from typing import List, Optional
from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy.orm import Session

from app.db.session import get_db
from app.models.todo import Todo as TodoModel
from app.schemas.todo import Todo, TodoCreate, TodoUpdate

router = APIRouter()

@router.get("/", response_model=List[Todo])
def read_todos(
    skip: int = 0, 
    limit: int = 100, 
    completed: Optional[bool] = None,
    db: Session = Depends(get_db)
):
    """
    Retrieve todos with optional filtering by completion status.
    """
    if completed is not None:
        return db.query(TodoModel).filter(TodoModel.completed == completed).offset(skip).limit(limit).all()
    return db.query(TodoModel).offset(skip).limit(limit).all()


@router.post("/", response_model=Todo, status_code=status.HTTP_201_CREATED)
def create_todo(
    todo: TodoCreate, 
    db: Session = Depends(get_db)
):
    """
    Create a new todo item.
    """
    db_todo = TodoModel(**todo.model_dump())
    db.add(db_todo)
    db.commit()
    db.refresh(db_todo)
    return db_todo


@router.get("/{todo_id}", response_model=Todo)
def read_todo(
    todo_id: int, 
    db: Session = Depends(get_db)
):
    """
    Get a specific todo by ID.
    """
    db_todo = db.query(TodoModel).filter(TodoModel.id == todo_id).first()
    if db_todo is None:
        raise HTTPException(status_code=404, detail="Todo not found")
    return db_todo


@router.put("/{todo_id}", response_model=Todo)
def update_todo(
    todo_id: int, 
    todo: TodoUpdate, 
    db: Session = Depends(get_db)
):
    """
    Update a todo item.
    """
    db_todo = db.query(TodoModel).filter(TodoModel.id == todo_id).first()
    if db_todo is None:
        raise HTTPException(status_code=404, detail="Todo not found")
    
    update_data = todo.model_dump(exclude_unset=True)
    for key, value in update_data.items():
        setattr(db_todo, key, value)
    
    db.add(db_todo)
    db.commit()
    db.refresh(db_todo)
    return db_todo


@router.delete("/{todo_id}", status_code=status.HTTP_204_NO_CONTENT, response_model=None)
def delete_todo(
    todo_id: int, 
    db: Session = Depends(get_db)
):
    """
    Delete a todo item.
    """
    db_todo = db.query(TodoModel).filter(TodoModel.id == todo_id).first()
    if db_todo is None:
        raise HTTPException(status_code=404, detail="Todo not found")
    
    db.delete(db_todo)
    db.commit()
    return None