/*
  Arduino RTC Clock
  3/1/26

  Encoder library:
  https://github.com/mathertel/RotaryEncoder/tree/master

  TO DO: Add code to set time / date via rotary encoder
*/

#include <LiquidCrystal.h>
#include <RotaryEncoder.h>
#include <RTClib.h>

const int RS = 12, EN = 11, D4 = 10, D5 = 9, D6 = 8, D7 = 7;
const int CK_PIN = 3;
const int DT_PIN = 2;
const int SW_PIN = 4;
const char daysOfTheWeek[7][4] = {
  "Sun",
  "Mon",
  "Tue",
  "Wed",
  "Thu",
  "Fri",
  "Sat"
};
const unsigned long ONE_SEC = 1000;

bool isMDY = true;
bool is12Hour = true;
unsigned long prevTime = 0;

LiquidCrystal lcd(RS, EN, D4, D5, D6, D7);
RotaryEncoder *encoder = nullptr;
RTC_DS1307 rtc;

void checkPosition()  {
  encoder->tick(); // just call tick() to check the state.
}

void showSplash() {
  lcd.setCursor(1, 0);
  lcd.print("Arduino Clock");
  lcd.setCursor(5, 1);
  lcd.print("V1.00");
  delay(2000);
  lcd.clear();
}

void setup() {
  Serial.begin(115200);
  lcd.begin(16, 2);
  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    Serial.flush();
    while (true);
  }
  // setup the rotary encoder functionality
  // use FOUR3 mode when CK_PIN, DT_PIN signals are always HIGH in latch position.
  encoder = new RotaryEncoder(CK_PIN, DT_PIN, RotaryEncoder::LatchMode::FOUR3);
  attachInterrupt(digitalPinToInterrupt(CK_PIN), checkPosition, CHANGE);
  attachInterrupt(digitalPinToInterrupt(DT_PIN), checkPosition, CHANGE);
  pinMode(SW_PIN, INPUT_PULLUP);
  showSplash();
}

void loop() {
  char dateBuffer[16];
  char timeBuffer[16];
  static int pos = 0;

  encoder->tick(); // just call tick() to check the state.

  int newPos = encoder->getPosition();
  if (pos != newPos) {
    Serial.print("pos:");
    Serial.print(newPos);
    Serial.print(" dir:");
    Serial.println((int)(encoder->getDirection()));
    pos = newPos;
  }

  if (millis() - prevTime >= ONE_SEC) {
    prevTime = millis();
    DateTime now = rtc.now();
    if (is12Hour) {
      snprintf(timeBuffer, 16, "%2d:%02d:%02d %s",
               now.twelveHour(),
               now.minute(),
               now.second(),
               now.isPM() ? "PM" : "AM"
              );
      lcd.setCursor(2, 0);
    } else {
      snprintf(timeBuffer, 16, "%2d:%02d:%02d",
               now.hour(),
               now.minute(),
               now.second()
              );
      lcd.setCursor(4, 0);
    }
    lcd.print(timeBuffer);
    Serial.print(timeBuffer);
    Serial.print("\t");
    if (isMDY)  {
      snprintf(dateBuffer, 16, "%s %2d/%2d/%4d",
               daysOfTheWeek[now.dayOfTheWeek()],
               now.month(),
               now.day(),
               now.year()
              );
    } else {
      snprintf(dateBuffer, 16, "%s %2d/%2d/%4d",
               daysOfTheWeek[now.dayOfTheWeek()],
               now.day(),
               now.month(),
               now.year()
              );
    }
    lcd.setCursor(1, 1);
    lcd.print(dateBuffer);
    Serial.println(dateBuffer);
  }
}