#include <LiquidCrystal.h>
#include <EEPROM.h>

// --- Hardware Definitions ---
const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);
const int BUZZER_PIN = 13;

// --- Constants ---
const int NUM_TIMERS = 4;
const int MASTER_CHANNEL = 0; 
const unsigned long UPDATE_INTERVAL = 200; 
const unsigned long ONE_HOUR_SECONDS = 3600;
const unsigned long LONG_PRESS_TIME = 3000; 
const unsigned long ALARM_INCREMENT = 60; 
const unsigned long INACTIVITY_RESET_TIME = 8000; 
const unsigned long ALARM_DURATION = 20; 
const unsigned long BLINKING_TIME = 500; 

// --- Button Pins ---
const int buttonPins[NUM_TIMERS] = {6, 7, 8, 9}; 
const int ALARM_BUTTON = 10; 

// --- EEPROM Addresses ---
const int EEPROM_START_ADDRESS = 0;
const int ALARM_TIME_SIZE = sizeof(unsigned long);

// --- Data Structures ---
struct TimerData {
  unsigned long startTime;
  unsigned long elapsedTime; 
  bool isRunning;
  bool longFormat; 
  unsigned long alarmTime; 
  unsigned long lastAlarmUpdateTime; 
  bool alarmTriggered; 
  unsigned long alarmEndTime; 
};

TimerData timers[NUM_TIMERS];
bool blinkColon = false;
unsigned long lastSecond = 0; 
bool alarmSetupMode = false; 
bool setupButtonHeld = false;
unsigned long lastActivityTime = 0; 

// --- Button Debouncing Variables ---
unsigned long lastDebounceTime[NUM_TIMERS + 1] = {0, 0, 0, 0, 0}; 
const int debounceDelay = 50; 
unsigned long lastAlarmButtonDebounceTime = 0;

// --- Long Press Variables ---
unsigned long buttonPressTime[NUM_TIMERS] = {0, 0, 0, 0};
bool buttonHeld[NUM_TIMERS] = {false, false, false, false};

// --- Last Displayed Values ---
unsigned long lastDisplayedTime[NUM_TIMERS]; 
unsigned long lastDisplayedAlarmTime[NUM_TIMERS]; 

// --- Blinking Variables ---
bool alarmBlinking[NUM_TIMERS] = {false}; 
unsigned long alarmBlinkTime = 0; 

// --- Function Declarations ---
void updateTimers();
void displayTimers();
void printTime(int timerIndex, unsigned long totalSeconds);
void checkButtons();
void displayAlarmSetup(); 
unsigned long readAlarmTimeFromEEPROM(int timerIndex);
void writeAlarmTimeToEEPROM(int timerIndex, unsigned long alarmTime);
void printAlarmTime(int timerIndex);
void incrementAlarmTime(int timerIndex);
void resetAlarmTime(int timerIndex);
void copyMasterAlarmToOthers();
void resetAllAlarmTimes();
void checkAlarms();

void setup() {
  lcd.begin(16, 2);

  Serial.begin(9600);
  Serial.println("Program Started");

  pinMode(BUZZER_PIN, OUTPUT);

  unsigned long currentTime = millis();
  for (int i = 0; i < NUM_TIMERS; i++) {
    timers[i].startTime = currentTime;
    timers[i].elapsedTime = 0;
    timers[i].isRunning = true; 
    timers[i].longFormat = false;
    timers[i].alarmTime = readAlarmTimeFromEEPROM(i); 
    timers[i].lastAlarmUpdateTime = 0; 
    timers[i].alarmTriggered = false; 
    timers[i].alarmEndTime = 0; 

    if (timers[i].alarmTime == 0xFFFFFFFF) { 
      timers[i].alarmTime = 0;
      writeAlarmTimeToEEPROM(i, timers[i].alarmTime); 
    }

    pinMode(buttonPins[i], INPUT_PULLUP);
    buttonPressTime[i] = 0;
    buttonHeld[i] = false;
    lastDisplayedTime[i] = 0xFFFFFFFF; 
    lastDisplayedAlarmTime[i] = 0xFFFFFFFF; 
  }

  pinMode(ALARM_BUTTON, INPUT_PULLUP);
  lastSecond = millis() / 1000; 
}

void loop() {
  checkButtons();
  updateTimers();

  if (!alarmSetupMode) {
    displayTimers();
  } else {
    displayAlarmSetup();
  }

  delay(UPDATE_INTERVAL);
}

void updateTimers() {
  unsigned long currentTime = millis();
  unsigned long currentSecond = currentTime / 1000;

  if (currentSecond != lastSecond) {
    blinkColon = !blinkColon;
    lastSecond = currentSecond;

    for (int i = 0; i < NUM_TIMERS; i++) {
      if (timers[i].isRunning) {
        timers[i].elapsedTime = (currentTime - timers[i].startTime) / 1000;

