sunnymattas

  public static void main(String[] args) {
    String type = args[0];
    String message = args[1];
    if ("slack".equals(type) && isValidForSlack(message)) {
      Slack slack = new Slack();
      slack.send(message);
    } else if ("skype".equals(type) && isValidForSkype(message)) {
      Skype skype = new Skype();
      skype.send(message);
    } else if ("hangout".equals(type) && isValidForHangout(message)) {

sunnymattas

  public static void main(String[] args) {
    String type = args[0];
    String message = args[1];
    Messenger messanger;
    if ("slack".equals(type)) {
      messanger = new Slack();
    } else if ("skype".equals(type)) {
      messanger = new Skype();
    } else if ("hangout".equals(type)) {
      messanger = new Hangout();

sunnymattas

public class Slack implements Messenger {

  @Override
  public void send(final String message) {
    if (isValid(message)) {
      SlackClient client = new SlackClient();
      client.send(message);
    }
  }

sunnymattas

  public static void main(String[] args) {
    String type = args[0];
    String message = args[1];

    getMessengers().stream()
        .filter(messenger -> messenger.matches(type, message))
        .findFirst()
        .orElseThrow(
            () ->
                new MessageSendFailed(

sunnymattas

public interface Messenger {
  void send(String message);

  boolean matches(final String type,final String message);
}

public class Hangout implements Messenger {

  @Override
  public boolean matches(final String type, final String message) {

sunnymattas

public class Admin implements Messenger {

  @Override
  public boolean matches(final String type, final String message) {
    return getType().equalsIgnoreCase(type) && isValid(message);
  }

  @Override
  public String getType() {
    return "admin";

sunnymattas

    getMessengers().stream()
        .filter(messenger -> messenger.matches(type, message))
        .findFirst()
        .orElseThrow(
            () ->
                new MessageSendFailed(
                    String.format(
                        "Your message has invalid text or messenger '%s' or not supported.", type)))
        .send(message);

sunnymattas

public class Messengers implements ForwardingStream<Messenger> {
  private final List<Messenger> messengerList;

  public Messengers(List<Messenger> messengers) {
    this.messengerList = messengers;
  }

  @Override
  public Stream<Messenger> getStream() {
    return this.messengerList.stream();

sunnymattas

public class OptionalMessenger {
  private final Optional<Messenger> messenger;

  private OptionalMessenger(Optional<Messenger> messenger) {
    this.messenger = messenger;
  }

  public static OptionalMessenger of(Messenger messenger) {
    return new OptionalMessenger(Optional.of(messenger));
  }

sunnymattas

public class MessengerClient {

  public static void main(String[] args) {
    String type = args[0];
    String message = args[1];

    getMessengers().findMatchingMessenger(type, message).send(type, message);
  }

  private static Messengers getMessengers() {