//===========================================================================
// $Id: Date.h,v 1.3 2002/10/18 05:56:10 tknarr Exp $
// Copyright (C) 2000, 2002
// Todd T. Knarr <tknarr@silverglass.org>

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

// Description:
//
// Provides a Date class which represents dates as
// Julian day numbers ( days since 1 Jan 4713 BC ).
// This class can handle all dates from  1 Jan 4713BC to 31 Dec 4999AD.
//
// Note: Years AD are positive, years BC are negative. There is
// no year 0AD, it goes from 1BC to 1AD. A year of 0 will be treated
// as 1BC. No attempt is made to validate ranges. Physical errors
// will not result from insane day-month combinations like the 87th
// day of the 45th month, but the results will obviously not make
// much sense.
//
// Date conversion routines  by Eric bergman-Terrell, Computer Language,
//     Dec 1990.
// Alternate method by David Burki, CUJ Feb 1993.
//
// To Do:
// * Add << and >> operators for iostreams. They should probably output
//   and input the string form.
//--------------------------------------------------------------------------
//
// 09/11/1995 - Todd Knarr
//   . initial release
//
// 16/08/2011 - Todd Knarr
//   . version 2.0
//
//===========================================================================

#include <cstdio>
#include <cstring>
#include <cctype>
#include <algorithm>
#include <cassert>
#include "utils/Date.hpp"
#include "utils/Parser.hpp"

using namespace std;
using namespace ccruncher;

/**************************************************************************//**
 * @details Create a date with the given day-month-year.
 * @param[in] day Date's day (1...31)
 * @param[in] month Date's month (1...12)
 * @param[in] year Date's year (>0)
 * @throw Exception If the given parameters don't conforms a valid date.
 */
ccruncher::Date::Date(const int day, const int month, const int year)
{
  if (!valid(day, month, year))
  {
    char buf[50];
    snprintf(buf, 50, "invalid date: %i/%i/%i", day, month, year);
    throw Exception(buf);
  }

  lJulianDay = YmdToJd( year, month, day );
}

/**************************************************************************//**
 * @details Create a date initialized to the date represented by a system
 *          time value.
 * @see http://www.cplusplus.com/reference/ctime/time_t/
 * @param[in] tSysTime System time.
 */
ccruncher::Date::Date( const time_t tSysTime )
{
  struct tm *ptm;
  int y, m, d;

  ptm = localtime( &tSysTime );
  y = ptm->tm_year + 1900;
  m = ptm->tm_mon + 1;
  d = ptm->tm_mday;
  lJulianDay = YmdToJd( y, m, d );
}

/**************************************************************************//**
 * @details Create a date from a string with format '<code>dd/MM/yyyy</code>.
 * @param[in] str String with the date in format dd/MM/yyyy.
 * @throw Exception If the given string don't represents a valid date.
 */
ccruncher::Date::Date(const std::string &str)
{
  parse(str.c_str());
}

/**************************************************************************//**
 * @details Create a date from a string with format '<code>dd/MM/yyyy</code>.
 * @param[in] str String with the date in format dd/MM/yyyy.
 * @throw Exception If the given string don't represents a valid date.
 */
ccruncher::Date::Date(const char *str)
{
  parse(str);
}

/**************************************************************************//**
 * @details Set value to the date represented by the given string.
 * @param[in] str String with the date in format dd/MM/yyyy.
 * @throw Exception If the given string don't represents a valid date.
 */
void ccruncher::Date::parse(const char *str)
{
  assert(str != nullptr);

  const char *ptr1 = str;
  const char *ptr2 = str;

  // parsing day
  while (isdigit(*ptr2)) ptr2++;
  if (ptr2-ptr1 > 0 && ptr2-ptr1 < 3 && *ptr2 == '/') {
    int d = atoi(ptr1);
    ptr2++;
    ptr1 = ptr2;

    // parsing month
    while (isdigit(*ptr2)) ptr2++;
    if (ptr2-ptr1 > 0 && ptr2-ptr1 < 3 && *ptr2 == '/') {
      int m = atoi(ptr1);
      ptr2++;
      ptr1 = ptr2;

