/**
 * Returns the WASI function name corresponding to a numeric opcode.
 *
 * @param num The function opcode.
 * @returns The name of the WASI function, or "unknown".
 */
export const get_func_name_from_number = (num: number): string => {
  switch (num) {
    case 7:
      return "fd_advise";
    case 8:
      return "fd_allocate";
    case 9:
      return "fd_close";
    case 10:
      return "fd_datasync";
    case 11:
      return "fd_fdstat_get";
    case 12:
      return "fd_fdstat_set_flags";
    case 13:
      return "fd_fdstat_set_rights";
    case 14:
      return "fd_filestat_get";
    case 15:
      return "fd_filestat_set_size";
    case 16:
      return "fd_filestat_set_times";
    case 17:
      return "fd_pread";
    case 18:
      return "fd_prestat_get";
    case 19:
      return "fd_prestat_dir_name";
    case 20:
      return "fd_pwrite";
    case 21:
      return "fd_read";
    case 22:
      return "fd_readdir";
    case 23:
      return "fd_renumber";
    case 24:
      return "fd_seek";
    case 25:
      return "fd_sync";
    case 26:
      return "fd_tell";
    case 27:
      return "fd_write";
    case 28:
      return "path_create_directory";
    case 29:
      return "path_filestat_get";
    case 30:
      return "path_filestat_set_times";
    case 31:
      return "path_link";
    case 32:
      return "path_open";
    case 33:
      return "path_readlink";
    case 34:
      return "path_remove_directory";
    case 35:
      return "path_rename";
    case 36:
      return "path_symlink";
    case 37:
      return "path_unlink_file";
    default:
      return "unknown";
  }
};

/**
 * Wraps an async function to allow external termination via a rejection signal.
 *
 * @param fn The async function to wrap.
 * @returns An object containing the promise and a terminate function.
 */
export function wrap_async(fn: () => Promise<void>): {
  promise: Promise<void>;
  terminate: () => void;
} {
  let terminate: () => void = () => {
    throw new Error("terminate called before async function started");
  };
  const promise = new Promise<void>((resolve, reject) => {
    terminate = () => reject();
    fn().then((v) => {
      resolve(v);
    });
  });
  return { promise, terminate };
}