prvi kod za live uporabu

backend/modules/invoicing/models.py

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+# backend/modules/invoicing/models.py
+
+import datetime
+from django.utils import timezone
+from core.base_models import BaseModel
+from django.db import models, transaction
+from django.utils.translation import gettext_lazy as _
+from django.conf import settings
+from .utils import generate_invoice_number
+
+class Invoice(BaseModel):
+    # Identifikacija (UUID i created_at dolaze iz BaseModel)
+    invoice_number = models.CharField(max_length=50, unique=True, verbose_name=_("Broj fakture"))
+    
+    # Relacije
+    creator = models.ForeignKey(
+        settings.AUTH_USER_MODEL, 
+        on_delete=models.PROTECT, 
+        related_name="invoices"
+    )
+    client = models.ForeignKey(
+        'crm.Client', 
+        on_delete=models.PROTECT, 
+        verbose_name=_("Klijent")
+    )
+    
+    # Financijski detalji
+    amount = models.DecimalField(max_digits=12, decimal_places=2, verbose_name=_("Iznos"))
+    currency = models.CharField(max_length=3, default="EUR")
+    tax_rate = models.DecimalField(max_digits=4, decimal_places=2, default=25.00)
+    
+    # Statusi
+    status = models.CharField(
+        max_length=20, 
+        choices=[
+            ('draft', 'Nacrt'),
+            ('sent', 'Poslano'),
+            ('paid', 'Plaćeno'),
+            ('cancelled', 'Stornirano')
+        ], 
+        default='draft'
+    )
+    
+    due_date = models.DateField(verbose_name=_("Rok plaćanja"))
+    
+    class Meta:
+        # Nasljeđujemo ordering iz BaseModel, ali ga možemo override-ati
+        verbose_name = _("Faktura")
+        verbose_name_plural = _("Fakture")
+
+    def __str__(self):
+        return f"{self.invoice_number} - {self.client}"
+    
+    def get_total_amount(self):
+        return self.items.aggregate(total=models.Sum(models.F('quantity') * models.F('unit_price')))['total'] or 0
+    
+    def save(self, *args, **kwargs):
+        if not self.invoice_number:
+            self.invoice_number = generate_invoice_number()
+        super().save(*args, **kwargs)
+
+class InvoiceItem(BaseModel):
+    # Relacija prema fakturi
+    invoice = models.ForeignKey(
+        Invoice, 
+        on_delete=models.CASCADE, 
+        related_name='items',
+        verbose_name=_("Faktura")
+    )
+    
+    # Detalji stavke
+    description = models.CharField(
+        max_length=255, 
+        verbose_name=_("Opis stavke")
+    )
+    quantity = models.DecimalField(
+        max_digits=10, 
+        decimal_places=2, 
+        default=1,
+        verbose_name=_("Količina")
+    )
+    unit_price = models.DecimalField(
+        max_digits=12, 
+        decimal_places=2, 
+        verbose_name=_("Cijena po jedinici")
+    )
+    
+    # Automatski izračun (property ne zauzima prostor u bazi)
+    @property
+    def total(self):
+        return self.quantity * self.unit_price
+
+    class Meta:
+        verbose_name = _("Stavka fakture")
+        verbose_name_plural = _("Stavke fakture")
+
+    def __str__(self):
+        # Koristimo prednost BaseModel __str__ metode
+        return f"{self.description} ({self.quantity} x {self.unit_price})"
+
+class InvoiceTransaction(BaseModel):
+    # Polja specifična za fakturiranje
+    invoice = models.ForeignKey(
+        Invoice, 
+        on_delete=models.PROTECT, 
+        related_name='transactions',
+        verbose_name=_("Faktura")
+    )
+    work_order = models.ForeignKey(
+        'fleet.WorkOrder',
+        on_delete=models.SET_NULL,
+        related_name='invoice_transactions',
+        null=True,
+        blank=True,
+        verbose_name=_("Putni nalog"),
+    )
+    invoice_number = models.CharField(max_length=50)
+    amount = models.DecimalField(max_digits=10, decimal_places=2)
+    payment_date = models.DateField(default=timezone.now)
+    
+    class Meta:
+        verbose_name = "Financijski zapis"
+        verbose_name_plural = "Financijski zapisi"