feat: create validated ZUGFeRD invoices in one console command

jr_einvoice/models.py

@@ -1,56 +1,98 @@
 from __future__ import annotations
 from datetime import date
-from pydantic import BaseModel, Field, field_validator
+from decimal import Decimal
+from pydantic import BaseModel, Field, ConfigDict, model_validator, field_validator
 from typing import List, Optional
 
-class Address(BaseModel):
-    street: str
-    postal_code: str
-    city: str
-    country: str = Field(min_length=2, max_length=2)
+class StrictModel(BaseModel):
+    model_config = ConfigDict(extra="forbid", str_strip_whitespace=True, allow_inf_nan=False)
 
-class Party(BaseModel):
-    name: str
+class Address(StrictModel):
+    street: str = Field(min_length=1)
+    postal_code: str = Field(min_length=1)
+    city: str = Field(min_length=1)
+    country: str = Field(pattern=r"^[A-Z]{2}$")
+
+class Party(StrictModel):
+    name: str = Field(min_length=1)
     vat_id: Optional[str] = None
     tax_number: Optional[str] = None
     email: Optional[str] = None
     address: Address
 
+    @field_validator("vat_id", "tax_number")
+    @classmethod
+    def nonempty_tax_id(cls, value):
+        if value is not None and not value:
+            raise ValueError("Tax identifiers must not be empty")
+        return value
+
     @field_validator("email")
     @classmethod
     def _email_shape(cls, v: Optional[str]):
         if v is None:
             return v
-        if "@" not in v or "." not in v.split("@")[-1]:
+        import re
+        if not re.fullmatch(r"[^\s@<>]+@[^\s@<>]+\.[^\s@<>]+", v):
             raise ValueError("email does not look valid")
         return v
 
-class Meta(BaseModel):
+class Meta(StrictModel):
     invoice_number: str = Field(min_length=1)
     invoice_date: date
     service_date: date
-    currency: str = Field(min_length=3, max_length=3, default="EUR")
+    currency: str = Field(pattern=r"^EUR$", default="EUR")
+    service_period_start: Optional[date] = None
+    service_period_end: Optional[date] = None
+    buyer_reference: Optional[str] = None
+    order_reference: Optional[str] = None
     language: Optional[str] = "de"
     notes: Optional[str] = None
 
-class Payment(BaseModel):
+class Payment(StrictModel):
     due_date: date
     reference: str = Field(min_length=1)
     iban: Optional[str] = None
     bic: Optional[str] = None
     bank_name: Optional[str] = None
 
-class Item(BaseModel):
+    @field_validator("iban")
+    @classmethod
+    def valid_iban(cls, value):
+        if value is None:
+            return value
+        import re
+        value = value.replace(" ", "").upper()
+        if not re.fullmatch(r"[A-Z]{2}[0-9]{2}[A-Z0-9]{11,30}", value):
+            raise ValueError("Invalid IBAN format")
+        rearranged = value[4:] + value[:4]
+        digits = ''.join(str(ord(c) - 55) if c.isalpha() else c for c in rearranged)
+        if int(digits) % 97 != 1:
+            raise ValueError("Invalid IBAN checksum")
+        return value
+
+class Item(StrictModel):
     name: str = Field(min_length=1)
     description: Optional[str] = None
-    quantity: float = Field(gt=0)
-    unit: str = Field(min_length=1)  # e.g. HUR, C62
-    unit_price_net: float = Field(ge=0)
-    tax_rate: float = Field(ge=0, le=100)
+    quantity: Decimal = Field(gt=0)
+    unit: str = Field(pattern=r"^[A-Z0-9]{2,3}$")  # e.g. HUR, C62
+    unit_price_net: Decimal = Field(ge=0)
+    tax_rate: Decimal = Field(gt=0, le=100)
 
-class Invoice(BaseModel):
+class Invoice(StrictModel):
     meta: Meta
     seller: Party
     buyer: Party
     payment: Payment
-    items: List[Item]
+    items: List[Item] = Field(min_length=1)
+
+    @model_validator(mode="after")
+    def check_invoice(self):
+        if not (self.seller.vat_id or self.seller.tax_number):
+            raise ValueError("Seller requires vat_id or tax_number")
+        if self.payment.due_date < self.meta.invoice_date:
+            raise ValueError("Payment due_date precedes invoice_date")
+        start, end = self.meta.service_period_start, self.meta.service_period_end
+        if bool(start) != bool(end) or (start and end and start > end):
+            raise ValueError("Service period requires ordered start and end")
+        return self