#include "boost/date_time/posix_time/posix_time.hpp"
#include "boost/date_time/local_time_adjustor.hpp"
#include "boost/date_time/c_local_time_adjustor.hpp"
#include <iostream>

void convertUtcTime(const boost::posix_time::ptime& tUtc);
boost::posix_time::ptime utc_to_local_workaround(const boost::posix_time::ptime& t);

int main() 
{
    using namespace boost::posix_time;
    using namespace boost::gregorian;
    typedef boost::date_time::c_local_adjustor<ptime> local_adj;

    const ptime tUtcGood(date(2038,Jan,19), hours(3));
    const ptime tUtcBad (date(2038,Jan,19), hours(4)); 

    convertUtcTime(tUtcGood);
    convertUtcTime(tUtcBad);

    return 0;
}


void convertUtcTime(const boost::posix_time::ptime& tUtc)
{
    using namespace boost::posix_time;
    using namespace boost::gregorian;
    typedef boost::date_time::c_local_adjustor<ptime> local_adj;

    std::cout << "Converting UTC time " << to_simple_string(tUtc) << ". ";
    boost::posix_time::ptime tLoc;
    try
    {
        tLoc = local_adj::utc_to_local(tUtc);
    }
    catch (std::exception& e)
    {
        std::cout << "Ouch, year 2038 problem: " << e.what() << ". " << std::endl << "Applying bug fix... ";
        tLoc = utc_to_local_workaround(tUtc);
    }
    std::cout << "Local time is " << to_simple_string(tLoc) << std::endl;
}


boost::posix_time::ptime utc_to_local_workaround(const boost::posix_time::ptime& t)
{
    // This code is a modified, non-templated version of boost::date_time::c_local_adjustor<ptime>

    typedef boost::posix_time::ptime time_type;
    typedef time_type::time_duration_type time_duration_type;
    typedef time_type::date_type date_type;
    typedef date_type::duration_type date_duration_type;

    date_type time_t_start_day(1970,1,1);
    time_type time_t_start_time(time_t_start_day,time_duration_type(0,0,0));
    if (t < time_t_start_time) {
        boost::throw_exception(std::out_of_range("Cannot convert dates prior to Jan 1, 1970"));
        BOOST_DATE_TIME_UNREACHABLE_EXPRESSION(return time_t_start_time); // should never reach
    }
    date_duration_type dd = t.date() - time_t_start_day;
    time_duration_type td = t.time_of_day();

    // The bugfix, needing generalization:
    std::time_t t2 = static_cast<__int64>(dd.days())*__int64(86400) + static_cast<__int64>(td.hours()*3600 + td.minutes()*60 + td.seconds());

    std::tm tms, *tms_ptr;
    tms_ptr = boost::date_time::c_time::localtime(&t2, &tms);
    date_type d(static_cast<unsigned short>(tms_ptr->tm_year + 1900),
        static_cast<unsigned short>(tms_ptr->tm_mon + 1),
        static_cast<unsigned short>(tms_ptr->tm_mday));
    time_duration_type td2(tms_ptr->tm_hour,
        tms_ptr->tm_min,
        tms_ptr->tm_sec,
        t.time_of_day().fractional_seconds());

    return time_type(d,td2);
}


/* Printout:

Converting UTC time 2038-Jan-19 03:00:00. Local time is 2038-Jan-19 04:00:00
Converting UTC time 2038-Jan-19 04:00:00. Ouch, year 2038 problem: could not convert calendar time to local time.
Applying bug fix... Local time is 2038-Jan-19 05:00:00
*/