Show and control channel subscriptions

Track the subscription state from the notifychannelsubscribed events, draw
subscribed and unsubscribed channels apart with the pack's icons (and the
built-in glyph as a hollow cone), and offer subscribe/unsubscribe entries —
channel and family — in the channel context menu.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

ts3-client/core/src/main/java/com/ts3client/net/ChannelNode.java

@@ -17,6 +17,8 @@ public final class ChannelNode {
     public int maxClients = -1;
     /** Id of the channel's custom icon in the server's file repository, or 0 for none. */
     public long iconId;
+    /** Whether the server sends us this channel's client list; set from the subscription events. */
+    public boolean subscribed;
 
     /** Populated when the tree is rebuilt. */
     public final List<ChannelNode> children = new ArrayList<>();
@@ -26,4 +28,35 @@ public final class ChannelNode {
         this.id = id;
         this.name = name;
     }
+
+    /** @return whether this channel or any channel below it is subscribed */
+    public boolean anySubscribed() {
+        if (subscribed) return true;
+        for (ChannelNode child : children) {
+            if (child.anySubscribed()) return true;
+        }
+        return false;
+    }
+
+    /** @return whether this channel and every channel below it is subscribed */
+    public boolean allSubscribed() {
+        if (!subscribed) return false;
+        for (ChannelNode child : children) {
+            if (!child.allSubscribed()) return false;
+        }
+        return true;
+    }
+
+    /** @return this channel's id, followed by those of the channels below it when {@code family} */
+    public List<Integer> familyIds(boolean family) {
+        List<Integer> ids = new ArrayList<>();
+        collectIds(family, ids);
+        return ids;
+    }
+
+    private void collectIds(boolean family, List<Integer> into) {
+        into.add(id);
+        if (!family) return;
+        for (ChannelNode child : children) child.collectIds(true, into);
+    }
 }

ts3-client/core/src/main/java/com/ts3client/net/TeamspeakConnection.java

@@ -2,6 +2,7 @@ package com.ts3client.net;
 
 import com.github.manevolent.ts3j.api.Channel;
 import com.github.manevolent.ts3j.api.Client;
+import com.github.manevolent.ts3j.command.MultiCommand;
 import com.github.manevolent.ts3j.command.SingleCommand;
 import com.github.manevolent.ts3j.command.parameter.CommandSingleParameter;
 import com.github.manevolent.ts3j.event.*;
@@ -24,6 +25,9 @@ import com.ts3client.sound.SoundNotifier;
 
 import java.io.File;
 import java.net.InetSocketAddress;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Consumer;
@@ -534,6 +538,28 @@ public final class TeamspeakConnection implements TS3Listener {
         }, "ts3j-move-channel").start();
     }
 
+    /**
+     * Subscribes to (or unsubscribes from) a set of channels in one command. The model
+     * is left alone: the server answers with the subscription events that update it.
+     */
+    public void setChannelsSubscribed(Collection<Integer> channelIds, boolean subscribed) {
+        if (channelIds.isEmpty()) return;
+        List<Integer> ids = List.copyOf(channelIds);
+        String name = subscribed ? "channelsubscribe" : "channelunsubscribe";
+        new Thread(() -> {
+            try {
+                List<SingleCommand> parts = new ArrayList<>(ids.size());
+                for (int id : ids) {
+                    parts.add(new SingleCommand(name, ProtocolRole.CLIENT,
+                            new CommandSingleParameter("cid", Integer.toString(id))));
+                }
+                client.executeCommand(new MultiCommand(name, ProtocolRole.CLIENT, parts)).complete();
+            } catch (Exception e) {
+                error((subscribed ? "Could not subscribe: " : "Could not unsubscribe: ") + rootMessage(e));
+            }
+        }, "ts3j-channel-subscribe").start();
+    }
+
     public void sendChannelMessage(String text) {
         new Thread(() -> {
             try {
@@ -926,6 +952,23 @@ public final class TeamspeakConnection implements TS3Listener {
         }
     }
 
+    @Override
+    public void onChannelSubscribed(ChannelSubscribedEvent e) {
+        setSubscribed(safeInt(e, "cid"), true);
+    }
+
+    @Override
+    public void onChannelUnsubscribed(ChannelUnsubscribedEvent e) {
+        setSubscribed(safeInt(e, "cid"), false);
+    }
+
+    private void setSubscribed(int cid, boolean subscribed) {
+        ChannelNode ch = model.getChannel(cid);
+        if (ch == null || ch.subscribed == subscribed) return;
+        ch.subscribed = subscribed;
+        ui.onModelChanged();
+    }
+
     @Override
     public void onServerEdit(ServerEditedEvent e) {
         if (has(e, "virtualserver_name")) model.setServerName(e.get("virtualserver_name"));