from django.conf import settings
from django.db import models
from django.db.models import Q
from django.utils import timezone


class TaskQuerySet(models.QuerySet):
    def get_ordered(self):
        return self.order_by('task_list')


class TaskManager(models.Manager):
    def get_tasks(self, user, completed):
        if completed:
            return self.get_queryset().get_ordered().filter(Q(assigned_to=user))
        else:
            return self.get_queryset().get_ordered().filter(
                Q(assigned_to=user)
                & Q(completed=completed)
            )

    def get_queryset(self):
        return TaskQuerySet(self.model, using=self._db)


class TaskList(models.Model):
    name = models.CharField(max_length=60)
    slug = models.SlugField(unique=True, null=True, blank=True)

    objects = models.Manager()

    def __str__(self):
        return self.name


class Task(models.Model):
    title = models.CharField(max_length=140)
    task_list = models.ForeignKey(TaskList, on_delete=models.CASCADE, null=True)

    created_date = models.DateTimeField(auto_now_add=True)
    due_date = models.DateField(blank=True, null=True)

    completed = models.BooleanField(default=False)
    completed_date = models.DateField(blank=True, null=True)

    created_by = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        related_name="todo_created_by",
        on_delete=models.CASCADE,
    )
    assigned_to = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        blank=True,
        null=True,
        related_name="todo_assigned_to",
        on_delete=models.CASCADE,
    )

    note = models.TextField(blank=True, null=True)
    priority = models.PositiveIntegerField(blank=True, null=True)

    objects = models.Manager()
    taskmanager = TaskManager()

    def __str__(self):
        return self.title

    def save(self, *args, **kwargs):
        if self.completed and not self.completed_date:
            self.completed_date = timezone.now().date()

        if not self.completed and self.completed_date:
            self.completed_date = None

        super().save(*args, **kwargs)