import uuid
from datetime import datetime, timezone
from sqlalchemy.orm import Mapped, mapped_column
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy import DateTime, String

def utcnow():
    return datetime.now(timezone.utc)

class UUIDMixin:
    id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)

class TimestampMixin:
    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow)
    updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=utcnow)
    responsible: Mapped[str] = mapped_column(String(200), nullable=False, default="Администратор системы")