import enum
import uuid

from sqlalchemy import (
    Column,
    DateTime,
    Enum,
    ForeignKey,
    Integer,
    String,
    Text,
)
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func

from app.db.base import Base


class InventoryStatus(str, enum.Enum):
    """Enum for inventory status."""
    IN_STOCK = "in_stock"
    LOW_STOCK = "low_stock"
    OUT_OF_STOCK = "out_of_stock"
    DISCONTINUED = "discontinued"


class InventoryItem(Base):
    """Inventory item model."""
    __tablename__ = "inventory_items"

    id = Column(String, primary_key=True, index=True, default=lambda: str(uuid.uuid4()))
    quantity = Column(Integer, default=0, nullable=False)
    status = Column(Enum(InventoryStatus), default=InventoryStatus.OUT_OF_STOCK, nullable=False)
    location = Column(String, nullable=True)
    notes = Column(Text, nullable=True)
    
    # Foreign keys
    product_id = Column(String, ForeignKey("products.id"), nullable=False)
    
    # Relationships
    product = relationship("Product", back_populates="inventory_items")
    
    # Audit timestamps
    created_at = Column(DateTime(timezone=True), server_default=func.now(), nullable=False)
    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False)


class InventoryTransaction(Base):
    """Inventory transaction model for tracking inventory changes."""
    __tablename__ = "inventory_transactions"

    id = Column(String, primary_key=True, index=True, default=lambda: str(uuid.uuid4()))
    product_id = Column(String, ForeignKey("products.id"), nullable=False)
    quantity_change = Column(Integer, nullable=False)  # Positive for additions, negative for subtractions
    notes = Column(Text, nullable=True)
    transaction_by = Column(String, ForeignKey("users.id"), nullable=True)
    
    # Audit timestamps
    created_at = Column(DateTime(timezone=True), server_default=func.now(), nullable=False)