# Copyright (C) 2020 by Animath
# SPDX-License-Identifier: GPL-3.0-or-later

from datetime import date, datetime

from django.contrib.sites.models import Site
from django.core.mail import send_mail
from django.core.validators import MaxValueValidator, MinValueValidator
from django.db import models
from django.template import loader
from django.urls import reverse, reverse_lazy
from django.utils import timezone, translation
from django.utils.crypto import get_random_string
from django.utils.encoding import force_bytes
from django.utils.http import urlsafe_base64_encode
from django.utils.text import format_lazy
from django.utils.timezone import localtime
from django.utils.translation import gettext_lazy as _
from phonenumber_field.modelfields import PhoneNumberField
from polymorphic.models import PolymorphicModel
from tfjm import helloasso
from tfjm.tokens import email_validation_token


class Registration(PolymorphicModel):
    """
    Registrations store extra content that are not asked in the User Model.
    This is specific to the role of the user, see StudentRegistration,
    CoachRegistration or VolunteerRegistration.
    """
    user = models.OneToOneField(
        "auth.User",
        on_delete=models.CASCADE,
        verbose_name=_("user"),
    )

    give_contact_to_animath = models.BooleanField(
        default=False,
        verbose_name=_("Grant Animath to contact me in the future about other actions"),
    )

    email_confirmed = models.BooleanField(
        default=False,
        verbose_name=_("email confirmed"),
    )

    def send_email_validation_link(self):
        """
        The account got created or the email got changed.
        Send an email that contains a link to validate the address.
        """
        subject = "[TFJM²] " + str(_("Activate your TFJM² account"))
        token = email_validation_token.make_token(self.user)
        uid = urlsafe_base64_encode(force_bytes(self.user.pk))
        site = Site.objects.first()
        message = loader.render_to_string('registration/mails/email_validation_email.txt',
                                          {
                                              'user': self.user,
                                              'domain': site.domain,
                                              'token': token,
                                              'uid': uid,
                                          })
        html = loader.render_to_string('registration/mails/email_validation_email.html',
                                       {
                                           'user': self.user,
                                           'domain': site.domain,
                                           'token': token,
                                           'uid': uid,
                                       })
        self.user.email_user(subject, message, html_message=html)

    @property
    def type(self):  # pragma: no cover
        raise NotImplementedError

    @property
    def form_class(self):  # pragma: no cover
        raise NotImplementedError

    @property
    def participates(self):
        return isinstance(self, ParticipantRegistration)

    @property
    def is_student(self):
        return isinstance(self, StudentRegistration)

    @property
    def is_coach(self):
        return isinstance(self, CoachRegistration)

    @property
    def is_admin(self):
        return isinstance(self, VolunteerRegistration) and self.admin or self.user.is_superuser

    @property
    def is_volunteer(self):
        return isinstance(self, VolunteerRegistration)

    def get_absolute_url(self):
        return reverse_lazy("registration:user_detail", args=(self.user_id,))

    def registration_informations(self):
        return []

    def important_informations(self):
        informations = []
        if not self.email_confirmed:
            text = _("Your email address is not validated. Please click on the link you received by email. "
                     "You can resend a mail by clicking on <a href=\"{send_email_url}\">this link</a>.")
            send_email_url = reverse_lazy("registration:email_validation_resend", args=(self.user_id,))
            content = format_lazy(text, send_email_url=send_email_url)
            informations.append({
                'title': "Validation e-mail",
                'type': "warning",
                'priority': 0,
                'content': content,
            })

        informations.extend(self.registration_informations())

        informations.sort(key=lambda info: (info['priority'], info['title']))
        return informations

    def __str__(self):
        return f"{self.user.first_name} {self.user.last_name}"

    class Meta:
        verbose_name = _("registration")
        verbose_name_plural = _("registrations")


def get_random_photo_filename(instance, filename):
    return "authorization/photo/" + get_random_string(64)


def get_random_health_filename(instance, filename):
    return "authorization/health/" + get_random_string(64)


def get_random_vaccine_filename(instance, filename):
    return "authorization/vaccine/" + get_random_string(64)


def get_random_parental_filename(instance, filename):
    return "authorization/parental/" + get_random_string(64)


class ParticipantRegistration(Registration):
    team = models.ForeignKey(
        "participation.Team",
        related_name="participants",
        on_delete=models.PROTECT,
        blank=True,
        null=True,
        default=None,
        verbose_name=_("team"),
    )

