// Erisian digital clock - v0.5
#include <Arduino.h>
#include <TimeLib.h>
#include <Thread.h>
#include <DS1307RTC.h>
#include <SevenSegmentExtended.h>      // DisplayLib // Extended TM1637 library https://github.com/bremme/arduino-tm1637
const byte PIN_CLK = 2;                // DisplaySetting // CLK pin
const byte PIN_DIO = 3;                // DisplaySetting // DIO pin
const byte buttonPin = 4;              // ButtonSetting // Button pin (a 10K resistor is necessary)
SevenSegmentExtended display(PIN_CLK, PIN_DIO); // DisplaySetting
Thread mainThread = Thread();          // mainThread
long buttonPressed = 0;                // Button press time counter
long previousButtonMillis = 0;         // Time of last button press
byte viewMode = 0;                     // View mode after pressing button
int buttonInterval = 21600;            // Interval for showing viewMode after pressing button
int buttonLongPress = 1728;            // Long button press interval
int mainCheck = 108;                   // The main interval is an eighth of a decimal second
byte octavo = 0;                       // Eight-count counter
byte colon = 0;                        // Colon status
float erisiansec;                      // Erisian second

// Custom settings:
int brightnessPercent = 32;            // Display brightness percentage value
long timezoneOffset = (-28800);        // Erisian timezoneOffset. Formula for calculating:
                                       // ((-5 christian chours) - (GMT hours))
                                       // Examples:
                                       // GMT+3: ( (-5)-(+3) )*60*60 = -28800
                                       // GMT-0:  ( (-5)-(0) )*60*60 = -18000
                                       // GMT-3: ( (-5)-(-3) )*60*60 = -7200
                                       // GMT-5: ( (-5)-(-5) )*60*60 = 0
                                       // GMT-7: ( (-5)-(-7) )*60*60 = 7200
                                       // The beginning of Discordian day (0 hours, 0 minutes,
                                       // 0 seconds) coincides with the beginning of Christian
                                       // day on Easter Island on winter time (GMT-5).
                                       // Details: https://discordia.fandom.com/wiki/Erisian_Time

void setup() {
  Serial.begin(9600);                  // Initializes the Serial connection @ 9600 baud for debug
  display.begin();                     // Display setting, initializes the display
  display.setBacklight(brightnessPercent); // Display brightness setting
  while (!Serial);                     // Wait until Arduino Serial Monitor opens
  setSyncProvider(RTC.get);            // The function to get the time from the RTC
  if(timeStatus()!= timeSet) {         // Checking the time setting
    Serial.println("Unable to sync with the RTC");
    display.print("_time_not_set_");   // Shows warning "time not set"
  } else {
    Serial.println("RTC has set the system time");
    display.print("HAIL_EriS");        // Shows display initialization
  }
  pinMode(buttonPin, INPUT);           // Button setting
  // Main thread initialization:
  mainThread.onRun(mainLoop);
  mainThread.setInterval(mainCheck);
}

void loop() {
  // Main thread:
  if (mainThread.shouldRun())
    mainThread.run();
  // Time check:
  if (timeStatus() != timeSet)
    display.print("SEt tiMe");
}

void mainLoop() {
  // Counting an eighth part of a decimal second:
  octavo++;
  if (octavo == 8) octavo = 0;
  // Update display every decimal second:
  if (octavo == 0) {
    if (viewMode == 0) {
       dtime();
    } else if (viewMode == 1) {
       dtime();
    } else if (viewMode == 2) {
       ddate();
    } else if (viewMode == 3) {
       ddate();
    } else if (viewMode == 4) {
       dyold();
    }
  }
  // Resets the view mode to the default state after buttonInterval expires:
  if (millis() - previousButtonMillis > buttonInterval) viewMode = 0;
  // Check the button state:
  if (digitalRead(buttonPin) == HIGH) {
    buttonPressed = buttonPressed + mainCheck;
    if (buttonPressed > buttonLongPress) {
      buttonPressed = 0;
      longPress();
    }
  } else {
    if (buttonPressed > 0) {
      if (viewMode < 4) viewMode += 1;
        else viewMode = 0;
      buttonPressed = 0;
      previousButtonMillis = millis();
    }
  }
}

