from datetime import datetime
from decimal import Decimal
from pydantic import BaseModel, Field, ConfigDict
from typing import Optional


class ProductCreate(BaseModel):
    name: str = Field(..., min_length=1, max_length=255)
    sku: str = Field(
        ...,
        min_length=1,
        max_length=100,
        description="Stock-keeping unit — must be unique",
    )
    quantity_in_stock: int = Field(
        ..., ge=0, description="Initial stock level, cannot be negative"
    )


class ProductUpdate(BaseModel):
    name: Optional[str] = Field(None, min_length=1, max_length=255)
    quantity_in_stock: Optional[int] = Field(None, ge=0)


class ProductOut(BaseModel):
    id: int
    name: str
    sku: str
    quantity_in_stock: int
    created_at: datetime
    updated_at: datetime

    model_config = ConfigDict(from_attributes=True)


class StockMovementOut(BaseModel):
    id: int
    product_id: int
    order_id: int
    movement_type: str
    quantity_change: int
    created_at: datetime

    model_config = ConfigDict(from_attributes=True)


class ReservedItem(BaseModel):
    product_id: int
    quantity: int


class FailedItem(BaseModel):
    product_id: int
    quantity: int


class StockReservedEvent(BaseModel):
    """
    Emitted on the 'inventory' topic when stock is successfully reserved.

    Example payload:
    {
        "order_id": 123,
        "status": "SUCCESS",
        "reserved_items": [
            {"product_id": 101, "quantity": 2},
            {"product_id": 102, "quantity": 1}
        ]
    }
    """

    order_id: int
    status: str = "SUCCESS"
    reserved_items: list[ReservedItem]


class StockReservationFailedEvent(BaseModel):
    """
    Emitted on the 'inventory' topic when stock cannot be reserved.

    Example payload:
    {
        "order_id": 123,
        "status": "FAILED",
        "reason": "INSUFFICIENT_STOCK",
        "failed_items": [{"product_id": 102, "quantity": 5}]
    }
    """

    order_id: int
    status: str = "FAILED"
    reason: str = "INSUFFICIENT_STOCK"
    failed_items: list[FailedItem]