    gender = models.CharField(
        max_length=6,
        verbose_name=_("gender"),
        choices=[
            ("female", _("Female")),
            ("male", _("Male")),
            ("other", _("Other")),
        ],
        default="other",
    )

    address = models.CharField(
        max_length=255,
        verbose_name=_("address"),
    )

    zip_code = models.PositiveIntegerField(
        verbose_name=_("zip code"),
        validators=[MinValueValidator(1000), MaxValueValidator(99999)],
    )

    city = models.CharField(
        max_length=255,
        verbose_name=_("city"),
    )

    phone_number = PhoneNumberField(
        verbose_name=_("phone number"),
        blank=True,
    )

    health_issues = models.TextField(
        verbose_name=_("health issues"),
        blank=True,
        help_text=_("You can indicate here your allergies or anything that is important to know for organizers."),
    )

    housing_constraints = models.TextField(
        verbose_name=_("housing constraints"),
        blank=True,
        help_text=_("You can fill in something here if you have any housing constraints, "
                    "e.g. medical problems, scheduling issues, gender issues, "
                    "or anything else you feel is relevant to the organizers. "
                    "Leave empty if you have nothing specific to declare."),
    )

    photo_authorization = models.FileField(
        verbose_name=_("photo authorization"),
        upload_to=get_random_photo_filename,
        blank=True,
        default="",
    )

    photo_authorization_final = models.FileField(
        verbose_name=_("photo authorization (final)"),
        upload_to=get_random_photo_filename,
        blank=True,
        default="",
    )

    @property
    def under_18(self):
        if isinstance(self, CoachRegistration):
            return False  # In normal case
        important_date = localtime(timezone.now()).date()
        if self.team and self.team.participation.tournament:
            important_date = self.team.participation.tournament.date_start
        over_18_on = self.birth_date.replace(year=self.birth_date.year + 18)
        return important_date < over_18_on

    @property
    def under_18_final(self):
        if isinstance(self, CoachRegistration):
            return False  # In normal case
        from participation.models import Tournament
        important_date = Tournament.final_tournament().date_start
        over_18_on = self.birth_date.replace(year=self.birth_date.year + 18)
        return important_date < over_18_on

    @property
    def type(self):  # pragma: no cover
        raise NotImplementedError

    @property
    def form_class(self):  # pragma: no cover
        raise NotImplementedError

    def registration_informations(self):
        informations = []
        if not self.team:
            text = _("You are not in a team. You can <a href=\"{create_url}\">create one</a> "
                     "or <a href=\"{join_url}\">join an existing one</a> to participate.")
            create_url = reverse_lazy("participation:create_team")
            join_url = reverse_lazy("participation:join_team")
            content = format_lazy(text, create_url=create_url, join_url=join_url)
            informations.append({
                'title': _("No team"),
                'type': "danger",
                'priority': 1,
                'content': content,
            })
        else:
            if self.team.participation.tournament:
                if not self.photo_authorization:
                    text = _("You have not uploaded your photo authorization. "
                             "You can do it by clicking on <a href=\"{photo_url}\">this link</a>.")
                    photo_url = reverse_lazy("registration:upload_user_photo_authorization", args=(self.id,))
                    content = format_lazy(text, photo_url=photo_url)
                    informations.append({
                        'title': _("Photo authorization"),
                        'type': "danger",
                        'priority': 5,
                        'content': content,
                    })

                if self.team.participation.final:
                    if not self.photo_authorization_final:
                        text = _("You have not uploaded your photo authorization for the final tournament. "
                                 "You can do it by clicking on <a href=\"{photo_url}\">this link</a>.")
                        photo_url = reverse_lazy("registration:upload_user_photo_authorization_final", args=(self.id,))
                        content = format_lazy(text, photo_url=photo_url)
                        informations.append({
                            'title': _("Photo authorization"),
                            'type': "danger",
                            'priority': 5,
                            'content': content,
                        })

            informations.extend(self.team.important_informations())