void dtime() {
  // Calculating discordian time:
  uint32_t timec;
  long christiansec;
  float dtimeconv;
  timec = now() + timezoneOffset;
  christiansec = timec % 86400;
  dtimeconv = float(86400) / float(christiansec);
  erisiansec = float(100000) / dtimeconv;
  if (viewMode == 0) dtimeHM();
    else if (viewMode == 1) dtimeMS();
    else dtimeHM();
  colon = !colon;
  display.setColonOn(colon);
}

void dtimeHM() {
  // Displaying of erisian hours and minutes:
  int dhour;
  dhour = int(erisiansec / float(10000));
  int dminute;
  dminute = (long(erisiansec) % 10000) / 100;
  byte  rawData[4];
  rawData[0] = display.encode(' ');
  rawData[1] = display.encode(dhour);
  rawData[2] = display.encode(dminute / 10);
  rawData[3] = display.encode(dminute % 10);
  display.printRaw(rawData);
}

void dtimeMS() {
  // Displaying of erisian minutes and seconds:
  int dminute;
  dminute = (long(erisiansec) % 10000) / 100;
  int dsecond;
  dsecond = (long(erisiansec) % 100);
  byte  rawData[4];
  rawData[0] = display.encode(dminute / 10);
  rawData[1] = display.encode(dminute % 10);
  rawData[2] = display.encode(dsecond / 10);
  rawData[3] = display.encode(dsecond % 10);
  display.printRaw(rawData);
}

void ddate() {
  // Calculating and displaying discordian date:
  uint32_t timec;
  timec = now() + timezoneOffset;
  byte dseason;
  short dday;
  short daynumber;
  short y = year(timec);
  short m = month(timec);
  short d = day(timec);
  // The algorithm for calculating the day's number is from here: https://forum.arduino.cc/index.php?topic=44476.0
  int days[]={0,31,59,90,120,151,181,212,243,273,304,334}; // Number of days at the beginning of the month in a not leap year.
  String outputstr;
  display.setColonOn(0);
  if (viewMode == 2) {
    if (m == 1 || m == 2) {
      daynumber = days[(m - 1)] + d;   // for any type of year, it calculate the number of days for January or February
      dday = daynumber;
      dseason = 0;
    }                                  // Now, try to calculate for the other months
    else if ((y % 4 == 0 && y % 100 != 0) || y % 400 == 0) { //those are the conditions to have a leap year
      daynumber = days[(m - 1)] + d + 1; // if leap year, calculate in the same way but increasing one day
      dday = (daynumber % 73) - 1;
      dseason = (daynumber - 1) / 73;
    }
    else {                             // if not a leap year, calculate in the normal way, such as January or February
      daynumber = days[(m - 1)] + d;
      dday = daynumber % 73;
      dseason = daynumber / 73;
    }
    if ( m == 2 && d == 29 ) outputstr = " tib";
      else {
        if (dseason == 0) outputstr = "ch";
        else if (dseason == 1) outputstr = "di";
        else if (dseason == 2) outputstr = "co";
        else if (dseason == 3) outputstr = "bu";
        else outputstr = "af";
        outputstr += (dday / 10);
        outputstr += (dday % 10);
      }
    display.print(outputstr);
  } else {
    // Calculating and displaying discordian weekday:
    byte dweekday;
    daynumber = days[(m - 1)] + d;
    if (daynumber < 6) dweekday = daynumber;
      else dweekday = daynumber % 5;
    if ( m == 2 && d == 29 ) outputstr = " tib";
      else {
        if (dweekday == 1) outputstr = "swee";
        else if (dweekday == 2) outputstr = "boom";
        else if (dweekday == 3) outputstr = "pung";
        else if (dweekday == 4) outputstr = "pric";
        else outputstr = "sett";
      }
    display.print(outputstr);
  }
}

void dyold() {
  // Calculating and displaying discordian yold:
  uint32_t timec;
  timec = now() + timezoneOffset;
  int yold;
  yold = year(timec) + 1166;
  display.setColonOn(0);
  display.print(yold);
}

void longPress() {
  // Long button press function
  display.setColonOn(0);
  display.print("HAIL_EriS");
  viewMode = 0;
}