Fix dead links in ChatGPT responses (#1276)

application/src/main/java/org/togetherjava/tjbot/features/help/HelpSystemHelper.java

@@ -29,6 +29,7 @@
 import org.togetherjava.tjbot.features.chatgpt.ChatGptService;
 import org.togetherjava.tjbot.features.componentids.ComponentIdInteractor;
 import org.togetherjava.tjbot.features.utils.Guilds;
+import org.togetherjava.tjbot.features.utils.LinkDetection;
 
 import java.awt.Color;
 import java.time.Instant;
@@ -41,6 +42,7 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.StringJoiner;
+import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
 import java.util.function.Function;
@@ -57,6 +59,7 @@
 public final class HelpSystemHelper {
     private static final Logger logger = LoggerFactory.getLogger(HelpSystemHelper.class);
     private static final ChatGptModel CHAT_GPT_MODEL = ChatGptModel.FAST;
+    private static final String BROKEN_LINK_REPLACEMENT = "(broken link removed)";
 
     static final Color AMBIENT_COLOR = new Color(255, 255, 165);
 
@@ -74,6 +77,7 @@ public final class HelpSystemHelper {
 
     private final Database database;
     private final ChatGptService chatGptService;
+    private final Function<String, CompletableFuture<String>> brokenLinkReplacer;
     private static final int MAX_QUESTION_LENGTH = 200;
     private static final int MIN_QUESTION_LENGTH = 10;
     private static final String CHATGPT_FAILURE_MESSAGE =
@@ -87,9 +91,16 @@ public final class HelpSystemHelper {
      * @param chatGptService the service used to ask ChatGPT questions via the API.
      */
     public HelpSystemHelper(Config config, Database database, ChatGptService chatGptService) {
+        this(config, database, chatGptService,
+                answer -> LinkDetection.replaceBrokenLinks(answer, BROKEN_LINK_REPLACEMENT));
+    }
+
+    HelpSystemHelper(Config config, Database database, ChatGptService chatGptService,
+            Function<String, CompletableFuture<String>> brokenLinkReplacer) {
         HelpSystemConfig helpConfig = config.getHelpSystem();
         this.database = database;
         this.chatGptService = chatGptService;
+        this.brokenLinkReplacer = brokenLinkReplacer;
 
         isTagManageRole = Pattern.compile(config.getTagManageRolePattern()).asMatchPredicate();
         helpForumPattern = helpConfig.getHelpForumPattern();
@@ -188,6 +199,7 @@ RestAction<Message> constructChatGptAttempt(ThreadChannel threadChannel,
     public MessageEmbed generateGptResponseEmbed(String answer, SelfUser selfUser, String title,
             ChatGptModel model) {
         String responseByGptFooter = "- AI generated response using %s model".formatted(model);
+        String sanitizedAnswer = sanitizeBrokenLinks(answer);
 
         int embedTitleLimit = MessageEmbed.TITLE_MAX_LENGTH;
         String capitalizedTitle = Character.toUpperCase(title.charAt(0)) + title.substring(1);
@@ -199,12 +211,21 @@ public MessageEmbed generateGptResponseEmbed(String answer, SelfUser selfUser, S
         return new EmbedBuilder()
             .setAuthor(selfUser.getName(), null, selfUser.getEffectiveAvatarUrl())
             .setTitle(titleForEmbed)
-            .setDescription(answer)
+            .setDescription(sanitizedAnswer)
             .setColor(Color.pink)
             .setFooter(responseByGptFooter)
             .build();
     }
 
+    private String sanitizeBrokenLinks(String answer) {
+        try {
+            return brokenLinkReplacer.apply(answer).join();
+        } catch (RuntimeException runtimeException) {
+            logger.debug("Failed to replace broken links in ChatGPT response", runtimeException);
+            return answer;
+        }
+    }
+
     private Button generateDismissButton(ComponentIdInteractor componentIdInteractor, String id) {
         String buttonId = componentIdInteractor.generateComponentId(id);
         return Button.danger(buttonId, "Dismiss");

application/src/test/java/org/togetherjava/tjbot/features/help/HelpSystemHelperTest.java

