# Copyright (C) 2018-2020 by BDE ENS Paris-Saclay
# SPDX-License-Identifier: GPL-3.0-or-later
from django.core.exceptions import ValidationError
from django.db import models, transaction
from django.urls import reverse
from django.utils import timezone
from django.utils.translation import gettext_lazy as _
from polymorphic.models import PolymorphicModel
from .notes import Note, NoteClub, NoteSpecial
from ..templatetags.pretty_money import pretty_money
"""
Defines transactions
"""
class TemplateCategory(models.Model):
"""
Defined a recurrent transaction category
Example: food, softs, ...
"""
name = models.CharField(
verbose_name=_("name"),
max_length=31,
unique=True,
)
class Meta:
verbose_name = _("transaction category")
verbose_name_plural = _("transaction categories")
def __str__(self):
return str(self.name)
class TransactionTemplate(models.Model):
"""
Defined a recurrent transaction
associated to selling something (a burger, a beer, ...)
"""
name = models.CharField(
verbose_name=_('name'),
max_length=255,
unique=True,
error_messages={'unique': _("A template with this name already exist")},
)
destination = models.ForeignKey(
NoteClub,
on_delete=models.PROTECT,
related_name='+', # no reverse
verbose_name=_('destination'),
)
amount = models.PositiveIntegerField(
verbose_name=_('amount'),
)
category = models.ForeignKey(
TemplateCategory,
on_delete=models.PROTECT,
related_name='templates',
verbose_name=_('type'),
max_length=31,
)
display = models.BooleanField(
default=True,
verbose_name=_("display"),
)
highlighted = models.BooleanField(
default=False,
verbose_name=_("highlighted"),
)
description = models.CharField(
verbose_name=_('description'),
max_length=255,
blank=True,
)
class Meta:
verbose_name = _("transaction template")
verbose_name_plural = _("transaction templates")
def get_absolute_url(self):
return reverse('note:template_update', args=(self.pk,))
class Transaction(PolymorphicModel):
"""
General transaction between two :model:`note.Note`
amount is store in centimes of currency, making it a positive integer
value. (from someone to someone else)
"""
source = models.ForeignKey(
Note,
on_delete=models.PROTECT,
related_name='+',
verbose_name=_('source'),
)
source_alias = models.CharField(
max_length=255,
default="", # Will be remplaced by the name of the note on save
verbose_name=_('used alias'),
)
destination = models.ForeignKey(
Note,
on_delete=models.PROTECT,
related_name='+',
verbose_name=_('destination'),
)
destination_alias = models.CharField(
max_length=255,
default="", # Will be remplaced by the name of the note on save
verbose_name=_('used alias'),
)
created_at = models.DateTimeField(
verbose_name=_('created at'),
default=timezone.now,
)
quantity = models.PositiveIntegerField(
verbose_name=_('quantity'),
default=1,
)
amount = models.PositiveIntegerField(
verbose_name=_('amount'),
)
reason = models.CharField(
verbose_name=_('reason'),
max_length=255,
)
valid = models.BooleanField(
verbose_name=_('valid'),
default=True,
)
invalidity_reason = models.CharField(
verbose_name=_('invalidity reason'),
max_length=255,
default=None,
null=True,
blank=True,
)
class Meta:
verbose_name = _("transaction")
verbose_name_plural = _("transactions")
indexes = [
models.Index(fields=['created_at']),
models.Index(fields=['source']),
models.Index(fields=['destination']),
]
def validate(self):
previous_source_balance = self.source.balance
previous_dest_balance = self.destination.balance
source_balance = self.source.balance
dest_balance = self.destination.balance
created = self.pk is None
to_transfer = self.amount * self.quantity
if not created:
# Revert old transaction
old_transaction = Transaction.objects.get(pk=self.pk)
# Check that nothing important changed
for field_name in ["source_id", "destination_id", "quantity", "amount"]:
if getattr(self, field_name) != getattr(old_transaction, field_name):
raise ValidationError(_("You can't update the {field} on a Transaction. "
"Please invalidate it and create one other.").format(field=field_name))
if old_transaction.valid == self.valid:
# Don't change anything
return 0, 0
if old_transaction.valid:
source_balance += to_transfer
dest_balance -= to_transfer
if self.valid:
source_balance -= to_transfer
dest_balance += to_transfer
# When a transaction is declared valid, we ensure that the invalidity reason is null, if it was
# previously invalid
self.invalidity_reason = None
if source_balance > 9223372036854775807 or source_balance < -9223372036854775808\
or dest_balance > 9223372036854775807 or dest_balance < -9223372036854775808:
raise ValidationError(_("The note balances must be between - 92 233 720 368 547 758.08 € "
"and 92 233 720 368 547 758.07 €."))
