telegram_example/src/main/java/org/telegram/updateshandlers/ChannelHandlers.java

package org.telegram.updateshandlers;

import org.telegram.BotConfig;
import org.telegram.telegrambots.TelegramApiException;
import org.telegram.telegrambots.api.methods.send.SendMessage;
import org.telegram.telegrambots.api.objects.Message;
import org.telegram.telegrambots.api.objects.Update;
import org.telegram.telegrambots.api.objects.replykeyboard.ForceReplyKeyboard;
import org.telegram.telegrambots.api.objects.replykeyboard.ReplyKeyboardMarkup;
import org.telegram.telegrambots.bots.TelegramLongPollingBot;
import org.telegram.telegrambots.logging.BotLogger;

import java.io.InvalidObjectException;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author Ruben Bermudez
 * @version 1.0
 * @brief Handler for updates to channel updates bot
 * This is a use case that will send a message to a channel if it is added as an admin to it.
 * @date 24 of June of 2015
 */
public class ChannelHandlers extends TelegramLongPollingBot {
    private static final String LOGTAG = "CHANNELHANDLERS";

    private static final int WAITINGCHANNEL = 1;

    private static final String HELP_TEXT = "Send me the channel username where you added me as admin.";
    private static final String CANCEL_COMMAND = "/stop";
    private static final String AFTER_CHANNEL_TEXT = "A message to provided channel will be sent if the bot was added to it as admin.";
    private static final String WRONG_CHANNEL_TEXT = "Wrong username, please remember to add *@* before the username and send only the username.";
    private static final String CHANNEL_MESSAGE_TEXT = "This message was sent by *@updateschannelbot*. Enjoy!";
    private static final String ERROR_MESSAGE_TEXT = "There was an error sending the message to channel *%s*, the error was: ```%s```";

    private final ConcurrentHashMap<Integer, Integer> userState = new ConcurrentHashMap<>();

    @Override
    public void onUpdateReceived(Update update) {
        try {
            Message message = update.getMessage();
            if (message != null && message.hasText()) {
                try {
                    handleIncomingMessage(message);
                } catch (InvalidObjectException e) {
                    BotLogger.severe(LOGTAG, e);
                }
            }
        } catch (Exception e) {
            BotLogger.error(LOGTAG, e);
        }
    }

    @Override
    public String getBotToken() {
        return BotConfig.TOKENCHANNEL;
    }


    @Override
    public String getBotUsername() {
        return BotConfig.USERNAMECHANNEL;
    }


    // region Incoming messages handlers

    private void handleIncomingMessage(Message message) throws InvalidObjectException {
        int state = userState.getOrDefault(message.getFrom().getId(), 0);
        switch(state) {
            case WAITINGCHANNEL:
                onWaitingChannelMessage(message);
                break;
            default:
                sendHelpMessage(message.getChatId().toString(), message.getMessageId(), null);
                userState.put(message.getFrom().getId(), WAITINGCHANNEL);
                break;
        }
    }

    private void onWaitingChannelMessage(Message message) throws InvalidObjectException {
        try {
            if (message.getText().equals(CANCEL_COMMAND)) {
                userState.remove(message.getFrom().getId());
                sendHelpMessage(message.getChatId().toString(), message.getMessageId(), null);
            } else {
                if (message.getText().startsWith("@") && !message.getText().trim().contains(" ")) {
                    sendMessage(getMessageToChannelSent(message));
                    sendMessageToChannel(message.getText(), message);
                    userState.remove(message.getFrom().getId());
                } else {
                    sendMessage(getWrongUsernameMessage(message));
                }
            }
        } catch (TelegramApiException e) {
            BotLogger.error(LOGTAG, e);
        }
    }

    private void sendMessageToChannel(String username, Message message) {
        SendMessage sendMessage = new SendMessage();
        sendMessage.enableMarkdown(true);
        sendMessage.setChatId(username.trim());

        sendMessage.setText(CHANNEL_MESSAGE_TEXT);
        sendMessage.enableMarkdown(true);

        try {
            sendMessage(sendMessage);
        } catch (TelegramApiException e) {
            sendErrorMessage(message, e.getMessage());
        }
    }

    private void sendErrorMessage(Message message, String errorText) {
        SendMessage sendMessage = new SendMessage();
        sendMessage.enableMarkdown(true);
        sendMessage.setChatId(message.getChatId().toString());
        sendMessage.setReplayToMessageId(message.getMessageId());

        sendMessage.setText(String.format(ERROR_MESSAGE_TEXT, message.getText().trim(), errorText.replace("\"", "\\\"")));
        sendMessage.enableMarkdown(true);

        try {
            sendMessage(sendMessage);
        } catch (TelegramApiException e) {
            BotLogger.error(LOGTAG, e);
        }
    }

    private static SendMessage getWrongUsernameMessage(Message message) {
        SendMessage sendMessage = new SendMessage();
        sendMessage.enableMarkdown(true);
        sendMessage.setChatId(message.getChatId().toString());
        sendMessage.setReplayToMessageId(message.getMessageId());

        ForceReplyKeyboard forceReplyKeyboard = new ForceReplyKeyboard();
        forceReplyKeyboard.setSelective(true);
        forceReplyKeyboard.setForceReply(true);
        sendMessage.setReplayMarkup(forceReplyKeyboard);

        sendMessage.setText(WRONG_CHANNEL_TEXT);
        sendMessage.enableMarkdown(true);
        return sendMessage;
    }

    private static SendMessage getMessageToChannelSent(Message message) {
        SendMessage sendMessage = new SendMessage();
        sendMessage.enableMarkdown(true);
        sendMessage.setChatId(message.getChatId().toString());
        sendMessage.setReplayToMessageId(message.getMessageId());

        sendMessage.setText(AFTER_CHANNEL_TEXT);
        return sendMessage;
    }

    private void sendHelpMessage(String chatId, Integer messageId, ReplyKeyboardMarkup replyKeyboardMarkup) {
        SendMessage sendMessage = new SendMessage();
        sendMessage.enableMarkdown(true);
        sendMessage.setChatId(chatId);
        sendMessage.setReplayToMessageId(messageId);
        if (replyKeyboardMarkup != null) {
            sendMessage.setReplayMarkup(replyKeyboardMarkup);
        }

        sendMessage.setText(HELP_TEXT);
        try {
            sendMessage(sendMessage);
        } catch (TelegramApiException e) {
            BotLogger.error(LOGTAG, e);
        }
    }
}