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 *

 * This file incorporates work covered by the following license notice:

 *

 *   Licensed to the Apache Software Foundation (ASF) under one or more

 *   contributor license agreements. See the NOTICE file distributed

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 *   ownership. The ASF licenses this file to you under the Apache

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 */

#include <comphelper/date.hxx>

namespace comphelper::date

{

// Once upon a time the number of days we internally handled in tools' class

// Date was limited to MAX_DAYS 3636532. That changed with a full 16-bit year.

// Assuming the first valid positive date in a proleptic Gregorian calendar is

// 0001-01-01, this resulted in an end date of 9957-06-26.

// Hence we documented that years up to and including 9956 are handled.

/* XXX: it is unclear history why this value was chosen, the representable

 * 9999-12-31 would be 3652060 days from 0001-01-01. Even 9998-12-31 to

 * distinguish from a maximum possible date would be 3651695.

 * There is connectivity/source/commontools/dbconversion.cxx that still has the

 * same value to calculate with css::util::Date */

/* XXX can that dbconversion cope with years > 9999 or negative years at all?

 * Database fields may be limited to positive 4 digits. */

constexpr sal_Int16 kYearMax = SAL_MAX_INT16;

constexpr sal_Int16 kYearMin = SAL_MIN_INT16;

constexpr sal_Int32 MIN_DAYS = convertDateToDays(1, 1, kYearMin); // -32768-01-01

static_assert(MIN_DAYS == -11968265);

constexpr sal_Int32 MAX_DAYS = convertDateToDays(31, 12, kYearMax); // 32767-12-31

static_assert(MAX_DAYS == 11967900);

constexpr sal_Int32 nNullDateDays = convertDateToDays(30, 12, 1899);

static_assert(nNullDateDays == 693594);

sal_Int32 convertDateToDaysNormalizing(sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear)

{

    // Speed-up the common null-date 1899-12-30.

    if (nYear == 1899 && nMonth == 12 && nDay == 30)

        return nNullDateDays;

    normalize(nDay, nMonth, nYear);

    return convertDateToDays(nDay, nMonth, nYear);

}

bool isValidDate(sal_uInt16 nDay, sal_uInt16 nMonth, sal_Int16 nYear)

{

    if (nYear == 0)

        return false;

    if (nMonth < 1 || 12 < nMonth)

        return false;

    if (nDay < 1 || (nDay > comphelper::date::getDaysInMonth(nMonth, nYear)))

        return false;

    return true;

}

void convertDaysToDate(sal_Int32 nDays, sal_uInt16& rDay, sal_uInt16& rMonth, sal_Int16& rYear)

{

    if (nDays <= MIN_DAYS)

    {

        rDay = 1;

        rMonth = 1;

        rYear = kYearMin;

        return;

    }

    if (nDays >= MAX_DAYS)

    {

        rDay = 31;

        rMonth = 12;

        rYear = kYearMax;

        return;

    }

    // Day 0 is -0001-12-31, day 1 is 0001-01-01

    const sal_Int16 nSign = (nDays <= 0 ? -1 : 1);

    sal_Int32 nTempDays;

    sal_Int32 i = 0;

    bool bCalc;

    do

    {

        rYear = static_cast<sal_Int16>((nDays / 365) - (i * nSign));

        if (rYear == 0)

            rYear = nSign;

        nTempDays = nDays - YearToDays(rYear);

        bCalc = false;

        if (nTempDays < 1)

        {

            i += nSign;

            bCalc = true;

        }

        else

        {

            if (nTempDays > 365)

            {

                if ((nTempDays != 366) || !isLeapYear(rYear))

                {

                    i -= nSign;

                    bCalc = true;

                }

            }

        }

    } while (bCalc);

    rMonth = 1;

    while (nTempDays > getDaysInMonth(rMonth, rYear))

    {

        nTempDays -= getDaysInMonth(rMonth, rYear);

        ++rMonth;

    }

    rDay = static_cast<sal_uInt16>(nTempDays);

}

bool normalize(sal_uInt16& rDay, sal_uInt16& rMonth, sal_Int16& rYear)

{

    if (isValidDate(rDay, rMonth, rYear))

        return false;

    if (rDay == 0 && rMonth == 0 && rYear == 0)

        return false; // empty date

    if (rDay == 0)

    {

        if (rMonth == 0)

            ; // nothing, handled below

        else

            --rMonth;

        // Last day of month is determined at the end.

    }

    if (rMonth > 12)

    {

        rYear += rMonth / 12;

        rMonth = rMonth % 12;

        if (rYear == 0)

            rYear = 1;

    }

    if (rMonth == 0)

    {

        --rYear;

        if (rYear == 0)

            rYear = -1;

        rMonth = 12;

    }

    if (rYear < 0)

    {

        sal_uInt16 nDays;

        while (rDay > (nDays = getDaysInMonth(rMonth, rYear)))

        {

            rDay -= nDays;

            if (rMonth > 1)

                --rMonth;

            else

            {

                if (rYear == kYearMin)

                {

                    rDay = 1;

                    rMonth = 1;

                    return true;

                }

                --rYear;

                rMonth = 12;

            }

        }

    }

    else

    {

        sal_uInt16 nDays;

        while (rDay > (nDays = getDaysInMonth(rMonth, rYear)))

        {

            rDay -= nDays;

            if (rMonth < 12)

                ++rMonth;

            else

            {

                if (rYear == kYearMax)

                {

                    rDay = 31;

                    rMonth = 12;

                    return true;

                }

                ++rYear;

                rMonth = 1;

            }

        }

    }

    if (rDay == 0)

        rDay = getDaysInMonth(rMonth, rYear);

    return true;

}

} // namespace comphelper::date

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