@@ -0,0 +1,87 @@
+package org.togetherjava.tjbot.features.help;
+
+import net.dv8tion.jda.api.entities.MessageEmbed;
+import net.dv8tion.jda.api.entities.SelfUser;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import org.togetherjava.tjbot.config.Config;
+import org.togetherjava.tjbot.config.HelpSystemConfig;
+import org.togetherjava.tjbot.db.Database;
+import org.togetherjava.tjbot.db.generated.tables.HelpThreads;
+import org.togetherjava.tjbot.features.chatgpt.ChatGptModel;
+import org.togetherjava.tjbot.features.chatgpt.ChatGptService;
+
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+final class HelpSystemHelperTest {
+    private static final String ORIGINAL_ANSWER = """
+            Useful links:
+            - https://broken.example
+            - https://working.example
+            """;
+    private static final String SANITIZED_ANSWER = """
+            Useful links:
+            - (broken link removed)
+            - https://working.example
+            """;
+    private HelpSystemHelper helper;
+    private SelfUser selfUser;
+
+    @BeforeEach
+    void setUp() {
+        Config config = mock(Config.class);
+        HelpSystemConfig helpSystemConfig = mock(HelpSystemConfig.class);
+        when(config.getHelpSystem()).thenReturn(helpSystemConfig);
+        when(config.getTagManageRolePattern()).thenReturn("tag-manage");
+        when(helpSystemConfig.getHelpForumPattern()).thenReturn("questions");
+        when(helpSystemConfig.getCategories()).thenReturn(List.of("java"));
+        when(helpSystemConfig.getCategoryRoleSuffix()).thenReturn(" helper");
+
+        Database database = Database.createMemoryDatabase(HelpThreads.HELP_THREADS);
+        ChatGptService chatGptService = mock(ChatGptService.class);
+        helper = new HelpSystemHelper(config, database, chatGptService, answer -> CompletableFuture
+            .completedFuture(answer.replace("https://broken.example", "(broken link removed)")));
+
+        selfUser = mock(SelfUser.class);
+        when(selfUser.getName()).thenReturn("TJ-Bot");
+        when(selfUser.getEffectiveAvatarUrl()).thenReturn("https://example.com/avatar.png");
+    }
+
+    @Test
+    @DisplayName("Replaces broken links before building AI response embed")
+    void replacesBrokenLinksInGeneratedEmbed() {
+        MessageEmbed embed = helper.generateGptResponseEmbed(ORIGINAL_ANSWER, selfUser,
+                "example question", ChatGptModel.FAST);
+
+        assertEquals(SANITIZED_ANSWER, embed.getDescription());
+    }
+
+    @Test
+    @DisplayName("Keeps original answer if broken-link replacement fails")
+    void keepsOriginalAnswerWhenReplacementFails() {
+        Config config = mock(Config.class);
+        HelpSystemConfig helpSystemConfig = mock(HelpSystemConfig.class);
+        when(config.getHelpSystem()).thenReturn(helpSystemConfig);
+        when(config.getTagManageRolePattern()).thenReturn("tag-manage");
+        when(helpSystemConfig.getHelpForumPattern()).thenReturn("questions");
+        when(helpSystemConfig.getCategories()).thenReturn(List.of("java"));
+        when(helpSystemConfig.getCategoryRoleSuffix()).thenReturn(" helper");
+
+        Database database = Database.createMemoryDatabase(HelpThreads.HELP_THREADS);
+        ChatGptService chatGptService = mock(ChatGptService.class);
+        HelpSystemHelper failingHelper = new HelpSystemHelper(config, database, chatGptService,
+                _ -> CompletableFuture.failedFuture(new IllegalStateException("boom")));
+
+        MessageEmbed embed = failingHelper.generateGptResponseEmbed(ORIGINAL_ANSWER, selfUser,
+                "example question", ChatGptModel.FAST);
+
+        assertEquals(ORIGINAL_ANSWER, embed.getDescription());
+    }
+}