AuROXTL/Include/auROXTL/auBuildTime.hpp

/***
    Copyright (C) 2023 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuBuildTime.hpp
    Date: 2023-2-22
    Author: Reece
    Credit: https://stackoverflow.com/a/44271643
***/

// extracts 1..4 characters from a string and interprets it as a decimal value
#define __AU_CONV_STR2DEC_1(str, i)  (str[i]>'0'?str[i]-'0':0)
#define __AU_CONV_STR2DEC_2(str, i)  (__AU_CONV_STR2DEC_1(str, i)*10 + str[i+1]-'0')
#define __AU_CONV_STR2DEC_3(str, i)  (__AU_CONV_STR2DEC_2(str, i)*10 + str[i+2]-'0')
#define __AU_CONV_STR2DEC_4(str, i)  (__AU_CONV_STR2DEC_3(str, i)*10 + str[i+3]-'0')

// Some definitions for calculation
#define __AU_SEC_PER_MIN             60UL
#define __AU_SEC_PER_HOUR            3600UL
#define __AU_SEC_PER_DAY             86400UL
#define __AU_SEC_PER_YEAR            (__AU_SEC_PER_DAY*365)
#define __AU_UNIX_START_YEAR         1970UL

// Custom "glue logic" to convert the month name to a usable number
#define __AU_GET_MONTH(str, i)   (str[i]=='J' && str[i+1]=='a' && str[i+2]=='n' ? 1 :     \
                                  str[i]=='F' && str[i+1]=='e' && str[i+2]=='b' ? 2 :     \
                                  str[i]=='M' && str[i+1]=='a' && str[i+2]=='r' ? 3 :     \
                                  str[i]=='A' && str[i+1]=='p' && str[i+2]=='r' ? 4 :     \
                                  str[i]=='M' && str[i+1]=='a' && str[i+2]=='y' ? 5 :     \
                                  str[i]=='J' && str[i+1]=='u' && str[i+2]=='n' ? 6 :     \
                                  str[i]=='J' && str[i+1]=='u' && str[i+2]=='l' ? 7 :     \
                                  str[i]=='A' && str[i+1]=='u' && str[i+2]=='g' ? 8 :     \
                                  str[i]=='S' && str[i+1]=='e' && str[i+2]=='p' ? 9 :     \
                                  str[i]=='O' && str[i+1]=='c' && str[i+2]=='t' ? 10 :    \
                                  str[i]=='N' && str[i+1]=='o' && str[i+2]=='v' ? 11 :    \
                                  str[i]=='D' && str[i+1]=='e' && str[i+2]=='c' ? 12 : 0)

#define __AU_GET_MONTH2DAYS(month)  ((month == 1 ? 0 : 31 +                      \
                                     (month == 2 ? 0 : 28 +                      \
                                     (month == 3 ? 0 : 31 +                      \
                                     (month == 4 ? 0 : 30 +                      \
                                     (month == 5 ? 0 : 31 +                      \
                                     (month == 6 ? 0 : 30 +                      \
                                     (month == 7 ? 0 : 31 +                      \
                                     (month == 8 ? 0 : 31 +                      \
                                     (month == 9 ? 0 : 30 +                      \
                                     (month == 10 ? 0 : 31 +                     \
                                     (month == 11 ? 0 : 30))))))))))))

#define __AU_TIME_SECONDS__        __AU_CONV_STR2DEC_2(__TIME__, 6)
#define __AU_TIME_MINUTES__        __AU_CONV_STR2DEC_2(__TIME__, 3)
#define __AU_TIME_HOURS__          __AU_CONV_STR2DEC_2(__TIME__, 0)
#define __AU_TIME_DAYS__           __AU_CONV_STR2DEC_2(__DATE__, 4)
#define __AU_TIME_MONTH__          __AU_GET_MONTH(__DATE__, 0)
#define __AU_TIME_YEARS__          __AU_CONV_STR2DEC_4(__DATE__, 7)


// Days in February
#define __AU_UNIX_TIMESTAMP_FDAY(year) \
    (((year) % 400) == 0UL ? 29UL : \
        (((year) % 100) == 0UL ? 28UL : \
            (((year) % 4) == 0UL ? 29UL : \
                28UL)))

// Days in the year
#define __AU_UNIX_TIMESTAMP_YDAY(year, month, day) \
    ( \
        /* January */    day \
        /* February */ + (month >=  2 ? 31UL : 0UL) \
        /* March */    + (month >=  3 ? __AU_UNIX_TIMESTAMP_FDAY(year) : 0UL) \
        /* April */    + (month >=  4 ? 31UL : 0UL) \
        /* May */      + (month >=  5 ? 30UL : 0UL) \
        /* June */     + (month >=  6 ? 31UL : 0UL) \
        /* July */     + (month >=  7 ? 30UL : 0UL) \
        /* August */   + (month >=  8 ? 31UL : 0UL) \
        /* September */+ (month >=  9 ? 31UL : 0UL) \
        /* October */  + (month >= 10 ? 30UL : 0UL) \
        /* November */ + (month >= 11 ? 31UL : 0UL) \
        /* December */ + (month >= 12 ? 30UL : 0UL) \
    )

// get the UNIX timestamp from a digits representation
#define __AU_UNIX_TIMESTAMP(year, month, day, hour, minute, second) \
    ( /* time */ second \
                + minute *__AU_SEC_PER_MIN \
                + hour *__AU_SEC_PER_HOUR \
    + /* year day (month + day) */ (__AU_UNIX_TIMESTAMP_YDAY(year, month, day) - 1) *__AU_SEC_PER_DAY \
    + /* year */ (year - 1970UL) *__AU_SEC_PER_YEAR \
                + ((year - 1969UL) / 4UL) *__AU_SEC_PER_DAY \
                - ((year - 1901UL) / 100UL) *__AU_SEC_PER_DAY \
                + ((year - 1601UL) / 400UL) *__AU_SEC_PER_DAY \
    )

static constexpr AuUInt64 AuGetBuildTimeUnix()
{
    return AuUInt64(__AU_UNIX_TIMESTAMP(__AU_TIME_YEARS__, __AU_TIME_MONTH__, __AU_TIME_DAYS__, __AU_TIME_HOURS__, __AU_TIME_MINUTES__, __AU_TIME_SECONDS__)) * 1000ull;
}

static constexpr AuUInt64 AuGetBuildTime()
{
    return AuGetBuildTimeUnix() - 999'080'100'000ull;
}

#undef __AU_TIME_SECONDS__
#undef __AU_TIME_MINUTES__
#undef __AU_TIME_HOURS__
#undef __AU_TIME_DAYS__
#undef __AU_TIME_MONTH__
#undef __AU_TIME_YEARS__
#undef __AU_GET_MONTH
#undef __AU_GET_MONTH2DAYS
#undef __AU_CONV_STR2DEC_1
#undef __AU_CONV_STR2DEC_2
#undef __AU_CONV_STR2DEC_3
#undef __AU_CONV_STR2DEC_4
#undef __AU_SEC_PER_MIN    
#undef __AU_SEC_PER_HOUR   
#undef __AU_SEC_PER_DAY    
#undef __AU_SEC_PER_YEAR   
#undef __AU_UNIX_START_YEAR
#undef __AU_UNIX_TIMESTAMP_FDAY
#undef __AU_UNIX_TIMESTAMP

#define AURORA_BUILD_TIME AuGetBuildTime()