#ifndef LOCAL_TIME_LOCAL_DATE_TIME_HPP__

#define LOCAL_TIME_LOCAL_DATE_TIME_HPP__

/* Copyright (c) 2003-2005 CrystalClear Software, Inc.

 * Subject to the Boost Software License, Version 1.0. 

 * (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)

 * Author: Jeff Garland, Bart Garst

 * $Date: 2008-11-12 14:37:53 -0500 (Wed, 12 Nov 2008) $

 */

#include <string>

#include <iomanip>

#include <sstream>

#include <stdexcept>

#include <boost/shared_ptr.hpp>

#include <boost/throw_exception.hpp>

#include <boost/date_time/time.hpp>

#include <boost/date_time/posix_time/posix_time.hpp> //todo remove?

#include <boost/date_time/dst_rules.hpp>

#include <boost/date_time/time_zone_base.hpp>

#include <boost/date_time/special_defs.hpp>

namespace boost {

namespace local_time {

  //! simple exception for reporting when STD or DST cannot be determined

  struct ambiguous_result : public std::logic_error

  {

    ambiguous_result (std::string const& msg = std::string()) :

      std::logic_error(std::string("Daylight Savings Results are ambiguous: " + msg)) {}

  };

  //! simple exception for when time label given cannot exist

  struct time_label_invalid : public std::logic_error

  {

    time_label_invalid (std::string const& msg = std::string()) :

      std::logic_error(std::string("Time label given is invalid: " + msg)) {}

  };

  struct dst_not_valid: public std::logic_error

  {

    dst_not_valid(std::string const& msg = std::string()) :

      std::logic_error(std::string("is_dst flag does not match resulting dst for time label given: " + msg)) {}

  };

  //TODO: I think these should be in local_date_time_base and not 

  // necessarily brought into the namespace

  using date_time::time_is_dst_result;

  using date_time::is_in_dst;

  using date_time::is_not_in_dst;

  using date_time::ambiguous;

  using date_time::invalid_time_label;

  //! Representation of "wall-clock" time in a particular time zone

  /*! Representation of "wall-clock" time in a particular time zone

   * Local_date_time_base holds a time value (date and time offset from 00:00) 

   * along with a time zone. The time value is stored as UTC and conversions 

   * to wall clock time are made as needed. This approach allows for 

   * operations between wall-clock times in different time zones, and 

   * daylight savings time considerations, to be made. Time zones are 

   * required to be in the form of a boost::shared_ptr<time_zone_base>.

   */

  template<class utc_time_=posix_time::ptime, 

           class tz_type=date_time::time_zone_base<utc_time_,char> >

  class local_date_time_base :  public date_time::base_time<utc_time_, 

                                                            boost::posix_time::posix_time_system> { 

  public:

    typedef utc_time_ utc_time_type;

    typedef typename utc_time_type::time_duration_type time_duration_type;

    typedef typename utc_time_type::date_type date_type;

    typedef typename date_type::duration_type date_duration_type;

    typedef typename utc_time_type::time_system_type time_system_type;

    /*! This constructor interprets the passed time as a UTC time.

     *  So, for example, if the passed timezone is UTC-5 then the

     *  time will be adjusted back 5 hours.  The time zone allows for 

     *  automatic calculation of whether the particular time is adjusted for

     *  daylight savings, etc.

     *  If the time zone shared pointer is null then time stays unadjusted.

     *@param t A UTC time

     *@param tz Timezone for to adjust the UTC time to.

     */

    local_date_time_base(utc_time_type t, 

                         boost::shared_ptr<tz_type> tz) : 

      date_time::base_time<utc_time_type, time_system_type>(t),

      zone_(tz)

    {

      // param was already utc so nothing more to do

    } 

    /*! This constructs a local time -- the passed time information 

     * understood to be in the passed tz. The DST flag must be passed 

     * to indicate whether the time is in daylight savings or not.  

     *  @throws -- time_label_invalid if the time passed does not exist in 

     *             the given locale. The non-existent case occurs typically 

     *             during the shift-back from daylight savings time.  When 

     *             the clock is shifted forward a range of times 

     *             (2 am to 3 am in the US) is skipped and hence is invalid.

     *  @throws -- dst_not_valid if the DST flag is passed for a period 

     *             where DST is not active.

