use pyo3::prelude::*;

use pyo3::types::PyDict;

/// Create the module, with `__package__` given from parent

///

/// According to PyO3 documentation, which links to

/// <https://github.com/PyO3/pyo3/issues/1517>, the same convoluted

/// write to sys.modules has to be made as with the `cpython` crate.

pub(crate) fn new_submodule<'py>(

    py: Python<'py>,

    package_name: &str,

    name: &str,

) -> PyResult<Bound<'py, PyModule>> {

    let dotted_name = &format!("{}.{}", package_name, name);

    let m = PyModule::new(py, name)?;

    m.add("__package__", package_name)?;

    m.add("__doc__", "DAG operations - Rust implementation")?;

    let sys = PyModule::import(py, "sys")?;

    // according to the doc, we could make a static PyString out of

    // "modules" with the `intern!` macro, but this is used only at

    // registration so it may not be worth the effort.

    let sys_modules: Bound<'_, PyDict> = sys.getattr("modules")?.extract()?;

    sys_modules.set_item(dotted_name, &m)?;

    // Example C code (see pyexpat.c and import.c) will "give away the

    // reference", but we won't because it will be consumed once the

    // Rust PyObject is dropped.

    Ok(m)

}