feat: add QuizQuestion and TriviaManager classes for Java trivia game

app/src/main/java/com/togetherjava/tjplays/Bot.java

@@ -4,6 +4,7 @@
 import java.nio.file.Path;
 import java.util.List;
 import com.togetherjava.tjplays.listeners.commands.*;
+import com.togetherjava.tjplays.trivia.TriviaManager;
 
 import net.dv8tion.jda.api.JDA;
 import net.dv8tion.jda.api.JDABuilder;
@@ -32,9 +33,12 @@ private static JDA createBot(Config config) {
     }
 
     private static List<SlashCommand> getCommands(Config config) {
-        return List.of(
+        // Construct JavaQuizCommand with TriviaManager and ChatGptService
+        TriviaManager triviaManager = new TriviaManager(new com.togetherjava.tjplays.services.chatgpt.ChatGptService(config.openAIApiKey()));
+        return java.util.Arrays.asList(
             new PingCommand(),
-            new Game2048Command()
+            new Game2048Command(),
+            new JavaQuizCommand(triviaManager)
         );
     }
 }

app/src/main/java/com/togetherjava/tjplays/listeners/commands/JavaQuizCommand.java

@@ -0,0 +1,117 @@
+package com.togetherjava.tjplays.listeners.commands;
+
+import com.togetherjava.tjplays.trivia.QuizQuestion;
+import com.togetherjava.tjplays.trivia.TriviaManager;
+
+import net.dv8tion.jda.api.events.interaction.command.SlashCommandInteractionEvent;
+import net.dv8tion.jda.api.events.interaction.component.ButtonInteractionEvent;
+import net.dv8tion.jda.api.interactions.commands.build.Commands;
+import net.dv8tion.jda.api.interactions.components.buttons.Button;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+
+/**
+ * Handles the /javaquiz command, presenting Java trivia questions to users.
+ * Uses TriviaManager to fetch questions and manages user quiz state.
+ * Future contributors can extend this for more quiz features.
+ */
+public final class JavaQuizCommand extends SlashCommand {
+    private static final String COMMAND_NAME = "javaquiz";
+
+    private final TriviaManager triviaManager;
+    // messageId -> QuizQuestion
+    private final ConcurrentHashMap<String, QuizQuestion> activeQuestions = new ConcurrentHashMap<>();
+    // userId -> messageId
+    private final ConcurrentHashMap<String, String> userActiveQuiz = new ConcurrentHashMap<>();
+
+    /**
+     * Constructs a JavaQuizCommand with a TriviaManager instance.
+     * @param triviaManager the TriviaManager to use for fetching questions
+     */
+    public JavaQuizCommand(TriviaManager triviaManager) {
+        super(Commands.slash(COMMAND_NAME, "Get a random Java trivia question"));
+        this.triviaManager = triviaManager;
+    }
+
+    @Override
+    public void onSlashCommand(SlashCommandInteractionEvent event) {
+        String userId = event.getUser().getId();
+        // Prevent new quiz if user has an active one
+        if (userActiveQuiz.containsKey(userId)) {
+            event.reply("You already have an active quiz. Please answer it before starting a new one.").setEphemeral(true).queue();
+            return;
+        }
+
+        event.deferReply().queue();
+
+        Optional<QuizQuestion> question = triviaManager.fetchRandomQuestion();
+        if (question.isEmpty()) {
+            event.getHook().editOriginal("Could not fetch a quiz question. Try again later.").queue();
+            return;
+        }
+
+        QuizQuestion quizQuestion = question.get();
+        List<String> choices = quizQuestion.getChoices();
+
+        String quizContent = String.format("**Java Quiz**\n\n%s\n\n%s",
+            quizQuestion.getQuestion(),
+            java.util.stream.IntStream.range(0, choices.size())
+                .mapToObj(i -> String.format("`%d`) %s", i + 1, choices.get(i)))
+                .collect(java.util.stream.Collectors.joining("\n"))
+        );
+
+        String messageId = event.getHook().editOriginal(quizContent)
+                .setActionRow(
+                    Button.primary(COMMAND_NAME + "-1-" + userId, "1"),
+                    Button.primary(COMMAND_NAME + "-2-" + userId, "2"),
+                    Button.primary(COMMAND_NAME + "-3-" + userId, "3"),
+                    Button.primary(COMMAND_NAME + "-4-" + userId, "4")
+                )
+                .complete()
+                .getId();
+
+        activeQuestions.put(messageId, quizQuestion);
+        userActiveQuiz.put(userId, messageId);
+    }
+
+    @Override
+    public void onButtonInteraction(ButtonInteractionEvent event) {
+        String buttonId = event.getButton().getId();
+        if (buttonId == null || !buttonId.startsWith(COMMAND_NAME)) {
+            return;
+        }
+
+        if (!buttonId.contains(event.getUser().getId())) {
+            event.reply("This isn't your quiz!").setEphemeral(true).queue();
+            return;
+        }
+
+        String userId = event.getUser().getId();
+        QuizQuestion quizQuestion = activeQuestions.remove(event.getMessageId());
+        // Remove user's active quiz
+        userActiveQuiz.remove(userId);
+        if (quizQuestion == null) {
+            event.reply("This quiz has already been answered.").setEphemeral(true).queue();
+            return;
+        }
+
+        int chosen = Character.getNumericValue(buttonId.charAt(COMMAND_NAME.length() + 1)) - 1;
+        boolean correct = chosen == quizQuestion.getCorrectAnswerIndex();
+
+        String correctAnswer = quizQuestion.getChoices().get(quizQuestion.getCorrectAnswerIndex());
+        String result = correct
+            ? "Correct! The answer is: **" + correctAnswer + "**"
+            : "Wrong! The correct answer was: **" + correctAnswer + "**";
+
+        event.editMessage(event.getMessage().getContentRaw() + "\n\n" + result)
+                .setActionRow(
+                    Button.primary(COMMAND_NAME + "-1-" + userId, "1").asDisabled(),
+                    Button.primary(COMMAND_NAME + "-2-" + userId, "2").asDisabled(),
+                    Button.primary(COMMAND_NAME + "-3-" + userId, "3").asDisabled(),
+                    Button.primary(COMMAND_NAME + "-4-" + userId, "4").asDisabled()
+                )
+                .queue();
+    }
+}