     */

    local_date_time_base(date_type d, 

                         time_duration_type td,

                         boost::shared_ptr<tz_type> tz, 

                         bool dst_flag) : //necessary for constr_adj()

      date_time::base_time<utc_time_type,time_system_type>(construction_adjustment(utc_time_type(d, td), tz, dst_flag)),

      zone_(tz)

    {

      if(tz != boost::shared_ptr<tz_type>() && tz->has_dst()){

        // d & td are already local so we use them

        time_is_dst_result result = check_dst(d, td, tz);

        bool in_dst = (result == is_in_dst); // less processing than is_dst()

        // ambig occurs at end, invalid at start

        if(result == invalid_time_label){

          // Ex: 2:15am local on trans-in day in nyc, dst_flag irrelevant

          std::ostringstream ss;

          ss << "time given: " << d << ' ' << td;

          boost::throw_exception(time_label_invalid(ss.str()));

        }

        else if(result != ambiguous && in_dst != dst_flag){

          // is dst_flag accurate?

          // Ex: false flag in NYC in June

          std::ostringstream ss;

          ss.setf(std::ios_base::boolalpha);

          ss << "flag given: dst=" << dst_flag << ", dst calculated: dst=" << in_dst;

          boost::throw_exception(dst_not_valid(ss.str()));

        }

        // everything checks out and conversion to utc already done

      }

    } 

    //TODO maybe not the right set...Ignore the last 2 for now...

    enum DST_CALC_OPTIONS { EXCEPTION_ON_ERROR, NOT_DATE_TIME_ON_ERROR }; 

                            //ASSUME_DST_ON_ERROR, ASSUME_NOT_DST_ON_ERROR };

    /*! This constructs a local time -- the passed time information 

     * understood to be in the passed tz.  The DST flag is calculated 

     * according to the specified rule. 

     */

    local_date_time_base(date_type d, 

                         time_duration_type td,

                         boost::shared_ptr<tz_type> tz, 

                         DST_CALC_OPTIONS calc_option) : 

      // dummy value - time_ is set in constructor code

      date_time::base_time<utc_time_type,time_system_type>(utc_time_type(d,td)),

      zone_(tz)

    {

      time_is_dst_result result = check_dst(d, td, tz);

      if(result == ambiguous) {

        if(calc_option == EXCEPTION_ON_ERROR){

          std::ostringstream ss;

          ss << "time given: " << d << ' ' << td;

          boost::throw_exception(ambiguous_result(ss.str()));

        }

        else{ // NADT on error

          this->time_ = posix_time::posix_time_system::get_time_rep(date_type(date_time::not_a_date_time), time_duration_type(date_time::not_a_date_time));

        }

      }

      else if(result == invalid_time_label){

        if(calc_option == EXCEPTION_ON_ERROR){

          std::ostringstream ss;

          ss << "time given: " << d << ' ' << td;

          boost::throw_exception(time_label_invalid(ss.str()));

        }

        else{ // NADT on error

          this->time_ = posix_time::posix_time_system::get_time_rep(date_type(date_time::not_a_date_time), time_duration_type(date_time::not_a_date_time));

        }

      }

      else if(result == is_in_dst){

        utc_time_type t = 

          construction_adjustment(utc_time_type(d, td), tz, true);

        this->time_ = posix_time::posix_time_system::get_time_rep(t.date(), 

                                                            t.time_of_day());

      }

      else{

        utc_time_type t = 

          construction_adjustment(utc_time_type(d, td), tz, false);

        this->time_ = posix_time::posix_time_system::get_time_rep(t.date(), 

                                                            t.time_of_day());

      }

    }

    //! Determines if given time label is in daylight savings for given zone

    /*! Determines if given time label is in daylight savings for given zone. 

     * Takes a date and time_duration representing a local time, along 

     * with time zone, and returns a time_is_dst_result object as result.

     */

    static time_is_dst_result check_dst(date_type d, 

                                        time_duration_type td,

                                        boost::shared_ptr<tz_type> tz) 

    {

      if(tz != boost::shared_ptr<tz_type>() && tz->has_dst()) {

        typedef typename date_time::dst_calculator<date_type, time_duration_type> dst_calculator;

        return dst_calculator::local_is_dst(

            d, td, 

            tz->dst_local_start_time(d.year()).date(), 

            tz->dst_local_start_time(d.year()).time_of_day(), 

            tz->dst_local_end_time(d.year()).date(), 

            tz->dst_local_end_time(d.year()).time_of_day(),

            tz->dst_offset()

        );

      }

      else{

        return is_not_in_dst;

      }

    }

    //! Simple destructor, releases time zone if last referrer

    ~local_date_time_base() {};

    //! Copy constructor

    local_date_time_base(const local_date_time_base& rhs) : 

      date_time::base_time<utc_time_type, time_system_type>(rhs),

      zone_(rhs.zone_)

    {}

    //! Special values constructor

    explicit local_date_time_base(const boost::date_time::special_values sv,

                                  boost::shared_ptr<tz_type> tz = boost::shared_ptr<tz_type>()) :

      date_time::base_time<utc_time_type, time_system_type>(utc_time_type(sv)),

      zone_(tz)

