import json

struct Result[T] {
    ok     bool
    result T
}

struct User {
    id       int
    username string
}

struct Box[T] {
    items []T
}

fn func[T]() !T {
    text := '{"ok": true, "result":{"id":37467243, "username": "ciao"}}'
    a := json.decode(Result[T], text)!
    return a.result
}

fn string_decode[T](text string) !T {
    return json.decode(T, text)
}

fn open_box[T](text string) ![]T {
    box := string_decode[Box[T]](text)!
    return box.items
}

fn test_decode_with_generic_struct() {
    ret := func[User]()!
    println(ret)
    assert ret.id == 37467243
    assert ret.username == 'ciao'
}

fn test_decode_with_nested_generic_struct() {
    text := '{"items":[{},{"id":37467243,"username":"ciao"},{}]}'
    items := open_box[User](text)!
    assert items.len == 3
    assert items[0].id == 0
    assert items[0].username == ''
    assert items[1].id == 37467243
    assert items[1].username == 'ciao'
    assert items[2].id == 0
    assert items[2].username == ''
}