# models/schema/inventory.py
from datetime import datetime
from typing import List, Optional
from pydantic import BaseModel, ConfigDict, Field


class InventoryBase(BaseModel):
    product_id: int = Field(..., description="Product ID in vendor catalog")
    location: str = Field(..., description="Storage location")


class InventoryCreate(InventoryBase):
    """Set exact inventory quantity (replaces existing)."""
    quantity: int = Field(..., description="Exact inventory quantity", ge=0)


class InventoryAdjust(InventoryBase):
    """Add or remove inventory quantity."""
    quantity: int = Field(..., description="Quantity to add (positive) or remove (negative)")


class InventoryUpdate(BaseModel):
    """Update inventory fields."""
    quantity: Optional[int] = Field(None, ge=0)
    reserved_quantity: Optional[int] = Field(None, ge=0)
    location: Optional[str] = None


class InventoryReserve(BaseModel):
    """Reserve inventory for orders."""
    product_id: int
    location: str
    quantity: int = Field(..., gt=0)


class InventoryResponse(BaseModel):
    model_config = ConfigDict(from_attributes=True)

    id: int
    product_id: int
    vendor_id: int
    location: str
    quantity: int
    reserved_quantity: int
    gtin: Optional[str]
    created_at: datetime
    updated_at: datetime

    @property
    def available_quantity(self):
        return max(0, self.quantity - self.reserved_quantity)


class InventoryLocationResponse(BaseModel):
    location: str
    quantity: int
    reserved_quantity: int
    available_quantity: int


class ProductInventorySummary(BaseModel):
    """Inventory summary for a product."""
    product_id: int
    vendor_id: int
    product_sku: Optional[str]
    product_title: str
    total_quantity: int
    total_reserved: int
    total_available: int
    locations: List[InventoryLocationResponse]


class InventoryListResponse(BaseModel):
    inventories: List[InventoryResponse]
    total: int
    skip: int
    limit: int