library BokkyPooBahsDateTimeLibrary {
    uint256 constant SECONDS_PER_DAY = 24 * 60 * 60;
    int256 constant OFFSET19700101 = 2440588;

    // ------------------------------------------------------------------------
    // Calculate year/month/day from the number of days since 1970/01/01 using
    // the date conversion algorithm from
    //   http://aa.usno.navy.mil/faq/docs/JD_Formula.php
    // and adding the offset 2440588 so that 1970/01/01 is day 0
    //
    // int L = days + 68569 + offset
    // int N = 4 * L / 146097
    // L = L - (146097 * N + 3) / 4
    // year = 4000 * (L + 1) / 1461001
    // L = L - 1461 * year / 4 + 31
    // month = 80 * L / 2447
    // dd = L - 2447 * month / 80
    // L = month / 11
    // month = month + 2 - 12 * L
    // year = 100 * (N - 49) + year + L
    // ------------------------------------------------------------------------
    function _daysToDate(uint256 _days)
        internal
        pure
        returns (
            uint256 year,
            uint256 month,
            uint256 day
        )
    {
        int256 __days = int256(_days);

        int256 L = __days + 68569 + OFFSET19700101;
        int256 N = (4 * L) / 146097;
        L = L - (146097 * N + 3) / 4;
        int256 _year = (4000 * (L + 1)) / 1461001;
        L = L - (1461 * _year) / 4 + 31;
        int256 _month = (80 * L) / 2447;
        int256 _day = L - (2447 * _month) / 80;
        L = _month / 11;
        _month = _month + 2 - 12 * L;
        _year = 100 * (N - 49) + _year + L;

        year = uint256(_year);
        month = uint256(_month);
        day = uint256(_day);
    }

    function timestampToDate(uint256 timestamp)
        internal
        pure
        returns (
            uint256 year,
            uint256 month,
            uint256 day
        )
    {
        (year, month, day) = _daysToDate(timestamp / SECONDS_PER_DAY);
    }
}
// ----------------------------------------------------------------------------
// BokkyPooBah's DateTime Library v1.01
//
// A gas-efficient Solidity date and time library
//
// https://github.com/bokkypoobah/BokkyPooBahsDateTimeLibrary
//
// Tested date range 1970/01/01 to 2345/12/31
//
// Conventions:
// Unit      | Range         | Notes
// :-------- |:-------------:|:-----
// timestamp | >= 0          | Unix timestamp, number of seconds since 1970/01/01 00:00:00 UTC
// year      | 1970 ... 2345 |
// month     | 1 ... 12      |
// day       | 1 ... 31      |
// hour      | 0 ... 23      |
// minute    | 0 ... 59      |
// second    | 0 ... 59      |
// dayOfWeek | 1 ... 7       | 1 = Monday, ..., 7 = Sunday
//
//
// Enjoy. (c) BokkyPooBah / Bok Consulting Pty Ltd 2018-2019. The MIT Licence.
// ----------------------------------------------------------------------------
function _daysToDate(uint256 _days)
    internal
    pure
    returns (
        uint256 year,
        uint256 month,
        uint256 day
    )
{
    int256 __days = int256(_days);

    int256 L = __days + 68569 + OFFSET19700101;
    int256 N = (4 * L) / 146097;
    L = L - (146097 * N + 3) / 4;
    int256 _year = (4000 * (L + 1)) / 1461001;
    L = L - (1461 * _year) / 4 + 31;
    int256 _month = (80 * L) / 2447;
    int256 _day = L - (2447 * _month) / 80;
    L = _month / 11;
    _month = _month + 2 - 12 * L;
    _year = 100 * (N - 49) + _year + L;

    year = uint256(_year);
    month = uint256(_month);
    day = uint256(_day);
}

// ------------------------------------------------------------------------
// Calculate year/month/day from the number of days since 1970/01/01 using
// the date conversion algorithm from
//   http://aa.usno.navy.mil/faq/docs/JD_Formula.php
// and adding the offset 2440588 so that 1970/01/01 is day 0
//
// int L = days + 68569 + offset
// int N = 4 * L / 146097
// L = L - (146097 * N + 3) / 4
// year = 4000 * (L + 1) / 1461001
// L = L - 1461 * year / 4 + 31
// month = 80 * L / 2447
// dd = L - 2447 * month / 80
// L = month / 11
// month = month + 2 - 12 * L
// year = 100 * (N - 49) + year + L
// ------------------------------------------------------------------------