// **************************************************************************
/** @class Time

@brief Adds some functionality to boost::posix_time::ptime for our needs

This is basically a wrapper around boost::posix_time::ptime which is made
to adapt the functionality to our needs. Time can store the current
data and time with a precision up to nanoseconds if provided by the
undrlaying system, otherwise microsecond precision is used.

It main purpose is to provide needed constructors and simplyfy the
conversion of dates and times from and to a string/stream.

Note that posix_time (as Posix times have) has a limited range. You cannot
use it for example for very early years of the last century.

@section Examples

 - An example can be found in \ref time.cc

@section References

 - <A HREF="http://www.boost.org/doc/libs/1_45_0/doc/html/date_time.html">BOOST++ date_time (V1.45.0)</A>

**/
// **************************************************************************
#include "Time.h"

using namespace std;
using namespace boost::posix_time;

const boost::gregorian::date Time::fUnixOffset(1970, 1, 1);

const Time Time::None(Time::none);

// strftime
const _time_format Time::reset = 0;
const _time_format Time::def   = "%c";
const _time_format Time::std   = "%x %X%F";
const _time_format Time::sql   = "%Y-%m-%d %H:%M:%S.%f";
const _time_format Time::iso   = "%Y%m%dT%H%M%S%F%q";
const _time_format Time::magic = "%Y %m %d %H %M %S %f";

/*
 using date_time::special_values;
 using date_time::not_special;
 using date_time::neg_infin;
 using date_time::pos_infin;
 using date_time::not_a_date_time;
 using date_time::max_date_time;
 using date_time::min_date_time;
 */

// --------------------------------------------------------------------------
//
//! Construct a Time object with either UTC or local time, or without any
//! particular time.
//!
//! @param typ
//!    enum as defined in Time::init_t
//
Time::Time(enum init_t typ)
{
    switch (typ)
    {
    case utc:
        *this = microsec_clock::universal_time();
        break;
    case local:
        *this = microsec_clock::local_time();
        break;
    case none:
        break;
    }
}

// --------------------------------------------------------------------------
//
//! Construct a Time object from seconds since 1970/1/1 and number of
//! milliseconds, as for example returned by gettimeofday()
//!
//! @param tm
//!    seconds since 1970/1/1
//!
//! @param millisec
//!    number of milliseconds
//
Time::Time(const time_t &tm, const int &millisec)
: ptime(fUnixOffset, time_duration(0, 0, tm, millisec))
{
}

// --------------------------------------------------------------------------
//
//! Construct a Time from a date and time.
//!
//! @param year, month, day, hh, mm, ss, microsec
//!    A full date and time down to microsecond precision. From the end
//!    arguments can be omitted.
//!
Time::Time(short year, unsigned char month, unsigned char day,
           unsigned char hh, unsigned char mm, unsigned char ss, unsigned int microsec)
// Last argument is fractional_seconds ( correct with num_fractional_digits() )
: ptime(boost::gregorian::date(year, month, day),
        time_duration(hh, mm, ss, microsec*pow(10, time_of_day().num_fractional_digits()-6)))
{
}

// --------------------------------------------------------------------------
//
//! Set the Time object to a given MJD. Note that this involves
//! conversion from double. So converting forth and back many many
//! times might results in drifts.
//!
//! @param mjd
//!    Modified Julian Date
//!
void Time::Mjd(double mjd)
{
    mjd -= 40587;
    mjd *= 24*60*60;

    const int exp = time_of_day().num_fractional_digits();
    const double frac = fmod(mjd, 1)*pow(10, exp);

    *this = ptime(fUnixOffset, time_duration(0, 0, mjd, frac));
}

// --------------------------------------------------------------------------
//
//! Get the current MJD. Note that this involves
//! conversion to double. So converting forth and back many many
//! times might results in drifts.
//!
//! @returns
//!    Modified Julian Date
//!
double Time::Mjd() const
{
    const time_duration tod = time_of_day();

    const int exp = tod.num_fractional_digits();
    const double sec = tod.fractional_seconds()/pow(10, exp);

    return date().modjulian_day()+sec/(24*60*60);

    /*
     const time_duration mjd = *this - ptime(fUnixOffset);
     const double sec = mjd.total_seconds()+mjd.fractional_seconds()/1e6;
     return sec/(24*60*60)+40587;
     */
}

// --------------------------------------------------------------------------
//
//! Returns a string with the contents of the Time object formated
//! as defined in format.
//!
//! @param format
//!    format description of the string to be returned. For details
//!    see the boost documentation or the man page of strftime
//!
//! @returns
//!    A string with the time formatted as requested. Note some special
//!    strings might be returned in case the time is invalid.
//
string Time::GetAsStr(const char *format) const
{
    stringstream out;
    out << Time::fmt(format) << *this;
    return out.str();
}

// --------------------------------------------------------------------------
//
//! Sets the time of the Time object to a time corresponding to
//! the one given as argument. It is evaluated according to the given
//! format.
//!
//! @param str
//!    The time as a string which should be converted to the Time object
//!
//! @param format
//!    format description of the string to be returned. For details
//!    see the boost documentation or the man page of strftime
//!
void Time::SetFromStr(const string &str, const char *format)
{
    // FIXME: exception handline
    stringstream stream;
    stream << str;
    stream >> Time::fmt(format) >> *this;
}

// --------------------------------------------------------------------------
//
//! A stream manipulator which sets the streams Time output format
//! as defined in the argument.
//!
//! @param format
//!    format description of the manipulator be returned. For details
//!    see the boost documentation or the man page of strftime
//!
//! @returns
//!    a stream manipulator for the given format
//!
const _time_format Time::fmt(const char *format)
{
    return format;
}

// --------------------------------------------------------------------------
//
//! Sets the locale discription of the stream (the way how a time is
//! output) to the format defined by the given manipulator.
//!
//! Example:
//! \code
//!    Time t();
//!    cout << Time::fmt("%Y:%m:%d %H:%M:%S.%f") << t << endl;
//! \endcode
//!
//! @param out
//!    Reference to the stream
//!
//! @param f
//!    Time format described by a manipulator
//!
//! @returns
//!    A reference to the stream
//!
ostream &operator<<(ostream &out, const _time_format &f)
{
    const locale loc(locale::classic(),
                     f.ptr==0 ? 0 : new time_facet(f.ptr));

    out.imbue(loc);

    return out;
}

// --------------------------------------------------------------------------
//
//! Sets the locale discription of the stream (the way how a time is
//! input) to the format defined by the given manipulator.
//!
//! Example:
//! \code
//!    stringstream s;
//!    s << "09.09.1974 21:59";
//!
//!    Time t;
//!    s >> Time::fmt("%d.%m.%Y %H:%M") >> t;
//! \endcode
//!
//! @param in
//!    Reference to the stream
//!
//! @param f
//!    Time format described by a manipulator
//!
//! @returns
//!    A reference to the stream
//!
istream &operator>>(istream &in, const _time_format &f)
{
    const locale loc(locale::classic(),
                     f.ptr==0 ? 0 : new time_input_facet(f.ptr));

    in.imbue(loc);

    return in;
}