ircd:Ⓜ️ Add preliminary skeleton linkage for room/event visibilty related.

include/ircd/m/event.h

@@ -27,6 +27,10 @@ namespace ircd::m
 	bool exists(const id::event &);
 	bool bad(const id::event &, uint64_t &);
 	bool bad(const id::event &);
+	bool visible(const event &, const id::user &);
+	bool visible(const event &, const id::node &);
+	bool visible(const id::event &, const id::user &);
+	bool visible(const id::event &, const id::node &);
 
 	// Depth comparison; expect unstable sorting.
 	bool operator<(const event &, const event &);

include/ircd/m/room.h

@@ -144,6 +144,8 @@ struct ircd::m::room
 	// misc
 	bool membership(const m::id::user &, const string_view &membership = "join") const;
 	string_view membership(const mutable_buffer &out, const m::id::user &) const;
+	bool visible(const id::user &) const;
+	bool visible(const id::node &) const;
 
 	room(const id &room_id, const string_view &event_id, const vm::copts *const &opts = nullptr)
 	:room_id{room_id}

ircd/m/m.cc

@@ -2731,6 +2731,71 @@ ircd::m::exists(const id::room_alias &room_alias,
 	return function(room_alias, remote_query);
 }
 
+///////////////////////////////////////////////////////////////////////////////
+//
+// m/event.h
+//
+
+bool
+ircd::m::visible(const event::id &event_id,
+                 const node::id &origin)
+{
+	m::room::id::buf room_id
+	{
+		get(event_id, "room_id", room_id)
+	};
+
+	const m::event event
+	{
+		{ "event_id",  event_id  },
+		{ "room_id",   room_id   }
+	};
+
+	return visible(event, origin);
+}
+
+bool
+ircd::m::visible(const event::id &event_id,
+                 const user::id &user_id)
+{
+	m::room::id::buf room_id
+	{
+		get(event_id, "room_id", room_id)
+	};
+
+	const m::event event
+	{
+		{ "event_id",  event_id  },
+		{ "room_id",   room_id   }
+	};
+
+	return visible(event, user_id);
+}
+
+bool
+ircd::m::visible(const event &event,
+                 const node::id &origin)
+{
+	const m::room room
+	{
+		at<"room_id"_>(event), at<"event_id"_>(event)
+	};
+
+	return room.visible(origin);
+}
+
+bool
+ircd::m::visible(const event &event,
+                 const user::id &user_id)
+{
+	const m::room room
+	{
+		at<"room_id"_>(event), at<"event_id"_>(event)
+	};
+
+	return room.visible(user_id);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 // m/txn.h

ircd/m/room.cc

@@ -161,6 +161,20 @@ ircd::m::my(const room &room)
 // room
 //
 
+bool
+ircd::m::room::visible(const m::user::id &user_id)
+const
+{
+	return true;
+}
+
+bool
+ircd::m::room::visible(const m::node::id &origin)
+const
+{
+	return true;
+}
+
 bool
 ircd::m::room::membership(const m::id::user &user_id,
                           const string_view &membership)