Implement PoC custom reaction selection.

Telegram/SourceFiles/data/data_message_reaction_id.cpp

@@ -0,0 +1,32 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "data/data_message_reaction_id.h"
+
+namespace Data {
+
+ReactionId ReactionFromMTP(const MTPReaction &reaction) {
+	return reaction.match([](MTPDreactionEmpty) {
+		return ReactionId{ QString() };
+	}, [](const MTPDreactionEmoji &data) {
+		return ReactionId{ qs(data.vemoticon()) };
+	}, [](const MTPDreactionCustomEmoji &data) {
+		return ReactionId{ DocumentId(data.vdocument_id().v) };
+	});
+}
+
+MTPReaction ReactionToMTP(ReactionId id) {
+	if (const auto custom = id.custom()) {
+		return MTP_reactionCustomEmoji(MTP_long(custom));
+	}
+	const auto emoji = id.emoji();
+	return emoji.isEmpty()
+		? MTP_reactionEmpty()
+		: MTP_reactionEmoji(MTP_string(emoji));
+}
+
+} // namespace Data