// Copyright (c) 2014-2017 Dr. Colin Hirsch and Daniel Frey
// Please see LICENSE for license or visit https://github.com/taocpp/PEGTL/

#ifndef TAOCPP_PEGTL_INCLUDE_INTERNAL_FILE_READER_HPP
#define TAOCPP_PEGTL_INCLUDE_INTERNAL_FILE_READER_HPP

#include <cstdio>
#include <memory>
#include <string>
#include <utility>

#include "../config.hpp"
#include "../input_error.hpp"

namespace tao
{
   namespace TAOCPP_PEGTL_NAMESPACE
   {
      namespace internal
      {
         struct file_close
         {
            void operator()( FILE* f ) const
            {
               std::fclose( f );
            }
         };

         class file_reader
         {
         public:
            explicit file_reader( const char* filename )
               : m_source( filename ),
                 m_file( open() )
            {
            }

            file_reader( const file_reader& ) = delete;
            void operator=( const file_reader& ) = delete;

            std::size_t size() const
            {
               errno = 0;
               if( std::fseek( m_file.get(), 0, SEEK_END ) != 0 ) {
                  TAOCPP_PEGTL_THROW_INPUT_ERROR( "unable to fseek() to end of file " << m_source );  // LCOV_EXCL_LINE
               }
               errno = 0;
               const auto s = std::ftell( m_file.get() );
               if( s < 0 ) {
                  TAOCPP_PEGTL_THROW_INPUT_ERROR( "unable to ftell() file size of file " << m_source );  // LCOV_EXCL_LINE
               }
               errno = 0;
               if( std::fseek( m_file.get(), 0, SEEK_SET ) != 0 ) {
                  TAOCPP_PEGTL_THROW_INPUT_ERROR( "unable to fseek() to beginning of file " << m_source );  // LCOV_EXCL_LINE
               }
               return std::size_t( s );
            }

            std::string read() const
            {
               std::string nrv;
               nrv.resize( size() );
               errno = 0;
               if( ( nrv.size() != 0 ) && ( std::fread( &nrv[ 0 ], nrv.size(), 1, m_file.get() ) != 1 ) ) {
                  TAOCPP_PEGTL_THROW_INPUT_ERROR( "unable to fread() file " << m_source << " size " << nrv.size() );  // LCOV_EXCL_LINE
               }
               return nrv;
            }

         private:
            const char* const m_source;
            const std::unique_ptr< std::FILE, file_close > m_file;

            std::FILE* open() const
            {
               errno = 0;
#if defined( _MSC_VER )
               std::FILE* file;
               if(::fopen_s( &file, m_source, "rb" ) == 0 )
#else
               if( auto* file = std::fopen( m_source, "rb" ) )
#endif
               {
                  return file;
               }
               TAOCPP_PEGTL_THROW_INPUT_ERROR( "unable to fopen() file " << m_source << " for reading" );
            }
         };

      }  // namespace internal

   }  // namespace TAOCPP_PEGTL_NAMESPACE

}  // namespace tao

#endif