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

// Keypad configuration
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Four columns
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte rowPins[ROWS] = {6, 7, 8, 9}; // Row pinouts
byte colPins[COLS] = {A0, A1, A2, A3}; // Column pinouts

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// LCD configuration (RS, E, D4, D5, D6, D7)
LiquidCrystal lcd(12, 11, 5, 4, 3, 2); // RS to Pin 12, E to Pin 11

// Pin for potentiometer
const int potPin = A4; // Connect potentiometer to A4

// Pin for buzzer
const int buzzerPin = 10; // Buzzer connected to digital pin D10

// Pin for alarm reset button
const int resetButtonPin = A5; // Button connected to A5

// Variables
String weightInput = ""; // String to hold weight input for calibration
bool inputMode = false;  // Flag to indicate if we are in input mode
float calibrationWeight = 0.0; // User inputted control weight for calibration
float currentWeight = 0.0; // Current weight reading from potentiometer
float calibrationOffset = 0.0; // Offset to apply after calibration

// EEPROM address for storing calibration weight
const int CALIBRATION_ADDR = 0;

// Variables for buzzer control
bool buzzerActive = false; // Flag to indicate if buzzer is active
unsigned long buzzerStartTime = 0; // Start time of buzzer
bool alarmRegistered = false; // Flag to check if alarm has been registered
bool alarmSuppressed = false; // Flag to indicate if alarm is suppressed
unsigned long suppressEndTime = 0; // Time to end the alarm suppression
unsigned long displayResetMessageEndTime = 0; // Time to end the reset message display

void setup() {
  Serial.begin(9600); // Initialize serial communication
  lcd.begin(16, 2); // Initialize the LCD's columns and rows
  lcd.clear(); // Clear the LCD
  
  pinMode(buzzerPin, OUTPUT); // Set buzzer pin as output
  pinMode(resetButtonPin, INPUT_PULLUP); // Set reset button pin as input with internal pull-up resistor
  
  // Retrieve the last calibration weight from EEPROM
  EEPROM.get(CALIBRATION_ADDR, calibrationWeight);
  
  if (calibrationWeight == 0) {
    lcd.print("Calibrate first!"); // Prompt for calibration if not set
  } else {
    lcd.print("Weight:");
  }
}

void loop() {
  char key = keypad.getKey(); // Get the pressed key

  // Check if the reset button is pressed
  if (digitalRead(resetButtonPin) == LOW && buzzerActive) { 
    buzzerActive = false; // Deactivate buzzer
    digitalWrite(buzzerPin, LOW); // Turn off the buzzer
    alarmSuppressed = true; // Suppress the alarm for 2 seconds
    suppressEndTime = millis() + 2000; // Set the suppression end time
    displayResetMessageEndTime = millis() + 1000; // Set the reset message display time (1 second)
    
    lcd.clear();
    lcd.print("Alarm Reset!"); // Display alarm reset message
  }

  // Check if it's time to stop displaying the reset message
  if (alarmSuppressed && millis() >= displayResetMessageEndTime) {
    lcd.clear();
    lcd.print("Weight:"); // Return to normal weight display
  }

  // Check if the alarm suppression time is over
  if (alarmSuppressed && millis() >= suppressEndTime) {
    alarmSuppressed = false; // Re-enable alarm after 2 seconds
  }

  if (key) { // Check if a key is pressed
    if (key == 'C' && !inputMode) { // If 'C' is pressed
      inputMode = true; // Enter input mode
      weightInput = ""; // Clear previous input
      lcd.clear();
      lcd.print("Enter Control:");
      lcd.setCursor(0, 1); // Move to the second line
    } 
    else if (inputMode) { // If we are in input mode
      if (key >= '0' && key <= '9') { // Check if the key is a digit
        weightInput += key; // Append the digit to weightInput
        lcd.print(key); // Display the digit
      } 
      else if (key == '#') { // If '#' is pressed (Backspace functionality)
        if (weightInput.length() > 0) {
          weightInput.remove(weightInput.length() - 1); // Remove the last character
          lcd.clear();
          lcd.print("Enter Control:");
          lcd.setCursor(0, 1); // Move to the second line
          lcd.print(weightInput); // Display the updated weight input
        }
      } 
      else if (key == 'D') { // If 'D' is pressed to confirm calibration
        inputMode = false; // Exit input mode
        calibrationWeight = weightInput.toFloat(); // Convert input to float
        
        // Calculate the offset based on the current potentiometer reading
        calibrationOffset = currentWeight - calibrationWeight;
        
        // Save the calibrated value to EEPROM
        EEPROM.put(CALIBRATION_ADDR, calibrationWeight);

        lcd.clear();
        lcd.print("Calibrated to: ");
        lcd.setCursor(0, 1);
        lcd.print(calibrationWeight); // Display the calibration weight
        delay(2000); // Show confirmation for 2 seconds
        lcd.clear(); // Clear the display
        lcd.print("Weight:"); // Prompt for weight input
      }
    }
  }

  // Get current weight reading based on potentiometer
  currentWeight = analogRead(potPin); // Read potentiometer value
  currentWeight = map(currentWeight, 0, 1023, 0, 1000); // Map to 0-1000 kg
  
  // Apply the calibration offset to the weight reading
  float displayedWeight = currentWeight - calibrationOffset;

  // Update the weight display on LCD when not in input mode
  if (!inputMode && !alarmSuppressed) { 
    lcd.setCursor(0, 1);
    lcd.print("Weight: ");
    lcd.setCursor(0, 8);
    lcd.print(displayedWeight, 2); // Display weight with 2 decimal places
    lcd.print(" kg");
    delay(500); // Update every half second
  }

  // Buzzer logic, if alarm is not suppressed
  if (!alarmSuppressed && (displayedWeight < 50 || displayedWeight > 950)) { // If weight is out of range
    if (!buzzerActive) {
      buzzerActive = true; // Activate buzzer
      buzzerStartTime = millis(); // Record the time buzzer started
      alarmRegistered = false; // Reset alarm registration for each new trigger
    }

    // Toggle buzzer ON and OFF for 1 second intervals
    if ((millis() - buzzerStartTime) % 2000 < 1000) {
      digitalWrite(buzzerPin, HIGH); // Turn on the buzzer for 1 second
    } else {
      digitalWrite(buzzerPin, LOW); // Turn off the buzzer for 1 second
    }

    // If buzzer has been active for more than 5 seconds, register alarm and display message
    if (millis() - buzzerStartTime >= 5000 && !alarmRegistered) {
      lcd.clear();
      lcd.print("Alarm Registered!");
      alarmRegistered = true; // Mark the alarm as registered
      delay(2000); // Display message for 2 seconds
      lcd.clear();
      lcd.print("Weight:"); // Return to normal weight display
    }

    // If buzzer has been active for more than 5 seconds, reset
    if (millis() - buzzerStartTime >= 5000) {
      buzzerActive = false; // Deactivate buzzer
      digitalWrite(buzzerPin, LOW); // Make sure buzzer is off
    }
  } 
  else if (!alarmSuppressed) { // If weight is within the acceptable range
    digitalWrite(buzzerPin, LOW); // Turn off the buzzer
    buzzerActive = false; // Reset buzzer flag
    alarmRegistered = false; // Reset the alarm registration once weight is back in range
  }

  // Print to Serial Monitor for debugging
  Serial.print("Current Weight: ");
  Serial.println(displayedWeight);
}