rhai-python/src/lib.rs

use pyo3::exceptions::PyRuntimeError;
use pyo3::prelude::*;
use pyo3::types::{PyDict, PyList};
use pyo3::IntoPyObjectExt;
use rhai::{Array, Dynamic, Engine, Map, Scope};

/// Convert Rhai Dynamic to Python object
fn dynamic_to_python(py: Python<'_>, value: Dynamic) -> PyResult<PyObject> {
    match value.type_name() {
        "i64" => Ok(value.as_int().unwrap().into_py_any(py).unwrap()),
        "f64" => Ok(value.as_float().unwrap().into_py_any(py).unwrap()),
        "bool" => Ok(value.as_bool().unwrap().into_py_any(py).unwrap()),
        "string" => Ok(value.into_string().unwrap().into_py_any(py).unwrap()),
        "char" => Ok(value
            .as_char()
            .unwrap()
            .to_string()
            .into_py_any(py)
            .unwrap()),
        "()" => Ok(py.None()),
        "array" => {
            let array = value.cast::<Array>();
            let py_list = PyList::empty(py);
            for item in array {
                py_list.append(dynamic_to_python(py, item)?)?;
            }
            Ok(py_list.into_py_any(py)?.into())
        }
        "map" => {
            let map = value.cast::<Map>();
            let py_dict = PyDict::new(py);
            for (key, value) in map {
                let py_key = key.to_string().into_py_any(py).unwrap();
                let py_value = dynamic_to_python(py, value)?;
                py_dict.set_item(py_key, py_value)?;
            }
            Ok(py_dict.into_py_any(py)?.into())
        }
        _ => Err(PyRuntimeError::new_err(format!(
            "Unsupported Rhai type: {}",
            value.type_name()
        ))),
    }
}

/// Convert Python object to Rhai Dynamic
fn python_to_dynamic(py: Python<'_>, obj: &Bound<'_, PyAny>) -> PyResult<Dynamic> {
    if obj.is_none() {
        Ok(Dynamic::UNIT)
    } else if let Ok(val) = obj.extract::<bool>() {
        Ok(Dynamic::from(val))
    } else if let Ok(val) = obj.extract::<i64>() {
        Ok(Dynamic::from(val))
    } else if let Ok(val) = obj.extract::<f64>() {
        Ok(Dynamic::from(val))
    } else if let Ok(val) = obj.extract::<String>() {
        Ok(Dynamic::from(val))
    } else if let Ok(py_list) = obj.downcast::<PyList>() {
        let mut array = Array::new();
        for item in py_list {
            array.push(python_to_dynamic(py, &item)?);
        }
        Ok(Dynamic::from(array))
    } else if let Ok(py_dict) = obj.downcast::<PyDict>() {
        let mut map = Map::new();
        for (key, value) in py_dict {
            let key_str = key.extract::<String>()?;
            let rhai_value = python_to_dynamic(py, &value)?;
            map.insert(key_str.into(), rhai_value);
        }
        Ok(Dynamic::from(map))
    } else {
        Err(PyRuntimeError::new_err(format!(
            "Unsupported Python type: {}",
            obj.get_type().name()?
        )))
    }
}

#[pyclass]
struct RhaiEngine {
    engine: Engine,
    scope: Scope<'static>,
}

#[pymethods]
impl RhaiEngine {
    #[new]
    fn new() -> Self {
        Self {
            engine: Engine::new(),
            scope: Scope::new(),
        }
    }

    /// Evaluate a Rhai script and return the result
    fn eval(&mut self, py: Python<'_>, script: &str) -> PyResult<PyObject> {
        match self
            .engine
            .eval_with_scope::<Dynamic>(&mut self.scope, script)
        {
            Ok(result) => dynamic_to_python(py, result),
            Err(err) => Err(PyRuntimeError::new_err(format!("Rhai error: {}", err))),
        }
    }

    /// Set a variable in the engine scope
    fn set_var(&mut self, py: Python<'_>, name: &str, value: &Bound<'_, PyAny>) -> PyResult<()> {
        let dynamic_value = python_to_dynamic(py, value)?;
        self.scope.set_value(name, dynamic_value);
        Ok(())
    }

    /// Get a variable from the engine scope
    fn get_var(&self, py: Python<'_>, name: &str) -> PyResult<PyObject> {
        match self.scope.get_value::<Dynamic>(name) {
            Some(value) => dynamic_to_python(py, value),
            None => Err(PyRuntimeError::new_err(format!(
                "Variable '{}' not found",
                name
            ))),
        }
    }

    /// Check if a variable exists in the scope
    fn has_var(&self, name: &str) -> bool {
        self.scope.contains(name)
    }

    /// Clear all variables from the scope
    fn clear_scope(&mut self) {
        self.scope.clear();
    }

    /// Compile a script and return whether it's valid
    fn compile(&self, script: &str) -> PyResult<bool> {
        match self.engine.compile(script) {
            Ok(_) => Ok(true),
            Err(err) => Err(PyRuntimeError::new_err(format!(
                "Compilation error: {}",
                err
            ))),
        }
    }

    /// Get the list of all variable names in the scope
    fn list_vars(&self) -> Vec<String> {
        self.scope
            .iter()
            .map(|(name, _, _)| name.to_string())
            .collect()
    }
}

/// A Python module implemented in Rust using PyO3
#[pymodule]
fn rhai_python(m: &Bound<'_, PyModule>) -> PyResult<()> {
    m.add_class::<RhaiEngine>()?;
    Ok(())
}