      // parsing year
      while (isdigit(*ptr2)) ptr2++;
      if (ptr2-ptr1 == 4 && *ptr2 == 0) {
        int y = atoi(ptr1);

        // setting date
        if (valid(d, m, y)) {
          lJulianDay = YmdToJd(y, m, d);
          return;
        }
      }
    }
  }

  throw Exception("invalid date: " + string(str));
}

/**************************************************************************//**
 * @details Internal routine that does the physical conversion from YMD
 *          form to Julian day number. Caution: this private method don't
 *          throw any exception. Coder must verify that given values are
 *          valid values (see Date#valid() method) previous to call.
 * @param[in] iDay Date's day (1...31)
 * @param[in] iMonth Date's month (1...12)
 * @param[in] iYear Date's year (>0)
 * @throw Exception If the given parameters don't conforms a valid date.
 */
long ccruncher::Date::YmdToJd( const int iYear, const int iMonth, const int iDay )
{
    long jul_day;

#ifndef JULDATE_USE_ALTERNATE_METHOD

    int b = 0;
    int year = iYear, month = iMonth, day = iDay;
    float year_corr;

    if ( year < 0 )
        year++;
    year_corr = ( year > 0 ? 0.0f : 0.75f );
    if ( month <= 2 )
    {
        year--;
        month += 12;
    }
    if ( year * 10000.0 + month * 100.0 + day >= 15821015.0 )
    {
        int a = year / 100;
        b = 2 - a + a / 4;
    }
    jul_day = (long) ( 365.25 * year - year_corr ) +
              (long) ( 30.6001 * ( month + 1 ) ) + day + 1720995L + b;

#else

    long lmonth = (long) iMonth, lday = (long) iDay, lyear = (long) iYear;

    // Adjust BC years
    if ( lyear < 0 )
        lyear++;

    jul_day = lday - 32075L +
        1461L * ( lyear + 4800L + ( lmonth - 14L ) / 12L ) / 4L +
        367L * ( lmonth - 2L - ( lmonth - 14L ) / 12L * 12L ) / 12L -
        3L * ( ( lyear + 4900L + ( lmonth - 14L ) / 12L ) / 100L ) / 4L;

#endif

    return jul_day;
}

/**************************************************************************//**
 * @details Internal routine that reverses the conversion, turning a
 *          Julian day number into YMD values.
 * @param[in] lJD Julian day number.
 * @param[out] piDay Date's day (1...12)
 * @param[out] piMonth Date's month (1...12)
 * @param[out] piYear Date's year (>0)
 */
void ccruncher::Date::JdToYmd( const long lJD, int *piYear, int *piMonth, int *piDay )
{
#ifndef JULDATE_USE_ALTERNATE_METHOD

    long a, b, c, d, e, z;

    z = lJD;
    if ( z < 2299161L )
        a = z;
    else
    {
        long alpha = (long) ( ( z - 1867216.25 ) / 36524.25 );
        a = z + 1 + alpha - alpha / 4;
    }
    b = a + 1524;
    c = (long) ( ( b - 122.1 ) / 365.25 );
    d = (long) ( 365.25 * c );
    e = (long) ( ( b - d ) / 30.6001 );
    *piDay = (int) b - d - (long) ( 30.6001 * e );
    *piMonth = (int) ( e < 14 ) ? e - 1 : e - 13;
    *piYear = (int) ( *piMonth > 2 ) ? ( c - 4716 ) : c - 4715;
    if ( *piYear <= 0 )
        *piYear -= 1;

#else

    long t1, t2, yr, mo;

    t1 = lJD + 68569L;
    t2 = 4L * t1 / 146097L;
    t1 = t1 - ( 146097L * t2 + 3L ) / 4L;
    yr = 4000L * ( t1 + 1L ) / 1461001L;
    t1 = t1 - 1461L * yr / 4L + 31L;
    mo = 80L * t1 / 2447L;
    *piDay = (int) ( t1 - 2447L * mo / 80L );
    t1 = mo / 11L;
    *piMonth = (int) ( mo + 2L - 12L * t1 );
    *piYear = (int) ( 100L * ( t2 - 49L ) + yr + t1 );

