from typing import Optional

from pydantic import BaseModel, Field


class ItemBase(BaseModel):
    """
    Base item schema with common attributes.
    """
    name: str = Field(..., description="Item name")
    description: Optional[str] = Field(None, description="Item description")
    sku: Optional[str] = Field(None, description="Stock Keeping Unit")
    barcode: Optional[str] = Field(None, description="Barcode/UPC")
    quantity: int = Field(0, description="Current stock quantity", ge=0)
    unit_price: float = Field(..., description="Unit price", gt=0)
    reorder_level: int = Field(10, description="Quantity at which to reorder", ge=0)
    category_id: Optional[int] = Field(None, description="ID of the category")
    supplier_id: Optional[int] = Field(None, description="ID of the supplier")


class ItemCreate(ItemBase):
    """
    Schema for item creation.
    """
    pass


class ItemUpdate(BaseModel):
    """
    Schema for updating item information.
    """
    name: Optional[str] = Field(None, description="Item name")
    description: Optional[str] = Field(None, description="Item description")
    sku: Optional[str] = Field(None, description="Stock Keeping Unit")
    barcode: Optional[str] = Field(None, description="Barcode/UPC")
    quantity: Optional[int] = Field(None, description="Current stock quantity", ge=0)
    unit_price: Optional[float] = Field(None, description="Unit price", gt=0)
    reorder_level: Optional[int] = Field(None, description="Quantity at which to reorder", ge=0)
    category_id: Optional[int] = Field(None, description="ID of the category")
    supplier_id: Optional[int] = Field(None, description="ID of the supplier")


class ItemInDBBase(ItemBase):
    """
    Base schema for items from the database.
    """
    id: int = Field(..., description="Item ID")

    class Config:
        from_attributes = True


class Item(ItemInDBBase):
    """
    Schema for item information returned to clients.
    """
    pass


class ItemWithRelations(ItemInDBBase):
    """
    Schema for item with related entities.
    """
    from app.schemas.category import Category
    from app.schemas.supplier import Supplier
    
    category: Optional[Category] = Field(None, description="Item category")
    supplier: Optional[Supplier] = Field(None, description="Item supplier")