/*----------------------------------------------------------------------*
 * Timezone library example sketch.                                     *
 * Self-adjusting clock for multiple time zones.                        *
 * Jack Christensen Mar 2012                                            *
 *                                                                      *
 * Sources for DST rule information:                                    *
 * http://www.timeanddate.com/worldclock/                               *
 * http://home.tiscali.nl/~t876506/TZworld.html                         *
 *                                                                      *
 * This work is licensed under the Creative Commons Attribution-        *
 * ShareAlike 3.0 Unported License. To view a copy of this license,     *
 * visit http://creativecommons.org/licenses/by-sa/3.0/ or send a       *
 * letter to Creative Commons, 171 Second Street, Suite 300,            *
 * San Francisco, California, 94105, USA.                               *
 *----------------------------------------------------------------------*/

#include <RTClib.h>
#include <TimeLib.h>        //http://www.arduino.cc/playground/Code/Time
#include <Timezone.h>    //https://github.com/JChristensen/Timezone

//Central European Time (Frankfurt, Paris)
TimeChangeRule CEST = {"CEST", Last, Sun, Mar, 2, 120};     //Central European Summer Time
TimeChangeRule CET = {"CET ", Last, Sun, Oct, 3, 60};       //Central European Standard Time
Timezone CE(CEST, CET);

//United Kingdom (London, Belfast)
TimeChangeRule BST = {"BST", Last, Sun, Mar, 1, 60};        //British Summer Time
TimeChangeRule GMT = {"GMT", Last, Sun, Oct, 2, 0};         //Standard Time
Timezone UK(BST, GMT);


TimeChangeRule *tcr;        //pointer to the time change rule, use to get the TZ abbrev
time_t utc;
RTC_DS3231 rtc;

void setup(void)
{
    Serial.begin(115200);
    //setTime(CE.toUTC(compileTime()));

    if (!rtc.begin()) {
      Serial.println("Couldn't find RTC");
      Serial.flush();
      abort();
    }
}

void loop(void)
{
    Serial.println();
    // see https://arduino.stackexchange.com/questions/17639/the-difference-between-time-t-and-datetime
    DateTime dt = rtc.now();
    utc = dt.unixtime();
    //utc = now();
    printTime(CE.toLocal(utc, &tcr), tcr -> abbrev, "Berlin");
    printTime(utc, "UTC", " Universal Coordinated Time");
    time_t t = CE.toLocal(utc, &tcr);
    Serial.print(hour(t));
    Serial.print(':');
    Serial.print(minute(t));
    Serial.print(':');
    Serial.print(second(t));
    // Serial.println(tcr -> abbrev);
    delay(10000);
}

//Function to return the compile date and time as a time_t value
time_t compileTime(void)
{
#define FUDGE 25        //fudge factor to allow for compile time (seconds, YMMV)

    char *compDate = __DATE__, *compTime = __TIME__, *months = "JanFebMarAprMayJunJulAugSepOctNovDec";
    char chMon[3], *m;
    int d, y;
    tmElements_t tm;
    time_t t;

    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);
    t = makeTime(tm);
    return t + FUDGE;        //add fudge factor to allow for compile time
}

//Function to print time with time zone
void printTime(time_t t, char *tz, char *loc)
{
    sPrintI00(hour(t));
    sPrintDigits(minute(t));
    sPrintDigits(second(t));
    Serial.print(' ');
    Serial.print(dayShortStr(weekday(t)));
    Serial.print(' ');
    sPrintI00(day(t));
    Serial.print(' ');
    Serial.print(monthShortStr(month(t)));
    Serial.print(' ');
    Serial.print(year(t));
    Serial.print(' ');
    Serial.print(tz);
    Serial.print(' ');
    Serial.print(loc);
    Serial.println();
}

//Print an integer in "00" format (with leading zero).
//Input value assumed to be between 0 and 99.
void sPrintI00(int val)
{
    if (val < 10) Serial.print('0');
    Serial.print(val, DEC);
    return;
}

//Print an integer in ":00" format (with leading zero).
//Input value assumed to be between 0 and 99.
void sPrintDigits(int val)
{
    Serial.print(':');
    if(val < 10) Serial.print('0');
    Serial.print(val, DEC);
}