from pydantic import BaseModel, Field, EmailStr, field_validator
from typing import List, Literal, Optional
from datetime import date

class Invoice(BaseModel):
    invoice_no: str = Field(pattern=r"^INV-\d{6}$")
    customer_email: EmailStr
    amount: float = Field(gt=0)
    currency: Literal["TRY", "USD", "EUR"]
    due_date: date
    items: List["InvoiceItem"] = Field(min_length=1)

    @field_validator("due_date")
    def must_be_future(cls, v):
        if v < date.today():
            raise ValueError("Vade geçmiş olamaz")
        return v

class InvoiceItem(BaseModel):
    description: str
    quantity: int = Field(gt=0)
    unit_price: float = Field(gt=0)

# Kullanım
raw_json = '{"invoice_no": "INV-123456", "customer_email": "x@y.com", ...}'
invoice = Invoice.model_validate_json(raw_json)
# Hata varsa: ValidationError fırlar