        return informations

    def send_email_final_selection(self):
        """
        The team is selected for final.
        """
        translation.activate('fr')
        subject = "[TFJM²] " + str(_("Team selected for the final tournament"))
        site = Site.objects.first()
        from participation.models import Tournament
        tournament = Tournament.final_tournament()
        payment = self.payments.filter(final=True).first() if self.is_student else None
        message = loader.render_to_string('registration/mails/final_selection.txt',
                                          {
                                              'user': self.user,
                                              'domain': site.domain,
                                              'tournament': tournament,
                                              'payment': payment,
                                          })
        html = loader.render_to_string('registration/mails/final_selection.html',
                                       {
                                           'user': self.user,
                                           'domain': site.domain,
                                           'tournament': tournament,
                                           'payment': payment,
                                       })
        self.user.email_user(subject, message, html_message=html)

    class Meta:
        verbose_name = _("participant registration")
        verbose_name_plural = _("participant registrations")


class StudentRegistration(ParticipantRegistration):
    """
    Specific registration for students.
    They have a team, a student class and a school.
    """
    birth_date = models.DateField(
        verbose_name=_("birth date"),
        default=date.today,
    )

    student_class = models.IntegerField(
        choices=[
            (12, _("12th grade")),
            (11, _("11th grade")),
            (10, _("10th grade or lower")),
        ],
        verbose_name=_("student class"),
    )

    school = models.CharField(
        max_length=255,
        verbose_name=_("school"),
    )

    responsible_name = models.CharField(
        max_length=255,
        verbose_name=_("responsible name"),
        default="",
    )

    responsible_phone = PhoneNumberField(
        verbose_name=_("responsible phone number"),
        default="",
    )

    responsible_email = models.EmailField(
        verbose_name=_("responsible email address"),
        default="",
    )

    parental_authorization = models.FileField(
        verbose_name=_("parental authorization"),
        upload_to=get_random_parental_filename,
        blank=True,
        default="",
    )

    parental_authorization_final = models.FileField(
        verbose_name=_("parental authorization (final)"),
        upload_to=get_random_parental_filename,
        blank=True,
        default="",
    )

    health_sheet = models.FileField(
        verbose_name=_("health sheet"),
        upload_to=get_random_health_filename,
        blank=True,
        default="",
    )

    vaccine_sheet = models.FileField(
        verbose_name=_("vaccine sheet"),
        upload_to=get_random_vaccine_filename,
        blank=True,
        default="",
    )

    @property
    def type(self):
        return _("student")

    @property
    def form_class(self):
        from registration.forms import StudentRegistrationForm
        return StudentRegistrationForm

    def registration_informations(self):
        informations = super().registration_informations()
        if self.team and self.team.participation.tournament and self.under_18:
            if not self.parental_authorization:
                text = _("You have not uploaded your parental authorization. "
                         "You can do it by clicking on <a href=\"{parental_url}\">this link</a>.")
                parental_url = reverse_lazy("registration:upload_user_parental_authorization", args=(self.id,))
                content = format_lazy(text, parental_url=parental_url)
                informations.append({
                    'title': _("Parental authorization"),
                    'type': "danger",
                    'priority': 5,
                    'content': content,
                })
            if not self.health_sheet:
                text = _("You have not uploaded your health sheet. "
                         "You can do it by clicking on <a href=\"{health_url}\">this link</a>.")
                health_url = reverse_lazy("registration:upload_user_health_sheet", args=(self.id,))
                content = format_lazy(text, health_url=health_url)
                informations.append({
                    'title': _("Health sheet"),
                    'type': "danger",
                    'priority': 5,
                    'content': content,
                })
            if not self.vaccine_sheet:
                text = _("You have not uploaded your vaccine sheet. "
                         "You can do it by clicking on <a href=\"{vaccine_url}\">this link</a>.")
                vaccine_url = reverse_lazy("registration:upload_user_vaccine_sheet", args=(self.id,))
                content = format_lazy(text, vaccine_url=vaccine_url)
                informations.append({
                    'title': _("Vaccine sheet"),
                    'type': "danger",
                    'priority': 5,
                    'content': content,
                })

        if self.team and self.team.participation.valid:
            for payment in self.payments.all():
                if payment.valid is False:
                    text = _("You have to pay {amount} € for your registration, or send a scholarship "
                             "notification or a payment proof. "
                             "You can do it on <a href=\"{url}\">the payment page</a>.")
                    url = reverse_lazy("registration:update_payment", args=(payment.id,))
                    content = format_lazy(text, amount=payment.amount, url=url)
                    informations.append({
                        'title': _("Payment"),
                        'type': "danger",
                        'priority': 3,
                        'content': content,
                    })
                elif payment.valid is None:
                    text = _("Your payment is under approval.")
                    content = text
                    informations.append({
                        'title': _("Payment"),
                        'type': "warning",
                        'priority': 3,
                        'content': content,
                    })

