from django.core.exceptions import ValidationError
from django.db import models
from django.urls import reverse
from django.utils import timezone

from la_chariotte.settings import AUTH_USER_MODEL


class GroupedOrder(models.Model):
    name = models.CharField(
        max_length=100, null=True, verbose_name="Titre de la commande"
    )
    orga = models.ForeignKey(
        AUTH_USER_MODEL, on_delete=models.CASCADE, verbose_name="Organisateur·ice"
    )
    delivery_date = models.DateField("Date de livraison")
    deadline = models.DateTimeField("Date limite de commande")
    place = models.CharField(
        max_length=100, null=True, blank=True, verbose_name="Lieu de livraison"
    )
    description = models.TextField("Description", null=True, blank=True)
    total_price = models.DecimalField(max_digits=10, decimal_places=2, default=0)

    def compute_total_price(self):
        price = 0
        for order in self.order_set.all():
            price += order.price
        self.total_price = price
        self.save()

    def compute_items_ordered_nb(self):
        """Updates the ordered_nb of all items fo the grouped_order"""
        for item in self.item_set.all():
            item.compute_ordered_nb()

    def is_ongoing(self):
        """Returns True if the grouped order is open for new Orders - False if it's too late"""
        return self.deadline >= timezone.now()

    def is_to_be_delivered(self):
        """Returns True if the grouped order has not been delivered yet - False if it's old"""
        return self.delivery_date >= timezone.now().date()

    def get_absolute_url(self):
        return reverse("order:manage_items", kwargs={"pk": self.pk})

    def clean_fields(self, exclude=None):
        super().clean_fields(exclude=exclude)
        if self.delivery_date < timezone.now().date() and not self.pk:
            # if the grouped order is being created (not updated), it cannot be in the past
            # if we are updating, it's ok
            raise ValidationError("La date de livraison ne doit pas être dans le passé")

        if self.delivery_date < self.deadline.date():
            raise ValidationError(
                "La date limite de commande doit être avant la date de livraison"
            )

    def __str__(self):  # pragma: no cover
        return (
            self.name
            if self.name
            else f"Commande groupée {self.pk} du {self.date} organisée par {self.orga}"
        )


class OrderAuthor(models.Model):
    """Created when a user orders without having an account - or when a user creates an account"""

    # TODO faire le lien avec CustomUser (CustomUser hérite de OrderAuthor), pour ensuite préremplir quand on est connecté·e
    first_name = models.CharField(verbose_name="Prénom")
    last_name = models.CharField(verbose_name="Nom")
    phone = models.CharField(
        verbose_name="Numéro de téléphone",
        help_text="Pour que l'organisateur·ice vous contacte en cas de besoin",
    )
    email = models.CharField(
        verbose_name="Adresse mail",
        help_text="Pour que l'organisateur·ice vous contacte en cas de besoin",
    )

    def __str__(self):  # pragma: no cover
        return f"{self.first_name} {self.last_name}"


class Order(models.Model):
    grouped_order = models.ForeignKey(
        GroupedOrder, on_delete=models.CASCADE, related_name="order_set"
    )
    author = models.ForeignKey(OrderAuthor, on_delete=models.CASCADE)
    articles_nb = models.PositiveIntegerField(default=0)
    price = models.DecimalField(max_digits=10, decimal_places=2, default=0)
    created_date = models.DateTimeField("Date de la commande", auto_now_add=True)
    note = models.TextField(max_length=200, null=True, blank=True)

    def compute_order_articles_nb(self):
        """Computes the number of articles in this order"""
        articles_nb = 0
        for ord_item in self.ordered_items.all():
            articles_nb += ord_item.nb
        self.articles_nb = articles_nb
        self.save()

    def compute_order_price(self):
        """Computes the total price of the order"""
        price = 0
        for ord_item in self.ordered_items.all():
            price += ord_item.get_price()
        self.price = price
        self.save()

    def __str__(self):  # pragma: no cover
        return f"Commande de {self.author} pour la commande groupée {self.grouped_order.pk}"


class Item(models.Model):
    name = models.CharField(max_length=100)
    grouped_order = models.ForeignKey(GroupedOrder, on_delete=models.CASCADE)
    price = models.DecimalField(max_digits=10, decimal_places=2)
    max_limit = models.PositiveSmallIntegerField(null=True, blank=True)

    ordered_nb = models.IntegerField(default=0)

    def compute_ordered_nb(self):
        """Computes the number of ordered articles for this item (in this grouped order)"""
        ordered_nb = 0
        for order in self.orders.all():
            ordered_nb += order.nb
        self.ordered_nb = ordered_nb
        self.save()

    def get_total_price(self):
        """Returns the price of all orders on this item"""
        return self.price * self.ordered_nb

    def get_remaining_nb(self):
        """Returns the number of remaining articles for this item in this grouped order"""
        if self.max_limit is not None:
            return self.max_limit - self.ordered_nb
        else:
            return None

    def get_absolute_url(self):
        return reverse("order:manage_items", kwargs={"pk": self.grouped_order.pk})

    def __str__(self):  # pragma: no cover
        return f"{self.name} ({self.price} €)"

    class Meta:
        ordering = ["name"]


class OrderedItem(models.Model):
    """Item in one specific Order, and the number of articles"""

    nb = models.PositiveSmallIntegerField(default=0)  # works up to 32767
    order = models.ForeignKey(
        Order, on_delete=models.CASCADE, related_name="ordered_items"
    )
    item = models.ForeignKey(Item, on_delete=models.CASCADE, related_name="orders")

    def get_price(self):
        return self.nb * self.item.price

    def __str__(self):  # pragma: no cover
        return f"{self.nb} {self.item}, dans la commande {self.order.pk}"