/*!
 \file generator.cpp
 \brief Fast binary encoding generator implementation
 \author Ivan Shynkarenka
 \date 20.04.2018
 \copyright MIT License
*/

#include "generator.h"

#if defined(_WIN32) || defined(_WIN64) || defined(__CYGWIN__)
#include <windows.h>
#endif

namespace FBE {

void Generator::Store(const CppCommon::Path& filename)
{
 std::string previous;

 // Try to read the previous file content
 if (filename.IsExists())
 {
 CppCommon::File file = filename;
 file.Open(true, false);
 previous = file.ReadAllText();
 file.Close();
 }

 // Compare the buffer with previous content in order to store only new content
 if (_buffer == previous)
 return;

 // Store the buffer into unique file
 CppCommon::Path unique = filename.parent() / CppCommon::Path::unique();
 CppCommon::File::WriteAllText(unique, _buffer);

#if defined(_WIN32) || defined(_WIN64) || defined(__CYGWIN__)
 // Sometimes it happens that Visual Studio opens generated files on a fly to analyze.
 // It opens them with mapping into its process with CreateFileMapping/MapViewOfFile.
 // As the result files cannot be replaced or removed. Therefore we need to have some
 // retry attempts with small delay to give a change for the file to be created.
 // https://stackoverflow.com/questions/41844842/when-error-1224-error-user-mapped-file-occurs
 const int attempts = 1000;
 const int sleep = 100;
 for (int attempt = 0; attempt < attempts; ++attempt)
 {
 try
 {
 // Rename the unique file inside a loop with retries
 CppCommon::Path::Rename(unique, filename);
 return;
 }
 catch (const CppCommon::FileSystemException& ex)
 {
 if ((ex.system_error() == ERROR_ACCESS_DENIED) || (ex.system_error() == ERROR_USER_MAPPED_FILE))
 {
 CppCommon::Thread::Sleep(sleep);
 continue;
 }
 throw;
 }
 }
 throwex CppCommon::FileSystemException("Cannot generate the output file!").Attach(filename);
#else
 // Rename the unique file inside a loop with retries
 CppCommon::Path::Rename(unique, filename);
#endif
}

} // namespace FBE