dc_calendar_internal.f90

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!-----------------------------------------------------------------------
! Copyright (c) 2000-2026 Gtool Development Group. All rights reserved.
!-----------------------------------------------------------------------
 
module dc_calendar_internal
 
  use dc_calendar_types, only: dc_cal, dc_cal_date
  use dc_types, only: dp
  implicit none
  private
  public:: default_cal_set, dccaldate_normalize, &
    &      dccaltype_str, dccaldate_str2ustr, &
    &      dccaldate_str2usym, dccaldate_ym2d
 
  type(dc_cal), save, target, public:: default_cal
 
  type(dc_cal_date), save, target, public:: default_date
 
contains
 
  subroutine default_cal_set
    use dc_calendar_types, only: cal_gregorian
    implicit none
    type(dc_cal), pointer:: calp =>null()
  continue
    calp => default_cal
 
    if ( calp % initialized ) return
 
    calp % cal_type = cal_gregorian
    calp % month_in_year = 12
    calp % hour_in_day   = 24
    calp % min_in_hour   = 60
    calp % sec_in_min    = 60.0_dp
    allocate( calp % day_in_month(1:12) )
    calp % day_in_month(1:12) = &
      & (/ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 /)
 
    calp % initialized = .true.
    nullify( calp )
  end subroutine default_cal_set
 
 
  function dccaldate_normalize( year, month, day, hour, min, sec, cal ) result(stat)
    use dc_error, only: dc_noerr, dc_einconsistcaldate
    use dc_calendar_types, only: &
      & cal_user_defined, cal_julian, cal_gregorian
    implicit none
    integer:: stat
    integer, intent(inout):: year
    integer, intent(inout):: month
    integer, intent(inout):: day
    integer, intent(inout):: hour
    integer, intent(inout):: min
    real(dp), intent(inout):: sec
    type(dc_cal), intent(in):: cal
 
    integer:: day_in_month_jg
    integer, pointer:: day_in_month(:) =>null()
 
    integer:: month_in_year
    integer:: hour_in_day
    integer:: min_in_hour
    real(dp):: sec_in_min
 
    real(dp):: wyear, wday, whour, wmin
    real(dp):: wdb, ychunk_e6, ychunk_e3, chunk_scale_e6, chunk_scale_e3
  continue
    stat = dc_noerr
 
    select case( cal % cal_type )
    case( cal_user_defined )
      if ( month > cal % month_in_year ) stat = dc_einconsistcaldate
    case default
      if ( month > 12 ) stat = dc_einconsistcaldate
    end select
 
    if ( stat /= dc_noerr ) return
 
    month_in_year = cal % month_in_year
    hour_in_day   = cal % hour_in_day
    min_in_hour   = cal % min_in_hour
    sec_in_min    = cal % sec_in_min
    day_in_month => cal % day_in_month
 
    select case( cal % cal_type )
    case( cal_julian )
      chunk_scale_e6 = 4.0e+5
      ychunk_e6 = 146100000.0_dp
      chunk_scale_e3 = 4.0e+2
      ychunk_e3 = 146100.0_dp
    case( cal_gregorian )
      chunk_scale_e6 = 4.0e+5
      ychunk_e6 = 146097000.0_dp
      chunk_scale_e3 = 4.0e+2
      ychunk_e3 = 146097.0_dp
    case default
      chunk_scale_e6 = 1.0e+6
      ychunk_e6 = chunk_scale_e6 * sum( day_in_month(:) )
      chunk_scale_e3 = 1.0e+3
      ychunk_e3 = chunk_scale_e3 * sum( day_in_month(:) )
    end select
 
    wyear  = real( year, dp )
    wday   = real( day, dp )
    whour  = real( hour, dp )
    wmin   = real( min, dp )
 
    if ( .not. sec < sec_in_min ) then
      wmin = wmin + aint( sec / sec_in_min )
      sec = mod( sec, sec_in_min )
    elseif ( sec < 0.0_dp ) then
      wdb = ceiling( abs(sec) / sec_in_min )
      wmin = wmin - wdb
      sec = sec + wdb * sec_in_min
    end if
 
    if ( .not. wmin < min_in_hour ) then
      whour = whour + aint( wmin / min_in_hour )
      wmin = mod( wmin, real( min_in_hour, dp ) )
    elseif ( wmin < 0 ) then
      wdb = ceiling( abs(wmin) / real(min_in_hour) )
      whour = whour - wdb
      wmin = wmin + wdb * min_in_hour
    end if
 
    if ( .not. whour < hour_in_day ) then
      wday = wday + aint( whour / hour_in_day )
      whour = mod( whour, real( hour_in_day, dp ) )
    elseif ( whour < 0 ) then
      wdb = ceiling( abs(whour) / real(hour_in_day) )
      wday = wday - wdb
      whour = whour + wdb * hour_in_day
    end if
 
