from django.db import models
from django.core.validators import MinValueValidator, MaxValueValidator
from django.core.exceptions import ValidationError
from django.urls import reverse


class CurrentPaymentManager(models.Manager):
    def get_queryset(self):
        qs = super().get_queryset()
        qs = qs.annotate(
                payment_method=models.Subquery(
                                PaymentUpdate.objects.filter(payment=models.OuterRef('pk'), validated=True)
                                                     .values('payment_method')[:1]
                )
        )
        qs = qs.annotate(
                active=models.Case(
                            models.When(payment_method__isnull=True, then=None),
                            models.When(payment_method=PaymentUpdate.STOP, then=False),
                            default=True,
                            output_field=models.NullBooleanField()
                )
        )
        return qs


class RecurringPayment(models.Model):
    objects = CurrentPaymentManager()

    @property
    def debtor(self):
        if hasattr(self, 'adhesion'):
            return self.adhesion
        if hasattr(self, 'service'):
            return self.service.adhesion

    def payment_type(self):
        if hasattr(self, 'adhesion'):
            return 'Adhésion'
        if hasattr(self, 'service'):
            return 'Service'
    payment_type.short_description = 'Type'

    def payment_object(self):
        return self.adhesion if hasattr(self, 'adhesion') else self.service

    def get_absolute_url(self):
        return reverse('admin:%s_%s_change' % (self._meta.app_label, self._meta.model_name), args=(self.pk,))

    def get_current_payment(self):
        return self.updates.filter(validated=True).first()

    def get_current_payment_display(self):
        current = self.get_current_payment()
        if current:
            return str(current)
        else:
            return 'non renseignée'

    class Meta:
        verbose_name = 'paiement récurrent'
        verbose_name_plural = 'paiements récurrents'

    def __str__(self):
        if hasattr(self, 'adhesion'):
            return "Cotisation %s" % self.adhesion
        else:
            return "Contribution %s" % self.service


class PaymentUpdate(models.Model):
    STOP = 0
    FREE = 1
    DEBIT = 2
    TRANSFER = 3
    CASH = 4
    INVOICE = 5
    PAYMENT_CHOICES = (
        (DEBIT, 'Prélèvement'),
        (TRANSFER, 'Virement'),
        (CASH, 'Liquide'),
        (INVOICE, 'Facture'),
        (FREE, 'Gratuit'),
        (STOP, 'Arrêt'),
    )
    created = models.DateTimeField(auto_now_add=True)
    payment = models.ForeignKey(RecurringPayment, related_name='updates', on_delete=models.CASCADE)
    amount = models.DecimalField(max_digits=9, decimal_places=2, verbose_name='Montant')
    period = models.PositiveIntegerField(validators=[MinValueValidator(1), MaxValueValidator(12)],
                                         verbose_name='Période (mois)')
    payment_method = models.IntegerField(choices=PAYMENT_CHOICES, default=DEBIT,
                                         verbose_name='Méthode de paiement')
    start = models.DateTimeField(verbose_name='Date')
    month_day = models.PositiveIntegerField(validators=[MinValueValidator(1), MaxValueValidator(25)],
                                            verbose_name='Jour souhaité de prélèvement',
                                            null=True, blank=True)
    validated = models.BooleanField(default=False, verbose_name='Saisie bancaire effectuée')

    class Meta:
        verbose_name = 'paiement'
        ordering = ('-start',)

    def clean(self):
        super().clean()
        errors = {}
        if self.payment_method == PaymentUpdate.STOP and self.amount:
            errors.update({'amount': "Pour l’arrêt d’un paiement, le montant doit être nul."})
        if errors:
            raise ValidationError(errors)

    def period_verbose(self):
        if self.period == 0:
            return 'non récurrent'
        elif self.period == 1:
            return 'mensuel'
        elif self.period == 3:
            return 'trimestriel'
        elif self.period == 6:
            return 'biannuel'
        elif self.period == 12:
            return 'annuel'
        else:
            return '%d mois' % self.period

    def __str__(self):
        if self.payment_method == self.STOP:
            return 'paiement arrêté'
        if self.payment_method == self.FREE:
            return 'libre'
        s = str(self.amount) + '€'
        if self.period:
            if self.period == 1:
                s += '/mois'
            elif self.period == 12:
                s += '/an'
            else:
                s += '/%d mois' % self.period
        if self.payment_method == self.DEBIT:
            s += ' (prélèvement)'
        elif self.payment_method == self.TRANSFER:
            s += ' (virement)'
        elif self.payment_method == self.CASH:
            s += ' (liquide)'
        elif self.payment_method == self.INVOICE:
            s += ' (sur facture)'
        return s