AWS Level 2 Provider FindKey

test/source/scwx/provider/aws_level2_data_provider.test.cpp

@@ -7,6 +7,32 @@ namespace scwx
 namespace provider
 {
 
+TEST(AwsLevel2DataProvider, FindKeyFixed)
+{
+   using namespace std::chrono;
+   using sys_days = time_point<system_clock, days>;
+
+   const auto date = sys_days {2021y / May / 27d};
+   const auto time = date + 17h + 59min;
+
+   AwsLevel2DataProvider provider("KLSX");
+
+   provider.ListObjects(date);
+   std::string key = provider.FindKey(time);
+
+   EXPECT_EQ(key, "2021/05/27/KLSX/KLSX20210527_175717_V06");
+}
+
+TEST(AwsLevel2DataProvider, FindKeyNow)
+{
+   AwsLevel2DataProvider provider("KLSX");
+
+   provider.Refresh();
+   std::string key = provider.FindKey(std::chrono::system_clock::now());
+
+   EXPECT_GT(key.size(), 0);
+}
+
 TEST(AwsLevel2DataProvider, LoadObjectByKey)
 {
    const std::string key = "2022/04/21/KLSX/KLSX20220421_160055_V06";

wxdata/include/scwx/provider/aws_level2_data_provider.hpp

@@ -30,6 +30,7 @@ public:
 
    size_t cache_size() const;
 
+   std::string FindKey(std::chrono::system_clock::time_point time);
    size_t      ListObjects(std::chrono::system_clock::time_point date);
    std::shared_ptr<wsr88d::Ar2vFile> LoadObjectByKey(const std::string& key);
    void                              Refresh();

wxdata/include/scwx/util/map.hpp

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <map>
+#include <optional>
+
+namespace scwx
+{
+namespace util
+{
+
+template<class Key, class T>
+std::optional<T> GetBoundedElement(std::map<Key, T>& map, Key key)
+{
+   std::optional<T> element = std::nullopt;
+
+   // Find the first element greater than the key requested
+   auto it = map.upper_bound(key);
+
+   // An element with a key greater was found
+   if (it != map.cend())
+   {
+      // Are there elements prior to this element?
+      if (it != map.cbegin())
+      {
+         // Get the element immediately preceding, this the element we are
+         // looking for
+         element = (--it)->second;
+      }
+   }
+   else if (map.size() > 0)
+   {
+      // An element with a key greater was not found. If it exists, it must be
+      // the last element.
+      element = map.rbegin()->second;
+   }
+
+   return element;
+}
+
+} // namespace util
+} // namespace scwx

wxdata/source/scwx/provider/aws_level2_data_provider.cpp

@@ -1,5 +1,7 @@
 #include <scwx/provider/aws_level2_data_provider.hpp>
 #include <scwx/util/logger.hpp>
+#include <scwx/util/map.hpp>
+#include <scwx/util/time.hpp>
 #include <scwx/wsr88d/nexrad_file_factory.hpp>
 
 #include <shared_mutex>
@@ -76,6 +78,24 @@ size_t AwsLevel2DataProvider::cache_size() const
    return p->objects_.size();
 }
 
+std::string
+AwsLevel2DataProvider::FindKey(std::chrono::system_clock::time_point time)
+{
+   logger_->debug("FindKey: {}", util::TimeString(time));
+
+   std::string key {};
+
+   std::optional<std::string> element =
+      util::GetBoundedElement(p->objects_, time);
+
+   if (element.has_value())
+   {
+      key = *element;
+   }
+
+   return key;
+}
+
 size_t
 AwsLevel2DataProvider::ListObjects(std::chrono::system_clock::time_point date)
 {

wxdata/wxdata.cmake

@@ -39,6 +39,7 @@ set(SRC_PROVIDER source/scwx/provider/aws_level2_data_provider.cpp)
 set(HDR_UTIL include/scwx/util/float.hpp
              include/scwx/util/iterator.hpp
              include/scwx/util/logger.hpp
+             include/scwx/util/map.hpp
              include/scwx/util/rangebuf.hpp
              include/scwx/util/streams.hpp
              include/scwx/util/threads.hpp