    if ( wday < 1.0_dp ) then
      select case( cal % cal_type )
      case( cal_julian )
        do while ( wday < 1.0_dp )
          if ( wday < - ychunk_e6 ) then
            wyear = wyear + chunk_scale_e6 * ( aint( wday / ychunk_e6 ) - 1.0_dp )
            wday = mod( wday, ychunk_e6 ) + ychunk_e6
          end if
          if ( wday < 1.0_dp ) then
            wyear = wyear + chunk_scale_e3 * ( aint( wday / ychunk_e3 ) - 1.0_dp )
            wday = mod( wday, ychunk_e3 ) + ychunk_e3
          end if
        end do
      case( cal_gregorian )
        do while ( wday < 1.0_dp )
          if ( wday < - ychunk_e6 ) then
            wyear = wyear + chunk_scale_e6 * ( aint( wday / ychunk_e6 ) - 1.0_dp )
            wday = mod( wday, ychunk_e6 ) + ychunk_e6
          end if
          if ( wday < 1.0_dp ) then
            wyear = wyear + chunk_scale_e3 * ( aint( wday / ychunk_e3 ) - 1.0_dp )
            wday = mod( wday, ychunk_e3 ) + ychunk_e3
          end if
        end do
      case default
        do while ( wday < 1.0_dp )
          if ( wday < - ychunk_e6 ) then
            wyear = wyear + chunk_scale_e6 * ( aint( wday / ychunk_e6 ) - 1.0_dp )
            wday = mod( wday, ychunk_e6 ) + ychunk_e6
          end if
          if ( wday < 1.0_dp ) then
            wyear = wyear + chunk_scale_e3 * ( aint( wday / ychunk_e3 ) - 1.0_dp )
            wday = mod( wday, ychunk_e3 ) + ychunk_e3
          end if
        end do
      end select
    end if
 
    select case( cal % cal_type )
    case( cal_julian )
      if ( wday > ychunk_e6 ) then
        wyear = wyear + chunk_scale_e6 * aint( wday / ychunk_e6 )
        wday = mod( wday, ychunk_e6 )
      end if
      if ( wday > ychunk_e3 ) then
        wyear = wyear + chunk_scale_e3 * aint( wday / ychunk_e3 )
        wday = mod( wday, ychunk_e3 )
      end if
      do
        if ( month == 2 ) then
          if ( mod( nint(wyear), 4 ) == 0 ) then
            day_in_month_jg = 29
          else
            day_in_month_jg = 28
          end if
        else
          day_in_month_jg = day_in_month(month)
        end if
        if ( .not. wday > day_in_month_jg ) exit
        wday = wday - day_in_month_jg
        month = month + 1
        if ( month > month_in_year ) then
          month = 1
          wyear = wyear + 1
        end if
      end do
    case( cal_gregorian )
      if ( wday > ychunk_e6 ) then
        wyear = wyear + chunk_scale_e6 * aint( wday / ychunk_e6 )
        wday = mod( wday, ychunk_e6 )
      end if
      if ( wday > ychunk_e3 ) then
        wyear = wyear + chunk_scale_e3 * aint( wday / ychunk_e3 )
        wday = mod( wday, ychunk_e3 )
      end if
      do
        if ( month == 2 ) then
          if ( mod( nint(wyear), 400 ) == 0 ) then
            day_in_month_jg = 29
          elseif ( mod( nint(wyear), 100 ) == 0 ) then
            day_in_month_jg = 28
          elseif ( mod( nint(wyear), 4 ) == 0 ) then
            day_in_month_jg = 29
          else
            day_in_month_jg = 28
          end if
        else
          day_in_month_jg = day_in_month(month)
        end if
        if ( .not. wday > day_in_month_jg ) exit
        wday = wday - day_in_month_jg
        month = month + 1
        if ( month > month_in_year ) then
          month = 1
          wyear = wyear + 1
        end if
      end do
    case default
      if ( wday > ychunk_e6 ) then
        wyear = wyear + chunk_scale_e6 * aint( wday / ychunk_e6 )
        wday = mod( wday, ychunk_e6 )
      end if
      if ( wday > ychunk_e3 ) then
        wyear = wyear + chunk_scale_e3 * aint( wday / ychunk_e3 )
        wday = mod( wday, ychunk_e3 )
      end if
      do while ( wday > day_in_month(month) )
        wday = wday - day_in_month(month)
        month = month + 1
        if ( month > month_in_year ) then
          month = 1
          wyear = wyear + 1
        end if
      end do
    end select
 
    year  = int(wyear)
    day   = int(wday)
    hour  = int(whour)
    min   = int(wmin)
 
  end function dccaldate_normalize
 
  function dccaldate_ym2d( year, month, day, cal, day_of_year ) result(stat)
    use dc_error, only: dc_noerr, dc_einconsistcaldate
    use dc_calendar_types, only: &
      & cal_user_defined, cal_julian, cal_gregorian
    implicit none
    integer:: stat
    integer, intent(in):: year
    integer, intent(in):: month
    integer, intent(in):: day
    real(dp), intent(out):: day_of_year
    type(dc_cal), intent(in):: cal
 