return source_balance - previous_source_balance, dest_balance - previous_dest_balance
@transaction.atomic
def save(self, *args, **kwargs):
"""
When saving, also transfer money between two notes
"""
if self.source.pk == self.destination.pk:
# When source == destination, no money is transferred and no transaction is created
return
# We refresh the notes with the "select for update" tag to avoid concurrency issues
self.source = Note.objects.filter(pk=self.source_id).select_for_update().get()
self.destination = Note.objects.filter(pk=self.destination_id).select_for_update().get()
# Check that the amounts stay between big integer bounds
diff_source, diff_dest = self.validate()
if not self.source.is_active or not self.destination.is_active:
raise ValidationError(_("The transaction can't be saved since the source note "
"or the destination note is not active."))
# If the aliases are not entered, we assume that the used alias is the name of the note
if not self.source_alias:
self.source_alias = str(self.source)
if not self.destination_alias:
self.destination_alias = str(self.destination)
# We save first the transaction, in case of the user has no right to transfer money
super().save(*args, **kwargs)
# Save notes
self.source.balance += diff_source
self.source._force_save = True
self.source.save()
self.destination.balance += diff_dest
self.destination._force_save = True
self.destination.save()
def delete(self, **kwargs):
"""
Whenever we want to delete a transaction (caution with this), we ensure the transaction is invalid first.
"""
self.valid = False
self.save(**kwargs)
super().delete(**kwargs)
@property
def total(self):
return self.amount * self.quantity
@property
def type(self):
return _('Transfer')
def __str__(self):
return self.__class__.__name__ + " from " + str(self.source) + " to " + str(self.destination) + " of "\
+ pretty_money(self.quantity * self.amount) + ("" if self.valid else " invalid")
class RecurrentTransaction(Transaction):
"""
Special type of :model:`note.Transaction` associated to a :model:`note.TransactionTemplate`.
"""
template = models.ForeignKey(
TransactionTemplate,
on_delete=models.PROTECT,
)
category = models.ForeignKey(
TemplateCategory,
on_delete=models.PROTECT,
)
@property
def type(self):
return _('Template')
class Meta:
verbose_name = _("recurrent transaction")
verbose_name_plural = _("recurrent transactions")
class SpecialTransaction(Transaction):
"""
Special type of :model:`note.Transaction` associated to transactions with special notes
"""
last_name = models.CharField(
max_length=255,
verbose_name=_("name"),
)
first_name = models.CharField(
max_length=255,
verbose_name=_("first_name"),
)
bank = models.CharField(
max_length=255,
verbose_name=_("bank"),
blank=True,
)
@property
def type(self):
return _('Credit') if isinstance(self.source, NoteSpecial) else _("Debit")
def is_credit(self):
return isinstance(self.source, NoteSpecial)
def is_debit(self):
return isinstance(self.destination, NoteSpecial)
def clean(self):
# SpecialTransaction are only possible with NoteSpecial object
if self.is_credit() == self.is_debit():
raise(ValidationError(_("A special transaction is only possible between a"
" Note associated to a payment method and a User or a Club")))
class Meta:
verbose_name = _("Special transaction")
verbose_name_plural = _("Special transactions")
class MembershipTransaction(Transaction):
"""
Special type of :model:`note.Transaction` associated to a :model:`member.Membership`.
"""
membership = models.OneToOneField(
'member.Membership',
on_delete=models.PROTECT,
related_name='transaction',
)
class Meta:
verbose_name = _("membership transaction")
verbose_name_plural = _("membership transactions")
@property
def type(self):
return _('membership transaction')