#include <DS3231.h>  // https://github.com/NorthernWidget/DS3231
#include <Wire.h>

DS3231 rtcDs3231;
RTClib rtcLib;


uint32_t uiBaudrate = 230400;
bool xCentury;
bool xH12;  // 12/24h Flag
bool xhPM;  //AM/PM Flag


void setup() {
  Serial.begin(uiBaudrate);
  Wire.begin();
  delay(500);

  rtcInit();
  ds3231SetupHandler();
  Serial.println("RTC Init done");
}

void loop() {
  // put your main code here, to run repeatedly:
  delay(1000);
}

void rtcInit() {
  // Checking OscillatorStopFlag
  Serial.println("Start Checking OSF");
  Wire.beginTransmission(0x68);
  Wire.write(0x0F);  //status register, which contains OSF Flag on 7th position
  Wire.endTransmission();
  Wire.requestFrom(0x68, 1);  //Request for getting content of status register

  byte by = Wire.read();
  if ((by & 0x80) != 0x80) {
    Serial.println("RTC running OSF=0");
  } else {
    Serial.println("RTC not running OSF=1");
  }
}

// ######### 
// RTC Setup wizard
// #########
// - Function for initial RTC Setup by using Serial Terminal
// - The Function will check the serial input whether it's in range or not
// - Consumption on MEGA2560: 14% global variables and 4% programm space

// ######### 
// NOTES
// #########
/* Clearing serial by closing Serial com. to play safe that Serial.available() loop is waiting until new input. For this reason i recommend 
to use this setup wizard on startup or if you want to work with this in loop() you have to play safe, 
that no other module is needing serial communication while the setup wizard is running to prevent possible communication problem. 
I've not tested yet what's the manner of external modules if i restarting the Serial communication.
*/ 
// 

void ds3231SetupHandler() {

  Serial.println("######### RTC Time Init! #########");

  bool xSetupActive = false;  // can getting false at iCase = 10
  // detecting if user want change more options
  do {
    if (xSetupActive == true)
      Serial.begin(uiBaudrate);
    // Wait until Input

    Serial.println("usage: <option>,<value>");
    Serial.println("Available Options - please consider the format!");
    Serial.println("1 = Year (YY)");
    Serial.println("2 = Month (MM)");
    Serial.println("3 = Day (DD)");
    Serial.println("4 = Day of Week (d)");
    Serial.println("5 = Hour (HH)");
    Serial.println("6 = Minutes (MM)");
    Serial.println("7 = Seconds (SS)");
    Serial.println("8 = Clockmode (1=12h / 0=24h)");
    Serial.println("9 = Cancel ");

    while (Serial.available() <= 0)
      ;

    // Read Serial for Getting input Option --> only one character
    if (Serial.available() > 0) {
      String sTerminalInput = Serial.readStringUntil('\n');
      char cTerminalInput[6];
      sTerminalInput.toCharArray(cTerminalInput, sizeof(cTerminalInput));  // Convert String to Char Array
      char *cOption = strtok(cTerminalInput, ",");                         // Parsing the Option Flag
      int iCase = atoi(cOption);                                           // Converting Byte to Int for Case Loop


      // Cancel if Option input is invalid
      if (iCase < 1 || iCase > 9) {
        Serial.println("Invalid <Option>");
        Serial.println("Please consider the syntax: <option>,<value>");
        return;
      } else {
        // go forward if Option could successfull parsed
        if (cOption) {
          char *cValue = strtok(NULL, " ");
          byte byValue = byte(atoi(cValue));
          String sError;

          //Depending of the option the value input will checked
          do {
            if (cValue) {
              // Set year
              if (iCase == 1) {
                if (byValue < 0 || byValue > 99) {
                  iCase = 100;
                  sError = "Valid input range: 0 - 99";
                } else {
                  rtcDs3231.setYear(byValue);
                  iCase = 10;
                }
                // Set Month
              } else if (iCase == 2) {
                if (byValue < 1 || byValue > 12) {
                  iCase = 100;
                  sError = "Valid input range: 1 - 12";
                } else {
                  rtcDs3231.setMonth(byValue);
                  iCase = 10;
                }
                // Set Day of Month
              } else if (iCase == 3) {
                byte byMonth = rtcDs3231.getMonth(xCentury);
                if (byValue < 1 || byValue > 31) {
                  iCase = 100;
                  sError = "Valid input range: 1-31, depending on the months";
                } else {
                  //Leapcear calculation for february
                  bool xLeapYear = false;
                  byte byYear = rtcDs3231.getYear();
                  byte byLeapYearConditions[3];
                  byLeapYearConditions[0] = byYear % 4;
                  byLeapYearConditions[1] = byYear % 100;
                  byLeapYearConditions[2] = byYear % 400;
                  Serial.println(byLeapYearConditions[0]);
                  Serial.println(byLeapYearConditions[1]);
                  Serial.println(byLeapYearConditions[2]);

