Added categorizing of active question overview

Author: Zabuzard

application/config.json.template

@@ -30,12 +30,12 @@
        "categories": [
            "Java",
            "Frameworks",
-           "JavaFX/Swing",
+           "JavaFX|Swing",
            "IDE",
            "Build Tools",
            "Database",
            "Android",
-           "C/C++",
+           "C|C++",
            "Algorithms",
            "Math",
            "Architecture",

application/src/main/java/org/togetherjava/tjbot/commands/help/HelpThreadOverviewUpdater.java

@@ -14,18 +14,21 @@
 import org.togetherjava.tjbot.config.HelpSystemConfig;
 
 import java.awt.Color;
-import java.util.List;
-import java.util.Optional;
-import java.util.StringJoiner;
+import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Predicate;
+import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 
 // FIXME Javadoc
 public final class HelpThreadOverviewUpdater extends MessageReceiverAdapter implements Routine {
     private static final Logger logger = LoggerFactory.getLogger(HelpThreadOverviewUpdater.class);
 
     private static final Color AMBIENT_COLOR = Color.decode("#CCCC00");
+    // FIXME Reduce code duplication with similar pattern in ChangeHelpCategoryCommand
+    private static final Pattern EXTRACT_CATEGORY_PATTERN =
+            Pattern.compile("(?:\\[(?<category>.+)] )?(?<title>.+)");
 
     private final HelpSystemConfig config;
     private final Predicate<String> isOverviewChannelName;
@@ -108,22 +111,15 @@ private void updateOverview(@NotNull Guild guild) {
         return maybeChannel;
     }
 
-    private static void updateOverview(@NotNull IThreadContainer stagingChannel,
+    private void updateOverview(@NotNull IThreadContainer stagingChannel,
             @NotNull MessageChannel overviewChannel) {
         List<ThreadChannel> activeThreads = stagingChannel.getThreadChannels()
             .stream()
             .filter(Predicate.not(ThreadChannel::isArchived))
             .toList();
 
-        // FIXME Do not add prefix if empty... (this should be reworked for nicer UI anyways)
-        StringJoiner description = new StringJoiner("\n• ", "• ", "");
-
-        for (ThreadChannel thread : activeThreads) {
-            description.add(thread.getAsMention());
-        }
-
         MessageEmbed embed = new EmbedBuilder().setTitle("Active questions")
-            .setDescription(description.toString())
+            .setDescription(createDescription(activeThreads))
             .setColor(AMBIENT_COLOR)
             .build();
 
@@ -137,6 +133,40 @@ private static void updateOverview(@NotNull IThreadContainer stagingChannel,
         }).queue();
     }
 
+    private @NotNull String createDescription(@NotNull Collection<ThreadChannel> activeThreads) {
+        if (activeThreads.isEmpty()) {
+            return "Currently none.";
+        }
+
+        List<String> allCategories = config.getCategories();
+
+        return activeThreads.stream()
+            .collect(Collectors
+                .groupingBy(thread -> getCategoryOfChannel(thread).orElse("Uncategorized")))
+            .entrySet()
+            .stream()
+            .map(CategoryWithThreads::ofEntry)
+            .sorted(Comparator.comparingInt(categoryWithThreads -> {
+                // Order based on config, unknown categories last
+                int indexOfCategory = allCategories.indexOf(categoryWithThreads.category);
+                if (indexOfCategory == -1) {
+                    return Integer.MAX_VALUE;
+                }
+                return indexOfCategory;
+            }))
+            .map(CategoryWithThreads::toDiscordString)
+            .collect(Collectors.joining("\n\n"));
+    }
+
+    private static @NotNull Optional<String> getCategoryOfChannel(@NotNull Channel channel) {
+        Matcher matcher = EXTRACT_CATEGORY_PATTERN.matcher(channel.getName());
+        if (!matcher.find()) {
+            return Optional.empty();
+        }
+
+        return Optional.ofNullable(matcher.group("category"));
+    }
+
     private static @NotNull RestAction<Optional<Message>> getLastMessage(
             @NotNull MessageChannel channel) {
         return channel.getHistory().retrievePast(1).map(messages -> messages.stream().findFirst());
@@ -146,4 +176,22 @@ private enum ChannelType {
         OVERVIEW,
         STAGING
     }
+
+    private record CategoryWithThreads(@NotNull String category,
+            @NotNull List<ThreadChannel> threads) {
+
+        String toDiscordString() {
+            String threadListText = threads.stream()
+                .map(ThreadChannel::getAsMention)
+                .collect(Collectors.joining("\n• ", "• ", ""));
+
+            return "**%s**:%n%s".formatted(category, threadListText);
+        }
+
+        static @NotNull CategoryWithThreads ofEntry(
+                Map.@NotNull Entry<String, ? extends List<ThreadChannel>> categoryAndThreads) {
+            return new CategoryWithThreads(categoryAndThreads.getKey(),
+                    categoryAndThreads.getValue());
+        }
+    }
 }