added concept of undo actions

used undo actions to delete the mod mail thread channel, if it already reached a certain state when initially setting up the mod mail thread

abstracto-application/core/core-interface/src/main/java/dev/sheldan/abstracto/core/exception/UndoActionException.java

@@ -0,0 +1,7 @@
+package dev.sheldan.abstracto.core.exception;
+
+public class UndoActionException extends AbstractoRunTimeException {
+    public UndoActionException(String message) {
+        super(message);
+    }
+}

abstracto-application/core/core-interface/src/main/java/dev/sheldan/abstracto/core/models/UndoAction.java

@@ -0,0 +1,5 @@
+package dev.sheldan.abstracto.core.models;
+
+public enum UndoAction {
+    DELETE_CHANNEL, DELETE_MESSAGE
+}

abstracto-application/core/core-interface/src/main/java/dev/sheldan/abstracto/core/models/UndoActionInstance.java

@@ -0,0 +1,24 @@
+package dev.sheldan.abstracto.core.models;
+
+import lombok.Builder;
+import lombok.Getter;
+import lombok.Setter;
+
+import java.util.Arrays;
+import java.util.List;
+
+@Getter
+@Builder
+@Setter
+public class UndoActionInstance {
+    private List<Long> ids;
+    private UndoAction action;
+
+    public static UndoActionInstance getChannelDeleteAction(Long channelId, Long serverId) {
+        return UndoActionInstance
+                .builder()
+                .action(UndoAction.DELETE_CHANNEL)
+                .ids(Arrays.asList(serverId, channelId))
+                .build();
+    }
+}

abstracto-application/core/core-interface/src/main/java/dev/sheldan/abstracto/core/service/ChannelService.java

@@ -27,6 +27,7 @@ public interface ChannelService {
     void editMessageInAChannel(MessageToSend messageToSend, AChannel channel, Long messageId);
     void editMessageInAChannel(MessageToSend messageToSend, MessageChannel channel, Long messageId);
     CompletableFuture<Void> deleteTextChannel(AChannel channel);
+    CompletableFuture<Void> deleteTextChannel(Long serverId, Long channelId);
     List<CompletableFuture<Message>> sendTemplateInChannel(String templateKey, Object model, MessageChannel channel);
 
     CompletableFuture<TextChannel> createTextChannel(String name, AServer server, Long categoryId);

abstracto-application/core/core-interface/src/main/java/dev/sheldan/abstracto/core/service/UndoActionService.java

@@ -0,0 +1,9 @@
+package dev.sheldan.abstracto.core.service;
+
+import dev.sheldan.abstracto.core.models.UndoActionInstance;
+
+import java.util.List;
+
+public interface UndoActionService {
+    void performActions(List<UndoActionInstance> actionsToPerform);
+}