                  //Basically all Year which divisible with 4 are leapyears
                  if (byLeapYearConditions[0] == 0) {
                    xLeapYear = true;
                    //Years which divisible with 4 and 100 are no leapyears
                    if (byLeapYearConditions[1] == 0) {
                      xLeapYear = false;
                      // But if the year divisible with 100 && 400 it's a leapyear yet
                      if (byLeapYearConditions[2] == 0) {
                        xLeapYear = true;
                      }
                    }
                  }
                  Serial.println(xLeapYear);

                  if ((byMonth == 1 || byMonth == 5 || byMonth == 7 || byMonth == 8 || byMonth == 10 || byMonth == 12) && byValue <= 31 ) {
                    rtcDs3231.setDate(byValue);
                    iCase = 10;
                  } else if (byMonth == 2 && xLeapYear == true) {
                    if(byValue > 29 )
                      iCase = 100; 
                    else{
                      rtcDs3231.setDate(byValue);
                      iCase = 10;
                    }
                  } else if (byMonth == 2 && xLeapYear == false){
                    if(byValue > 28 )
                      iCase = 100; 
                    else{
                      rtcDs3231.setDate(byValue);
                      iCase = 10;
                    }
                  } else if ((byMonth == 4 || byMonth == 6 || byMonth == 9 || byMonth == 11) && byValue <= 30){
                    if(byValue > 30 )
                      iCase = 100; 
                    else{
                      rtcDs3231.setDate(byValue);
                      iCase = 10;
                    }
                  }
                  
                }
              } // Set Day of Week
                else if (iCase == 4) {
                if (byValue < 1 || byValue > 7) {
                  iCase = 100;
                  sError = "Valid input range: 1 - 7";
                } else {
                  rtcDs3231.setDoW(byValue);
                  iCase = 10;
                }
                // Set Time: Hour
              } else if (iCase == 5) {
                if (byValue < 0 || byValue > 23) {
                  iCase = 100;
                  sError = "Valid input range: 0 - 23";
                } else {
                  rtcDs3231.setHour(byValue);
                  iCase = 10;
                }
                // Set Time: Minutes
              } else if (iCase == 6) {
                if (byValue < 0 || byValue > 59) {
                  iCase = 100;
                  sError = "Valid input range: 0 - 59";
                } else {
                  rtcDs3231.setMinute(byValue);
                  iCase = 10;
                }
                // Set Time: Seconds
              } else if (iCase == 7) {
                if (byValue < 0 || byValue > 59) {
                  iCase = 100;
                  sError = "Valid input range: 0 - 59";
                } else {
                  rtcDs3231.setSecond(byValue);
                  iCase = 10;
                }
                // Set Clockmode: AM/PM or 24h mode
              } else if (iCase == 8) {
                if (byValue < 0 || byValue > 1) {
                  iCase = 100;
                  sError = "Valid input range: 0 = 12h / 1 = 24h";
                } else {
                  rtcDs3231.setClockMode(byValue);
                  iCase = 10;
                }
                // Cancel the setup routine
              } else if (iCase == 9) {
                Serial.println("Setup canceled...");
                return;
                // Handling correct insertion and asking for furthermore changes
              } else if (iCase == 10) {
                rtcLib.now();
                Serial.println("The RTC was set on: ");
                Serial.print(rtcDs3231.getYear());
                Serial.print("/");
                Serial.print(rtcDs3231.getMonth(xCentury));
                Serial.print("/");
                Serial.println(rtcDs3231.getDate());
                Serial.print("Current Day of Week: ");
                Serial.println(rtcDs3231.getDoW());
                Serial.print("Current Time: ");
                Serial.print(rtcDs3231.getHour(xH12, xhPM));
                Serial.print(" : ");
                Serial.print(rtcDs3231.getMinute());
                Serial.print(" : ");
                Serial.println(rtcDs3231.getSecond());

                Serial.print("Do you want change more option?");
                Serial.println("(Y/N)");

                while (Serial.available() <= 0)
                  ;

                if (Serial.available() > 0) {
                  char cYesNo = Serial.read();
                  if (cYesNo == 'N' || cYesNo == 'n') {
                    return;
                  } else if (cYesNo == 'Y' || cYesNo == 'y') {
                    xSetupActive = true;
                    iCase = 0;
                    Serial.end();
                  }
                }
              } else if (iCase == 100) {
                Serial.println("Invalid <value>");
                Serial.println("Please consider the syntax: <option>,<value>");
                Serial.end();
                xSetupActive = true;
                iCase = 0;
              }
            }
          } while (iCase == 10 || iCase == 100);
        }
      }
    }
  } while (xSetupActive == true);
}