// Arduino Timezone Library Copyright (C) 2018 by Jack Christensen and
// licensed under GNU GPL v3.0, https://www.gnu.org/licenses/gpl.html
//
// Arduino Timezone Library example sketch.
// Self-adjusting clock for one time zone.
// TimeChangeRules can be hard-coded or read from EEPROM, see comments.
// Jack Christensen Mar 2012

#include <Timezone.h>   // https://github.com/JChristensen/Timezone

// US Eastern Time Zone (New York, Detroit)
TimeChangeRule myDST = {"EDT", Second, Sun, Mar, 2, -240};    // Daylight time = UTC - 4 hours
TimeChangeRule mySTD = {"EST", First, Sun, Nov, 2, -300};     // Standard time = UTC - 5 hours
Timezone myTZ(myDST, mySTD);

// If TimeChangeRules are already stored in EEPROM, comment out the three
// lines above and uncomment the line below.
//Timezone myTZ(100);       // assumes rules stored at EEPROM address 100

TimeChangeRule *tcr;        // pointer to the time change rule, use to get TZ abbrev

void setup()
{
    Serial.begin(115200);
    setTime(myTZ.toUTC(compileTime()));
    //setTime(01, 55, 00, 11, 3, 2012);        //another way to set the time (hr,min,sec,day,mnth,yr)
}

void loop()
{
    time_t utc = now();
    time_t local = myTZ.toLocal(utc, &tcr);
    Serial.println();
    printDateTime(utc, "UTC");
    printDateTime(local, tcr -> abbrev);
    delay(10000);
}

// Function to return the compile date and time as a time_t value
time_t compileTime()
{
    const time_t FUDGE(10);     // fudge factor to allow for compile time (seconds, YMMV)
    const char *compDate = __DATE__, *compTime = __TIME__, *months = "JanFebMarAprMayJunJulAugSepOctNovDec";
    char chMon[3], *m;
    tmElements_t tm;

    strncpy(chMon, compDate, 3);
    chMon[3] = '\0';
    m = strstr(months, chMon);
    tm.Month = ((m - months) / 3 + 1);

    tm.Day = atoi(compDate + 4);
    tm.Year = atoi(compDate + 7) - 1970;
    tm.Hour = atoi(compTime);
    tm.Minute = atoi(compTime + 3);
    tm.Second = atoi(compTime + 6);
    time_t t = makeTime(tm);
    return t + FUDGE;           // add fudge factor to allow for compile time
}

// format and print a time_t value, with a time zone appended.
void printDateTime(time_t t, const char *tz)
{
    char buf[32];
    char m[4];    // temporary storage for month string (DateStrings.cpp uses shared buffer)
    strcpy(m, monthShortStr(month(t)));
    sprintf(buf, "%.2d:%.2d:%.2d %s %.2d %s %d %s",
        hour(t), minute(t), second(t), dayShortStr(weekday(t)), day(t), m, year(t), tz);
    Serial.println(buf);
}