    {}

    //! returns time zone associated with calling instance

    boost::shared_ptr<tz_type> zone() const 

    {

      return zone_;

    }

    //! returns false is time_zone is NULL and if time value is a special_value

    bool is_dst() const

    {

      if(zone_ != boost::shared_ptr<tz_type>() && zone_->has_dst() && !this->is_special()) {

        // check_dst takes a local time, *this is utc

        utc_time_type lt(this->time_);

        lt += zone_->base_utc_offset();

        // dst_offset only needs to be considered with ambiguous time labels

        // make that adjustment there

        switch(check_dst(lt.date(), lt.time_of_day(), zone_)){

          case is_not_in_dst:

            return false;

          case is_in_dst:

            return true;

          case ambiguous: 

            if(lt + zone_->dst_offset() < zone_->dst_local_end_time(lt.date().year())) {

              return true;

            }

            break;

          case invalid_time_label: 

            if(lt >= zone_->dst_local_start_time(lt.date().year())) {

              return true;

            }

            break;

        }

      }

      return false;

    }

    //! Returns object's time value as a utc representation

    utc_time_type utc_time() const 

    {

      return utc_time_type(this->time_);

    }

    //! Returns object's time value as a local representation

    utc_time_type local_time() const 

    {

      if(zone_ != boost::shared_ptr<tz_type>()){

        utc_time_type lt = this->utc_time() + zone_->base_utc_offset();

        if (is_dst()) {

          lt += zone_->dst_offset();

        }

        return lt;

      }

      return utc_time_type(this->time_);

    }

    //! Returns string in the form "2003-Aug-20 05:00:00 EDT"

    /*! Returns string in the form "2003-Aug-20 05:00:00 EDT". If

     * time_zone is NULL the time zone abbreviation will be "UTC". The time 

     * zone abbrev will not be included if calling object is a special_value*/

    std::string to_string() const

    {

      //TODO is this a temporary function ???

      std::ostringstream ss;

      if(this->is_special()){

        ss << utc_time();

        return ss.str();

      }

      if(zone_ == boost::shared_ptr<tz_type>()) {

        ss << utc_time() << " UTC";

        return ss.str();

      }

      bool is_dst_ = is_dst();

      utc_time_type lt = this->utc_time() + zone_->base_utc_offset();

      if (is_dst_) {

        lt += zone_->dst_offset();

      }

      ss << local_time() << " ";

      if (is_dst()) {

        ss << zone_->dst_zone_abbrev();

      }

      else {

        ss << zone_->std_zone_abbrev();

      }

      return ss.str();

    }

    /*! returns a local_date_time_base in the given time zone with the 

     * optional time_duration added. */

    local_date_time_base local_time_in(boost::shared_ptr<tz_type> new_tz, 

                                       time_duration_type td=time_duration_type(0,0,0)) const 

    {

      return local_date_time_base(utc_time_type(this->time_) + td, new_tz);

    }

    //! Returns name of associated time zone or "Coordinated Universal Time".

    /*! Optional bool parameter will return time zone as an offset 

     * (ie "+07:00" extended iso format). Empty string is returned for 

     * classes that do not use a time_zone */

    std::string zone_name(bool as_offset=false) const

    {

      if(zone_ == boost::shared_ptr<tz_type>()) {

        if(as_offset) {

          return std::string("Z");

        }

        else {

          return std::string("Coordinated Universal Time");

        }

      }

      if (is_dst()) {

        if(as_offset) {

          time_duration_type td = zone_->base_utc_offset();

          td += zone_->dst_offset();

          return zone_as_offset(td, ":");

        }

        else {

          return zone_->dst_zone_name();

        }

      }

      else {

        if(as_offset) {

          time_duration_type td = zone_->base_utc_offset();

          return zone_as_offset(td, ":");

        }

        else {

          return zone_->std_zone_name();

        }

      }

    }

    //! Returns abbreviation of associated time zone or "UTC".

    /*! Optional bool parameter will return time zone as an offset 

     * (ie "+0700" iso format). Empty string is returned for classes 

     * that do not use a time_zone */

    std::string zone_abbrev(bool as_offset=false) const

    {

      if(zone_ == boost::shared_ptr<tz_type>()) {

        if(as_offset) {

          return std::string("Z");

        }

        else {

          return std::string("UTC");

        }

      }

      if (is_dst()) {

        if(as_offset) {

          time_duration_type td = zone_->base_utc_offset();

          td += zone_->dst_offset();

          return zone_as_offset(td, "");

        }

        else {

          return zone_->dst_zone_abbrev();

        }

      }

      else {

        if(as_offset) {

          time_duration_type td = zone_->base_utc_offset();

          return zone_as_offset(td, "");

        }

        else {

          return zone_->std_zone_abbrev();