    // Correct for BC years
    if ( *piYear <= 0 )
        *piYear -= 1;

#endif

    return;
}

/**************************************************************************//**
 * @return Date year (>0, eg. 2014).
 */
int ccruncher::Date::getYear( void ) const
{
    int y, m, d;

    JdToYmd( lJulianDay, &y, &m, &d );
    return y;
}

/**************************************************************************//**
 * @return Date month (1...12).
 */
int ccruncher::Date::getMonth( void ) const
{
    int y, m, d;

    JdToYmd( lJulianDay, &y, &m, &d );
    return m;
}

/**************************************************************************//**
 * @return Date day (1...31).
 */
int ccruncher::Date::getDay( void ) const
{
    int y, m, d;

    JdToYmd( lJulianDay, &y, &m, &d );
    return d;
}

/**************************************************************************//**
 * @details Returns the day of the year, with 1 Jan being day 1
 * @return Day of the year (1...366).
 */
int ccruncher::Date::getDayOfYear( void ) const
{
    int y, m, d;
    long soy;

    JdToYmd( lJulianDay, &y, &m, &d );
    soy = YmdToJd( y, 1, 1 );
    return (int) ( lJulianDay - soy + 1 );
}

/**************************************************************************//**
 * @details Return the day of the week, from 0 through 6.
 *          0 = Sunday, ...,  6 = Saturday
 * @return Day of the week (0...6).
 */
int ccruncher::Date::getDayOfWeek( void ) const
{
    return ( ( ( (int) ( lJulianDay % 7L ) ) + 1 ) % 7 );
}

/**************************************************************************//**
 * @details Return the day of the week, from 0 through 6.
 *          0 = Monday, ..., 6 = Sunday
 * @return Day of the week (0...6).
 */
int ccruncher::Date::getDayOfWorkWeek( void ) const
{
    return ( (int) ( lJulianDay % 7L ) );
}

/**************************************************************************//**
 * @details Check if the year is divisible by 4 or is divisible by 400.
 * @param[in] year Year to check if it is a leap year.
 * @return true=leap year, false=otherwise.
 */
bool ccruncher::Date::isLeapYear( const int year )
{
    return ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0));

    // Todd's original code
    // more accurate (consider calendar corrections)
    // but non-optimal for performance.
    // CCruncher's dates are > 1900.
    /*
    long jd1, jd2;
    jd1 = YmdToJd( iYear, 2, 28 );
    jd2 = YmdToJd( iYear, 3, 1 );
    return ( ( jd2 - jd1 ) > 1 );
    */
}

/**************************************************************************//**
 * @details Check if the year is divisible by 4 or is divisible by 400.
 * @return true=leap year, false=otherwise.
 */
bool ccruncher::Date::isLeapYear( void ) const
{
    int y, m, d;
    JdToYmd( lJulianDay, &y, &m, &d );
    return isLeapYear( y );
}

/**************************************************************************//**
 * @details Puts the year, month and day values directly into three integer
 *          variables, for times when you need all three at the same time.
 * @param[out] pD Date's day (1...12).
 * @param[out] pM Date's month (1...12).
 * @param[out] pY Date's year (>0).
 */
void ccruncher::Date::YMD( int *pY, int *pM, int *pD ) const
{
    JdToYmd( lJulianDay, pY, pM, pD );
    return;
}

/**************************************************************************//**
 * @details Converts the date to a time_t value representing midnight of
 *          that date.
 * @see http://www.cplusplus.com/reference/ctime/time_t/
 * @return Current date as system date.
 */
time_t ccruncher::Date::toSysTime( void ) const
{
    struct tm tmRep;
    int y, m, d;
    time_t t;
    