app/src/main/java/com/togetherjava/tjplays/services/chatgpt/ChatGptService.java

@@ -11,7 +11,6 @@
 
 import java.time.Duration;
 import java.util.List;
-import java.util.Objects;
 import java.util.Optional;
 
 /**

app/src/main/java/com/togetherjava/tjplays/trivia/QuizQuestion.java

@@ -0,0 +1,34 @@
+package com.togetherjava.tjplays.trivia;
+
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import java.util.List;
+
+/**
+ * Represents a single quiz question for Java trivia.
+ * Used by TriviaManager and JavaQuizCommand to display questions and validate answers.
+ * Future contributors can use this for any quiz/trivia feature needing a question, choices, and answer index.
+ */
+public record QuizQuestion(
+    @JsonProperty("question") String question,
+    @JsonProperty("choices") List<String> choices,
+    @JsonProperty("correct") int correctAnswerIndex
+) {
+    @JsonCreator
+    public QuizQuestion {}
+
+    public String getQuestion() {
+        return question;
+    }
+
+    public List<String> getChoices() {
+        return choices;
+    }
+
+    /**
+     * Returns the index of the correct answer in the choices list.
+     */
+    public int getCorrectAnswerIndex() {
+        return correctAnswerIndex;
+    }
+}

app/src/main/java/com/togetherjava/tjplays/trivia/TriviaManager.java

@@ -0,0 +1,34 @@
+package com.togetherjava.tjplays.trivia;
+
+import com.togetherjava.tjplays.services.chatgpt.ChatGptService;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import java.util.Optional;
+
+/**
+ * Manages Java trivia questions using ChatGptService.
+ * Used by quiz commands to fetch questions for users.
+ * Future contributors can use this for any trivia/quiz feature.
+ */
+public class TriviaManager {
+    private final ChatGptService chatGptService;
+    private final ObjectMapper mapper = new ObjectMapper();
+
+    public TriviaManager(ChatGptService chatGptService) {
+        this.chatGptService = chatGptService;
+    }
+
+    public Optional<QuizQuestion> fetchRandomQuestion() {
+        String prompt = "Provide one Java trivia question as a JSON object like"
+                + " {\"question\":\"...\",\"choices\":[\"A\",\"B\",\"C\",\"D\"],\"correct\":<index>}";
+        Optional<String> raw = chatGptService.ask(prompt, "java quiz");
+        if (raw.isEmpty()) {
+            return Optional.empty();
+        }
+        try {
+            QuizQuestion question = mapper.readValue(raw.get(), QuizQuestion.class);
+            return Optional.of(question);
+        } catch (Exception e) {
+            return Optional.empty();
+        }
+    }
+}