"""
Modèles de données — JB Compta.

Conçus pour rester valables si le statut évolue : les taux et seuils
ne sont jamais codés en dur, ils vivent dans le modèle `Bareme`
(par activité et par année).
"""
from decimal import Decimal

from django.db import models
from django.db.models import Sum


class Activite(models.TextChoices):
    VENTE = "vente", "Vente de marchandises (BIC)"
    SERVICE_BIC = "service_bic", "Prestation de services (BIC)"
    SERVICE_BNC = "service_bnc", "Prestation de services / libéral (BNC)"


class StatutFacture(models.TextChoices):
    BROUILLON = "brouillon", "Brouillon"
    ENVOYEE = "envoyee", "Envoyée"
    ENCAISSEE = "encaissee", "Encaissée"
    ANNULEE = "annulee", "Annulée"


class Bareme(models.Model):
    """Taux et seuils officiels, par activité et par année (paramétrable)."""
    activite = models.CharField(max_length=20, choices=Activite.choices)
    annee = models.PositiveIntegerField()
    taux_urssaf = models.DecimalField(
        "Taux cotisations URSSAF (%)", max_digits=5, decimal_places=2)
    abattement_fiscal = models.DecimalField(
        "Abattement forfaitaire (%)", max_digits=5, decimal_places=2)
    taux_vl = models.DecimalField(
        "Taux versement libératoire (%)", max_digits=4, decimal_places=2)
    seuil_ca = models.DecimalField(
        "Plafond CA micro (€)", max_digits=12, decimal_places=2)
    seuil_tva_base = models.DecimalField(
        "Seuil franchise TVA (€)", max_digits=12, decimal_places=2)
    seuil_tva_majore = models.DecimalField(
        "Seuil franchise TVA majoré (€)", max_digits=12, decimal_places=2)

    class Meta:
        verbose_name = "Barème"
        verbose_name_plural = "Barèmes"
        unique_together = ("activite", "annee")
        ordering = ["-annee", "activite"]

    def __str__(self):
        return f"{self.get_activite_display()} — {self.annee}"


class Entreprise(models.Model):
    nom = models.CharField(max_length=200)
    siret = models.CharField(max_length=20, blank=True)
    activite = models.CharField(
        "Activité principale", max_length=20, choices=Activite.choices,
        default=Activite.SERVICE_BNC,
        help_text="Activité par défaut des nouvelles factures. "
                  "Une entreprise peut avoir plusieurs activités : "
                  "chaque facture/dépense porte la sienne.")
    franchise_tva = models.BooleanField(
        "En franchise de TVA", default=False,
        help_text="Décochez si vous facturez et déclarez la TVA.")
    taux_tva_defaut = models.DecimalField(
        "Taux de TVA par défaut (%)", max_digits=4, decimal_places=2,
        default=Decimal("20.00"))
    versement_liberatoire = models.BooleanField(
        "Option versement libératoire", default=False)
    email = models.EmailField(blank=True)
    adresse = models.TextField(blank=True)
    cree_le = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name = "Entreprise"
        verbose_name_plural = "Entreprises"
        ordering = ["nom"]

    def __str__(self):
        return self.nom

    def bareme(self, annee):
        return Bareme.objects.filter(activite=self.activite, annee=annee).first()


class Client(models.Model):
    entreprise = models.ForeignKey(Entreprise, on_delete=models.CASCADE,
                                   related_name="clients")
    nom = models.CharField(max_length=200)
    email = models.EmailField(blank=True)
    siret = models.CharField(max_length=20, blank=True)
    adresse = models.TextField(blank=True)
    cree_le = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name = "Client"
        verbose_name_plural = "Clients"
        ordering = ["nom"]

    def __str__(self):
        return self.nom


class Facture(models.Model):
    entreprise = models.ForeignKey(Entreprise, on_delete=models.CASCADE,
                                   related_name="factures")
    client = models.ForeignKey(Client, on_delete=models.PROTECT,
                               related_name="factures")
    numero = models.CharField(max_length=50)
    activite = models.CharField(max_length=20, choices=Activite.choices)
    date_emission = models.DateField()
    date_encaissement = models.DateField(
        null=True, blank=True,
        help_text="À renseigner une fois la facture payée. "
                  "Le CA micro est compté à l'encaissement.")
    statut = models.CharField(max_length=12, choices=StatutFacture.choices,
                              default=StatutFacture.BROUILLON)
    montant_ht = models.DecimalField(max_digits=12, decimal_places=2,
                                     default=Decimal("0"))
    montant_tva = models.DecimalField(max_digits=12, decimal_places=2,
                                      default=Decimal("0"))
    montant_ttc = models.DecimalField(max_digits=12, decimal_places=2,
                                      default=Decimal("0"))
    notes = models.TextField(blank=True)
    cree_le = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name = "Facture"
        verbose_name_plural = "Factures"
        unique_together = ("entreprise", "numero")
        ordering = ["-date_emission", "numero"]

    def __str__(self):
        return f"{self.numero} — {self.client}"

    def recompute_totaux(self, save=True):
        """Recalcule HT/TVA/TTC à partir des lignes."""
        ht = Decimal("0")
        tva = Decimal("0")
        for ligne in self.lignes.all():
            l_ht = ligne.montant_ht
            ht += l_ht
            tva += (l_ht * ligne.taux_tva / Decimal("100"))
        self.montant_ht = ht.quantize(Decimal("0.01"))
        self.montant_tva = tva.quantize(Decimal("0.01"))
        self.montant_ttc = (self.montant_ht + self.montant_tva)
        if save:
            super().save(update_fields=["montant_ht", "montant_tva", "montant_ttc"])


class LigneFacture(models.Model):
    facture = models.ForeignKey(Facture, on_delete=models.CASCADE,
                                related_name="lignes")
    designation = models.CharField(max_length=255)
    quantite = models.DecimalField(max_digits=12, decimal_places=3,
                                   default=Decimal("1"))
    prix_unitaire_ht = models.DecimalField(max_digits=12, decimal_places=2)
    taux_tva = models.DecimalField(max_digits=4, decimal_places=2,
                                   default=Decimal("0"))

    class Meta:
        verbose_name = "Ligne de facture"
        verbose_name_plural = "Lignes de facture"

    def __str__(self):
        return self.designation

    @property
    def montant_ht(self):
        return (self.quantite * self.prix_unitaire_ht).quantize(Decimal("0.01"))


class Depense(models.Model):
    entreprise = models.ForeignKey(Entreprise, on_delete=models.CASCADE,
                                   related_name="depenses")
    date = models.DateField()
    activite = models.CharField(
        max_length=20, choices=Activite.choices, blank=True,
        help_text="Activité concernée (facultatif, pour la ventilation).")
    categorie = models.CharField(max_length=100, blank=True)
    libelle = models.CharField(max_length=255)
    montant_ttc = models.DecimalField(max_digits=12, decimal_places=2)
    montant_tva = models.DecimalField(
        "TVA déductible (€)", max_digits=12, decimal_places=2,
        default=Decimal("0"))
    cree_le = models.DateTimeField(auto_now_add=True)

    class Meta:
        verbose_name = "Dépense"
        verbose_name_plural = "Dépenses"
        ordering = ["-date"]

    def __str__(self):
        return f"{self.date} — {self.libelle}"

    @property
    def montant_ht(self):
        return (self.montant_ttc - self.montant_tva).quantize(Decimal("0.01"))