from sqlalchemy import Column, String, Integer, Numeric, DateTime, ForeignKey
from sqlalchemy.sql import func
from sqlalchemy.orm import relationship
from app.core.database.db_session import Base

class PurchaseOrder(Base):
    __tablename__ = "purchase_orders"

    purchase_order_id = Column(String(26), primary_key=True)
    po_number = Column(String(50), unique=True, nullable=False)
    supplier_name = Column(String(255), nullable=False)
    status = Column(String(20), default="Draft") # Draft, Ordered, Received, Cancelled
    total_amount = Column(Numeric(10, 2), default=0.00)
    created_at = Column(DateTime, server_default=func.now())

    items = relationship("PurchaseOrderItem", back_populates="purchase_order", cascade="all, delete-orphan")

class PurchaseOrderItem(Base):
    __tablename__ = "purchase_order_items"

    id = Column(String(26), primary_key=True)
    purchase_order_id = Column(String(26), ForeignKey("purchase_orders.purchase_order_id", ondelete="CASCADE"), nullable=False)
    part_id = Column(String(26), ForeignKey("parts.part_id", ondelete="RESTRICT"), nullable=False)
    quantity_ordered = Column(Integer, nullable=False)
    quantity_received = Column(Integer, default=0)
    unit_price = Column(Numeric(10, 2), nullable=False)

    purchase_order = relationship("PurchaseOrder", back_populates="items")
    part = relationship("Part")