/**
* @file lldateutil.cpp
*
* $LicenseInfo:firstyear=2009&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2010, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
* $/LicenseInfo$
*/

#include "llviewerprecompiledheaders.h"

#include "lldateutil.h"

#include <boost/date_time/gregorian/gregorian.hpp>
#include <boost/date_time/posix_time/ptime.hpp>

// Linden libraries
#include "lltrans.h"
#include "llui.h"

using namespace boost::gregorian;
using namespace boost::posix_time;

static S32 DAYS_PER_MONTH_NOLEAP[] =
    { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
static S32 DAYS_PER_MONTH_LEAP[] =
    { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

static S32 days_from_month(S32 year, S32 month)
{
    llassert_always(1 <= month);
    llassert_always(month <= 12);

    if (year % 4 == 0
        && year % 100 != 0)
    {
        // leap year
        return DAYS_PER_MONTH_LEAP[month - 1];
    }
    else
    {
        return DAYS_PER_MONTH_NOLEAP[month - 1];
    }
}

bool LLDateUtil::dateFromPDTString(LLDate& date, const std::string& str)
{
    S32 month, day, year;
    S32 matched = sscanf(str.c_str(), "%d/%d/%d", &month, &day, &year);
    if (matched != 3) return false;
    date.fromYMDHMS(year, month, day);
    F64 secs_since_epoch = date.secondsSinceEpoch();
    // Correct for the fact that specified date is in Pacific time, == UTC - 8
    secs_since_epoch += 8.0 * 60.0 * 60.0;
    date.secondsSinceEpoch(secs_since_epoch);
    return true;
}

std::string LLDateUtil::ageFromDate(const LLDate& born_date, const LLDate& now)
{
    S32 born_month, born_day, born_year;
    // explode out to month/day/year again
    born_date.split(&born_year, &born_month, &born_day);

    S32 now_year, now_month, now_day;
    now.split(&now_year, &now_month, &now_day);

    // Do grade-school subtraction, from right-to-left, borrowing from the left
    // when things go negative
    S32 age_days = (now_day - born_day);
    if (age_days < 0)
    {
        now_month -= 1;
        if (now_month == 0)
        {
            now_year -= 1;
            now_month = 12;
        }
        age_days += days_from_month(now_year, now_month);
    }
    S32 age_months = (now_month - born_month);
    if (age_months < 0)
    {
        now_year -= 1;
        age_months += 12;
    }
    S32 age_years = (now_year - born_year);

    // Noun pluralization depends on language
    std::string lang = LLUI::getLanguage();

    // Try for age in round number of years
    LLStringUtil::format_map_t args;

    if (age_months > 0 || age_years > 0)
    {
        args["[AGEYEARS]"] =
            LLTrans::getCountString(lang, "AgeYears", age_years);
        args["[AGEMONTHS]"] =
            LLTrans::getCountString(lang, "AgeMonths", age_months);

        // We want to display times like:
        // 2 year 2 months
        // 2 years (implicitly 0 months)
        // 11 months
        if (age_years > 0)
        {
            if (age_months > 0)
            {
                return LLTrans::getString("YearsMonthsOld", args);
            }
            else
            {
                return LLTrans::getString("YearsOld", args);
            }
        }
        else // age_years == 0
        {
            return LLTrans::getString("MonthsOld", args);
        }
    }
    // you're 0 months old, display in weeks or days

    // Now for age in weeks
    S32 age_weeks = age_days / 7;
    age_days = age_days % 7;
    if (age_weeks > 0)
    {
        args["[AGEWEEKS]"] =
            LLTrans::getCountString(lang, "AgeWeeks", age_weeks);
        return LLTrans::getString("WeeksOld", args);
    }

    // Down to days now
    if (age_days > 0)
    {
        args["[AGEDAYS]"] =
            LLTrans::getCountString(lang, "AgeDays", age_days);
        return LLTrans::getString("DaysOld", args);
    }

    return LLTrans::getString("TodayOld");
}

std::string LLDateUtil::ageFromDate(const std::string& date_string, const LLDate& now)
{
    LLDate born_date;

    if (!dateFromPDTString(born_date, date_string))
        return "???";

    return ageFromDate(born_date, now);
}

std::string LLDateUtil::ageFromDate(const std::string& date_string)
{
    return ageFromDate(date_string, LLDate::now());
}

//std::string LLDateUtil::ageFromDateISO(const std::string& date_string,
//                                     const LLDate& now)
//{
//  S32 born_month, born_day, born_year;
//  S32 matched = sscanf(date_string.c_str(), "%d-%d-%d",
//          &born_year, &born_month, &born_day);
//  if (matched != 3) return "???";
//  date.fromYMDHMS(year, month, day);
//  F64 secs_since_epoch = date.secondsSinceEpoch();
//  // Correct for the fact that specified date is in Pacific time, == UTC - 8
//  secs_since_epoch += 8.0 * 60.0 * 60.0;
//  date.secondsSinceEpoch(secs_since_epoch);
//  return ageFromDate(born_year, born_month, born_day, now);
//}
//
//std::string LLDateUtil::ageFromDateISO(const std::string& date_string)
//{
//  return ageFromDateISO(date_string, LLDate::now());
//}

S32 LLDateUtil::secondsSinceEpochFromString(const std::string& format, const std::string& str)
{
    date_input_facet *facet = new date_input_facet(format);

    std::stringstream ss;
    ss << str;
    ss.imbue(std::locale(ss.getloc(), facet));

    date d;
    ss >> d;

    ptime time_t_date(d);
    ptime time_t_epoch(date(1970,1,1));

    // We assume that the date defined by str is in UTC, so the difference
    // is calculated with no time zone corrections.
    time_duration diff = time_t_date - time_t_epoch;

    return (S32)diff.total_seconds();
}