use mlua::{Error, FromLua, Function, Lua, RegistryKey, Value};

#[derive(Debug)]
pub struct OwnedFunction {
    key: RegistryKey,
}

impl OwnedFunction {
    pub fn new<'lua>(value: Value<'lua>, lua: &'lua Lua) -> Self {
        let key = lua.create_registry_value(value).unwrap();
        Self { key }
    }

    pub fn get<'lua>(&self, lua: &'lua Lua) -> Function<'lua> {
        lua.registry_value(&self.key).unwrap()
    }
}

impl<'lua> FromLua<'lua> for OwnedFunction {
    fn from_lua(value: Value<'lua>, lua: &'lua Lua) -> mlua::prelude::LuaResult<Self> {
        if value.is_function() {
            Ok(OwnedFunction::new(value, lua))
        } else {
            Err(Error::runtime("value needs to be function"))
        }
    }
}