""" the particulars for this instance of BookWyrm """
import datetime

from django.db import models, IntegrityError
from django.dispatch import receiver
from django.utils import timezone
from model_utils import FieldTracker

from bookwyrm.preview_images import generate_site_preview_image_task
from bookwyrm.settings import DOMAIN, ENABLE_PREVIEW_IMAGES
from .base_model import BookWyrmModel, new_access_code
from .user import User


class SiteSettings(models.Model):
    """customized settings for this instance"""

    name = models.CharField(default="BookWyrm", max_length=100)
    instance_tagline = models.CharField(
        max_length=150, default="Social Reading and Reviewing"
    )
    instance_description = models.TextField(default="This instance has no description.")
    instance_short_description = models.CharField(max_length=255, blank=True, null=True)

    # about page
    registration_closed_text = models.TextField(
        default='We aren\'t taking new users at this time. You can find an open instance at <a href="https://joinbookwyrm.com/instances">joinbookwyrm.com/instances</a>.'
    )
    invite_request_text = models.TextField(
        default="If your request is approved, you will receive an email with a registration link."
    )
    code_of_conduct = models.TextField(default="Add a code of conduct here.")
    privacy_policy = models.TextField(default="Add a privacy policy here.")

    # registration
    allow_registration = models.BooleanField(default=True)
    allow_invite_requests = models.BooleanField(default=True)
    require_confirm_email = models.BooleanField(default=True)

    # images
    logo = models.ImageField(upload_to="logos/", null=True, blank=True)
    logo_small = models.ImageField(upload_to="logos/", null=True, blank=True)
    favicon = models.ImageField(upload_to="logos/", null=True, blank=True)
    preview_image = models.ImageField(
        upload_to="previews/logos/", null=True, blank=True
    )

    # footer
    support_link = models.CharField(max_length=255, null=True, blank=True)
    support_title = models.CharField(max_length=100, null=True, blank=True)
    admin_email = models.EmailField(max_length=255, null=True, blank=True)
    footer_item = models.TextField(null=True, blank=True)

    field_tracker = FieldTracker(fields=["name", "instance_tagline", "logo"])

    @classmethod
    def get(cls):
        """gets the site settings db entry or defaults"""
        try:
            return cls.objects.get(id=1)
        except cls.DoesNotExist:
            default_settings = SiteSettings(id=1)
            default_settings.save()
            return default_settings


class SiteInvite(models.Model):
    """gives someone access to create an account on the instance"""

    created_date = models.DateTimeField(auto_now_add=True)
    code = models.CharField(max_length=32, default=new_access_code)
    expiry = models.DateTimeField(blank=True, null=True)
    use_limit = models.IntegerField(blank=True, null=True)
    times_used = models.IntegerField(default=0)
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    invitees = models.ManyToManyField(User, related_name="invitees")

    def valid(self):
        """make sure it hasn't expired or been used"""
        return (self.expiry is None or self.expiry > timezone.now()) and (
            self.use_limit is None or self.times_used < self.use_limit
        )

    @property
    def link(self):
        """formats the invite link"""
        return "https://{}/invite/{}".format(DOMAIN, self.code)


class InviteRequest(BookWyrmModel):
    """prospective users can request an invite"""

    email = models.EmailField(max_length=255, unique=True)
    invite = models.ForeignKey(
        SiteInvite, on_delete=models.SET_NULL, null=True, blank=True
    )
    invite_sent = models.BooleanField(default=False)
    ignored = models.BooleanField(default=False)

    def save(self, *args, **kwargs):
        """don't create a request for a registered email"""
        if not self.id and User.objects.filter(email=self.email).exists():
            raise IntegrityError()
        super().save(*args, **kwargs)


def get_passowrd_reset_expiry():
    """give people a limited time to use the link"""
    now = timezone.now()
    return now + datetime.timedelta(days=1)


class PasswordReset(models.Model):
    """gives someone access to create an account on the instance"""

    code = models.CharField(max_length=32, default=new_access_code)
    expiry = models.DateTimeField(default=get_passowrd_reset_expiry)
    user = models.OneToOneField(User, on_delete=models.CASCADE)

    def valid(self):
        """make sure it hasn't expired or been used"""
        return self.expiry > timezone.now()

    @property
    def link(self):
        """formats the invite link"""
        return "https://{}/password-reset/{}".format(DOMAIN, self.code)


# pylint: disable=unused-argument
@receiver(models.signals.post_save, sender=SiteSettings)
def preview_image(instance, *args, **kwargs):
    """Update image preview for the default site image"""
    if not ENABLE_PREVIEW_IMAGES:
        return
    changed_fields = instance.field_tracker.changed()

    if len(changed_fields) > 0:
        generate_site_preview_image_task.delay()