from django.db import models
from django.contrib.contenttypes.fields import GenericForeignKey
from django.contrib.contenttypes.models import ContentType
from django.core.validators import MaxValueValidator
from django.core.urlresolvers import reverse
from django.core.exceptions import ValidationError
from django.urls import reverse
from django.core.exceptions import PermissionDenied
from django.utils import timezone

from djadhere.utils import is_overlapping, get_active_filter


class Payment(models.Model):
    TRANSFERT = 0
    WITHDRAWAL = 1
    PAYMENT_CHOICES = (
        (TRANSFERT, 'Virement'),
        (WITHDRAWAL, 'Prélèvement'),
    )
    ADHESION = 0
    SERVICE = 1
    limit = models.Q(app_label='adhesions', model='adhesion') \
        | models.Q(app_label='services', model='service')
    reason_type = models.ForeignKey(ContentType, on_delete=models.CASCADE,
                                    limit_choices_to=limit)
    reason_id = models.PositiveIntegerField()
    reason = GenericForeignKey('reason_type', 'reason_id')
    amount = models.DecimalField(max_digits=9, decimal_places=2, verbose_name='Montant')
    period = models.PositiveIntegerField(validators=[MaxValueValidator(12)],
                                         verbose_name='Période (mois) (0 si non récurrent)')
    payment_method = models.IntegerField(choices=PAYMENT_CHOICES,
                                         verbose_name='Méthode de paiement')
    start = models.DateField(verbose_name='Date de paiement ou de début de paiement')
    end = models.DateField(null=True, blank=True, verbose_name='Date de fin de paiement (si récurrent)')
    validated = models.BooleanField(default=False, verbose_name='Paiement validé')

    class Meta:
        verbose_name = 'paiement'
        permissions = (
            ('validate_payment', 'Peut valider les paiements'),
        )

    @property
    def active(self):
        # Contrairement aux allocations d’IP, un paiement est considéré actif même s’il commence dans le futur
        # Seul les paiements récurrents peuvent être actifs
        if self.period == 0:
            return None
        today = timezone.localtime(timezone.now()).date()
        return self.end is None or (self.start <= today and self.end > today)

    @property
    def type(self):
        if self.reason_type.app_label == 'adhesions' \
                and self.reason_type.model == 'adhesion':
            return Payment.ADHESION
        if self.reason_type.app_label == 'services' \
                and self.reason_type.model == 'service':
            return Payment.SERVICE

    def type_verbose(self):
        if self.type == Payment.ADHESION:
            return 'Cotisation'
        if self.type == Payment.SERVICE:
            return 'Service'
    type_verbose.short_description = 'Type'

    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

    # FIXME
    @property
    def adherent(self):
        return self.get_adhesion().adherent

    def get_adhesion(self):
        if self.reason_type.app_label == 'adhesions' \
                and self.reason_type.model == 'adhesion':
            return self.reason
        if self.reason_type.app_label == 'services' \
                and self.reason_type.model == 'service':
            return self.reason.adhesion
    get_adhesion.short_description = 'Adhésion'

    # Penser à appele la méthode save !
    def stop(self):
        if not self.active:
            raise PermissionDenied
        today = timezone.localtime(timezone.now()).date()
        self.end = max(self.start, today)

    def clean(self):
        super().clean()
        # S’il s’agit d’un paiement non récurrent, le champ end doit rester blanc
        if self.period == 0 and self.end:
            raise ValidationError({'end': "Un paiement non récurrent ne doit pas avoir de date de fin."})
        # Vérification de la cohérence des champs start et end
        if self.end and self.start > self.end:
            raise ValidationError("La date de début de paiement doit être antérieur à la date de fin de paiement.")
        # Vérification de l’absence de chevauchement avec une période existante
        # FIXME ne fonctionne pas vraiment via les inlines…
        if self.reason:
            payments = Payment.objects.filter(reason_type=self.reason_type, reason_id=self.reason_id)
            if is_overlapping(self, payments):
                raise ValidationError("Les périodes de paiement ne doivent pas se chevaucher.")

    def get_absolute_url(self):
        return reverse('payment-detail', kwargs={'pk': self.pk})

    def __str__(self):
        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.TRANSFERT:
            s += ' (virement)'
        elif self.payment_method == self.WITHDRAWAL:
            s += ' (prélèvement)'
        return s