Chat Preview API

[BillyGalbreath]

Opening this as a PR to get feedback before merging in.

Speak now, or forever hold your peace ;)

How this works

1. The client will send a chat preview packet to the server with every keystroke into the chat textbox containing a query string of the textbox contents.
2. The server will try to decorate this query and return it to the client.
3. The client will determine if the decorated text differs from the text box contents when the chat message is sent (enter key pressed).
   • If the decoration differs, the signature is made from the contents of the decoration.
   • If the text is the same, the signature is made from the contents of the original message.
4. The server will receive the chat message and try to decorate the message again
   • If the decoration differs, the signature of the decoration is used to verify the message
   • If the text is the same, the signature of the original message is used to verify the message
5. The server then displays the original message in the chat box.
   • Note that because of this, your preview should match whatever your chat event does for the desired results.

Example usage

This is a simple plugin to convert raw input to minimessage, do not do this on production..

public class TestPlugin extends JavaPlugin {
    @Override
    public void onEnable() {
        getServer().getPluginManager().registerEvents(new Listener() {
            @EventHandler
            public void on(PlayerPreviewChatEvent event) {
                event.setQuery(handleChat(event.getQuery()));
            }

            @EventHandler
            public void on(AsyncChatEvent event) {
                event.message(handleChat(event.message()));
            }

            private Component handleChat(Component component) {
                String raw = LegacyComponentSerializer.legacyAmpersand().serialize(component);
                return MiniMessage.miniMessage().deserialize(raw);
            }
        }, this);
    }
}

[encode42]

Haven't tested, but code looks good to me

[YouHaveTrouble]

Tested for a little bit, seems to work just fine.