#
# Copyright 2023 © AE UTBM
# ae@utbm.fr / ae.info@utbm.fr
#
# This file is part of the website of the UTBM Student Association (AE UTBM),
# https://ae.utbm.fr.
#
# You can find the source code of the website at https://github.com/ae-utbm/sith3
#
# LICENSED UNDER THE GNU GENERAL PUBLIC LICENSE VERSION 3 (GPLv3)
# SEE : https://raw.githubusercontent.com/ae-utbm/sith3/master/LICENSE
# OR WITHIN THE LOCAL FILE "LICENSE"
#
#

import math
from datetime import date, timedelta

from dateutil.relativedelta import relativedelta
from django.conf import settings
from django.contrib.auth.forms import PasswordResetForm
from django.core.exceptions import ValidationError
from django.db import models
from django.urls import reverse
from django.utils.translation import gettext_lazy as _

from core.models import User
from core.utils import get_start_of_semester


def validate_type(value):
    if value not in settings.SITH_SUBSCRIPTIONS.keys():
        raise ValidationError(_("Bad subscription type"))


def validate_payment(value):
    if value not in settings.SITH_SUBSCRIPTION_PAYMENT_METHOD:
        raise ValidationError(_("Bad payment method"))


class Subscription(models.Model):
    member = models.ForeignKey(
        User, related_name="subscriptions", on_delete=models.CASCADE
    )
    subscription_type = models.CharField(
        _("subscription type"),
        max_length=255,
        choices=(
            (k, v["name"]) for k, v in sorted(settings.SITH_SUBSCRIPTIONS.items())
        ),
    )
    subscription_start = models.DateField(_("subscription start"))
    subscription_end = models.DateField(_("subscription end"))
    payment_method = models.CharField(
        _("payment method"),
        max_length=255,
        choices=settings.SITH_SUBSCRIPTION_PAYMENT_METHOD,
    )
    location = models.CharField(
        choices=settings.SITH_SUBSCRIPTION_LOCATIONS,
        max_length=20,
        verbose_name=_("location"),
    )

    class Meta:
        ordering = ["subscription_start"]

    def clean(self):
        try:
            for s in (
                Subscription.objects.filter(member=self.member)
                .exclude(pk=self.pk)
                .all()
            ):
                if (
                    s.is_valid_now()
                    and s.subscription_end
                    - timedelta(weeks=settings.SITH_SUBSCRIPTION_END)
                    > date.today()
                ):
                    raise ValidationError(
                        _("You can not subscribe many time for the same period")
                    )
        except:  # This should not happen, because the form should have handled the data before, but sadly, it still
            # calls the model validation :'(
            # TODO see SubscriptionForm's clean method
            raise ValidationError(_("Subscription error"))

    def save(self, *args, **kwargs):
        super().save()
        from counter.models import Customer

        _, created = Customer.get_or_create(self.member)
        if created:
            form = PasswordResetForm({"email": self.member.email})
            if form.is_valid():
                form.save(
                    use_https=True,
                    email_template_name="core/new_user_email.jinja",
                    subject_template_name="core/new_user_email_subject.jinja",
                    from_email="ae@utbm.fr",
                )
        self.member.make_home()

    def get_absolute_url(self):
        return reverse("core:user_edit", kwargs={"user_id": self.member.pk})

    def __str__(self):
        if hasattr(self, "member") and self.member is not None:
            return self.member.username + " - " + str(self.pk)
        else:
            return "No user - " + str(self.pk)

    @staticmethod
    def compute_start(d: date = None, duration: int = 1, user: User = None) -> date:
        """
        This function computes the start date of the subscription with respect to the given date (default is today),
        and the start date given in settings.SITH_SEMESTER_START_AUTUMN.
        It takes the nearest past start date.
        Exemples: with SITH_SEMESTER_START_AUTUMN = (8, 15)
            Today      -> Start date
            2015-03-17 -> 2015-02-15
            2015-01-11 -> 2014-08-15
        """
        if not d:
            d = date.today()
        if user is not None and user.subscriptions.exists():
            last = user.subscriptions.last()
            if last.is_valid_now():
                d = last.subscription_end
        if duration <= 2:  # Sliding subscriptions for 1 or 2 semesters
            return d
        return get_start_of_semester(d)

    @staticmethod
    def compute_end(duration: int, start: date = None, user: User = None) -> date:
        """
        This function compute the end date of the subscription given a start date and a duration in number of semester
        Exemple:
            Start - Duration -> End date
            2015-09-18 - 1 -> 2016-03-18
            2015-09-18 - 2 -> 2016-09-18
            2015-09-18 - 3 -> 2017-03-18
            2015-09-18 - 4 -> 2017-09-18
        """
        if start is None:
            start = Subscription.compute_start(duration=duration, user=user)

        return start + relativedelta(
            months=round(6 * duration),
            days=math.ceil((6 * duration - round(6 * duration)) * 30),
        )

    def can_be_edited_by(self, user: User):
        return user.is_board_member or user.is_root

    def is_valid_now(self):
        return self.subscription_start <= date.today() <= self.subscription_end