// Copyright 2022 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "echo_component.h"
// [START greeting]
#include <numeric>

namespace echo {

static std::string join(std::vector<std::string> &input_list,
                        const std::string &separator) {
  return std::accumulate(
      std::begin(input_list), std::end(input_list), std::string(""),
      [&separator](std::string current, std::string &next) {
        return current.empty() ? next : (std::move(current) + separator + next);
      });
}

// Return a proper greeting for the list
std::string greeting(std::vector<std::string> &names) {
  // Join the list of names based on length
  auto number_of_names = names.size();
  switch (number_of_names) {
  case 0:
    return "Nobody!";
  case 1:
    return join(names, "");
  case 2:
    return join(names, " and ");
  default:
    return join(names, ", ");
  }
}

} // namespace echo
// [END greeting]