delete blacklisted attachments from message and replace with webhook

src/main/java/net/discordjug/javabot/data/config/GuildConfig.java

@@ -18,6 +18,7 @@
 import java.lang.reflect.Field;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.util.List;
 import java.util.Optional;
 
 /**
@@ -37,6 +38,7 @@ public class GuildConfig {
 	private StarboardConfig starboardConfig;
 	private MessageCacheConfig messageCacheConfig;
 	private ServerLockConfig serverLockConfig;
+	private List<String> blacklistedMessageExtensions = List.of("jar", "exe", "zip");
 
 	/**
 	 * Constructor that initializes all Config classes.

src/main/java/net/discordjug/javabot/listener/filter/BlacklistedMessageAttachmentFilter.java

@@ -0,0 +1,41 @@
+package net.discordjug.javabot.listener.filter;
+
+import lombok.RequiredArgsConstructor;
+import net.discordjug.javabot.data.config.BotConfig;
+import net.discordjug.javabot.data.config.GuildConfig;
+import net.dv8tion.jda.api.EmbedBuilder;
+import net.dv8tion.jda.api.entities.Message;
+import net.dv8tion.jda.api.entities.MessageEmbed;
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+
+/**
+ * This {@link MessageFilter} blocks attachments blacklisted using {@link GuildConfig}.
+ */
+@Component
+@RequiredArgsConstructor
+public class BlacklistedMessageAttachmentFilter implements MessageFilter {
+
+	private final BotConfig botConfig;
+
+	@Override
+	public MessageModificationStatus processMessage(MessageContent content) {
+		MessageReceivedEvent event = content.event();
+		List<Message.Attachment> attachments = content.attachments();
+		List<MessageEmbed> embeds = content.embeds();
+		GuildConfig guildConfig = botConfig.get(event.getGuild());
+		List<String> blacklistedMessageExtensions = guildConfig.getBlacklistedMessageExtensions();
+		boolean removed = attachments.removeIf(attachment -> blacklistedMessageExtensions.contains(attachment.getFileExtension()));
+		if (removed) {
+			MessageEmbed attachmentRemovedInfo = new EmbedBuilder()
+					.setDescription("Disallowed attachments have been removed from this message.")
+					.build();
+			embeds.add(attachmentRemovedInfo);
+			return MessageModificationStatus.MODIFIED;
+		} else {
+			return MessageModificationStatus.NOT_MODIFIED;
+		}
+	}
+}

src/main/java/net/discordjug/javabot/listener/filter/HugFilter.java

@@ -0,0 +1,74 @@
+package net.discordjug.javabot.listener.filter;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Component;
+
+import java.util.Objects;
+import java.util.regex.Pattern;
+
+/**
+ * This {@link MessageFilter} replaces all occurrences of 'fuck' in incoming messages with 'hug'.
+ */
+@Component
+@RequiredArgsConstructor
+public class HugFilter implements MessageFilter {
+
+	private static final Pattern FUCKER = Pattern.compile(
+			"(fuck)(ing|er|ed|k+)?",
+			Pattern.CASE_INSENSITIVE
+	);
+
+	@Override
+	public MessageModificationStatus processMessage(MessageContent content) {
+		if (!content.event().getMessage().getMentions().getUsers().isEmpty()) {
+			return MessageModificationStatus.NOT_MODIFIED;
+		}
+		String before = content.messageText().toString();
+		String processed = replaceFucks(content.messageText().toString());
+		if (!before.equals(processed)) {
+			content.messageText().setLength(0);
+			content.messageText().append(processed);
+			return MessageModificationStatus.MODIFIED;
+		} else {
+			return MessageModificationStatus.NOT_MODIFIED;
+		}
+	}
+
+	private static String processHug(String originalText) {
+		// FucK -> HuG, FuCk -> Hug
+		return String.valueOf(copyCase(originalText, 0, 'h')) + copyCase(originalText, 1, 'u') +
+				copyCase(originalText, 3, 'g');
+	}
+
+	private static String replaceFucks(String str) {
+		return FUCKER.matcher(str).replaceAll(matchResult -> {
+			String theFuck = matchResult.group(1);
+			String suffix = Objects.requireNonNullElse(matchResult.group(2), "");
+			String processedSuffix = switch (suffix.toLowerCase()) {
+				case "er", "ed", "ing" -> copyCase(suffix, 0, 'g') + suffix; // fucking, fucker, fucked
+				case "" -> ""; // just fuck
+				default -> copyCase(suffix, "g".repeat(suffix.length())); // fuckkkkk...
+			};
+			return processHug(theFuck) + processedSuffix;
+		});
+	}
+
+	private static String copyCase(String source, String toChange) {
+		if (source.length() != toChange.length()) {
+			throw new IllegalArgumentException("lengths differ");
+		}
+		StringBuilder sb = new StringBuilder();
+		for (int i = 0; i < source.length(); i++) {
+			sb.append(copyCase(source, i, toChange.charAt(i)));
+		}
+		return sb.toString();
+	}
+
+	private static char copyCase(String original, int index, char newChar) {
+		if (Character.isUpperCase(original.charAt(index))) {
+			return Character.toUpperCase(newChar);
+		} else {
+			return newChar;
+		}
+	}
+}

src/main/java/net/discordjug/javabot/listener/filter/MessageContent.java

@@ -0,0 +1,20 @@
+package net.discordjug.javabot.listener.filter;
+
+import net.dv8tion.jda.api.entities.Message;
+import net.dv8tion.jda.api.entities.MessageEmbed;
+import net.dv8tion.jda.api.events.message.MessageReceivedEvent;
+
+import java.util.List;
+
+/**
+ * A class containing modifiable content of a message that has been received.
+ * @param event 		The event associated with receiving the message
+ * @param messageText 	The text associated with the message
+ * @param attachments 	The attachments associated with the message
+ * @param embeds 		The embeds associated with the message
+ */
+public record MessageContent(MessageReceivedEvent event,
+							StringBuilder messageText,
+							List<Message.Attachment> attachments,
+							List<MessageEmbed> embeds) {
+}

src/main/java/net/discordjug/javabot/listener/filter/MessageFilter.java

@@ -0,0 +1,23 @@
+package net.discordjug.javabot.listener.filter;
+
+/**
+ * This interface is implemented by all message filters.
+ *
+ * The {@link MessageContent} is processed by every class implementing {@link MessageFilter}
+ * unless one of the filters returns {@link MessageModificationStatus#STOP_PROCESSING} which stops further filters from executing.
+ */
+public interface MessageFilter {
+
+	/**
+	 * When a message is received, it is processed by the registered filters.
+	 *
+	 * @param content The content of the new message that will be reposted instead of the received message
+	 * if at least one filter returns {@link MessageModificationStatus#MODIFIED}
+	 * and no filter returns {@link MessageModificationStatus#STOP_PROCESSING}.
+	 * This {@link MessageContent} is built up incrementally by the filters.
+	 * @return the appropriate {@link MessageModificationStatus} based on the filter's processing.
+	 * @see MessageFilterHandler
+	 */
+	MessageModificationStatus processMessage(MessageContent content);
+
+}