"""
Base Model with Common Fields
All models inherit from this for consistent timestamps and ID handling
"""
from datetime import datetime
from typing import Optional
from sqlalchemy import Integer, DateTime, func
from sqlalchemy.orm import Mapped, mapped_column, declared_attr

from app.database import Base


class TimestampMixin:
    """Mixin for created_at and updated_at timestamps"""
    
    created_at: Mapped[datetime] = mapped_column(
        DateTime,
        default=func.now(),
        server_default=func.now(),
        nullable=False
    )
    
    updated_at: Mapped[datetime] = mapped_column(
        DateTime,
        default=func.now(),
        server_default=func.now(),
        onupdate=func.now(),
        nullable=False
    )


class BaseModel(Base, TimestampMixin):
    """
    Base model class with auto-incrementing BigInt ID and timestamps.
    All models should inherit from this class.
    """
    __abstract__ = True
    
    id: Mapped[int] = mapped_column(
        Integer,
        primary_key=True,
        autoincrement=True,
        index=True
    )
    
    @declared_attr.directive
    def __tablename__(cls) -> str:
        """Generate table name from class name (snake_case)"""
        import re
        name = cls.__name__
        return re.sub(r'(?<!^)(?=[A-Z])', '_', name).lower() + 's'
    
    def to_dict(self) -> dict:
        """Convert model to dictionary"""
        return {
            column.name: getattr(self, column.name)
            for column in self.__table__.columns
        }
    
    def __repr__(self) -> str:
        return f"<{self.__class__.__name__}(id={self.id})>"