use mlua::Lua;
use std::error::Error;

#[test]
fn wasmer_examples_instance() -> Result<(), Box<dyn Error>> {
    let lua = Lua::new();
    mlua_wasmer::preload(&lua)?;
    let script = r#"
            -- Let's declare the Wasm module.
            local wasm_bytes = [[
                (module
                    (type $add_one_t (func (param i32) (result i32)))
                    (func $add_one_f (type $add_one_t) (param $value i32) (result i32)
                        local.get $value
                        i32.const 1
                        i32.add)
                    (export "add_one" (func $add_one_f)))
            ]]

            -- Create a Store.            
            local wasmer = require('wasmer')
            local store = wasmer.Store:default()
            
            -- Let's compile the Wasm module.
            print('Compiling module...')
            local module = wasmer.Module:new(store, wasm_bytes)
            
            -- Create an empty import object.
            local import_object = wasmer.Imports:new()
            
            -- Let's instantiate the Wasm module.
            print('Instantiating module...')
            local instance = wasmer.Instance:new(store, module, import_object)
            
            -- We now have an instance ready to be used.
            --
            -- From an `Instance` we can retrieve any exported entities.
            -- Each of these entities is covered in others examples.
            --
            -- Here we are retrieving the exported function. We won't go into details here
            -- as the main focus of this example is to show how to create an instance out
            -- of a Wasm module and have basic interactions with it.
            local add_one = instance.exports:get_function('add_one')
            
            print('Calling add_one function...')
            local result = add_one:call(store, 1)
            
            print(string.format('Results of add_one: %d', result))
            return result
        "#;
    let result: i32 = lua.load(script).eval()?;
    assert_eq!(result, 2);
    Ok(())
}