from books.models import Module
from core.utils import sync_hidden_for, sync_visible_for
from django.contrib.auth import get_user_model
from django.db import models
from users.models import SchoolClass


class ObjectiveGroup(models.Model):
    class Meta:
        verbose_name = "Lernzielgruppe"
        verbose_name_plural = "Lernzielgruppen"
        ordering = ["pk"]

    LANGUAGE_COMMUNICATION = "language_communication"
    SOCIETY = "society"
    INTERDISCIPLINARY = "interdisciplinary"

    TITLE_CHOICES = (
        (LANGUAGE_COMMUNICATION, "Sprache & Kommunikation"),
        (SOCIETY, "Gesellschaft"),
        (INTERDISCIPLINARY, "Überfachliche Lernziele"),
    )

    title = models.CharField(
        "title",
        blank=True,
        null=False,
        max_length=255,
        choices=TITLE_CHOICES,
        default=LANGUAGE_COMMUNICATION,
    )
    module = models.ForeignKey(
        Module,
        blank=False,
        null=False,
        on_delete=models.CASCADE,
        related_name="objective_groups",
    )

    hidden_for = models.ManyToManyField(
        SchoolClass, related_name="hidden_objective_groups", blank=True
    )

    def __str__(self):
        return "{} - {}".format(self.module, self.title)

    def sync_visibility(self, school_class_template, school_class_to_sync):
        # if self.hidden_for.filter(id=school_class_template.id).exists() and not self.hidden_for.filter(id=school_class_to_sync.id).exists():
        #     self.hidden_for.add(school_class_to_sync)
        #
        # if self.hidden_for.filter(id=school_class_to_sync.id).exists() and not self.hidden_for.filter(id=school_class_template.id).exists():
        #     self.hidden_for.remove(school_class_to_sync)
        sync_hidden_for(self, school_class_template, school_class_to_sync)

        for objective in self.objectives.all():
            objective.sync_visibility(school_class_template, school_class_to_sync)


class Objective(models.Model):
    class Meta:
        verbose_name = "Lernziel"
        verbose_name_plural = "Lernziele"
        # todo: reinstate ordering in resolver
        # ordering = [F('owner').asc(nulls_first=True), F('order').asc(nulls_last=True)]

    text = models.CharField("text", blank=True, null=False, max_length=255)
    group = models.ForeignKey(
        ObjectiveGroup,
        blank=False,
        null=False,
        on_delete=models.CASCADE,
        related_name="objectives",
    )
    owner = models.ForeignKey(
        get_user_model(), blank=True, null=True, on_delete=models.PROTECT
    )
    hidden_for = models.ManyToManyField(
        SchoolClass, related_name="hidden_objectives", blank=True
    )
    visible_for = models.ManyToManyField(
        SchoolClass, related_name="visible_objectives", blank=True
    )
    order = models.IntegerField(null=True, blank=True)

    def __str__(self):
        return "Objective {}-{}".format(self.id, self.text)

    def sync_visibility(self, school_class_template, school_class_to_sync):
        sync_hidden_for(self, school_class_template, school_class_to_sync)
        sync_visible_for(self, school_class_template, school_class_to_sync)

    def is_hidden_for_class(self, school_class):
        return (
            self.owner is None and self.hidden_for.filter(id=school_class.id).exists()
        ) or (
            self.owner is not None
            and not self.visible_for.filter(id=school_class.id).exists()
        )


class ObjectiveSnapshot(Objective):
    hidden = models.BooleanField(default=False)
    snapshot = models.ForeignKey(
        "books.Snapshot",
        on_delete=models.SET_NULL,
        null=True,
        related_name="custom_objectives",
    )

    def to_regular_objective(self, owner, school_class):
        objective = Objective.objects.create(
            owner=owner, text=self.text, group=self.group, order=self.order
        )

        objective.visible_for.add(school_class)
        objective.save()

        return objective