New cpp folder structure

Signed-off-by: Alexander Borsuk <me@alex.bio>

libs/platform/settings.hpp

@@ -0,0 +1,86 @@
+#pragma once
+
+#include "platform/string_storage_base.hpp"
+
+#include "base/macros.hpp"
+
+#include <string>
+
+namespace settings
+{
+/// Metric or Imperial.
+extern std::string_view kMeasurementUnits;
+extern std::string_view kDeveloperMode;
+extern std::string_view kMapLanguageCode;
+// The following two settings are configured externally at the metaserver.
+extern std::string_view kDonateUrl;
+extern std::string_view kNY;
+
+template <class T>
+bool FromString(std::string const & str, T & outValue);
+
+template <class T>
+std::string ToString(T const & value);
+
+class StringStorage : public platform::StringStorageBase
+{
+public:
+  static StringStorage & Instance();
+
+private:
+  StringStorage();
+};
+
+/// Retrieve setting
+/// @return false if setting is absent
+template <class Value>
+[[nodiscard]] bool Get(std::string_view key, Value & outValue)
+{
+  std::string strVal;
+  return StringStorage::Instance().GetValue(key, strVal) && FromString(strVal, outValue);
+}
+
+template <class Value>
+void TryGet(std::string_view key, Value & outValue)
+{
+  bool unused = Get(key, outValue);
+  UNUSED_VALUE(unused);
+}
+
+/// Automatically saves setting to external file
+template <class Value>
+void Set(std::string_view key, Value const & value)
+{
+  StringStorage::Instance().SetValue(key, ToString(value));
+}
+
+/// Automatically saves settings to external file
+inline void Update(std::map<std::string, std::string> const & settings)
+{
+  StringStorage::Instance().Update(settings);
+}
+
+inline void Delete(std::string_view key) { StringStorage::Instance().DeleteKeyAndValue(key); }
+inline void Clear() { StringStorage::Instance().Clear(); }
+
+class UsageStats
+{
+  static uint64_t TimeSinceEpoch();
+  uint64_t m_enterForegroundTime = 0;
+  uint64_t m_totalForegroundTime = 0;
+  uint64_t m_sessionsCount = 0;
+
+  std::string_view m_firstLaunch, m_lastBackground, m_totalForeground, m_sessions;
+
+  StringStorage & m_ss;
+
+public:
+  UsageStats();
+
+  void EnterForeground();
+  void EnterBackground();
+
+  bool IsLoyalUser() const;
+};
+
+} // namespace settings