import datetime

from django.conf import settings
from django.contrib.auth import get_user_model
from django.core import signing
from django.db import models
from django.db.models import Index, Q
from django.db.models.constraints import UniqueConstraint
from django.db.models.functions import Upper
from django.utils import timezone
from django.utils.translation import gettext_lazy as _

from . import app_settings, signals
from .adapter import get_adapter
from .managers import EmailAddressManager, EmailConfirmationManager


class EmailAddress(models.Model):
    user = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        verbose_name=_("user"),
        on_delete=models.CASCADE,
    )
    email = models.EmailField(
        max_length=app_settings.EMAIL_MAX_LENGTH,
        verbose_name=_("email address"),
    )
    verified = models.BooleanField(verbose_name=_("verified"), default=False)
    primary = models.BooleanField(verbose_name=_("primary"), default=False)

    objects = EmailAddressManager()

    class Meta:
        verbose_name = _("email address")
        verbose_name_plural = _("email addresses")
        unique_together = [("user", "email")]
        if app_settings.UNIQUE_EMAIL:
            constraints = [
                UniqueConstraint(
                    fields=["email"],
                    name="unique_verified_email",
                    condition=Q(verified=True),
                )
            ]
        indexes = [Index(Upper("email"), name="account_emailaddress_upper")]

    def __str__(self):
        return self.email

    def can_set_verified(self):
        if self.verified:
            return True
        conflict = False
        if app_settings.UNIQUE_EMAIL:
            conflict = (
                EmailAddress.objects.exclude(pk=self.pk)
                .filter(verified=True, email__iexact=self.email)
                .exists()
            )
        return not conflict

    def set_verified(self, commit=True):
        if self.verified:
            return True
        if self.can_set_verified():
            self.verified = True
            if commit:
                self.save(update_fields=["verified"])
        return self.verified

    def set_as_primary(self, conditional=False):
        """Marks the email address as primary. In case of `conditional`, it is
        only marked as primary if there is no other primary email address set.
        """
        from allauth.account.utils import user_email

        old_primary = EmailAddress.objects.get_primary(self.user)
        if old_primary:
            if conditional:
                return False
            old_primary.primary = False
            old_primary.save()
        self.primary = True
        self.save()
        user_email(self.user, self.email, commit=True)
        return True

    def send_confirmation(self, request=None, signup=False):
        if app_settings.EMAIL_CONFIRMATION_HMAC:
            confirmation = EmailConfirmationHMAC(self)
        else:
            confirmation = EmailConfirmation.create(self)
        confirmation.send(request, signup=signup)
        return confirmation

    def remove(self):
        from allauth.account.utils import user_email

        self.delete()
        if user_email(self.user) == self.email:
            alt = (
                EmailAddress.objects.filter(user=self.user)
                .order_by("-verified")
                .first()
            )
            alt_email = ""
            if alt:
                alt_email = alt.email
            user_email(self.user, alt_email, commit=True)


class EmailConfirmationMixin:
    def confirm(self, request):
        email_address = self.email_address
        if not email_address.verified:
            confirmed = get_adapter().confirm_email(request, email_address)
            if confirmed:
                signals.email_confirmed.send(
                    sender=self.__class__,
                    request=request,
                    email_address=email_address,
                )
                return email_address

    def send(self, request=None, signup=False):
        get_adapter().send_confirmation_mail(request, self, signup)
        signals.email_confirmation_sent.send(
            sender=self.__class__,
            request=request,
            confirmation=self,
            signup=signup,
        )


class EmailConfirmation(EmailConfirmationMixin, models.Model):
    email_address = models.ForeignKey(
        EmailAddress,
        verbose_name=_("email address"),
        on_delete=models.CASCADE,
    )
    created = models.DateTimeField(verbose_name=_("created"), default=timezone.now)
    sent = models.DateTimeField(verbose_name=_("sent"), null=True)
    key = models.CharField(verbose_name=_("key"), max_length=64, unique=True)

