#ifndef _DATE_TIME_WRAPPING_INT_HPP__

#define _DATE_TIME_WRAPPING_INT_HPP__

/* Copyright (c) 2002,2003,2005 CrystalClear Software, Inc.

 * Use, modification and distribution is 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) $

 */

namespace boost {

namespace date_time {

//! A wrapping integer used to support time durations (WARNING: only instantiate with a signed type)

/*! In composite date and time types this type is used to

 *  wrap at the day boundary.

 *  Ex: 

 *  A wrapping_int<short, 10> will roll over after nine, and 

 *  roll under below zero. This gives a range of [0,9]

 *

 * NOTE: it is strongly recommended that wrapping_int2 be used 

 * instead of wrapping_int as wrapping_int is to be depricated 

 * at some point soon.

 *

 * Also Note that warnings will occur if instantiated with an 

 * unsigned type. Only a signed type should be used!

 */

template<typename int_type_, int_type_ wrap_val>

class wrapping_int {

public:

  typedef int_type_ int_type;

  //typedef overflow_type_ overflow_type;

  static int_type wrap_value() {return wrap_val;}

  //!Add, return true if wrapped

  wrapping_int(int_type v) : value_(v) {};

  //! Explicit converion method

  int_type as_int()   const   {return value_;}

  operator int_type() const   {return value_;}

  //!Add, return number of wraps performed

  /*! The sign of the returned value will indicate which direction the 

   * wraps went. Ex: add a negative number and wrapping under could occur,

   * this would be indicated by a negative return value. If wrapping over 

   * took place, a positive value would be returned */

  template< typename IntT >

  IntT add(IntT v) 

  {

    int_type remainder = static_cast<int_type>(v % (wrap_val));

    IntT overflow = static_cast<IntT>(v / (wrap_val));

    value_ = static_cast<int_type>(value_ + remainder);

    return calculate_wrap(overflow);

  }

  //! Subtract will return '+d' if wrapping under took place ('d' is the number of wraps)

  /*! The sign of the returned value will indicate which direction the

   * wraps went (positive indicates wrap under, negative indicates wrap over). 

   * Ex: subtract a negative number and wrapping over could 

   * occur, this would be indicated by a negative return value. If 

   * wrapping under took place, a positive value would be returned. */

  template< typename IntT >

  IntT subtract(IntT v) 

  {

    int_type remainder = static_cast<int_type>(v % (wrap_val));

    IntT underflow = static_cast<IntT>(-(v / (wrap_val)));

    value_ = static_cast<int_type>(value_ - remainder);

    return calculate_wrap(underflow) * -1;

  }

private:

  int_type value_;

  template< typename IntT >

  IntT calculate_wrap(IntT wrap)

  {

    if ((value_) >= wrap_val) 

    {

      ++wrap;

      value_ -= (wrap_val);

    }

    else if(value_ < 0) 

    {

      --wrap;

      value_ += (wrap_val);

    }

    return wrap;

  }

};

//! A wrapping integer used to wrap around at the top (WARNING: only instantiate with a signed type)

/*! Bad name, quick impl to fix a bug -- fix later!!

 *  This allows the wrap to restart at a value other than 0.

 */

template<typename int_type_, int_type_ wrap_min, int_type_ wrap_max>

class wrapping_int2 {

public:

  typedef int_type_ int_type;

  static int_type wrap_value() {return wrap_max;}

  static int_type min_value()  {return wrap_min;}

  /*! If initializing value is out of range of [wrap_min, wrap_max],

   * value will be initialized to closest of min or max */

  wrapping_int2(int_type v) : value_(v) {

    if(value_ < wrap_min)

    {

      value_ = wrap_min;

    }

    if(value_ > wrap_max)

    {

      value_ = wrap_max;

    }

  }

  //! Explicit converion method

  int_type as_int()   const   {return value_;}

  operator int_type() const {return value_;}

  //!Add, return number of wraps performed

  /*! The sign of the returned value will indicate which direction the 

   * wraps went. Ex: add a negative number and wrapping under could occur,

   * this would be indicated by a negative return value. If wrapping over 

   * took place, a positive value would be returned */

  template< typename IntT >

  IntT add(IntT v) 

  {

    int_type remainder = static_cast<int_type>(v % (wrap_max - wrap_min + 1));

    IntT overflow = static_cast<IntT>(v / (wrap_max - wrap_min + 1));

    value_ = static_cast<int_type>(value_ + remainder);

    return calculate_wrap(overflow);

  }

  //! Subtract will return '-d' if wrapping under took place ('d' is the number of wraps)

  /*! The sign of the returned value will indicate which direction the

   * wraps went. Ex: subtract a negative number and wrapping over could 

   * occur, this would be indicated by a positive return value. If 

   * wrapping under took place, a negative value would be returned */

  template< typename IntT >

  IntT subtract(IntT v) 

  {

    int_type remainder = static_cast<int_type>(v % (wrap_max - wrap_min + 1));

    IntT underflow = static_cast<IntT>(-(v / (wrap_max - wrap_min + 1)));

    value_ = static_cast<int_type>(value_ - remainder);

    return calculate_wrap(underflow);

  }

private:

  int_type value_;

  template< typename IntT >

  IntT calculate_wrap(IntT wrap)

  {

    if ((value_) > wrap_max) 

    {

      ++wrap;

      value_ -= (wrap_max - wrap_min + 1);

    }

    else if((value_) < wrap_min) 

    {

      --wrap;

      value_ += (wrap_max - wrap_min + 1);

    }

    return wrap;

  }

};

} } //namespace date_time

#endif