Add discount_percentage.

td/generate/scheme/td_api.tl

@@ -469,10 +469,11 @@ chatAdministratorRights can_manage_chat:Bool can_change_info:Bool can_post_messa
 //@description Describes an option for gifting Telegram Premium to a user
 //@currency ISO 4217 currency code for Telegram Premium subscription payment
 //@amount The amount to pay, in the smallest units of the currency
+//@discount_percentage The discount associated with this gift option, as a percentage
 //@month_count Number of month the Telegram Premium subscription will be active
 //@store_product_id Identifier of the store product associated with the option
 //@payment_link An internal link to be opened for gifting Telegram Premium to the user if store payment isn't possible; may be null if direct payment isn't available
-premiumGiftOption currency:string amount:int53 month_count:int32 store_product_id:string payment_link:InternalLinkType = PremiumGiftOption;
+premiumGiftOption currency:string amount:int53 discount_percentage:int32 month_count:int32 store_product_id:string payment_link:InternalLinkType = PremiumGiftOption;
 
 
 //@description Represents a user

td/telegram/ContactsManager.cpp

@@ -16769,8 +16769,11 @@ tl_object_ptr<td_api::userFullInfo> ContactsManager::get_user_full_info_object(U
     }
     bio_object = get_formatted_text_object(bio, true, 0);
   }
-  auto premium_gift_options = transform(user_full->premium_gift_options,
-                                        [](const auto &option) { return option.get_premium_gift_option_object(); });
+  auto base_premium_gift_it =
+      std::min_element(user_full->premium_gift_options.begin(), user_full->premium_gift_options.end());
+  auto premium_gift_options = transform(user_full->premium_gift_options, [&base_premium_gift_it](const auto &option) {
+    return option.get_premium_gift_option_object(*base_premium_gift_it);
+  });
   auto voice_messages_forbidden = is_premium ? user_full->voice_messages_forbidden : false;
   return make_tl_object<td_api::userFullInfo>(
       get_chat_photo_object(td_->file_manager_.get(), user_full->photo), user_full->is_blocked,

td/telegram/PremiumGiftOption.cpp

@@ -10,6 +10,9 @@
 
 #include "td/utils/common.h"
 
+#include <limits>
+#include <tuple>
+
 namespace td {
 
 PremiumGiftOption::PremiumGiftOption(telegram_api::object_ptr<telegram_api::premiumGiftOption> &&option)
@@ -20,13 +23,30 @@ PremiumGiftOption::PremiumGiftOption(telegram_api::object_ptr<telegram_api::prem
     , store_product_(std::move(option->store_product_)) {
 }
 
-td_api::object_ptr<td_api::premiumGiftOption> PremiumGiftOption::get_premium_gift_option_object() const {
+double PremiumGiftOption::get_monthly_price() const {
+  return static_cast<double>(amount_) / static_cast<double>(months_);
+}
+
+td_api::object_ptr<td_api::premiumGiftOption> PremiumGiftOption::get_premium_gift_option_object(
+    const PremiumGiftOption &base_option) const {
   auto link_type = LinkManager::parse_internal_link(bot_url_, true);
+  int32 discount_percentage = 0;
+  if (base_option.months_ > 0 && months_ > 0 && base_option.amount_ > 0 && amount_ > 0) {
+    double relative_price = get_monthly_price() / base_option.get_monthly_price();
+    if (relative_price < 1.0) {
+      discount_percentage = static_cast<int32>(100 * (1.0 - relative_price));
+    }
+  }
   return td_api::make_object<td_api::premiumGiftOption>(
-      currency_, amount_, months_, store_product_,
+      currency_, amount_, discount_percentage, months_, store_product_,
       link_type == nullptr ? nullptr : link_type->get_internal_link_type_object());
 }
 
+bool operator<(const PremiumGiftOption &lhs, const PremiumGiftOption &rhs) {
+  return std::tie(lhs.months_, lhs.amount_, lhs.currency_, lhs.store_product_, lhs.bot_url_) <
+         std::tie(rhs.months_, rhs.amount_, rhs.currency_, rhs.store_product_, rhs.bot_url_);
+}
+
 bool operator==(const PremiumGiftOption &lhs, const PremiumGiftOption &rhs) {
   return lhs.months_ == rhs.months_ && lhs.currency_ == rhs.currency_ && lhs.amount_ == rhs.amount_ &&
          lhs.bot_url_ == rhs.bot_url_ && lhs.store_product_ == rhs.store_product_;

td/telegram/PremiumGiftOption.h

@@ -20,13 +20,18 @@ class PremiumGiftOption {
   string bot_url_;
   string store_product_;
 
+  friend bool operator<(const PremiumGiftOption &lhs, const PremiumGiftOption &rhs);
+
   friend bool operator==(const PremiumGiftOption &lhs, const PremiumGiftOption &rhs);
 
+  double get_monthly_price() const;
+
  public:
   PremiumGiftOption() = default;
   explicit PremiumGiftOption(telegram_api::object_ptr<telegram_api::premiumGiftOption> &&option);
 
-  td_api::object_ptr<td_api::premiumGiftOption> get_premium_gift_option_object() const;
+  td_api::object_ptr<td_api::premiumGiftOption> get_premium_gift_option_object(
+      const PremiumGiftOption &base_option) const;
 
   template <class StorerT>
   void store(StorerT &storer) const;