    objects = EmailConfirmationManager()

    class Meta:
        verbose_name = _("email confirmation")
        verbose_name_plural = _("email confirmations")

    def __str__(self):
        return "confirmation for %s" % self.email_address

    @classmethod
    def create(cls, email_address):
        key = get_adapter().generate_emailconfirmation_key(email_address.email)
        return cls._default_manager.create(email_address=email_address, key=key)

    def key_expired(self):
        expiration_date = self.sent + datetime.timedelta(
            days=app_settings.EMAIL_CONFIRMATION_EXPIRE_DAYS
        )
        return expiration_date <= timezone.now()

    key_expired.boolean = True

    def confirm(self, request):
        if not self.key_expired():
            return super().confirm(request)

    def send(self, request=None, signup=False):
        super().send(request=request, signup=signup)
        self.sent = timezone.now()
        self.save()


class EmailConfirmationHMAC(EmailConfirmationMixin, object):
    def __init__(self, email_address):
        self.email_address = email_address

    @property
    def key(self):
        return signing.dumps(obj=self.email_address.pk, salt=app_settings.SALT)

    @classmethod
    def from_key(cls, key):
        try:
            max_age = 60 * 60 * 24 * app_settings.EMAIL_CONFIRMATION_EXPIRE_DAYS
            pk = signing.loads(key, max_age=max_age, salt=app_settings.SALT)
            ret = EmailConfirmationHMAC(EmailAddress.objects.get(pk=pk, verified=False))
        except (
            signing.SignatureExpired,
            signing.BadSignature,
            EmailAddress.DoesNotExist,
        ):
            ret = None
        return ret


class Login:
    """
    Represents a user that is in the process of logging in.
    """

    def __init__(
        self,
        user,
        email_verification,
        redirect_url=None,
        signal_kwargs=None,
        signup=False,
        email=None,
        state=None,
    ):
        self.user = user
        self.email_verification = email_verification
        self.redirect_url = redirect_url
        self.signal_kwargs = signal_kwargs
        self.signup = signup
        self.email = email
        self.state = {} if state is None else state

    def serialize(self):
        from allauth.account.utils import user_pk_to_url_str

        # :-( Knowledge of the `socialaccount` is entering the `account` app.
        signal_kwargs = self.signal_kwargs
        if signal_kwargs is not None:
            sociallogin = signal_kwargs.get("sociallogin")
            if sociallogin is not None:
                signal_kwargs = signal_kwargs.copy()
                signal_kwargs["sociallogin"] = sociallogin.serialize()

        data = {
            "user_pk": user_pk_to_url_str(self.user),
            "email_verification": self.email_verification,
            "signup": self.signup,
            "redirect_url": self.redirect_url,
            "email": self.email,
            "signal_kwargs": signal_kwargs,
            "state": self.state,
        }
        return data

    @classmethod
    def deserialize(cls, data):
        from allauth.account.utils import url_str_to_user_pk
        from allauth.socialaccount.models import SocialLogin

        user = (
            get_user_model()
            .objects.filter(pk=url_str_to_user_pk(data["user_pk"]))
            .first()
        )
        if user is None:
            raise ValueError()
        try:
            # :-( Knowledge of the `socialaccount` is entering the `account` app.
            signal_kwargs = data["signal_kwargs"]
            if signal_kwargs is not None:
                sociallogin = signal_kwargs.get("sociallogin")
                if sociallogin is not None:
                    signal_kwargs = signal_kwargs.copy()
                    signal_kwargs["sociallogin"] = SocialLogin.deserialize(sociallogin)

            return Login(
                user=user,
                email_verification=data["email_verification"],
                redirect_url=data["redirect_url"],
                signup=data["signup"],
                signal_kwargs=signal_kwargs,
                state=data["state"],
            )
        except KeyError:
            raise ValueError()