from datetime import datetime
import enum

from sqlalchemy import Column, DateTime, Enum, Float, ForeignKey, Integer, String
from sqlalchemy.orm import relationship

from app.db.base import Base


class TransactionType(str, enum.Enum):
    """
    Enum for transaction types (stock in or out).
    """
    STOCK_IN = "stock_in"
    STOCK_OUT = "stock_out"


class Transaction(Base):
    """
    Transaction model for tracking inventory movements.
    """
    __tablename__ = "transactions"

    id = Column(Integer, primary_key=True, index=True)
    quantity = Column(Integer, nullable=False)
    transaction_type = Column(Enum(TransactionType), nullable=False)
    unit_price = Column(Float, nullable=False)
    total_price = Column(Float, nullable=False)
    reference = Column(String, nullable=True)
    notes = Column(String, nullable=True)
    timestamp = Column(DateTime, default=datetime.utcnow, nullable=False)
    
    # Foreign keys
    item_id = Column(Integer, ForeignKey("items.id"), nullable=False)
    user_id = Column(Integer, ForeignKey("users.id"), nullable=False)
    
    # Relationships
    item = relationship("Item", back_populates="transactions")
    user = relationship("User", back_populates="transactions")