Nexrad File Factory

wxdata/source/scwx/wsr88d/nexrad_file_factory.cpp

@@ -0,0 +1,125 @@
+#include <scwx/wsr88d/nexrad_file_factory.hpp>
+#include <scwx/wsr88d/ar2v_file.hpp>
+#include <scwx/wsr88d/level3_file.hpp>
+
+#include <fstream>
+#include <sstream>
+
+#include <boost/iostreams/copy.hpp>
+#include <boost/iostreams/filtering_streambuf.hpp>
+#include <boost/iostreams/filter/gzip.hpp>
+#include <boost/log/trivial.hpp>
+
+namespace scwx
+{
+namespace wsr88d
+{
+
+static const std::string logPrefix_ = "[scwx::wsr88d::nexrad_file_factory] ";
+
+std::shared_ptr<NexradFile>
+NexradFileFactory::Create(const std::string& filename)
+{
+   BOOST_LOG_TRIVIAL(debug) << logPrefix_ << "Create(" << filename << ")";
+
+   std::shared_ptr<NexradFile> nexradFile = nullptr;
+   bool                        fileValid  = true;
+
+   std::ifstream f(filename, std::ios_base::in | std::ios_base::binary);
+   if (!f.good())
+   {
+      BOOST_LOG_TRIVIAL(warning)
+         << logPrefix_ << "Could not open file for reading: " << filename;
+      fileValid = false;
+   }
+
+   if (fileValid)
+   {
+      nexradFile = Create(f);
+   }
+
+   return nexradFile;
+}
+
+std::shared_ptr<NexradFile> NexradFileFactory::Create(std::istream& is)
+{
+   std::shared_ptr<NexradFile> message = nullptr;
+
+   std::istream*     pis      = &is;
+   std::streampos    pisBegin = is.tellg();
+   std::stringstream ss;
+   std::string       buffer;
+   bool              dataValid;
+
+   buffer.resize(4);
+
+   is.read(buffer.data(), 4);
+   dataValid = is.good();
+   is.seekg(pisBegin, std::ios_base::beg);
+
+   if (dataValid && buffer.starts_with("\x1f\x8b"))
+   {
+      boost::iostreams::filtering_streambuf<boost::iostreams::input> in;
+      in.push(boost::iostreams::gzip_decompressor());
+      in.push(is);
+
+      try
+      {
+         std::streamsize bytesCopied = boost::iostreams::copy(in, ss);
+
+         pis      = &ss;
+         pisBegin = ss.tellg();
+
+         ss.read(buffer.data(), 4);
+         dataValid = ss.good();
+         ss.seekg(pisBegin, std::ios_base::beg);
+
+         BOOST_LOG_TRIVIAL(trace)
+            << logPrefix_ << "Decompressed file = " << bytesCopied << " bytes";
+
+         if (!dataValid)
+         {
+            BOOST_LOG_TRIVIAL(warning)
+               << logPrefix_ << "Error reading decompressed stream";
+         }
+      }
+      catch (const boost::iostreams::gzip_error& ex)
+      {
+         BOOST_LOG_TRIVIAL(warning)
+            << logPrefix_ << "Error decompressing file: " << ex.what();
+
+         dataValid = false;
+      }
+   }
+   else if (!dataValid)
+   {
+      BOOST_LOG_TRIVIAL(warning) << logPrefix_ << "Error reading file";
+   }
+
+   if (dataValid)
+   {
+      if (buffer.starts_with("AR2V"))
+      {
+         message = std::make_shared<Ar2vFile>();
+      }
+      else
+      {
+         message = std::make_shared<Level3File>();
+      }
+   }
+
+   if (message != nullptr)
+   {
+      dataValid = message->LoadData(*pis);
+
+      if (!dataValid)
+      {
+         message = nullptr;
+      }
+   }
+
+   return message;
+}
+
+} // namespace wsr88d
+} // namespace scwx