/*****************************************************************************/
/**
 * \file portable_oarchive.hpp
 * \brief Provides an archive to create portable binary files.
 * \author christian.pfligersdorffer@gmx.at
 * \version 5.1
 *
 * This pair of archives brings the advantages of binary streams to the cross
 * platform boost::serialization user. While being almost as fast as the native
 * binary archive it allows its files to be exchanged between cpu architectures
 * using different byte order (endianness). Speaking of speed: in serializing
 * numbers the (portable) binary approach is approximately ten times faster than
 * the ascii implementation (that is inherently portable)!
 *
 * Based on the portable archive example by Robert Ramey this implementation
 * uses Beman Dawes endian library and fp_utilities from Johan Rade, both being
 * in boost since 1.36. Prior to that you need to add them both (header only)
 * to your boost directory before you're able to use the archives provided. 
 * Our archives have been tested successfully for boost versions 1.33 to 1.49!
 *
 * \note Correct behaviour has so far been confirmed using PowerPC-32, x86-32
 *       and x86-64 platforms featuring different byte order. So there is a good
 *       chance it will instantly work for your specific setup. If you encounter
 *       problems or have suggestions please contact the author.
 *
 * \note Version 5.1 is now compatible with boost up to version 1.59. Thanks to
 *       ecotax for pointing to the issue with shared_ptr_helper.
 *
 * \note Version 5.0 is now compatible with boost up to version 1.49 and enables
 *       serialization of std::wstring by converting it to/from utf8 (thanks to
 *       Arash Abghari for this suggestion). With that all unit tests from the
 *       serialization library pass again with the notable exception of user
 *       defined primitive types. Those are not supported and as a result any
 *       user defined type to be used with the portable archives are required 
 *       to be at least object_serializable.
 *
 * \note Oliver Putz pointed out that -0.0 was not serialized correctly, so
 *       version 4.3 provides a fix for that. Thanks Ollie!
 *
 * \note Version 4.2 maintains compatibility with the latest boost 1.45 and adds
 *       serialization of special floating point values inf and NaN as proposed
 *       by Francois Mauger.
 *
 * \note Version 4.1 makes the archives work together with boost 1.40 and 1.41.
 *       Thanks to Francois Mauger for his suggestions.
 *
 * \note Version 4 removes one level of the inheritance hierarchy and directly
 *       builds upon binary primitive and basic binary archive, thereby fixing
 *       the last open issue regarding array serialization. Thanks to Robert
 *       Ramey for the hint.
 *
 * \note A few fixes introduced in version 3.1 let the archives pass all of the
 *       serialization tests. Thanks to Sergey Morozov for running the tests.
 *       Wouter Bijlsma pointed out where to find the fp_utilities and endian
 *       libraries headers inside the boost distribution. I would never have
 *       found them so thank him it works out of the box since boost 1.36.
 *
 * \note With Version 3.0 the archives have been made portable across different
 *       boost versions. For that purpose a header is added to the data that
 *       supplies the underlying serialization library version. Backwards
 *       compatibility is maintained by assuming library version boost 1.33 if
 *       the iarchive is created using the no_header flag. Whether a header is
 *       present or not can be guessed by peeking into the stream: the header's
 *       first byte is the magic number 127 coinciding with 'e'|'o'|'s' :-)
 *
 * \note Version 2.1 removes several compiler warnings and enhances floating
 *       point diagnostics to inform the user if some preconditions are violated
 *		 on his platform. We do not strive for the universally portable solution
 *       in binary floating point serialization as desired by some boost users.
 *       Instead we support only the most widely used IEEE 754 format and try to
 *       detect when requirements are not met and hence our approach must fail.
 *       Contributions we made by Johan Rade and Ákos Maróy.
 *
 * \note Version 2.0 fixes a serious bug that effectively transformed most
 *       of negative integral values into positive values! For example the two
 *       numbers -12 and 234 were stored in the same 8-bit pattern and later
 *       always restored to 234. This was fixed in this version in a way that
 *       does not change the interpretation of existing archives that did work
 *       because there were no negative numbers. The other way round archives
 *       created by version 2.0 and containing negative numbers will raise an
 *       integer type size exception when reading it with version 1.0. Thanks
 *       to Markus Frohnmaier for testing the archives and finding the bug.
 *
 * \copyright The boost software license applies.
 */
/*****************************************************************************/

#ifndef CondFormats_Serialization_portable_oarchive_hpp
#define CondFormats_Serialization_portable_oarchive_hpp

#include <ostream>

// basic headers
#include <boost/version.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/archive/basic_binary_oprimitive.hpp>
#include <boost/archive/basic_binary_oarchive.hpp>

