from datetime import datetime
from typing import Optional

from pydantic import BaseModel, Field


class TodoBase(BaseModel):
    """Base Todo schema with common attributes"""
    title: str = Field(..., min_length=1, max_length=100, description="Title of the todo")
    description: Optional[str] = Field(
        None, max_length=500, description="Detailed description of the todo",
    )
    completed: bool = Field(False, description="Whether the todo is completed")


class TodoCreate(TodoBase):
    """Schema for creating a new todo"""
    pass


class TodoUpdate(BaseModel):
    """Schema for updating an existing todo, all fields are optional"""
    title: Optional[str] = Field(
        None, min_length=1, max_length=100, description="Title of the todo",
    )
    description: Optional[str] = Field(
        None, max_length=500, description="Detailed description of the todo",
    )
    completed: Optional[bool] = Field(None, description="Whether the todo is completed")


class TodoResponse(TodoBase):
    """Schema for todo response that includes database fields"""
    id: int
    created_at: datetime
    updated_at: Optional[datetime] = None

    class Config:
        """ORM mode config for the TodoResponse schema"""
        orm_mode = True
        from_attributes = True