MotD (#13655)

* MOTD

* Message of the Day

* Pretty sure the tests aren't me. Let's check.

* Update Content.Shared/CCVar/CCVars.cs

Co-authored-by: AJCM-git <60196617+AJCM-git@users.noreply.github.com>

* command dependencies and moving MOTD to its own system

* Some doc comments

* Let's try those tests again

* More doc comments, most of the github reviews, and aliases for get-motd and set-motd

* Clear test MOTD

* Localized motd commands and completion hints

* Makes set-motd only show up in the alias command if the player has access to it.

---------

Co-authored-by: AJCM-git <60196617+AJCM-git@users.noreply.github.com>

Content.Server/Motd/MOTDSystem.cs

@@ -0,0 +1,101 @@
+using Content.Server.Chat.Managers;
+using Content.Server.GameTicking;
+using Content.Shared.CCVar;
+using Content.Shared.Chat;
+using Robust.Server.Player;
+using Robust.Shared.Console;
+using Robust.Shared.Configuration;
+
+namespace Content.Server.Motd;
+
+/// <summary>
+/// The system that handles broadcasting the Message Of The Day to players when they join the lobby/the MOTD changes/they ask for it to be printed.
+/// </summary>
+public sealed class MOTDSystem : EntitySystem
+{
+    [Dependency] private readonly IChatManager _chatManager = default!;
+    [Dependency] private readonly IConfigurationManager _configurationManager = default!;
+
+    /// <summary>
+    /// The cached value of the Message of the Day. Used for fast access.
+    /// </summary>
+    private string _messageOfTheDay = "";
+
+    public override void Initialize()
+    {
+        base.Initialize();
+        _configurationManager.OnValueChanged(CCVars.MOTD, OnMOTDChanged, invokeImmediately: true);
+        SubscribeLocalEvent<PlayerJoinedLobbyEvent>(OnPlayerJoinedLobby);
+    }
+
+    public override void Shutdown()
+    {
+        _configurationManager.UnsubValueChanged(CCVars.MOTD, OnMOTDChanged);
+        base.Shutdown();
+    }
+
+    /// <summary>
+    /// Sends the Message Of The Day, if any, to all connected players.
+    /// </summary>
+    public void TrySendMOTD()
+    {
+        if (string.IsNullOrEmpty(_messageOfTheDay))
+            return;
+        
+        var wrappedMessage = Loc.GetString("motd-wrap-message", ("motd", _messageOfTheDay));
+        _chatManager.ChatMessageToAll(ChatChannel.Server, _messageOfTheDay, wrappedMessage, source: EntityUid.Invalid, hideChat: false, recordReplay: true);
+    }
+
+    /// <summary>
+    /// Sends the Message Of The Day, if any, to a specific player.
+    /// </summary>
+    public void TrySendMOTD(IPlayerSession player)
+    {
+        if (string.IsNullOrEmpty(_messageOfTheDay))
+            return;
+        
+        var wrappedMessage = Loc.GetString("motd-wrap-message", ("motd", _messageOfTheDay));
+        _chatManager.ChatMessageToOne(ChatChannel.Server, _messageOfTheDay, wrappedMessage, source: EntityUid.Invalid, hideChat: false, client: player.ConnectedClient);
+    }
+
+    /// <summary>
+    /// Sends the Message Of The Day, if any, to a specific player's console and chat.
+    /// </summary>
+    /// <remarks>
+    /// This is used by the MOTD console command because we can't tell whether the player is using `console or /console so we send the message to both.
+    /// </remarks>
+    public void TrySendMOTD(IConsoleShell shell)
+    {
+        if (string.IsNullOrEmpty(_messageOfTheDay))
+            return;
+        
+        var wrappedMessage = Loc.GetString("motd-wrap-message", ("motd", _messageOfTheDay));
+        shell.WriteLine(wrappedMessage);
+        if (shell.Player is IPlayerSession player)
+            _chatManager.ChatMessageToOne(ChatChannel.Server, _messageOfTheDay, wrappedMessage, source: EntityUid.Invalid, hideChat: false, client: player.ConnectedClient);
+    }
+
+    #region Event Handlers
+
+    /// <summary>
+    /// Posts the Message Of The Day to any players who join the lobby.
+    /// </summary>
+    private void OnPlayerJoinedLobby(PlayerJoinedLobbyEvent ev)
+    {
+        TrySendMOTD(ev.PlayerSession);
+    }
+
+    /// <summary>
+    /// Broadcasts changes to the Message Of The Day to all players.
+    /// </summary>
+    private void OnMOTDChanged(string val)
+    {
+        if (val == _messageOfTheDay)
+            return;
+        
+        _messageOfTheDay = val;
+        TrySendMOTD();
+    }
+
+    #endregion Event Handlers
+}