#if BOOST_VERSION >= 103500 && BOOST_VERSION < 105600
#include <boost/archive/shared_ptr_helper.hpp>
#endif

#if BOOST_VERSION >= 104500
#include <boost/program_options/config.hpp>
#include <boost/program_options/detail/convert.hpp>
#endif

// funny polymorphics
#if BOOST_VERSION < 103500
#include <boost/archive/detail/polymorphic_oarchive_impl.hpp>
#define POLYMORPHIC(T) boost::archive::detail::polymorphic_oarchive_impl<T>

#elif BOOST_VERSION < 103600
#include <boost/archive/detail/polymorphic_oarchive_dispatch.hpp>
#define POLYMORPHIC(T) boost::archive::detail::polymorphic_oarchive_dispatch<T>

#else
#include <boost/archive/detail/polymorphic_oarchive_route.hpp>
#define POLYMORPHIC(T) boost::archive::detail::polymorphic_oarchive_route<T>
#endif

// endian and fpclassify
#include <boost/math/special_functions/fpclassify.hpp>
#include <boost/endian/conversion.hpp>

// namespace alias fp_classify
#if BOOST_VERSION < 103800
namespace fp = boost::math;
#elif BOOST_VERSION >= 106900
namespace fp = boost::math;
#else
namespace fp = boost::spirit::math;
#endif

#if BOOST_VERSION >= 104500 && !defined BOOST_NO_STD_WSTRING
// used for wstring to utf8 conversion
#include <boost/program_options/config.hpp>
#include <boost/program_options/detail/convert.hpp>
#endif

// generic type traits for numeric types
#include <boost/type_traits/is_integral.hpp>
#include <boost/type_traits/is_signed.hpp>
#include <boost/type_traits/is_arithmetic.hpp>
#include <boost/type_traits/is_floating_point.hpp>

#include "portable_archive_exception.hpp"

// hint from Johan Rade: on VMS there is still support for
// the VAX floating point format and this macro detects it
#if defined(__vms) && defined(__DECCXX) && !__IEEE_FLOAT
#error "VAX floating point format is not supported!"
#endif

namespace eos {

  // forward declaration
  class portable_oarchive;

  typedef boost::archive::basic_binary_oprimitive<portable_oarchive
#if BOOST_VERSION < 103400
                                                  ,
                                                  std::ostream
#else
                                                  ,
                                                  std::ostream::char_type,
                                                  std::ostream::traits_type
#endif
                                                  >
      portable_oprimitive;

  /**
	 * \brief Portable binary output archive using little endian format.
	 *
	 * This archive addresses integer size, endianness and floating point types so
	 * that data can be transferred across different systems. The archive consists
	 * primarily of three different save implementations for integral types,
	 * floating point types and string types. Those functions are templates and use
	 * enable_if to be correctly selected for overloading.
	 *
	 * \note The class is based on the portable binary example by Robert Ramey and
	 *       uses Beman Dawes endian library plus fp_utilities by Johan Rade.
	 */
  class portable_oarchive : public portable_oprimitive

      // the example derives from common_oarchive but that lacks the
      // save_override functions so we chose to stay one level higher
      ,
                            public boost::archive::basic_binary_oarchive<portable_oarchive>
#if BOOST_VERSION >= 103500 && BOOST_VERSION < 105600
      // mix-in helper class for serializing shared_ptr
      ,
                            public boost::archive::detail::shared_ptr_helper
#endif
  {
    // workaround for gcc: use a dummy struct
    // as additional argument type for overloading
    template <int>
    struct dummy {
      dummy(int) {}
    };

    // stores a signed char directly to stream
    inline void save_signed_char(const signed char& c) { portable_oprimitive::save(c); }

    // archive initialization
    void init(unsigned flags) {
      // it is vital to have version information if the archive is
      // to be parsed with a newer version of boost::serialization
      // therefor we create a header, no header means boost 1.33
      if (flags & boost::archive::no_header)
        BOOST_ASSERT(archive_version == 3);
      else {
        // write our minimalistic header (magic byte plus version)
        // the boost archives write a string instead - by calling
        // boost::archive::basic_binary_oarchive<derived_t>::init()
        save_signed_char(magic_byte);

