from pydantic import BaseModel
from typing import Optional
from datetime import datetime


class Snapshot(BaseModel):
    name: str
    dataset: str  # parent dataset
    created: int  # Unix timestamp
    used: int  # bytes
    referenced: int  # bytes
    creation_datetime: Optional[str] = None  # ISO format for API

    class Config:
        json_schema_extra = {
            "example": {
                "name": "tank/share@2026-04-14-120000",
                "dataset": "tank/share",
                "created": 1713089400,
                "used": 0,
                "referenced": 1900000000,
                "creation_datetime": "2026-04-14T12:00:00Z"
            }
        }