automatically clear old help notifications

Author: danthe1st

src/main/java/net/discordjug/javabot/systems/help/ClearOldHelpNotificationJob.java

@@ -0,0 +1,73 @@
+package net.discordjug.javabot.systems.help;
+
+import java.time.OffsetDateTime;
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Service;
+
+import lombok.RequiredArgsConstructor;
+import net.discordjug.javabot.data.config.BotConfig;
+import net.discordjug.javabot.util.ExceptionLogger;
+import net.dv8tion.jda.api.JDA;
+import net.dv8tion.jda.api.entities.Guild;
+import net.dv8tion.jda.api.entities.Message;
+import net.dv8tion.jda.api.entities.MessageHistory;
+import net.dv8tion.jda.api.entities.channel.concrete.TextChannel;
+
+/**
+ * Automatically delete old help notifications.
+ * Once a day, this class deletes old messages of the bot in the help notification channel.
+ */
+@Service
+@RequiredArgsConstructor
+public class ClearOldHelpNotificationJob {
+	private final BotConfig botConfig;
+	private final JDA jda;
+	
+	/**
+	 * Runs the message deletion.
+	 */
+	@Scheduled(cron="0 0 0 * * *")//00:00 UTC
+	public void execute() {
+		for (Guild guild : jda.getGuilds()) {
+			TextChannel helpNotificationChannel = botConfig.get(guild).getHelpConfig().getHelpNotificationChannel();
+			if(helpNotificationChannel != null) {
+				MessageHistory history = helpNotificationChannel.getHistory();
+				deleteOldMessagesInChannel(helpNotificationChannel, history, new ArrayList<>());
+			}
+		}
+	}
+
+	private void deleteOldMessagesInChannel(TextChannel helpNotificationChannel, MessageHistory history, List<Message> foundSoFar) {
+		history.retrievePast(50).queue(msgs -> {
+			boolean deleteMore = addMessagesToDelete(foundSoFar, msgs);
+			if (deleteMore) {
+				deleteOldMessagesInChannel(helpNotificationChannel, history, foundSoFar);
+			}else {
+				helpNotificationChannel.purgeMessages(foundSoFar);
+			}
+		}, e -> {
+			ExceptionLogger.capture(e, getClass().getName());
+			helpNotificationChannel.purgeMessages(foundSoFar);
+		});
+	}
+
+	private boolean addMessagesToDelete(List<Message> toDelete, List<Message> msgs) {
+		for (Message message : msgs) {
+			if (message.getAuthor().getIdLong() == message.getJDA().getSelfUser().getIdLong() &&
+					//only delete messages older than 5 days
+					message.getTimeCreated().isBefore(OffsetDateTime.now().minusDays(5))) {
+				
+				//only messages sent within the past two weeks can be deleted
+				//stop when messages near that are found
+				if (message.getTimeCreated().isBefore(OffsetDateTime.now().minusDays(13))) {
+					return false;
+				}
+				toDelete.add(message);
+			}
+		}
+		return true;
+	}
+}