        }

      }

    }

    //! returns a posix_time_zone string for the associated time_zone. If no time_zone, "UTC+00" is returned.

    std::string zone_as_posix_string() const

    {

      if(zone_ == shared_ptr<tz_type>()) {

        return std::string("UTC+00");

      }

      return zone_->to_posix_string();

    }

    //! Equality comparison operator

    /*bool operator==(const date_time::base_time<boost::posix_time::ptime,boost::posix_time::posix_time_system>& rhs) const

    { // fails due to rhs.time_ being protected

      return date_time::base_time<boost::posix_time::ptime,boost::posix_time::posix_time_system>::operator==(rhs);

      //return this->time_ == rhs.time_;

    }*/

    //! Equality comparison operator

    bool operator==(const local_date_time_base& rhs) const

    {

      return time_system_type::is_equal(this->time_, rhs.time_);

    }

    //! Non-Equality comparison operator

    bool operator!=(const local_date_time_base& rhs) const

    {

      return !(*this == rhs);

    }

    //! Less than comparison operator

    bool operator<(const local_date_time_base& rhs) const

    {

      return time_system_type::is_less(this->time_, rhs.time_);

    }

    //! Less than or equal to comparison operator

    bool operator<=(const local_date_time_base& rhs) const

    {

      return (*this < rhs || *this == rhs);

    }

    //! Greater than comparison operator

    bool operator>(const local_date_time_base& rhs) const

    {

      return !(*this <= rhs);

    }

    //! Greater than or equal to comparison operator

    bool operator>=(const local_date_time_base& rhs) const

    {

      return (*this > rhs || *this == rhs);

    }

    //! Local_date_time + date_duration 

    local_date_time_base operator+(const date_duration_type& dd) const

    {

      return local_date_time_base(time_system_type::add_days(this->time_,dd), zone_);

    }

    //! Local_date_time += date_duration 

    local_date_time_base operator+=(const date_duration_type& dd)

    {

      this->time_ = time_system_type::add_days(this->time_,dd);

      return *this;

    }

    //! Local_date_time - date_duration 

    local_date_time_base operator-(const date_duration_type& dd) const

    {

      return local_date_time_base(time_system_type::subtract_days(this->time_,dd), zone_);

    }

    //! Local_date_time -= date_duration 

    local_date_time_base operator-=(const date_duration_type& dd)

    {

      this->time_ = time_system_type::subtract_days(this->time_,dd);

      return *this;

    }

    //! Local_date_time + time_duration 

    local_date_time_base operator+(const time_duration_type& td) const

    {

      return local_date_time_base(time_system_type::add_time_duration(this->time_,td), zone_);

    }

    //! Local_date_time += time_duration 

    local_date_time_base operator+=(const time_duration_type& td) 

    {

      this->time_ = time_system_type::add_time_duration(this->time_,td);

      return *this;

    }

    //! Local_date_time - time_duration 

    local_date_time_base operator-(const time_duration_type& td) const

    {

      return local_date_time_base(time_system_type::subtract_time_duration(this->time_,td), zone_);

    }

    //! Local_date_time -= time_duration 

    local_date_time_base operator-=(const time_duration_type& td)

    {

      this->time_ = time_system_type::subtract_time_duration(this->time_,td);

      return *this;

    }

    //! local_date_time -= local_date_time --> time_duration_type

    time_duration_type operator-(const local_date_time_base& rhs) const

    {

      return utc_time_type(this->time_) - utc_time_type(rhs.time_);

    }

  private:

    boost::shared_ptr<tz_type> zone_;

    //bool is_dst_;

    /*! Adjust the passed in time to UTC?

     */

    utc_time_type construction_adjustment(utc_time_type t, 

                                          boost::shared_ptr<tz_type> z,

                                          bool dst_flag)

    {

      if(z != boost::shared_ptr<tz_type>()) {

        if(dst_flag && z->has_dst()) {

          t -= z->dst_offset();

        } // else no adjust

        t -= z->base_utc_offset();

      }

      return t;

    }

    /*! Simple formatting code -- todo remove this?

     */

    std::string zone_as_offset(const time_duration_type& td, 

                               const std::string& separator) const

    {

      std::ostringstream ss;

      if(td.is_negative()) {

        // a negative duration is represented as "-[h]h:mm"

        // we require two digits for the hour. A positive duration 

        // with the %H flag will always give two digits

        ss << "-";

      }

      else {

        ss << "+";

      }

      ss  << std::setw(2) << std::setfill('0') 

          << date_time::absolute_value(td.hours()) 

          << separator

          << std::setw(2) << std::setfill('0')

          << date_time::absolute_value(td.minutes());

      return ss.str();

    }

  };

  //!Use the default parameters to define local_date_time

  typedef local_date_time_base<> local_date_time;

} }

#endif