use mlua::prelude::*;

fn sum(_: &Lua, (a, b): (i64, i64)) -> LuaResult<i64> {
 Ok(a + b)
}

fn used_memory(lua: &Lua, _: ()) -> LuaResult<usize> {
 Ok(lua.used_memory())
}

fn check_userdata(_: &Lua, ud: LuaAnyUserData) -> LuaResult<i32> {
 Ok(ud.borrow::<MyUserData>()?.0)
}

#[mlua::lua_module]
fn test_module(lua: &Lua) -> LuaResult<LuaTable> {
 let exports = lua.create_table()?;
 exports.set("sum", lua.create_function(sum)?)?;
 exports.set("used_memory", lua.create_function(used_memory)?)?;
 exports.set("check_userdata", lua.create_function(check_userdata)?)?;
 Ok(exports)
}

#[derive(Clone, Copy)]
struct MyUserData(i32);

impl LuaUserData for MyUserData {}

#[mlua::lua_module(name = "test_module_second", skip_memory_check)]
fn test_module2(lua: &Lua) -> LuaResult<LuaTable> {
 let exports = lua.create_table()?;
 exports.set("userdata", MyUserData(123))?;
 Ok(exports)
}

#[mlua::lua_module]
fn test_module_new_vm(lua: &Lua) -> LuaResult<LuaTable> {
 let eval = lua.create_function(|_, prog: String| {
 let lua = Lua::new();
 lua.load(prog).eval::<Option<String>>()
 })?;

 let exports = lua.create_table()?;
 exports.set("eval", eval)?;
 Ok(exports)
}

#[mlua::lua_module]
fn test_module_error(_: &Lua) -> LuaResult<LuaTable> {
 Err("custom module error".into_lua_err())
}