1 files changed, 60 insertions, 4 deletions

diff --git a/include/modules/ircv3.h b/include/modules/ircv3.h
index e03ee16fa..338abdeba 100644
--- a/include/modules/ircv3.h
+++ b/include/modules/ircv3.h
@@ -19,27 +19,83 @@
 
 #pragma once
 
+#include "modules/cap.h"
+
 namespace IRCv3
 {
 	class WriteNeighborsWithCap;
+	template <typename T>
+	class CapTag;
 }
 
 class IRCv3::WriteNeighborsWithCap : public User::ForEachNeighborHandler
 {
 	const Cap::Capability& cap;
-	const std::string& msg;
+	ClientProtocol::Event& protoev;
 
 	void Execute(LocalUser* user) CXX11_OVERRIDE
 	{
 		if (cap.get(user))
-			user->Write(msg);
+			user->Send(protoev);
 	}
 
  public:
-	WriteNeighborsWithCap(User* user, const std::string& message, const Cap::Capability& capability)
+	WriteNeighborsWithCap(User* user, ClientProtocol::Event& ev, const Cap::Capability& capability)
 		: cap(capability)
-		, msg(message)
+		, protoev(ev)
 	{
 		user->ForEachNeighbor(*this, false);
 	}
 };
+
+/** Base class for simple message tags.
+ * Message tags provided by classes derived from this class will be sent to clients that have negotiated
+ * a client capability, also managed by this class.
+ *
+ * Derived classes specify the name of the capability and the message tag and provide a public GetValue()
+ * method with the following signature: const std::string* GetValue(ClientProtocol::Message& msg).
+ * The returned value determines whether to attach the tag to the message. If it is NULL, the tag won't
+ * be attached. If it is non-NULL the tag will be attached with the value in the string. If the string is
+ * empty the tag is attached without a value.
+ *
+ * Providers inheriting from this class don't accept incoming tags by default.
+ *
+ * For more control, inherit from ClientProtocol::MessageTagProvider directly.
+ *
+ * Template parameter T is the derived class.
+ */
+template <typename T>
+class IRCv3::CapTag : public ClientProtocol::MessageTagProvider
+{
+	Cap::Capability cap;
+	const std::string tagname;
+
+	bool ShouldSendTag(LocalUser* user, const ClientProtocol::MessageTagData& tagdata) CXX11_OVERRIDE
+	{
+		return cap.get(user);
+	}
+
+	void OnClientProtocolPopulateTags(ClientProtocol::Message& msg) CXX11_OVERRIDE
+	{
+		T& tag = static_cast<T&>(*this);
+		const std::string* const val = tag.GetValue(msg);
+		if (val)
+			msg.AddTag(tagname, this, *val);
+	}
+
+ public:
+	/** Constructor.
+	 * @param mod Module that owns the tag.
+	 * @param capname Name of the client capability.
+	 * A client capability with this name will be created. It will be available to all clients and it won't
+	 * have a value.
+	 * See Cap::Capability for more info on client capabilities.
+	 * @param Tagname Name of the message tag, to use in the protocol.
+	 */
+	CapTag(Module* mod, const std::string& capname, const std::string& Tagname)
+		: ClientProtocol::MessageTagProvider(mod)
+		, cap(mod, capname)
+		, tagname(Tagname)
+	{
+	}
+};