import os
from django.db import models
from django.dispatch import receiver
from django.urls import reverse

from .fields import ChoiceArrayField


class Ingredient(models.Model):
    nom = models.CharField("Nom", max_length=200)

    class Meta:
        ordering = ('nom',)

    def __str__(self):
        return self.nom


class Unite(models.Model):
    nom = models.CharField("Unité", max_length=200)

    def __str__(self):
        return self.nom


class Recette(models.Model):
    SAISON_CHOICES = (
        ('printemps', 'Printemps'),
        ('été', 'Été'),
        ('automne', 'Automne'),
        ('hiver', 'Hiver'),
    )
    nom = models.CharField("Nom", max_length=200)
    photo = models.ImageField("Photo", upload_to='photos', blank=True)
    photo_instr = models.ImageField("Photo des instructions", upload_to='photos', blank=True)
    nb_pers = models.IntegerField(default=4)
    saison = ChoiceArrayField(
        models.CharField(max_length=10, choices=SAISON_CHOICES, blank=True),
        verbose_name="Saison",
    )
    is_veget = models.BooleanField("Mets végétarien", default=False)
    is_dessert = models.BooleanField("Dessert", default=False)
    prep = models.TextField("Préparation", blank=True)
    source = models.CharField("Source", max_length=200, blank=True)
    ingredients = models.ManyToManyField(Ingredient, through='Composition', blank=True)

    class Meta:
        ordering = ('nom',)

    def __str__(self):
        return self.nom

    def get_absolute_url(self):
        return reverse('recette', args=[self.pk])


class Composition(models.Model):
    recette = models.ForeignKey(Recette, on_delete=models.CASCADE)
    ingredient = models.ForeignKey(Ingredient, on_delete=models.PROTECT)
    quantite = models.DecimalField(max_digits=6, decimal_places=3, null=True, blank=True)
    unite = models.ForeignKey(Unite, null=True, blank=True, on_delete=models.PROTECT)

    def __str__(self):
        return "%s %s %s" % (
            self.quantite_formatted or '', self.unite.nom if self.unite else '', self.ingredient.nom
        )

    @property
    def quantite_formatted(self):
        if self.quantite is None:
            return ''
        return str(self.quantite).rstrip('0').rstrip('.')


@receiver(models.signals.post_delete, sender=Recette)
def auto_delete_photo_on_delete(sender, instance, **kwargs):
    """
    Delete file from filesystem
    when corresponding `Recette` object is deleted.
    """
    if instance.photo:
        if os.path.isfile(instance.photo.path):
            os.remove(instance.photo.path)


@receiver(models.signals.pre_save, sender=Recette)
def auto_delete_photo_on_change(sender, instance, **kwargs):
    """
    Delete old file from filesystem
    when corresponding `Recette` object is updated
    with new file.
    """
    if not instance.pk:
        return False

    try:
        old_file = Recette.objects.get(pk=instance.pk).photo
    except Recette.DoesNotExist:
        return False

    if old_file and old_file != instance.photo and os.path.isfile(old_file.path):
        os.remove(old_file.path)