erp-nutzfahrzeuge/backend/app/models/sale.py

"""SQLAlchemy model for sales (Verkauf)."""

import enum
import uuid
from datetime import date, datetime
from decimal import Decimal
from typing import TYPE_CHECKING

from sqlalchemy import (
    Boolean,
    CheckConstraint,
    Date,
    DateTime,
    ForeignKey,
    Numeric,
    String,
    func,
)
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base

if TYPE_CHECKING:
    from app.models.contact import Contact
    from app.models.vehicle import Vehicle


class SaleStatus(str, enum.Enum):
    draft = "draft"
    completed = "completed"
    cancelled = "cancelled"


class Sale(Base):
    """Sale entity linking a vehicle to a buyer (and optionally a seller)."""

    __tablename__ = "sales"
    __table_args__ = (
        CheckConstraint(
            "status IN ('draft', 'completed', 'cancelled')",
            name="ck_sales_status",
        ),
    )

    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
    )
    vehicle_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("vehicles.id", ondelete="RESTRICT"),
        nullable=False,
        index=True,
    )
    buyer_contact_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("contacts.id", ondelete="RESTRICT"),
        nullable=False,
        index=True,
    )
    seller_contact_id: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("contacts.id", ondelete="SET NULL"),
        nullable=True,
        index=True,
    )
    sale_price: Mapped[Decimal] = mapped_column(
        Numeric(12, 2), nullable=False
    )
    sale_date: Mapped[date] = mapped_column(
        Date, nullable=False, default=func.current_date()
    )
    status: Mapped[str] = mapped_column(
        String(20), nullable=False, default="draft"
    )
    is_gwg: Mapped[bool] = mapped_column(
        Boolean, nullable=False, default=False
    )
    contract_pdf_path: Mapped[str | None] = mapped_column(
        String(500), nullable=True
    )
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), nullable=False, server_default=func.now()
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True),
        nullable=False,
        server_default=func.now(),
        onupdate=func.now(),
    )

    vehicle: Mapped["Vehicle"] = relationship(lazy="selectin")
    buyer: Mapped["Contact"] = relationship(
        "Contact",
        foreign_keys=[buyer_contact_id],
        lazy="selectin",
    )
    seller: Mapped["Contact | None"] = relationship(
        "Contact",
        foreign_keys=[seller_contact_id],
        lazy="selectin",
    )

    def __repr__(self) -> str:
        return f"<Sale id={self.id} vehicle_id={self.vehicle_id} status={self.status}>"

    def to_dict(self) -> dict:
        """Serialize sale for API responses."""
        return {
            "id": str(self.id),
            "vehicle_id": str(self.vehicle_id),
            "buyer_contact_id": str(self.buyer_contact_id),
            "seller_contact_id": (
                str(self.seller_contact_id) if self.seller_contact_id else None
            ),
            "sale_price": float(self.sale_price) if self.sale_price is not None else None,
            "sale_date": self.sale_date.isoformat() if self.sale_date else None,
            "status": self.status,
            "is_gwg": self.is_gwg,
            "contract_pdf_path": self.contract_pdf_path,
            "created_at": self.created_at.isoformat() if self.created_at else None,
            "updated_at": self.updated_at.isoformat() if self.updated_at else None,
        }