ircd:Ⓜ️:room::state: Add preliminary purge_replaced() w/ console cmd.

include/ircd/m/room/state.h

@@ -108,4 +108,5 @@ struct ircd::m::room::state
 	static size_t rebuild_history(const state &);
 	static size_t rebuild_present(const state &);
 	static bool force_present(const event &);
+	static size_t purge_replaced(const state &);
 };

ircd/m.cc

@@ -4049,6 +4049,19 @@ ircd::m::room::purge(const room &room)
 	return call(room);
 }
 
+size_t
+ircd::m::room::state::purge_replaced(const state &state)
+{
+	using prototype = size_t (const room::state &);
+
+	static mods::import<prototype> call
+	{
+		"m_room", "ircd::m::room::state::purge_replaced"
+	};
+
+	return call(state);
+}
+
 bool
 ircd::m::room::state::force_present(const event &event)
 {

modules/console.cc

@@ -7512,6 +7512,33 @@ console_cmd__room__state__force(opt &out, const string_view &line)
 	return true;
 }
 
+bool
+console_cmd__room__state__purge__replaced(opt &out, const string_view &line)
+{
+	const params param{line, " ",
+	{
+		"room_id",
+	}};
+
+	const auto &room_id
+	{
+		m::room_id(param.at(0))
+	};
+
+	const m::room::state state
+	{
+		room_id
+	};
+
+	const size_t ret
+	{
+		m::room::state::purge_replaced(state)
+	};
+
+	out << "erased " << ret << std::endl;
+	return true;
+}
+
 bool
 console_cmd__room__state__rebuild__present(opt &out, const string_view &line)
 {

modules/m_room.cc

@@ -561,6 +561,39 @@ ircd::m::is_complete(const room &room)
 	return { true, depth };
 }
 
+size_t
+IRCD_MODULE_EXPORT
+ircd::m::room::state::purge_replaced(const state &state)
+{
+	db::txn txn
+	{
+		*m::dbs::events
+	};
+
+	size_t ret(0);
+	m::room::messages it
+	{
+		state.room_id, uint64_t(0)
+	};
+
+	if(!it)
+		return ret;
+
+	for(; it; ++it)
+	{
+		const m::event::idx &event_idx(it.event_idx());
+		if(!m::get(std::nothrow, event_idx, "state_key", [](const auto &) {}))
+			continue;
+
+		if(!m::event::refs(event_idx).count(m::dbs::ref::STATE))
+			continue;
+
+		// TODO: erase event
+	}
+
+	return ret;
+}
+
 bool
 IRCD_MODULE_EXPORT
 ircd::m::room::state::force_present(const m::event &event)