            if self.team.participation.final:
                if self.under_18_final and not self.parental_authorization_final:
                    text = _("You have not uploaded your parental authorization for the final tournament. "
                             "You can do it by clicking on <a href=\"{parental_url}\">this link</a>.")
                    parental_url = reverse_lazy("registration:upload_user_parental_authorization_final",
                                                args=(self.id,))
                    content = format_lazy(text, parental_url=parental_url)
                    informations.append({
                        'title': _("Parental authorization"),
                        'type': "danger",
                        'priority': 5,
                        'content': content,
                    })

        return informations

    class Meta:
        verbose_name = _("student registration")
        verbose_name_plural = _("student registrations")


class CoachRegistration(ParticipantRegistration):
    """
    Specific registration for coaches.
    They have a team and a professional activity.
    """
    last_degree = models.CharField(
        max_length=255,
        default="",
        verbose_name=_("most recent degree in mathematics, computer science or physics"),
        help_text=_("Your most recent degree in maths, computer science or physics, "
                    "or your last entrance exam (CAPES, Agrégation,…)"),
    )

    professional_activity = models.TextField(
        verbose_name=_("professional activity"),
    )

    @property
    def type(self):
        return _("coach")

    @property
    def form_class(self):
        from registration.forms import CoachRegistrationForm
        return CoachRegistrationForm

    class Meta:
        verbose_name = _("coach registration")
        verbose_name_plural = _("coach registrations")


class VolunteerRegistration(Registration):
    """
    Specific registration for organizers and juries.
    """
    professional_activity = models.TextField(
        verbose_name=_("professional activity"),
    )

    admin = models.BooleanField(
        verbose_name=_("administrator"),
        help_text=_("An administrator has all rights. Please don't give this right to all juries and volunteers."),
        default=False,
    )

    @property
    def interesting_tournaments(self) -> set:
        return set(self.organized_tournaments.all()).union(map(lambda pool: pool.tournament, self.jury_in.all()))

    @property
    def type(self):
        return _('admin') if self.is_admin else _('volunteer')

    @property
    def form_class(self):
        from registration.forms import VolunteerRegistrationForm
        return VolunteerRegistrationForm

    def important_informations(self):
        informations = []

        for tournament in self.organized_tournaments.all():
            if timezone.now() < tournament.inscription_limit \
                    or tournament.participations.filter(valid=True).count() < tournament.max_teams:
                text = _("Registrations for tournament {tournament} are closing on {date:%Y-%m-%d %H:%M}. "
                         "There are for now {validated_teams} validated teams (+ {pending_teams} pending) "
                         "on {max_teams} expected.")
                content = format_lazy(text, tournament=tournament.name, date=localtime(tournament.inscription_limit),
                                      validated_teams=tournament.participations.filter(valid=True).count(),
                                      pending_teams=tournament.participations.filter(valid=False).count(),
                                      max_teams=tournament.max_teams)
                informations.append({
                    'title': _("Registrations"),
                    'type': "info",
                    'priority': 2,
                    'content': content,
                })

            for pending_participation in tournament.participations.filter(valid=False).all():
                text = _("The team {trigram} requested to be validated for the tournament of {tournament}. "
                         "You can check the status of the team on the <a href=\"{url}\">team page</a>.")
                url = reverse_lazy("participation:team_detail", args=(pending_participation.team.id,))
                content = format_lazy(text, trigram=pending_participation.team.trigram,
                                      tournament=tournament.name, url=url)
                informations.append({
                    'title': _("Pending validation"),
                    'type': "warning",
                    'priority': 4,
                    'content': content,
                })

            payments = Payment.objects.filter(registrations__team__participation__tournament=tournament).all()
            valid = payments.filter(valid=True).count()
            pending = payments.filter(valid=None).count()
            invalid = payments.filter(valid=False).count()
            if pending + invalid > 0:
                text = _("There are {valid} validated payments, {pending} pending and {invalid} invalid for the "
                         "tournament of {tournament}. You can check the status of the payments on the "
                         "<a href=\"{url}\">payments list</a>.")
                url = reverse_lazy("participation:tournament_payments", args=(tournament.id,))
                content = format_lazy(text, valid=valid, pending=pending, invalid=invalid, tournament=tournament.name,
                                      url=url)
                informations.append({
                    'title': _("Payments"),
                    'type': "info",
                    'priority': 5,
                    'content': content,
                })

