use pyo3::prelude::*;

use pyo3_sharedref::*;

#[pyclass]

struct Owner {

    string: PyShareable<String>,

}

#[pymethods]

impl Owner {

    #[new]

    fn new(s: String) -> Self {

        Self { string: s.into() }

    }

}

fn with_setup(

    test: impl FnOnce(Python<'_>, &Bound<'_, Owner>) -> PyResult<()>,

) -> PyResult<()> {

    pyo3::prepare_freethreaded_python();

    Python::with_gil(|py| {

        let owner = Bound::new(py, Owner::new("new".to_owned()))?;

        test(py, &owner)

    })

}

/// "leak" in the sense of `SharedByPyObject` the `string` data field,

/// taking care of all the boilerplate

fn leak_string(owner: &Bound<'_, Owner>) -> SharedByPyObject<&'static String> {

    let cell = &owner.borrow().string;

}

fn try_leak_string(

    owner: &Bound<'_, Owner>,

) -> Result<SharedByPyObject<&'static String>, TryShareError> {

    let cell = &owner.borrow().string;

}

/// Mutate the `string` field of `owner` as would be done from Python code

///

/// This is to simulate normal mutation of the owner object from

/// the Python interpreter. This could be replaced by methods of [`Owner`]

/// (wih closure replaced by a small fixed operations)

/// and perhaps will, once we are done converting the original tests

/// from rust-cpython

fn mutate_string<'py>(

    owner: &'py Bound<'py, Owner>,

    f: impl FnOnce(&mut String),

) -> () {

    let cell = &owner.borrow_mut().string;

    let shared_ref = unsafe { cell.borrow_with_owner(owner) };

    f(&mut shared_ref.write());

}

#[test]

fn test_leaked_borrow() -> PyResult<()> {

    with_setup(|py, owner| {

        let leaked = leak_string(owner);

        let leaked_ref = unsafe { leaked.try_borrow(py) }.unwrap();

        assert_eq!(*leaked_ref, "new");

        Ok(())

    })

}

#[test]

fn test_leaked_borrow_mut() -> PyResult<()> {

    with_setup(|py, owner| {

        let leaked = leak_string(owner);

        let mut leaked_iter = unsafe { leaked.map(py, |s| s.chars()) };

        let mut leaked_ref =

            unsafe { leaked_iter.try_borrow_mut(py) }.unwrap();

        assert_eq!(leaked_ref.next(), Some('n'));

        assert_eq!(leaked_ref.next(), Some('e'));

        assert_eq!(leaked_ref.next(), Some('w'));

        assert_eq!(leaked_ref.next(), None);

        Ok(())

    })

}

#[test]

fn test_leaked_borrow_after_mut() -> PyResult<()> {

    with_setup(|py, owner| {

        let leaked = leak_string(owner);

        mutate_string(owner, String::clear);

        assert!(unsafe { leaked.try_borrow(py) }.is_err());

        Ok(())

    })

}

#[test]

fn test_leaked_borrow_mut_after_mut() -> PyResult<()> {

    with_setup(|py, owner| {

        let leaked = leak_string(owner);

        let mut leaked_iter = unsafe { leaked.map(py, |s| s.chars()) };

        mutate_string(owner, String::clear);

        assert!(unsafe { leaked_iter.try_borrow_mut(py) }.is_err());

        Ok(())

    })

}

#[test]

#[should_panic(expected = "map() over invalidated shared reference")]

fn test_leaked_map_after_mut() {

    with_setup(|py, owner| {

        let leaked = leak_string(owner);

        mutate_string(owner, String::clear);

        let _leaked_iter = unsafe { leaked.map(py, |s| s.chars()) };

        Ok(())

    })

    .expect("should already have panicked")

}

/// run `try_borrow_mut` on the `string` field and assert it is not an error

///

/// Simply returning the `Result` is not possible, because that is

/// returning a reference to data owned by the function

fn assert_try_write_string_ok(owner: &Bound<'_, Owner>) {

    let cell = &owner.borrow().string;

    let shared_ref = unsafe { cell.borrow_with_owner(owner) };

    assert!(shared_ref.try_write().is_ok());