        if (timers[i].elapsedTime >= ONE_HOUR_SECONDS && !timers[i].longFormat) {
          timers[i].longFormat = true;
        }

        if (timers[i].elapsedTime >= (99 * ONE_HOUR_SECONDS + (59 * 60))) { 
          timers[i].isRunning = false;
          timers[i].elapsedTime = (99 * ONE_HOUR_SECONDS + (59 * 60));
        }
      }
    }
  }

  if (!alarmSetupMode) {
    checkAlarms(); 
  }
}

void displayTimers() {
  unsigned long currentTime = millis();
  for (int i = 0; i < NUM_TIMERS; i++) {
    int row = i / 2;
    int col = (i % 2) * 8;

    lcd.setCursor(col, row);
    lcd.print(i + 1);
    lcd.print("-");

    if (alarmBlinking[i]) {
      if ((currentTime - alarmBlinkTime) % (BLINKING_TIME * 2) < BLINKING_TIME) {
        printTime(i, timers[i].elapsedTime);
      } else {
        lcd.setCursor(col + 2, row); 
        lcd.print("      ");
      }
    } else {
      printTime(i, timers[i].elapsedTime);
    }
  }
}

void printTime(int timerIndex, unsigned long totalSeconds) {
  int hours = totalSeconds / ONE_HOUR_SECONDS;
  int minutes = (totalSeconds % ONE_HOUR_SECONDS) / 60;
  int seconds = totalSeconds % 60;

  lcd.setCursor((timerIndex % 2) * 8 + 2, timerIndex / 2); 

  if (timers[timerIndex].longFormat) {
    if (hours < 10) lcd.print("0");
    lcd.print(hours);
    lcd.print(blinkColon ? ":" : " ");
    if (minutes < 10) lcd.print("0");
    lcd.print(minutes);
  } else {
    if (minutes < 10) lcd.print("0");
    lcd.print(minutes);
    lcd.print(blinkColon ? ":" : " ");
    if (seconds < 10) lcd.print("0");
    lcd.print(seconds);
  }
}

void checkButtons() {
  int alarmButtonState = digitalRead(ALARM_BUTTON);
  unsigned long currentTime = millis();

  if (alarmButtonState == LOW) {
    if (millis() - lastAlarmButtonDebounceTime > debounceDelay) {
      if (!setupButtonHeld) {
        alarmSetupMode = true; 
        lastAlarmButtonDebounceTime = millis();
        setupButtonHeld = true;
        lastActivityTime = currentTime; 

        noTone(BUZZER_PIN);
        for (int i = 0; i < NUM_TIMERS; i++) {
          timers[i].alarmTriggered = false;
          timers[i].alarmEndTime = 0;
        }
      }
    }
  } else {
    if (millis() - lastAlarmButtonDebounceTime > debounceDelay) {
      if (setupButtonHeld) {
        alarmSetupMode = false; 
        lastAlarmButtonDebounceTime = millis();
        setupButtonHeld = false;

        for (int i = 0; i < NUM_TIMERS; i++) {
          writeAlarmTimeToEEPROM(i, timers[i].alarmTime);
        }

        for (int i = 0; i < NUM_TIMERS; i++) {
          timers[i].alarmTriggered = false;
          timers[i].alarmEndTime = 0;
        }

        for (int i = 0; i < NUM_TIMERS; i++) {
          if (timers[i].alarmTime > 0 && timers[i].alarmTime > timers[i].elapsedTime) {
            timers[i].lastAlarmUpdateTime = millis();
          } else {
            timers[i].lastAlarmUpdateTime = 0; 
          }
        }
      }
    }
  }

  if (alarmSetupMode && (currentTime - lastActivityTime > INACTIVITY_RESET_TIME)) {
    resetAllAlarmTimes();
    lastActivityTime = currentTime + 100000; 
  }

  for (int i = 0; i < NUM_TIMERS; i++) {
    int buttonState = digitalRead(buttonPins[i]);

    if (alarmSetupMode && buttonState == LOW) {
      if (millis() - lastDebounceTime[i] > debounceDelay) {
        lastDebounceTime[i] = millis();

        if (!buttonHeld[i]) {
          buttonHeld[i] = true;
          buttonPressTime[i] = millis();
          incrementAlarmTime(i); 
          if (i == MASTER_CHANNEL) {
            copyMasterAlarmToOthers();
          }
          lastActivityTime = currentTime; 
          timers[i].alarmTriggered = false; 
        }
      }

      if ((millis() - buttonPressTime[i]) >= LONG_PRESS_TIME) {
        resetAlarmTime(i);
        if (i == MASTER_CHANNEL) {
          copyMasterAlarmToOthers();
        }
        buttonPressTime[i] = millis() + 100000;
        lastActivityTime = currentTime;
        timers[i].alarmTriggered = false; 
      }
    } else {
      if (buttonState == LOW) {
        if (millis() - lastDebounceTime[i] > debounceDelay) {
          lastDebounceTime[i] = millis();