            if timezone.now() > tournament.solution_limit and timezone.now() < tournament.solutions_draw:
                text = _("<p>The draw of the solutions for the tournament {tournament} is planned on the "
                         "{date:%Y-%m-%d %H:%M}. You can join it on <a href='{url}'>this link</a>.</p>")
                url = reverse_lazy("draw:index")
                content = format_lazy(text, tournament=tournament.name,
                                      date=localtime(tournament.solutions_draw),
                                      url=url)
                informations.append({
                    'title': _("Draw of solutions"),
                    'type': "info",
                    'priority': 1,
                    'content': content,
                })

        for tournament in self.interesting_tournaments:
            pools = tournament.pools.filter(juries=self).order_by('round').all()
            for pool in pools:
                if pool.round == 1 and timezone.now().date() <= tournament.date_start:
                    text = _("<p>You are in the jury of the pool {pool} for the tournament of {tournament}. "
                             "You can find the pool page <a href='{pool_url}'>here</a>.</p>")
                    pool_url = reverse_lazy("participation:pool_detail", args=(pool.id,))
                    content = format_lazy(text, pool=pool.short_name, tournament=tournament.name, pool_url=pool_url)
                    informations.append({
                        'title': _("First round"),
                        'type': "info",
                        'priority': 1,
                        'content': content,
                    })
                elif pool.round == 2 and timezone.now().date() <= tournament.date_end:
                    text = _("<p>You are in the jury of the pool {pool} for the tournament of {tournament}. "
                             "You can find the pool page <a href='{pool_url}'>here</a>.</p>")
                    pool_url = reverse_lazy("participation:pool_detail", args=(pool.id,))
                    content = format_lazy(text, pool=pool.short_name, tournament=tournament.name, pool_url=pool_url)
                    informations.append({
                        'title': _("Second round"),
                        'type': "info",
                        'priority': 2,
                        'content': content,
                    })

                for note in self.notes.filter(passage__pool=pool).all():
                    if not note.has_any_note():
                        text = _("<p>You don't have given any note as a jury for the passage {passage} "
                                 "in the pool {pool} of {tournament}. "
                                 "You can set your notes <a href='{passage_url}'>here</a>.</p>")
                        passage_url = reverse_lazy("participation:passage_detail", args=(note.passage.id,))
                        content = format_lazy(text, passage=note.passage.position, pool=pool.short_name,
                                              tournament=tournament.name, passage_url=passage_url)
                        informations.append({
                            'title': _("Note"),
                            'type': "warning",
                            'priority': 3 + note.passage.position,
                            'content': content,
                        })

        return informations

    class Meta:
        verbose_name = _("volunteer registration")
        verbose_name_plural = _("volunteer registrations")


def get_receipt_filename(instance, filename):
    return f"authorization/receipt/receipt_{instance.id}"


def get_random_token():
    return get_random_string(32)


class Payment(models.Model):
    registrations = models.ManyToManyField(
        ParticipantRegistration,
        related_name="payments",
        verbose_name=_("registrations"),
    )

    grouped = models.BooleanField(
        verbose_name=_("grouped"),
        default=False,
        help_text=_("If set to true, then one payment is made for the full team, "
                    "for example if the school pays for all."),
    )

    amount = models.PositiveSmallIntegerField(
        verbose_name=_("total amount"),
        help_text=_("Corresponds to the total required amount to pay, in euros."),
        default=0,
    )

    token = models.CharField(
        verbose_name=_("token"),
        max_length=32,
        default=get_random_token,
        help_text=_("A token to authorize external users to make this payment."),
    )

    final = models.BooleanField(
        verbose_name=_("for final tournament"),
        default=False,
    )

    type = models.CharField(
        verbose_name=_("type"),
        max_length=16,
        choices=[
            ('', _("No payment")),
            ('helloasso', _("Credit card")),
            ('scholarship', _("Scholarship")),
            ('bank_transfer', _("Bank transfer")),
            ('other', _("Other (please indicate)")),
            ('free', _("The tournament is free")),
        ],
        blank=True,
        default="",
    )

    checkout_intent_id = models.IntegerField(
        verbose_name=_("Hello Asso checkout intent ID"),
        blank=True,
        null=True,
        default=None,
    )

    receipt = models.FileField(
        verbose_name=_("receipt"),
        help_text=_("only if you have a scholarship or if you chose a bank transfer."),
        upload_to=get_receipt_filename,
        blank=True,
        default="",
    )

    additional_information = models.TextField(
        verbose_name=_("additional information"),
        help_text=_("To help us to find your payment."),
        blank=True,
        default="",
    )

    valid = models.BooleanField(
        verbose_name=_("payment valid"),
        null=True,
        default=False,
    )

