""" the particulars for this instance of BookWyrm """
import datetime
from typing import Optional, Iterable
from urllib.parse import urljoin
import uuid

import django.contrib.auth.models as auth_models
from django.core.exceptions import PermissionDenied
from django.db import models, IntegrityError
from django.dispatch import receiver
from django.utils import timezone
from model_utils import FieldTracker

from bookwyrm.connectors.abstract_connector import get_data
from bookwyrm.preview_images import generate_site_preview_image_task
from bookwyrm.settings import BASE_URL, ENABLE_PREVIEW_IMAGES, STATIC_FULL_URL
from bookwyrm.settings import RELEASE_API
from bookwyrm.tasks import app, MISC
from bookwyrm.utils.db import add_update_fields
from .base_model import BookWyrmModel, new_access_code
from .user import User
from .fields import get_absolute_url


class SiteModel(models.Model):
    """we just need edit perms"""

    class Meta:
        """this is just here to provide default fields for other models"""

        abstract = True

    # pylint: disable=no-self-use
    def raise_not_editable(self, viewer):
        """Check if the user has the right permissions"""
        if viewer.has_perm("bookwyrm.edit_instance_settings"):
            return
        raise PermissionDenied()


class SiteSettings(SiteModel):
    """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)
    default_theme = models.ForeignKey(
        "Theme", null=True, blank=True, on_delete=models.SET_NULL
    )
    available_version = models.CharField(null=True, blank=True, max_length=10)

    # admin setup options
    install_mode = models.BooleanField(default=False)
    admin_code = models.CharField(max_length=50, default=uuid.uuid4)

    # 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.")
    impressum = models.TextField(default="Add a impressum here.")
    show_impressum = models.BooleanField(default=False)

    # registration
    allow_registration = models.BooleanField(default=False)
    allow_invite_requests = models.BooleanField(default=True)
    invite_request_question = models.BooleanField(default=False)
    require_confirm_email = models.BooleanField(default=True)
    default_user_auth_group = models.ForeignKey(
        auth_models.Group, null=True, blank=True, on_delete=models.RESTRICT
    )

    invite_question_text = models.CharField(
        max_length=255, blank=True, default="What is your favourite book?"
    )
    # 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)

    # controls
    imports_enabled = models.BooleanField(default=True)
    import_size_limit = models.IntegerField(default=0)
    import_limit_reset = models.IntegerField(default=0)
    user_exports_enabled = models.BooleanField(default=False)
    user_import_time_limit = models.IntegerField(default=48)

    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

    @property
    def logo_url(self):
        """helper to build the logo url"""
        return self.get_url("logo", "images/logo.png")

    @property
    def logo_small_url(self):
        """helper to build the logo url"""
        return self.get_url("logo_small", "images/logo-small.png")

    @property
    def favicon_url(self):
        """helper to build the logo url"""
        return self.get_url("favicon", "images/favicon.png")

    def get_url(self, field, default_path):
        """get a media url or a default static path"""
        uploaded = getattr(self, field, None)
        if uploaded:
            return get_absolute_url(uploaded)
        return urljoin(STATIC_FULL_URL, default_path)

    def save(self, *args, update_fields: Optional[Iterable[str]] = None, **kwargs):
        """if require_confirm_email is disabled, make sure no users are pending,
        if enabled, make sure invite_question_text is not empty"""
        if not self.invite_question_text:
            self.invite_question_text = "What is your favourite book?"
            update_fields = add_update_fields(update_fields, "invite_question_text")

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

        if not self.require_confirm_email:
            User.objects.filter(is_active=False, deactivation_reason="pending").update(
                is_active=True, deactivation_reason=None
            )


class Theme(SiteModel):
    """Theme files"""

    created_date = models.DateTimeField(auto_now_add=True)
    name = models.CharField(max_length=50, unique=True)
    path = models.CharField(max_length=50, unique=True)
    loads = models.BooleanField(null=True, blank=True)

    def __str__(self):
        # pylint: disable=invalid-str-returned
        return self.name


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")

    # pylint: disable=no-self-use
    def raise_not_editable(self, viewer):
        """Admins only"""
        if viewer.has_perm("bookwyrm.create_invites"):
            return
        raise PermissionDenied()

    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 f"{BASE_URL}/invite/{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
    )
    answer = models.TextField(max_length=255, unique=False, null=True, blank=True)
    invite_sent = models.BooleanField(default=False)
    ignored = models.BooleanField(default=False)

    def raise_not_editable(self, viewer):
        """Only check perms on edit, not create"""
        if not self.id or viewer.has_perm("bookwyrm.create_invites"):
            return
        raise PermissionDenied()

    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_password_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_password_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 f"{BASE_URL}/password-reset/{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()


@app.task(queue=MISC)
def check_for_updates_task():
    """See if git remote knows about a new version"""
    site = SiteSettings.objects.get()
    release = get_data(RELEASE_API, timeout=3)
    available_version = release.get("tag_name", None)
    if available_version:
        site.available_version = available_version
        site.save(update_fields=["available_version"])