#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Keypad.h>

// Define LCD properties
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define Keypad properties
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {3, 4, 5, 6}; // Connect to the row pinouts of the keypad
byte colPins[COLS] = {7, 8, 9, 10}; // Connect to the column pinouts of the keypad
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Define relay properties for 2-channel relay module
const int relayPin1 = 12; // Connect the first relay to pin 12
const int relayPin2 = 13; // Connect the second relay to pin 13

// Define variables to store timer values
int hours = 0;
int minutes = 0;
int seconds = 0;
int currentPosition = 0; // 0 - Hours, 1 - Minutes, 2 - Seconds

bool timerRunning = false;

// Define IR sensor pin and RPM calculation variables
const int IR_PIN = 2;  // IR sensor input pin
volatile unsigned int counter = 0;  // Counter variable for revolutions
unsigned long previousMillis = 0;  // Variable to store previous time
unsigned int rpm = 0;  // Variable to store RPM value

// Interrupt service routine for IR sensor
void IRinterrupt() {
  counter++;
}

// Function to update timer on LCD
void updateTimerLCD() {
  Serial.print("Updating Timer: ");
  Serial.print(hours);
  Serial.print(":");
  Serial.print(minutes);
  Serial.print(":");
  Serial.println(seconds);
  lcd.setCursor(0, 0);
  lcd.print("Timer: ");
  if (hours < 10) lcd.print("0");
  lcd.print(hours);
  lcd.print(":");
  if (minutes < 10) lcd.print("0");
  lcd.print(minutes);
  lcd.print(":");
  if (seconds < 10) lcd.print("0");
  lcd.print(seconds);
  lcd.print("  "); // Clear any previous digits
}

// Function to update RPM on LCD
void updateRPMLCD() {
  Serial.print("Updating RPM: ");
  Serial.println(rpm);
  lcd.setCursor(0, 1);
  lcd.print("RPM:   ");
  lcd.print(rpm);
  lcd.print("      "); // Clear any previous digits
}

void setup() {
  // Initialize Serial for debugging
  Serial.begin(9600);

  // Initialize LCD
  lcd.init();
  lcd.backlight();

  // Initialize relay pins
  pinMode(relayPin1, OUTPUT);
  digitalWrite(relayPin1, HIGH); // Initially turn off the first relay
  pinMode(relayPin2, OUTPUT);
  digitalWrite(relayPin2, HIGH); // Initially turn off the second relay

  // Display initial timer values
  updateTimerLCD();
  updateRPMLCD();

  // Initialize IR sensor pin and attach the interrupt
  pinMode(IR_PIN, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(IR_PIN), IRinterrupt, FALLING);
}

void loop() {
  unsigned long currentMillis = millis();

  // Check for keypad input
  char key = keypad.getKey();

  if (key) {
    delay(50); // Debounce delay
    if (timerRunning) {
      if (key == '*') { // Allow only reset key
        resetTimer();
        updateTimerLCD();
      }
    } else {
      handleKeypadInput(key);
      updateTimerLCD();
    }
  }

  // Handle timer countdown
  static unsigned long lastTimerUpdate = 0;
  if (timerRunning && currentMillis - lastTimerUpdate >= 1000) {
    lastTimerUpdate = currentMillis;
    updateCountdown();
    updateTimerLCD();
  }

  // Calculate RPM every second
  if (currentMillis - previousMillis >= 1000) {
    calculateRPM();
    updateRPMLCD();
  }
}

// Function to handle keypad input
void handleKeypadInput(char key) {
  switch (key) {
    case 'A': // Set hours
      currentPosition = 0;
      break;
    case 'B': // Set minutes
      currentPosition = 1;
      break;
    case 'C': // Set seconds
      currentPosition = 2;
      break;
    case 'D': // Start timer
      if (hours > 0 || minutes > 0 || seconds > 0) {
        timerRunning = true;
        digitalWrite(relayPin1, LOW); // Energize the first relay when the timer starts
      }
      break;
    case '#': // Delete last digit
      deleteDigit();
      break;
    case '*': // Reset timer
      resetTimer();
      break;
    default:
      updateTimer(key);
      break;
  }
}

// Function to update the timer based on keypad input
void updateTimer(char key) {
  int value = key - '0';
  switch (currentPosition) {
    case 0: // Update hours
      hours = (hours * 10 + value) % 100; // Temporarily allow up to 99 to handle digit input
      if (hours > 12) {
        hours = 12; // Limit hours to a maximum of 12
      }
      break;
    case 1: // Update minutes
      minutes = (minutes * 10 + value) % 60;
      break;
    case 2: // Update seconds
      seconds = (seconds * 10 + value) % 60;
      break;
    default:
      break;
  }
}

// Function to delete the last entered digit
void deleteDigit() {
  switch (currentPosition) {
    case 0: // Delete hours
      hours /= 10;
      break;
    case 1: // Delete minutes
      minutes /= 10;
      break;
    case 2: // Delete seconds
      seconds /= 10;
      break;
    default:
      break;
  }
}

// Function to reset the timer
void resetTimer() {
  hours = 0;
  minutes = 0;
  seconds = 0;
  timerRunning = false;
  digitalWrite(relayPin1, HIGH); // Ensure the first relay is de-energized
  digitalWrite(relayPin2, HIGH); // Ensure the second relay is de-energized
  updateTimerLCD(); // Update the timer display
}

// Function to handle the timer countdown
void updateCountdown() {
  seconds--;
  if (seconds < 0) {
    seconds = 59;
    minutes--;
    if (minutes < 0) {
      minutes = 59;
      hours--;
      if (hours < 0) {
        // Timer has run out
        timerRunning = false;
        hours = 0;
        minutes = 0;
        seconds = 0;
        handleTimerEnd();
      }
    }
  }
}

// Function to handle the end of the timer
void handleTimerEnd() {
  digitalWrite(relayPin1, HIGH); // De-energize the first relay
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("STOPPED");
  digitalWrite(relayPin2, LOW); // Energize the second relay
  delay(5000); // Wait for 5 seconds
  digitalWrite(relayPin2, HIGH); // De-energize the second relay
  resetTimer();
}

// Function to calculate RPM
void calculateRPM() {
  detachInterrupt(digitalPinToInterrupt(IR_PIN));
  rpm = counter * 60;  // Calculate RPM
  counter = 0;
  attachInterrupt(digitalPinToInterrupt(IR_PIN), IRinterrupt, FALLING);
  previousMillis = millis();
}