    @property
    def team(self):
        return self.registrations.first().team
    team.fget.short_description = _("team")
    team.fget.admin_order_field = 'registrations__team__trigram'

    @property
    def tournament(self):
        if self.final:
            from participation.models import Tournament
            return Tournament.final_tournament()
        return self.registrations.first().team.participation.tournament
    tournament.fget.short_description = _("tournament")
    tournament.fget.admin_order_field = 'registrations__team__participation__tournament'

    def get_checkout_intent(self, none_if_link_disabled=False):
        if self.checkout_intent_id is None:
            return None
        return helloasso.get_checkout_intent(self.checkout_intent_id, none_if_link_disabled=none_if_link_disabled)

    def create_checkout_intent(self):
        checkout_intent = self.get_checkout_intent(none_if_link_disabled=True)
        if checkout_intent is not None:
            return checkout_intent

        tournament = self.tournament
        year = datetime.now().year
        base_site = "https://" + Site.objects.first().domain
        checkout_intent = helloasso.create_checkout_intent(
            amount=100 * self.amount,
            name=f"Participation au TFJM² {year} - {tournament.name} - {self.team.trigram}",
            back_url=base_site + reverse('registration:update_payment', args=(self.id,)),
            error_url=f"{base_site}{reverse('registration:payment_hello_asso_return', args=(self.id,))}?type=error",
            return_url=f"{base_site}{reverse('registration:payment_hello_asso_return', args=(self.id,))}?type=return",
            contains_donation=False,
            metadata=dict(
                users=[
                    dict(user_id=registration.user.id,
                         first_name=registration.user.first_name,
                         last_name=registration.user.last_name,
                         email=registration.user.email,)
                    for registration in self.registrations.all()
                ],
                payment_id=self.id,
                final=self.final,
                tournament_id=tournament.id,
            )
        )
        self.checkout_intent_id = checkout_intent["id"]
        self.save()

        return checkout_intent

    def send_remind_mail(self):
        translation.activate('fr')
        subject = "[TFJM²] " + str(_("Reminder for your payment"))
        site = Site.objects.first()
        for registration in self.registrations.all():
            message = loader.render_to_string('registration/mails/payment_reminder.txt',
                                              dict(registration=registration, payment=self, domain=site.domain))
            html = loader.render_to_string('registration/mails/payment_reminder.html',
                                           dict(registration=registration, payment=self, domain=site.domain))
            registration.user.email_user(subject, message, html_message=html)

    def send_helloasso_payment_confirmation_mail(self):
        translation.activate('fr')
        subject = "[TFJM²] " + str(_("Payment confirmation"))
        site = Site.objects.first()
        for registration in self.registrations.all():
            message = loader.render_to_string('registration/mails/payment_confirmation.txt',
                                              dict(registration=registration, payment=self, domain=site.domain))
            html = loader.render_to_string('registration/mails/payment_confirmation.html',
                                           dict(registration=registration, payment=self, domain=site.domain))
            registration.user.email_user(subject, message, html_message=html)

        payer = self.get_checkout_intent()['order']['payer']
        payer_name = f"{payer['firstName']} {payer['lastName']}"
        if not self.registrations.filter(user__email=payer['email']).exists():
            message = loader.render_to_string('registration/mails/payment_confirmation.txt',
                                              dict(registration=payer_name, payment=self, domain=site.domain))
            html = loader.render_to_string('registration/mails/payment_confirmation.html',
                                           dict(registration=payer_name, payment=self, domain=site.domain))
            send_mail(subject, message, None, [payer['email']], html_message=html)

    def get_absolute_url(self):
        return reverse_lazy("registration:update_payment", args=(self.pk,))

    def __str__(self):
        return _("Payment of {registrations}").format(registrations=", ".join(map(str, self.registrations.all())))

    class Meta:
        verbose_name = _("payment")
        verbose_name_plural = _("payments")