    JdToYmd( lJulianDay, &y, &m, &d );
    if ( y < 1970 )
    {
        y = 70;
        m = 1;
        d = 1;
    }
    tmRep.tm_year = y - 1900 ;
    tmRep.tm_mon = m-1;
    tmRep.tm_mday = d;
    tmRep.tm_hour = 0;
    tmRep.tm_min = 0;
    tmRep.tm_sec = 0;
    tmRep.tm_isdst = 0;
    
    t = mktime( &tmRep );
    return t;
}

/**************************************************************************//**
 * @return Current date formated as <code>dd/MM/yyyy</code>.
 */
string ccruncher::Date::toString() const
{
  int y, m, d;
  char aux[] = "dd/MM/yyyy "; // ending space used by '0'
  aux[10] = 0;
  JdToYmd( lJulianDay, &y, &m, &d );
  snprintf(aux, 11, "%02d/%02d/%04d", d, m, y);
  return string(aux);
}

/**************************************************************************//**
 * @param[in] m Month (1...12).
 * @param[in] y Year (>0).
 * @return Number of days in month (28, 29, 30 or 31).
 */
int ccruncher::Date::numDaysInMonth(int m, int y)
{
  if (m==4 || m==6 || m==9 || m==11)
  {
    return 30;
  }
  else if (m == 2)
  {
    if (Date::isLeapYear(y))
    {
      return 29;
    }
    else
    {
      return 28;
    }
  }
  else
  {
    return 31;
  }
}

/**************************************************************************//**
 * @param[in] y Year (>0).
 * @return Number of days in year (365 or 366).
 */
int ccruncher::Date::numDaysInYear(int y)
{
  if (isLeapYear(y))
  {
    return 366;
  }
  else
  {
    return 365;
  }
}

/**************************************************************************//**
 * @see http://www.cplusplus.com/reference/ostream/ostream/
 * @param[in,out] os Output stream.
 * @param[in] d Date to print.
 * @return Reference to the given stream.
 */
ostream & ccruncher::operator << (ostream& os, const Date& d)
{
  os << d.toString();
  return os;
}

/**************************************************************************//**
 * @details This method manages leap years and distinct month sizes.
 * @param[in] date Date to increment.
 * @param[in] num Number of units to increase.
 * @param[in] units Allowed units are: D=days, M=months, Y=years
 * @return date + num units
 * @throw Exception Units value not recognized.
 */
Date ccruncher::add(const Date &date, int num, char units)
{
  if (num == 0)
  {
    return date;
  }
  else if (units == 'D') // days
  {
    return date + num;
  }
  else if (units == 'M') // months
  {
    int y1, m1, d1;
    date.YMD( &y1, &m1, &d1 );

    y1 += num/12;

    int nmonths = num%12;
    if (nmonths == 0) {
      return Date(d1, m1, y1);
    }

    if (num > 0) {
      if (m1+nmonths<=12) {
        int nd = std::min(d1, Date::numDaysInMonth(m1+nmonths, y1));
        return Date(nd, m1+nmonths, y1);
      }
      else {
        int nd = std::min(d1, Date::numDaysInMonth(m1+nmonths-12, y1+1));
        return Date(nd, m1+nmonths-12, y1+1);
      }
    }
    else {
      if (m1+nmonths>=1) {
        int nd = std::min(d1, Date::numDaysInMonth(m1+nmonths, y1));
        return Date(nd, m1+nmonths, y1);
      }
      else {
        int nd = std::min(d1, Date::numDaysInMonth(m1+nmonths+12, y1-1));
        return Date(nd, m1+nmonths+12, y1-1);
      }
    }
  }
  else if (units == 'Y') // years
  {
    int y, m, d;
    date.YMD(&y, &m, &d);
    if (Date::valid(d, m, y+num)) return Date(d, m, y+num);
    else return Date(d-1,m,y+num); //29-Feb case
  }
  else // otherwise
  {
    throw Exception("invalid units. allowed units are D, M, Y");
  }
}

/**************************************************************************//**
 * @param[in] d1 First date.
 * @param[in] d2 Second date.
 * @return min(d1,d2)
 */
Date ccruncher::min(const Date &d1, const Date &d2)
{
  if (d1 < d2)
  {
    return d1;
  }
  else 
  {
    return d2;
  }
}

/**************************************************************************//**
 * @param[in] d1 First date.
 * @param[in] d2 Second date.
 * @return max(d1,d2)
 */
Date ccruncher::max(const Date &d1, const Date &d2)
{
  if (d1 < d2)
  {
    return d2;
  }
  else 
  {
    return d1;
  }
}

