/*
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2026 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 *
 * Added: 2026-01-29
 */

/*
 * Rust FFI demo opcode with argument: OP_RUST_HELLO_ARGS_RETURN
 * Pops a string from the stack, asks Rust to return it back (no printing).
 * Pushes the returned string, or Nil on error.
 */
case OP_RUST_HELLO_ARGS_RETURN: {
#ifdef FUN_WITH_RUST
  Value vmsg = pop_value(vm);
  char *msg = value_to_string_alloc(&vmsg);
  free_value(vmsg);
  if (msg) {
    char *ret = fun_rust_echo_string(msg);
    free(msg);
    if (ret) {
      push_value(vm, make_string(ret));
      fun_rust_string_free(ret);
    } else {
      push_value(vm, make_nil());
    }
  } else {
    char *ret = fun_rust_echo_string("");
    if (ret) {
      push_value(vm, make_string(ret));
      fun_rust_string_free(ret);
    } else {
      push_value(vm, make_nil());
    }
  }
#else
  /* Still pop and free the arg to keep stack sane */
  Value vmsg = pop_value(vm);
  free_value(vmsg);
  vm_raise_error(vm, "RUST_HELLO_ARGS_RETURN requires FUN_WITH_RUST=ON at build time");
  push_value(vm, make_nil());
#endif
  break;
}
