)

    color = models.CharField(max_length=7, default="#000000")
    background_color = models.CharField(max_length=7, default="#ffffff")
    header_background_color = models.CharField(max_length=7, default="#317796")
    header_font_color = models.CharField(max_length=7, default="#f5f5f5")
    header_h1_color = models.CharField(max_length=7, default="#317796")
    chyron_background_color = models.CharField(max_length=7, default="#317796")
    chyron_font_color = models.CharField(max_length=7, default="#ffffff")
    show_header_footer = models.BooleanField(default=True)
    show_title = models.BooleanField(default=True)
    show_logo = models.BooleanField(default=True)

    name = models.CharField(max_length=255, unique=True)

    reference_projector = models.ForeignKey(
        "self",
        on_delete=SET_NULL_AND_AUTOUPDATE,
        null=True,
        blank=True,
        related_name="references",
    )

    class Meta:
        """
        Contains general permissions that can not be placed in a specific app.
        """

        default_permissions = ()
        permissions = (
            ("can_see_projector", "Can see the projector"),
            ("can_manage_projector", "Can manage the projector"),
            ("can_see_frontpage", "Can see the front page"),
            ("can_see_livestream", "Can see the live stream"),
            ("can_see_autopilot", "Can see the autopilot"),
        )


class ProjectionDefault(RESTModelMixin, models.Model):
    """
    Model for the projection defaults like motions, agenda, list of
    speakers and thelike. The name is the technical name like 'topics' or
    'motions'. For apps the name should be the app name to get keep the
    ProjectionDefault for apps generic. But it is possible to give some
    special name like 'list_of_speakers'. The display_name is the shown
    name on the front end for the user.
    """

    name = models.CharField(max_length=256)

    display_name = models.CharField(max_length=256)

    projector = models.ForeignKey(
        Projector, on_delete=models.PROTECT, related_name="projectiondefaults"
    )

    class Meta:
        default_permissions = ()

    def __str__(self):
        return self.display_name


class Tag(RESTModelMixin, models.Model):
    """
    Model for tags. This tags can be used for other models like agenda items,
    motions or assignments.
    """

    name = models.CharField(max_length=255, unique=True)

    class Meta:
        ordering = ("name",)
        default_permissions = ()
        permissions = (("can_manage_tags", "Can manage tags"),)

    def __str__(self):
        return self.name


class ConfigStore(RESTModelMixin, models.Model):
    """
    A model class to store all config variables in the database.
    """

    key = models.CharField(max_length=255, unique=True, db_index=True)
    """A string, the key of the config variable."""

    value = JSONField()
    """The value of the config variable. """

    class Meta:
        default_permissions = ()
        permissions = (
            ("can_manage_config", "Can manage configuration"),
            ("can_manage_logos_and_fonts", "Can manage logos and fonts"),
        )

    @classmethod
    def get_collection_string(cls):
        return "core/config"


class ProjectorMessage(RESTModelMixin, models.Model):
    """
    Model for ProjectorMessages.
    """

    message = models.TextField(blank=True)

    class Meta:
        default_permissions = ()


class Countdown(RESTModelMixin, models.Model):
    """
    Model for countdowns.
    """

    title = models.CharField(max_length=256, unique=True)

    description = models.CharField(max_length=256, blank=True)

    running = models.BooleanField(default=False)

    default_time = models.PositiveIntegerField(default=60)

    countdown_time = models.FloatField(default=60)

    class Meta:
        default_permissions = ()

    def control(self, action, skip_autoupdate=False):
        if action not in ("start", "stop", "reset"):
            raise ValueError(
                f"Action must be 'start', 'stop' or 'reset', not {action}."
            )

        if action == "start":
            self.running = True
            self.countdown_time = now().timestamp() + self.default_time
        elif action == "stop" and self.running:
            self.running = False
            self.countdown_time = self.countdown_time - now().timestamp()
        else:  # reset
            self.running = False
            self.countdown_time = self.default_time
        self.save(skip_autoupdate=skip_autoupdate)


class HistoryData(models.Model):
    """
    Django model to save the history of OpenSlides.

    This is not a RESTModel. It is not cachable and can only be reached by a
    special viewset.
    """

    full_data = JSONField()

    class Meta:
        default_permissions = ()


class HistoryManager(BaseManager):
    """
    Customized model manager for the history model.
    """

    def add_elements(self, elements: Iterable[AutoupdateElement]):
        """
        Method to add elements to the history. This does not trigger autoupdate.
        """
        history_time = now()
        elements = [
            element for element in elements if not element.get("disable_history", False)
        ]

        with transaction.atomic():
            if is_postgres():
                return self._add_elements_postgres(elements, history_time)
            else:
                return self._add_elements_other_dbs(elements, history_time)

    def _add_elements_postgres(self, elements, history_time):
        """
        Postgres supports returning ids from bulk requests, so after doing `bulk_create`
        every HistoryData has an id. This can be used to bulk_create History-Models in a
        second step.
        """
        history_data = [
            HistoryData(full_data=element.get("full_data")) for element in elements
        ]
        HistoryData.objects.bulk_create(history_data)

        history_entries = [
            self.model(
                element_id=get_element_id(element["collection_string"], element["id"]),
                now=history_time,
                information=element.get("information", []),
                user_id=element.get("user_id"),
                full_data_id=hd.id,
            )
            for element, hd in zip(elements, history_data)
        ]
        self.bulk_create(history_entries)
        return history_entries

    def _add_elements_other_dbs(self, elements, history_time):
        history_entries = []
        for element in elements:
            # HistoryData is not a root rest element so there is no autoupdate and not history saving here.
            data = HistoryData.objects.create(full_data=element.get("full_data"))
            instance = self.model(
                element_id=get_element_id(element["collection_string"], element["id"]),
                now=history_time,
                information=element.get("information", []),
                user_id=element.get("user_id"),
                full_data=data,
            )
            instance.save()
            history_entries.append(instance)
        return history_entries

    def build_history(self):
        """
        Method to add all cacheables to the history.
        """
        async_to_sync(self.async_build_history)()

    async def async_build_history(self):
        lock_name = "build_cache"
        if await locking.set(lock_name):
            try:
                if self.all().count() == 0:
                    elements = []
                    all_full_data = await element_cache.get_all_data_list()
                    for collection_string, data in all_full_data.items():
                        for full_data in data:
                            elements.append(
                                AutoupdateElement(
                                    id=full_data["id"],
                                    collection_string=collection_string,
                                    full_data=full_data,
                                )
                            )
                    self.add_elements(elements)
            finally:
                await locking.delete(lock_name)


class History(models.Model):
    """
    Django model to save the history of OpenSlides.

    This model itself is not part of the history. This means that if you
    delete a user you may lose the information of the user field here.
    """

    objects = HistoryManager()

    element_id = models.CharField(max_length=255)

    now = models.DateTimeField()

    information = JSONField()

    user = models.ForeignKey(
        settings.AUTH_USER_MODEL, null=True, on_delete=models.SET_NULL
    )

    full_data = models.OneToOneField(HistoryData, on_delete=models.CASCADE)

    class Meta:
        default_permissions = ()
        permissions = (("can_see_history", "Can see history"),)