from typing import Optional

from sqlalchemy.orm import Session

from api.schemas.todo import TodoCreate, TodoUpdate
from db.models import Todo


def get_todos(db: Session, user_id: int, skip: int = 0, limit: int = 100) -> list[Todo]:
    """
    Get all todos for a user with pagination
    """
    return db.query(Todo).filter(Todo.owner_id == user_id).offset(skip).limit(limit).all()


def get_todo(db: Session, todo_id: int, user_id: int) -> Optional[Todo]:
    """
    Get a specific todo by ID for a specific user
    """
    return db.query(Todo).filter(Todo.id == todo_id, Todo.owner_id == user_id).first()


def create_todo(db: Session, todo: TodoCreate, user_id: int) -> Todo:
    """
    Create a new todo for a user
    """
    db_todo = Todo(**todo.dict(), owner_id=user_id)
    db.add(db_todo)
    db.commit()
    db.refresh(db_todo)
    return db_todo


def update_todo(db: Session, todo_id: int, todo: TodoUpdate, user_id: int) -> Optional[Todo]:
    """
    Update an existing todo for a user
    """
    db_todo = get_todo(db, todo_id, user_id)
    if db_todo is None:
        return None

    # Update only provided fields
    todo_data = todo.dict(exclude_unset=True)
    for key, value in todo_data.items():
        setattr(db_todo, key, value)

    db.commit()
    db.refresh(db_todo)
    return db_todo


def delete_todo(db: Session, todo_id: int, user_id: int) -> bool:
    """
    Delete a todo by ID for a user
    Returns True if the todo was deleted, False if it didn't exist
    """
    db_todo = get_todo(db, todo_id, user_id)
    if db_todo is None:
        return False

    db.delete(db_todo)
    db.commit()
    return True