from django.db import models
from django.contrib.auth.models import User
from django.db.models.signals import post_save
from django.dispatch import receiver

import os
from uuid import uuid4


def path_and_rename(instance, filename):
    upload_to = 'avatars/'
    ext = filename.split('.')[-1]
    # get filename
    if instance.pk:
        filename = '{}.{}'.format(instance.pk, ext)
    else:
        # set filename as random string
        filename = '{}.{}'.format(uuid4().hex, ext)
    # return the whole path to the file
    return os.path.join(upload_to, filename)


class Profile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    avatar = models.ImageField(upload_to=path_and_rename, null=True, blank=True)
    birthdate = models.DateTimeField(null=True, blank=True)
    use_gravatar = models.BooleanField(blank=True, default=False, verbose_name='Use Avatars from Gravatar?')
    location = models.CharField(max_length=100, null=True, blank=True)

    def __str__(self):
        return self.user.username


@receiver(post_save, sender=User)
def create_or_update_user_profile(sender, instance, created, **kwargs):
    if created:
        Profile.objects.create(user=instance)
    instance.profile.save()


@receiver(models.signals.post_delete, sender=Profile)
def auto_delete_file_on_delete(sender, instance, **kwargs):
    """
    Deletes file from filesystem
    when corresponding `Profile` object is deleted.
    """
    if instance.avatar:
        instance.avatar.delete(save=False)


@receiver(models.signals.pre_save, sender=Profile)
def auto_delete_file_on_change(sender, instance, **kwargs):
    """
    Deletes old file from filesystem
    when corresponding `Profile` object is updated
    with new file.
    """
    if not instance.pk:
        return False

    try:
        old_avatar = Profile.objects.get(pk=instance.pk).avatar
    except Profile.DoesNotExist:
        return False

    new_avatar = instance.avatar
    if not old_avatar == new_avatar:
        old_avatar.delete(save=False)