        // write current version
        //				save<unsigned>(archive_version);
        operator<<(archive_version);
      }
    }

  public:
    /**
		 * \brief Constructor on a stream using ios::binary mode!
		 *
		 * We cannot call basic_binary_oprimitive::init which stores type
		 * sizes to the archive in order to detect transfers to non-compatible
		 * platforms.
		 *
		 * We could have called basic_binary_oarchive::init which would create
		 * the boost::serialization standard archive header containing also the
		 * library version. Due to efficiency we stick with our own.
		 */
    portable_oarchive(std::ostream& os, unsigned flags = 0)
#if BOOST_VERSION < 103400
        : portable_oprimitive(os, flags & boost::archive::no_codecvt)
#else
        : portable_oprimitive(*os.rdbuf(), flags & boost::archive::no_codecvt)
#endif
          ,
          boost::archive::basic_binary_oarchive<portable_oarchive>(flags) {
      init(flags);
    }

#if BOOST_VERSION >= 103400
    portable_oarchive(std::streambuf& sb, unsigned flags = 0)
        : portable_oprimitive(sb, flags & boost::archive::no_codecvt),
          boost::archive::basic_binary_oarchive<portable_oarchive>(flags) {
      init(flags);
    }
#endif

    //! Save narrow strings.
    void save(const std::string& s) { portable_oprimitive::save(s); }

#ifndef BOOST_NO_STD_WSTRING
    /**
		 * \brief Save wide strings.
		 *
		 * This is rather tricky to get right for true portability as there
		 * are so many different character encodings around. However, wide
		 * strings that are encoded in one of the Unicode schemes only need
		 * to be _transcoded_ which is a lot easier actually.
		 *
		 * We expect the input string to be encoded in the system's native
		 * format, ie. UTF-16 on Windows and UTF-32 on Linux machines. Don't
		 * know about Mac here so I can't really say about that.
		 */
    void save(const std::wstring& s) { save(boost::to_utf8(s)); }
#endif

    /**
         * \brief Saving bool type.
         *
         * Saving bool directly, not by const reference
         * because of tracking_type's operator (bool).
         *
         * \note If you cannot compile your application and it says something
         * about save(bool) cannot convert your type const A& into bool then
         * you should check your BOOST_CLASS_IMPLEMENTATION setting for A, as
         * portable_archive is not able to handle custom primitive types in
         * a general manner.
         */
    void save(const bool& b) {
      save_signed_char(b);
      if (b)
        save_signed_char('T');
    }

    /**
		 * \brief Save integer types.
		 *
		 * First we save the size information ie. the number of bytes that hold the
		 * actual data. We subsequently transform the data using store_little_endian
		 * and store non-zero bytes to the stream.
		 */
    template <typename T>
    typename boost::enable_if<boost::is_integral<T> >::type save(const T& t, dummy<2> = 0) {
      if (T temp = t) {
        // examine the number of bytes
        // needed to represent the number
        signed char size = 0;
        if (sizeof(T) == 1) {
          size = 1;
        } else {
          do {
            temp >>= CHAR_BIT;
            ++size;
          } while (temp != 0 && temp != (T)-1);
        }

        // encode the sign bit into the size
        save_signed_char(t > 0 ? size : -size);
        BOOST_ASSERT(t > 0 || boost::is_signed<T>::value);

        // we choose to use little endian because this way we just
        // save the first size bytes to the stream and skip the rest
        temp = boost::endian::native_to_little(t);
        save_binary(&temp, size);
      }
      // zero optimization
      else
        save_signed_char(0);
    }

    /**
		 * \brief Save floating point types.
		 * 
		 * We simply rely on fp_traits_non_native to extract the bit pattern into an (unsigned)
		 * integral type and store that into the stream. Francois Mauger provided
		 * standardized behaviour for special values like inf and NaN, that need to
		 * be serialized in his application.
		 *
		 * \note by Johan Rade (author of the floating point utilities library):
		 * Be warned that the math::detail::fp_traits_non_native<T,U>::get_bits() function 
		 * is *not* guaranteed to give you all bits of the floating point number. It
		 * will give you all bits if and only if there is an integer type that has
		 * the same size as the floating point you are copying from. It will not
		 * give you all bits for double if there is no uint64_t. It will not give
		 * you all bits for long double if sizeof(long double) > 8 or there is no
		 * uint64_t. 
		 * 
		 * The member fp_traits<T>::type::coverage will tell you whether all bits
		 * are copied. This is a typedef for either math::detail::all_bits or
		 * math::detail::not_all_bits. 
		 * 
		 * If the function does not copy all bits, then it will copy the most
		 * significant bits. So if you serialize and deserialize the way you
		 * describe, and fp_traits<T>::type::coverage is math::detail::not_all_bits,
		 * then your floating point numbers will be truncated. This will introduce
		 * small rounding off errors. 
		 */
    template <typename T>
    typename boost::enable_if<boost::is_floating_point<T> >::type save(const T& t, dummy<3> = 0) {
      typedef typename fp::detail::size_to_precision<sizeof(T), ::std::is_floating_point<T>::value>::type precision;
      typedef typename fp::detail::fp_traits_non_native<T, precision> traits;

