gvtimezone.cpp

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//
// Copyright (C) 2017 Graeme Walker
// 
// 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 3 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, see <http://www.gnu.org/licenses/>.
// ===
//
// gvtimezone.cpp
//

#include "gdef.h"
#include "gvtimezone.h"
#include "gdatetime.h"
#include "gdate.h"
#include "gtime.h"
#include "gassert.h"
#include "gstr.h"
#include <stdexcept>

Gv::Timezone::Timezone( int hours ) :
    m_minutes(hours*60)
{
    if( hours < -11 || hours > 12 )
        throw std::runtime_error( "timezone must be between -11 and 12" ) ;
}

Gv::Timezone::Timezone( const std::string & hours_in )
{
    std::string hours( hours_in ) ;
    bool negative = !hours.empty() && hours.at(0U) == '-' ;
    bool positive = !hours.empty() && hours.at(0U) == '+' ;
    if( negative || positive ) hours.erase(0U,1U) ;
    std::string::size_type pos = hours.find(".") ;
    std::string head = G::Str::head( hours , pos , hours ) ;
    std::string tail = G::Str::tail( hours , pos , "0" ) ;

    if( hours.empty() || 
        head.empty() || !G::Str::isUInt(head) || tail.empty() || !G::Str::isUInt(tail) ||
        G::Str::toUInt(head) > (negative?11U:12U) || 
        (G::Str::toUInt(tail) != 0U && G::Str::toUInt(tail)!=5U) )
            throw std::runtime_error( "invalid timezone: use a signed integral number of hours" ) ;

    unsigned int minutes = G::Str::toUInt(head)*60U + (G::Str::toUInt(tail)==5U?30U:0U) ;
    m_minutes = static_cast<int>(minutes) ;
    if( negative ) m_minutes = -m_minutes ;
}

bool Gv::Timezone::zero() const
{
    return m_minutes == 0 ;
}

std::time_t Gv::Timezone::seconds() const
{
    G_ASSERT( std::time_t(-1) < std::time_t(0) ) ;
    return std::time_t(m_minutes) * 60 ;
}

std::string Gv::Timezone::str() const
{
    unsigned int uminutes = m_minutes < 0 ? 
        static_cast<unsigned int>(-m_minutes) : 
        static_cast<unsigned int>(m_minutes) ;

    unsigned int hh = uminutes / 60U ;
    unsigned int mm = uminutes % 60U ;

    std::ostringstream ss ;
    ss << (m_minutes<0?'-':'+') << (hh/10U) << (hh%10U) << (mm/10U) << (mm%10U) ;
    return ss.str() ;
}

/// \file gvtimezone.cpp