/**************************************************************************//**
 * @param[in] d Date day (1...31)
 * @param[in] m Date month (1...12)
 * @param[in] y Date year (>0)
 * @return true=is a valid date, false=otherwise
 */
bool ccruncher::Date::valid(int d, int m, int y)
{
  if (y<0)
  {
    return false;
  }
  else if (m>12 || m<1)
  {
    return false;
  }
  else if (d < 1 || d > numDaysInMonth(m,y))
  {
    return false;
  }
  else
  {
    return true;
  }
}

/**************************************************************************//**
 * @details Returns the numbers of days/months/years between two dates
 *          as a fractional value. This method manages leap years, and
 *          distinct month sizes.
 * @param[in] date1 Date
 * @param[in] date2
 * @param[in] units Allowed units are: D=days, M=months, Y=years
 * @return date2-date1 as fractional value in days/months/years
 * @throw Exception Units value not recognized.
 */
double ccruncher::diff(const Date &date1, const Date &date2, char units)
{
  if (date2 < date1)
  {
    return -diff(date2, date1, units);
  }
  else if (units == 'D')
  {
    return (double)(date2 - date1);
  }
  else if (units == 'M')
  {
    int y1, m1, d1;
    int y2, m2, d2;
    date1.YMD(&y1, &m1, &d1 );
    date2.YMD(&y2, &m2, &d2 );
    double ret = 0.0;
    ret += 12.0 * (y2 - y1);
    ret += (m2 - m1);
    ret += (d2 - d1) / 30.0;
    return ret;
  }
  else if (units == 'Y')
  {
    int y1, m1, d1;
    int y2, m2, d2;
    date1.YMD(&y1, &m1, &d1 );
    date2.YMD(&y2, &m2, &d2 );
    double ret = 0.0;
    ret += (y2 - y1);
    ret += (m2 - m1) / 12.0;
    ret += (d2 - d1) / (12.0*30.0);
    return ret;
  }
  else
  {
    throw Exception("invalid units. allowed units are D, M, Y");
  }
}

/**************************************************************************//**
 * Checks that the input string has the following pattern:<br/>
 * <code>^([+-])?([0-9])+[DMY]</code>.
 * @param[in] str String to check.
 * @return true=is a valid interval, false=otherwise.
 */
bool ccruncher::isInterval(const char *str) 
{
  if (!str) return false;
  size_t l = strlen(str);
  if (l < 2) return false;
  if ((str[l-1]!='D') && (str[l-1]!='M') && (str[l-1]!='Y'))
    return false;
  if ((str[0]!='+') && (str[0]!='-') && ((str[0]<'0') || (str[0]>'9')))
    return false;
  for(size_t i=1; i<l-1; i++) {
    if ((str[i]<'0') || (str[i]>'9'))
    return false;
  }
  return true;
}

/**************************************************************************//**
 * @see Date#isInterval
 * @param[in] str String containing interval (eg. +450D, -3M, +5Y).
 * @throw Exception invalid interval.
 */
void ccruncher::Date::add(const char *str)
{
  int interval;
  char buffer[25];
  int l = strlen(str);

  // trim and copy to local buffer
  while(isspace(str[l-1]) && l>0) l--; // right trim
  if (l <= 1 || l >= 25) throw Exception("invalid date increment");
  strncpy(buffer, str, l);

  // removing extension (D, M or Y) + setting terminating null byte
  if (buffer[l-1] == 'M' || buffer[l-1] == 'Y' || buffer[l-1] == 'D') buffer[l-1] = '\0';
  else throw Exception("invalid increment unit (allowed units are: D, M, Y)");
  interval = Parser::intValue(buffer);

  if (str[l-1] == 'D') { // increment in days. eg. 365D
    lJulianDay += interval;
  }
  else if (str[l-1] == 'M') { // increment in months. eg. 3M
    *this = ccruncher::add(*this, interval, 'M');
  }
  else if (str[l-1] == 'Y') { // increment in years. eg. 5Y
    *this = ccruncher::add(*this, interval, 'Y');
  }
  else {
    assert(false);
  }
}