from fastapi.testclient import TestClient
from sqlalchemy import create_engine, Column, Integer, String, Date, Enum
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

DATABASE_URL = "sqlite:///./test_todo.db"
engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False})
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

class Todo(Base):
    __tablename__ = "todos"
    id = Column(Integer, primary_key=True, index=True)
    title = Column(String(100), nullable=False)
    description = Column(String(500))
    due_date = Column(Date, nullable=False)
    status = Column(Enum('pending', 'completed'), default='pending')

Base.metadata.create_all(bind=engine)

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

app = FastAPI()

@app.post("/todos/", response_model=Todo, status_code=201)
def create_todo(todo: TodoCreate, db: Session = Depends(get_db)):
    db_todo = Todo(**todo.model_dump())
    db.add(db_todo)
    db.commit()
    db.refresh(db_todo)
    return db_todo

@app.get("/todos/", response_model=list[Todo])
def list_todos(status: str | None = None, db: Session = Depends(get_db)):
    if status:
        query = db.query(Todo).filter_by(status=status)
    else:
        query = db.query(Todo)
    return query.all()

@app.get("/todos/{todo_id}", response_model=Todo)
def get_todo(todo_id: int, db: Session = Depends(get_db)):
    todo = db.query(Todo).filter(Todo.id == todo_id).first()
    if not todo:
        raise HTTPException(status_code=404, detail="Not found")
    return todo

@app.put("/todos/{todo_id}", response_model=Todo)
def update_todo(todo_id: int, todo: TodoCreate, db: Session = Depends(get_db)):
    db_todo = db.query(Todo).filter(Todo.id == todo_id).first()
    if not db_todo:
        raise HTTPException(status_code=404, detail="Not found")
    for key, value in todo.model_dump().items():
        setattr(db_todo, key, value)
    db.commit()
    db.refresh(db_todo)
    return db_todo

@app.delete("/todos/{todo_id}", status_code=204)
def delete_todo(todo_id: int, db: Session = Depends(get_db)):
    db_todo = db.query(Todo).filter(Todo.id == todo_id).first()
    if not db_todo:
        raise HTTPException(status_code=404, detail="Not found")
    db.delete(db_todo)
    db.commit()

client = TestClient(app)

def test_create_todo():
    response = client.post("/todos/", json={"title": "Test Todo", "description": "This is a test todo.", "due_date": "2023-12-31"})
    assert response.status_code == 201
    data = response.json()
    assert "id" in data
    assert data["title"] == "Test Todo"
    assert data["description"] == "This is a test todo."
    assert data["due_date"] == "2023-12-31"
    assert data["status"] == "pending"

def test_list_todos():
    response = client.get("/todos/")
    assert response.status_code == 200
    data = response.json()
    assert len(data) > 0

def test_get_todo_by_id():
    todo_id = create_test_todo().json()["id"]
    response = client.get(f"/todos/{todo_id}")
    assert response.status_code == 200
    data = response.json()
    assert "id" in data
    assert data["title"] == "Test Todo"

def test_get_nonexistent_todo():
    response = client.get("/todos/999")
    assert response.status_code == 404

def test_update_todo():
    todo_id = create_test_todo().json()["id"]
    response = client.put(f"/todos/{todo_id}", json={"title": "Updated Todo"})
    assert response.status_code == 200
    data = response.json()
    assert "id" in data
    assert data["title"] == "Updated Todo"

def test_delete_todo():
    todo_id = create_test_todo().json()["id"]
    response = client.delete(f"/todos/{todo_id}")
    assert response.status_code == 204

def create_test_todo():
    return client.post("/todos/", json={"title": "Test Todo", "description": "This is a test todo.", "due_date": "2023