Add and use ReplyMarkup::has_buy_button.

Author: levlam

td/telegram/InlineKeyboardButton.h

@@ -62,6 +62,10 @@ struct InlineKeyboardButton {
   InlineKeyboardButton clone(DialogId dialog_id, const MessageContentDupType &dup_type, bool is_via_bot,
                              bool is_rich_message) const;
 
+  bool is_buy() const {
+    return type == Type::Buy;
+  }
+
   bool is_disabled() const {
     return type == Type::Disabled;
   }

td/telegram/MessagesManager.cpp

@@ -36601,9 +36601,7 @@ Result<MessagesManager::InvoiceMessageInfo> MessagesManager::get_invoice_message
   if (!m->message_id.is_server() || m->ephemeral_message != nullptr) {
     return Status::Error(400, "Wrong message identifier");
   }
-  if (m->reply_markup == nullptr || m->reply_markup->inline_keyboard.empty() ||
-      m->reply_markup->inline_keyboard[0].empty() ||
-      m->reply_markup->inline_keyboard[0][0].type != InlineKeyboardButton::Type::Buy) {
+  if (m->reply_markup == nullptr || !m->reply_markup->has_buy_button()) {
     if (content_type != MessageContentType::PaidMedia) {
       return Status::Error(400, "Message has no Pay button");
     }

td/telegram/ReplyMarkup.cpp

@@ -467,6 +467,10 @@ const RequestedDialogType *ReplyMarkup::get_requested_dialog_type(int32 button_i
   return nullptr;
 }
 
+bool ReplyMarkup::has_buy_button() const {
+  return !inline_keyboard.empty() && !inline_keyboard[0].empty() && inline_keyboard[0][0].is_buy();
+}
+
 bool ReplyMarkup::has_disabled_buttons() const {
   for (auto &row : inline_keyboard) {
     for (auto &button : row) {

td/telegram/ReplyMarkup.h

@@ -47,6 +47,8 @@ struct ReplyMarkup {
 
   const RequestedDialogType *get_requested_dialog_type(int32 button_id) const;
 
+  bool has_buy_button() const;
+
   bool has_disabled_buttons() const;
 };