      // if the no_infnan flag is set we must throw here
      if (get_flags() & no_infnan && !fp::isfinite(t))
        throw portable_archive_exception(t);

      // if you end here there are three possibilities:
      // 1. you're serializing a long double which is not portable
      // 2. you're serializing a double but have no 64 bit integer
      // 3. your machine is using an unknown floating point format
      // after reading the note above you still might decide to
      // deactivate this static assert and try if it works out.
      typename traits::bits bits;
      static_assert(sizeof(bits) == sizeof(T));
      static_assert(std::numeric_limits<T>::is_iec559);

      // examine value closely
      switch (fp::fpclassify(t)) {
//case FP_ZERO: bits = 0; break;
#if BOOST_VERSION >= 106900
        case FP_NAN:
          bits = traits::exponent | traits::significand;
          break;
#else
        case FP_NAN:
          bits = traits::exponent | traits::mantissa;
          break;
#endif
        case FP_INFINITE:
          bits = traits::exponent | (t < 0) * traits::sign;
          break;
        case FP_SUBNORMAL:
          assert(std::numeric_limits<T>::has_denorm);  // pass
        case FP_ZERO:                                  // note that floats can be ±0.0
        case FP_NORMAL:
          traits::get_bits(t, bits);
          break;
        default:
          throw portable_archive_exception(t);
      }

      save(bits);
    }

    // in boost 1.44 version_type was splitted into library_version_type and
    // item_version_type, plus a whole bunch of additional strong typedefs.
    template <typename T>
    typename boost::disable_if<boost::is_arithmetic<T> >::type save(const T& t, dummy<4> = 0) {
      // we provide a generic save routine for all types that feature
      // conversion operators into an unsigned integer value like those
      // created through BOOST_STRONG_TYPEDEF(X, some unsigned int) like
      // library_version_type, collection_size_type, item_version_type,
      // class_id_type, object_id_type, version_type and tracking_type
      save((typename boost::uint_t<sizeof(T) * CHAR_BIT>::least)(t));
    }
  };

  // polymorphic portable binary oarchive typedef
  typedef POLYMORPHIC(portable_oarchive) polymorphic_portable_oarchive;
#undef POLYMORPHIC

}  // namespace eos

// required by export
#if BOOST_VERSION < 103500
#define BOOST_ARCHIVE_CUSTOM_OARCHIVE_TYPES eos::portable_oarchive
#else
BOOST_SERIALIZATION_REGISTER_ARCHIVE(eos::portable_oarchive)
BOOST_SERIALIZATION_REGISTER_ARCHIVE(eos::polymorphic_portable_oarchive)
#endif

// if you include this header multiple times and your compiler is picky
// about multiple template instantiations (eg. gcc is) then you need to
// define NO_EXPLICIT_TEMPLATE_INSTANTIATION before every include but one
// or you move the instantiation section into an implementation file
// #ifndef NO_EXPLICIT_TEMPLATE_INSTANTIATION
//
// #include <boost/archive/impl/basic_binary_oarchive.ipp>
// #include <boost/archive/impl/basic_binary_oprimitive.ipp>
//
// #if BOOST_VERSION < 104000
// #include <boost/archive/impl/archive_pointer_oserializer.ipp>
// #elif !defined BOOST_ARCHIVE_SERIALIZER_INCLUDED
// #include <boost/archive/impl/archive_serializer_map.ipp>
// #define BOOST_ARCHIVE_SERIALIZER_INCLUDED
// #endif
//
// namespace boost {
//   namespace archive {
//
//     // explicitly instantiate for this type of binary stream
//     template class basic_binary_oarchive<eos::portable_oarchive>;
//
//     template class basic_binary_oprimitive<eos::portable_oarchive
// #if BOOST_VERSION < 103400
//                                            ,
//                                            std::ostream
// #else
//                                            ,
//                                            std::ostream::char_type,
//                                            std::ostream::traits_type
// #endif
//                                            >;
//
// #if BOOST_VERSION < 104000
//     template class detail::archive_pointer_oserializer<eos::portable_oarchive>;
// #else
//     template class detail::archive_serializer_map<eos::portable_oarchive>;
//     //template class detail::archive_serializer_map<eos::polymorphic_portable_oarchive>;
// #endif
//
//   }  // namespace archive
// }  // namespace boost
//
// #endif

#endif