prevent nation leader from leaving the nation

Author: zefir-git

src/main/java/pro/cloudnode/smp/smpcore/Messages.java

@@ -423,6 +423,10 @@ public Messages() {
         return MiniMessage.miniMessage().deserialize(Objects.requireNonNull(config.getString("error.kick-leadership")));
     }
 
+    public @NotNull Component errorLeaderLeave() {
+        return MiniMessage.miniMessage().deserialize(Objects.requireNonNull(config.getString("error.leader-leave")));
+    }
+
     public @NotNull Component errorNationNotFound(final @NotNull String nation) {
         return MiniMessage.miniMessage().deserialize(Objects.requireNonNull(config.getString("error.nation-not-found")), Placeholder.unparsed("nation", nation));
     }

src/main/java/pro/cloudnode/smp/smpcore/Nation.java

@@ -139,6 +139,18 @@ public void add(final @NotNull Member member) {
     }
 
     public void remove(final @NotNull Member member) {
+        if (!id.equals(member.nationID))
+            throw new IllegalStateException("Member " + member.uuid + " is not in nation " + id);
+        if (member.uuid.equals(leaderUUID))
+            throw new IllegalStateException("Cannot remove leader " + member.uuid + " from nation " + id);
+
+        Audience.audience(onlinePlayers()).sendMessage(SMPCore.messages().nationJoinLeft(member));
+
+        if (member.uuid.equals(viceLeaderUUID)) {
+            this.viceLeaderUUID = this.leaderUUID;
+            save();
+        }
+
         member.nationID = null;
         member.save();
         getTeam().removePlayer(member.player());

src/main/java/pro/cloudnode/smp/smpcore/command/NationCommand.java

@@ -215,13 +215,19 @@ public boolean join(
         if (member == null)
             return sendMessage(sender, SMPCore.messages().errorNotMember());
 
-        if (!hasAnyPermission(sender, Permission.NATION_JOIN_REQUEST, Permission.NATION_INVITE_ACCEPT) || (
-                member.nationID != null && !hasAnyPermission(
-                        sender,
-                        Permission.NATION_JOIN_REQUEST_SWITCH,
-                        Permission.NATION_INVITE_ACCEPT_SWITCH
-                )
-        ))
+        if (member.nationID != null) {
+            if (!hasAnyPermission(
+                    sender,
+                    Permission.NATION_JOIN_REQUEST_SWITCH,
+                    Permission.NATION_INVITE_ACCEPT_SWITCH
+            ))
+                return sendMessage(sender, SMPCore.messages().errorAlreadyCitizen());
+            final @NotNull Nation nation = member.nation().orElseThrow(() -> new IllegalStateException("Could not find nation " + member.nationID + " of member " + member.uuid));
+            if (member.uuid.equals(nation.leaderUUID))
+                return sendMessage(sender, SMPCore.messages().errorLeaderLeave());
+        }
+
+        if (!hasAnyPermission(sender, Permission.NATION_JOIN_REQUEST, Permission.NATION_INVITE_ACCEPT))
             return sendMessage(sender, SMPCore.messages().errorNoPermission());
 
         if (args.length < 1)

src/main/resources/messages.yml

@@ -86,6 +86,7 @@ error:
   not-citizen: <red>(!) Member <gray><player></gray> is not a citizen of the nation.</red>
   not-player: <red>(!) You must be a player to use this command.</red>
   kick-leadership: <red>(!) You cannot kick a member of the nation's leadership.</red>
+  leader-leave: <red>(!) You cannot leave your nation because you are the leader!</red>
   nation-not-found: <red>(!) Nation <gray><nation></gray> not found.</red>
   already-citizen: <red>(!) You are already a citizen of a nation.</red>
   already-citizen-nation: <red>(!) You are already a citizen of <gray><nation></gray>.</red>