use cpython::exc::ValueError;

use cpython::{PyBytes, PyDict, PyErr, PyObject, PyResult, PyTuple, Python};

use hg::revlog::Node;

use std::convert::TryFrom;

// Necessary evil for the time being, could maybe be moved to

// a TryFrom in Node itself

const NODE_BYTES_LENGTH: usize = 20;

type NodeData = [u8; NODE_BYTES_LENGTH];

/// Copy incoming Python bytes given as `PyObject` into `Node`,

/// doing the necessary checks

pub fn node_from_py_object<'a>(

    py: Python,

    bytes: &'a PyObject,

) -> PyResult<Node> {

    let as_py_bytes: &'a PyBytes = bytes.extract(py)?;

    node_from_py_bytes(py, as_py_bytes)

}

/// Clone incoming Python bytes given as `PyBytes` as a `Node`,

/// doing the necessary checks.

pub fn node_from_py_bytes<'a>(

    py: Python,

    bytes: &'a PyBytes,

) -> PyResult<Node> {

    <NodeData>::try_from(bytes.data(py))

        .map_err(|_| {

            PyErr::new::<ValueError, _>(

                py,

                format!("{}-byte hash required", NODE_BYTES_LENGTH),

            )

        })

        .map(|n| n.into())

}