          if (!buttonHeld[i]) {
            buttonHeld[i] = true;
            buttonPressTime[i] = millis();
          }
        }

        if ((millis() - buttonPressTime[i]) >= LONG_PRESS_TIME) { 
          timers[i].elapsedTime = 0;
          timers[i].startTime = millis();
          displayTimers();
          timers[i].alarmTriggered = false;
          alarmBlinking[i] = false; 
        }
      } else {
        if (buttonHeld[i]) {
          buttonHeld[i] = false;
        }
      }
    }
  }
}

void displayAlarmSetup() {
  lcd.setCursor(0, 0);
  lcd.print("A>");
  printAlarmTime(0);
  lcd.print(" A>");
  printAlarmTime(1);
  lcd.setCursor(0, 1);
  lcd.print("A>");
  printAlarmTime(2);
  lcd.print(" A>");
  printAlarmTime(3);
}

void printAlarmTime(int timerIndex) {
  unsigned long alarmTime = timers[timerIndex].alarmTime;
  int alarmHours = (alarmTime / 3600) % 100;
  int alarmMinutes = (alarmTime % 3600) / 60;

  lcd.setCursor((timerIndex % 2) * 8 + 2, timerIndex / 2); 

  if (alarmHours < 10) {
    lcd.print("0");
  }
  lcd.print(alarmHours);
  lcd.print(":");

  if (alarmMinutes < 10) {
    lcd.print("0");
  }
  lcd.print(alarmMinutes);
}

unsigned long readAlarmTimeFromEEPROM(int timerIndex) {
  int address = EEPROM_START_ADDRESS + (timerIndex * ALARM_TIME_SIZE);
  unsigned long alarmTime;
  EEPROM.get(address, alarmTime);
  return alarmTime;
}

void writeAlarmTimeToEEPROM(int timerIndex, unsigned long alarmTime) {
  int address = EEPROM_START_ADDRESS + (timerIndex * ALARM_TIME_SIZE);
  EEPROM.put(address, alarmTime);
}

void incrementAlarmTime(int timerIndex) {
  timers[timerIndex].alarmTime += ALARM_INCREMENT;

  if (timers[timerIndex].alarmTime >= 360000) { 
    timers[timerIndex].alarmTime = 0; 
  }

  timers[timerIndex].alarmTriggered = false; 
  timers[timerIndex].alarmEndTime = 0; 
  timers[timerIndex].lastAlarmUpdateTime = millis(); 
  displayAlarmSetup(); 
}

void resetAlarmTime(int timerIndex) {
  timers[timerIndex].alarmTime = 0;
  timers[timerIndex].alarmTriggered = false; 
  timers[timerIndex].alarmEndTime = 0; 
  displayAlarmSetup();
}

void copyMasterAlarmToOthers() {
  unsigned long masterAlarmTime = timers[MASTER_CHANNEL].alarmTime;
  for (int i = 0; i < NUM_TIMERS; i++) {
    if (i != MASTER_CHANNEL) {
      timers[i].alarmTime = masterAlarmTime;
    }
  }
  displayAlarmSetup(); 
}

void resetAllAlarmTimes() {
  for (int i = 0; i < NUM_TIMERS; i++) {
    timers[i].alarmTime = 0;
  }
  displayAlarmSetup();
}

void resetTimer(int timerIndex) {
  timers[timerIndex].elapsedTime = 0;
  timers[timerIndex].startTime = millis();
  timers[timerIndex].alarmTriggered = false; 
  timers[timerIndex].alarmEndTime = 0; 
  alarmBlinking[timerIndex] = false; 
  displayTimers();
}

void checkAlarms() {
  unsigned long currentTime = millis() / 1000; 
  for (int i = 0; i < NUM_TIMERS; i++) {
    if (timers[i].alarmTime > 0 && timers[i].alarmTime <= timers[i].elapsedTime && timers[i].alarmTime > timers[i].elapsedTime - 1 && !timers[i].alarmTriggered) {
      timers[i].alarmEndTime = currentTime + ALARM_DURATION;
      timers[i].alarmTriggered = true;
      tone(BUZZER_PIN, 1000); 
      alarmBlinking[i] = true; 
      alarmBlinkTime = millis(); 
    }

    if (timers[i].alarmEndTime > 0 && currentTime < timers[i].alarmEndTime) {
      tone(BUZZER_PIN, 1000); 
    } else {
      noTone(BUZZER_PIN); 
      if (timers[i].alarmEndTime > 0 && currentTime >= timers[i].alarmEndTime) {
        timers[i].alarmEndTime = 0; 
        timers[i].alarmTriggered = false; 
      }
    }
  }
}