dodati payment kodovi, generisanje kodova, pdf view,promena payment page

backend/core/models.py

@@ -171,4 +171,15 @@ class DocumentRiskControl(models.Model):
     likelihood = models.IntegerField(null=True, blank=True)
 
     class Meta:
-        unique_together = ('document', 'risk', 'control')
+        unique_together = ('document', 'risk', 'control')
+
+
+class PaymentCode(models.Model):
+    code = models.CharField(max_length=10, unique=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+    used = models.BooleanField(default=False)
+    used_at = models.DateTimeField(null=True, blank=True)
+    company = models.ForeignKey(Organization, null=True, blank=True, on_delete=models.SET_NULL)
+
+    def __str__(self):
+        return (f"{self.code} - {'Used' if self.used else 'Available'}")