from datetime import datetime, timezone, UTC
from typing import Optional, List
from pydantic import BaseModel, Field, model_validator


class Post(BaseModel):
    id: Optional[str] = None
    date: datetime
    topic: str
    generation_ids: List[str] = Field(default_factory=list)
    project_id: Optional[str] = None
    created_by: str
    is_deleted: bool = False
    created_at: datetime = Field(default_factory=lambda: datetime.now(UTC))
    updated_at: datetime = Field(default_factory=lambda: datetime.now(UTC))

    @model_validator(mode="after")
    def ensure_tz_aware(self):
        for field in ("date", "created_at", "updated_at"):
            val = getattr(self, field)
            if val is not None and val.tzinfo is None:
                setattr(self, field, val.replace(tzinfo=timezone.utc))
        return self