}

fn assert_try_write_string_err(owner: &Bound<'_, Owner>) {

    let cell = &owner.borrow().string;

    let shared_ref = unsafe { cell.borrow_with_owner(owner) };

    assert!(shared_ref.try_write().is_err());

}

fn assert_try_read_string_err(owner: &Bound<'_, Owner>) {

    let cell = &owner.borrow().string;

    let shared_ref = unsafe { cell.borrow_with_owner(owner) };

    assert!(shared_ref.try_read().is_err());

}

#[test]

fn test_try_write_while_leaked_ref() -> PyResult<()> {

    with_setup(|py, owner| {

        assert_try_write_string_ok(owner);

        let leaked = leak_string(owner);

        {

            let _leaked_ref = unsafe { leaked.try_borrow(py) }.unwrap();

            assert_try_write_string_err(owner);

            {

                let _leaked_ref2 = unsafe { leaked.try_borrow(py) }.unwrap();

                assert_try_write_string_err(owner);

            }

            assert_try_write_string_err(owner);

        }

        assert_try_write_string_ok(owner);

        Ok(())

    })

}

#[test]

fn test_try_write_while_leaked_ref_mut() -> PyResult<()> {

    with_setup(|py, owner| {

        assert_try_write_string_ok(owner);

        let leaked = leak_string(owner);

        let mut leaked_iter = unsafe { leaked.map(py, |s| s.chars()) };

        {

            let _leaked_ref =

                unsafe { leaked_iter.try_borrow_mut(py) }.unwrap();

            assert_try_write_string_err(owner);

        }

        assert_try_write_string_ok(owner);

        Ok(())

    })

}

#[test]

fn test_try_leak_while_write() -> PyResult<()> {

    with_setup(|_py, owner| {

        let cell = &owner.borrow().string;

        let shared_ref = unsafe { cell.borrow_with_owner(owner) };

        let _mut_ref = shared_ref.write();

        assert!(try_leak_string(owner).is_err());

        Ok(())

    })

}

#[test]

#[should_panic(expected = "already mutably borrowed")]

fn test_leak_while_write() {

    with_setup(|_py, owner| {

        let cell = &owner.borrow().string;

        let shared_ref = unsafe { cell.borrow_with_owner(owner) };

        let _mut_ref = shared_ref.write();

        leak_string(owner);

        Ok(())

    })

    .expect("should already have panicked")

}

#[test]

fn test_try_write_while_borrow() -> PyResult<()> {

    with_setup(|_py, owner| {

        let cell = &owner.borrow().string;

        let shared_ref = unsafe { cell.borrow_with_owner(owner) };

        let _ref = shared_ref.read();

        assert_try_write_string_err(owner);

        Ok(())

    })

}

#[test]

#[should_panic(expected = "already borrowed")]

fn test_write_while_borrow() {

    with_setup(|_py, owner| {

        let cell = &owner.borrow().string;

        let shared_ref = unsafe { cell.borrow_with_owner(owner) };

        let _ref = shared_ref.read();

        let shared_ref2 = unsafe { cell.borrow_with_owner(owner) };

        let _mut_ref = shared_ref2.write();

        Ok(())

    })

    .expect("should already have panicked")

}

#[test]

fn test_try_borrow_while_write() -> PyResult<()> {

    with_setup(|_py, owner| {

        let cell = &owner.borrow().string;

        let shared_ref = unsafe { cell.borrow_with_owner(owner) };

        let _mut_ref = shared_ref.write();

        assert_try_read_string_err(owner);

        Ok(())

    })

}

#[test]

#[should_panic(expected = "already mutably borrowed")]

fn test_borrow_while_write() {

    with_setup(|_py, owner| {

        let cell = &owner.borrow().string;

        let shared_ref = unsafe { cell.borrow_with_owner(owner) };

        let _mut_ref = shared_ref.write();

        let shared_ref2 = unsafe { cell.borrow_with_owner(owner) };

        let _ref = shared_ref2.read();

        Ok(())

    })

    .expect("should already have panicked")

}