    integer:: i
 
  continue
    stat = dc_noerr
 
    select case( cal % cal_type )
    case( cal_user_defined )
      if ( month > cal % month_in_year ) stat = dc_einconsistcaldate
    case default
      if ( month > 12 ) stat = dc_einconsistcaldate
    end select
 
    if ( stat /= dc_noerr ) return
 
    day_of_year  = real( day, dp )
 
    select case( cal % cal_type )
    case( cal_julian )
      do i = 1, month - 1
        if ( i == 2 ) then
          if ( mod( year, 4 ) == 0 ) then
            day_of_year = day_of_year + 29
          else
            day_of_year = day_of_year + 28
          end if
        else
          day_of_year = day_of_year + cal % day_in_month(i)
        end if
      end do
    case( cal_gregorian )
      do i = 1, month - 1
        if ( i == 2 ) then
          if ( mod( year, 400 ) == 0 ) then
            day_of_year = day_of_year + 29
          elseif ( mod( year, 100 ) == 0 ) then
            day_of_year = day_of_year + 28
          elseif ( mod( year, 4 ) == 0 ) then
            day_of_year = day_of_year + 29
          else
            day_of_year = day_of_year + 28
          end if
        else
          day_of_year = day_of_year + cal % day_in_month(i)
        end if
      end do
    case default
      do i = 1, month - 1
        day_of_year = day_of_year + cal % day_in_month(i)
      end do
    end select
 
  end function dccaldate_ym2d
 
 
  function dccaltype_str( cal_type ) result(str)
    use dc_calendar_types, only: &
      & cal_user_defined, &
      & cal_cyclic, cal_noleap, cal_julian, cal_gregorian, cal_360day
    use dc_types, only: token
    implicit none
    character(TOKEN):: str
    integer, intent(in):: cal_type
 
  continue
    select case( cal_type )
    case(cal_user_defined) ; str = 'user_defined'
    case(cal_cyclic)       ; str = 'cyclic      '
    case(cal_noleap)       ; str = 'noleap      '
    case(cal_julian)       ; str = 'julian      '
    case(cal_gregorian)    ; str = 'gregorian   '
    case(cal_360day)       ; str = '360day      '
    case default           ; str = '            '
    end select
  end function dccaltype_str
 
 
  function dccaldate_str2ustr(str) result(unit)
    use dc_types, only: token
    use dc_calendar_types, only: unit_year, unit_month, unit_day, &
      & unit_hour, unit_min, unit_sec
    use dc_string, only: strieq
    implicit none
    character(*), intent(in):: str
    character(TOKEN):: unit
    integer :: unit_str_size, i
  continue
    unit = adjustl(str)
 
    unit_str_size = size(unit_sec)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_sec(i)))) then
        unit = unit_sec(1)
        return
      end if
    end do
 
    unit_str_size = size(unit_min)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_min(i)))) then
        unit = unit_min(1)
        return
      end if
    end do
 
    unit_str_size = size(unit_hour)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_hour(i)))) then
        unit = unit_hour(1)
        return
      end if
    end do
 
    unit_str_size = size(unit_day)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_day(i)))) then
        unit = unit_day(1)
        return
      end if
    end do
 
    unit_str_size = size(unit_month)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_month(i)))) then
        unit = unit_month(1)
        return
      end if
    end do
 
    unit_str_size = size(unit_year)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_year(i)))) then
        unit = unit_year(1)
        return
      end if
    end do
 
    unit = ''
 
  end function dccaldate_str2ustr
 
  function dccaldate_str2usym(str) result(symbol)
    use dc_types, only: token
    use dc_calendar_types, only: unit_year, unit_month, unit_day, &
      & unit_hour, unit_min, unit_sec, &
      & unit_symbol_year, unit_symbol_month, unit_symbol_day, &
      & unit_symbol_hour, unit_symbol_min, unit_symbol_sec, &
      & unit_symbol_err
    use dc_string, only: strieq
    implicit none
    character(*), intent(in):: str
    integer:: symbol
    integer:: unit_str_size, i
    character(TOKEN):: unit
  continue
    unit = adjustl(str)
 
    unit_str_size = size(unit_sec)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_sec(i)))) then
        symbol = unit_symbol_sec
        return
      end if
    end do
 
    unit_str_size = size(unit_min)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_min(i)))) then
        symbol = unit_symbol_min
        return
      end if
    end do
 
    unit_str_size = size(unit_hour)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_hour(i)))) then
        symbol = unit_symbol_hour
        return
      end if
    end do
 
    unit_str_size = size(unit_day)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_day(i)))) then
        symbol = unit_symbol_day
        return
      end if
    end do
 
    unit_str_size = size(unit_month)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_month(i)))) then
        symbol = unit_symbol_month
        return
      end if
    end do
 
    unit_str_size = size(unit_year)
    do i = 1, unit_str_size
      if (strieq(trim(unit), trim(unit_year(i)))) then
        symbol = unit_symbol_year
        return
      end if
    end do
 
    symbol = unit_symbol_err
 
  end function dccaldate_str2usym
 
end module dc_calendar_internal