Adding generic level 2 data provider, and documenting virtual functions

wxdata/include/scwx/provider/level2_data_provider.hpp

@@ -0,0 +1,74 @@
+#pragma once
+
+#include <scwx/wsr88d/ar2v_file.hpp>
+
+#include <chrono>
+#include <memory>
+#include <string>
+
+namespace scwx
+{
+namespace provider
+{
+
+class Level2DataProviderImpl;
+
+class Level2DataProvider
+{
+public:
+   explicit Level2DataProvider();
+   ~Level2DataProvider();
+
+   Level2DataProvider(const Level2DataProvider&) = delete;
+   Level2DataProvider& operator=(const Level2DataProvider&) = delete;
+
+   Level2DataProvider(Level2DataProvider&&) noexcept;
+   Level2DataProvider& operator=(Level2DataProvider&&) noexcept;
+
+   virtual size_t cache_size() const = 0;
+
+   /**
+    * Finds the most recent key in the cache, no later than the time provided.
+    *
+    * @param time Upper-bound time for the key search
+    *
+    * @return Level 2 data key
+    */
+   virtual std::string FindKey(std::chrono::system_clock::time_point time) = 0;
+
+   /**
+    * Lists level 2 objects for the date supplied, and adds them to the cache.
+    *
+    * @param date Date for which to list objects
+    *
+    * @return - New objects found for the given date
+    *         - Total objects found for the given date
+    */
+   virtual std::pair<size_t, size_t>
+   ListObjects(std::chrono::system_clock::time_point date) = 0;
+
+   /**
+    * Loads a level 2 object by the given key.
+    *
+    * @param key Level 2 data key
+    *
+    * @return Level 2 data
+    */
+   virtual std::shared_ptr<wsr88d::Ar2vFile>
+   LoadObjectByKey(const std::string& key) = 0;
+
+   /**
+    * Lists level 2 objects for the current date, and adds them to the cache. If
+    * no objects have been added to the cache for the current date, the previous
+    * date is also queried for data.
+    *
+    * @return New objects found
+    */
+   virtual size_t Refresh() = 0;
+
+private:
+   std::unique_ptr<Level2DataProviderImpl> p;
+};
+
+} // namespace provider
+} // namespace scwx