#include <LiquidCrystal.h>
#include <IRremote.h>

// Initialize the LCD (RS, EN, D4, D5, D6, D7)
LiquidCrystal lcd(7, 8, 9, 10, 11, 12);

// Define pins for the ultrasonic sensor, buzzer, LED, and IR receiver
const int trigPin = 2;
const int echoPin = 3;
const int buzzerPin = 6;
const int ledPin = 5;
const int irPin = 4; // IR receiver pin

// Define variables
long echoDuration;
int distance;
int averageDistance;
const int thresholdDistance = 20; // Distance threshold for alarm
const int MAX_VALID_DISTANCE = 400; // Maximum valid distance in cm
bool alarmEnabled = true;  // State of the alarm system

// IR Remote variables
IRrecv irReceiver(irPin);

// Variables for manual tone generation
unsigned long previousBuzzMicros = 0;
const unsigned int buzzIntervalMicros = 500; // Half period in microseconds for 1 kHz tone
bool buzzState = false;
bool buzzerActive = false; // Tracks if the buzzer should be active

// Variables for filtering sensor readings
#define NUM_READINGS 5
int readings[NUM_READINGS];      // Array to hold distance readings
int readIndex = 0;               // Index of the current reading
int total = 0;                   // Total of the readings

void setup() {
  // Pin modes
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(ledPin, OUTPUT);

  // Initialize LCD
  lcd.begin(16, 2);
  lcd.setCursor(0, 0);
  lcd.print("Fire Alarm Ready");

  // Initialize Serial Monitor
  Serial.begin(9600);

  // Initialize IR receiver
  IrReceiver.begin(irPin, ENABLE_LED_FEEDBACK); // Start the IR receiver

  // Initialize readings array
  for (int i = 0; i < NUM_READINGS; i++) {
    readings[i] = MAX_VALID_DISTANCE;
    total += readings[i];
  }
}

void loop() {
  // Handle IR remote input
  handleIRRemote();

  // Trigger the ultrasonic sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the duration of the echo pulse
  echoDuration = pulseIn(echoPin, HIGH, 30000); // Timeout after 30ms

  // Calculate the distance in cm
  if (echoDuration == 0 || echoDuration >= 30000) {
    // No echo received or timeout
    distance = MAX_VALID_DISTANCE;
    Serial.println("No echo received or timeout.");
  } else {
    distance = echoDuration * 0.034 / 2;
    Serial.print("Echo Duration: ");
    Serial.print(echoDuration);
    Serial.print(" us, Distance: ");
    Serial.print(distance);
    Serial.println(" cm");
  }

  // Filter the distance readings
  total = total - readings[readIndex];   // Subtract the oldest reading
  readings[readIndex] = distance;        // Store the new reading
  total = total + readings[readIndex];   // Add the new reading to total
  readIndex = (readIndex + 1) % NUM_READINGS; // Advance index
  averageDistance = total / NUM_READINGS;

  Serial.print("Average Distance: ");
  Serial.println(averageDistance);

  unsigned long currentMillis = millis();
  unsigned long currentMicros = micros(); // For buzzer timing

  // Alarm logic
  if (alarmEnabled) {
    if (averageDistance > 0 && averageDistance < thresholdDistance) {
      digitalWrite(ledPin, HIGH); // Turn ON LED
      buzzerActive = true;        // Activate the buzzer

      // Display alarm message
      lcd.setCursor(0, 1);
      lcd.print("Smoke Detected! ");
    } else {
      digitalWrite(ledPin, LOW);  // Turn OFF LED
      buzzerActive = false;       // Deactivate the buzzer
      digitalWrite(buzzerPin, LOW); // Ensure buzzer is OFF
      buzzState = false;          // Reset buzz state

      // Clear LCD message if necessary
      lcd.setCursor(0, 1);
      lcd.print("                "); // Clear the row
    }
  } else {
    // If the alarm system is disabled
    digitalWrite(ledPin, LOW);     // Ensure LED is OFF
    buzzerActive = false;          // Deactivate the buzzer
    digitalWrite(buzzerPin, LOW);  // Ensure buzzer is OFF
    buzzState = false;             // Reset buzz state

    lcd.setCursor(0, 1);
    lcd.print("ALARM DISABLED  "); // Display disabled message
  }

  // Manual buzzer control
  if (buzzerActive) {
    if (currentMicros - previousBuzzMicros >= buzzIntervalMicros) {
      previousBuzzMicros = currentMicros;
      buzzState = !buzzState;
      digitalWrite(buzzerPin, buzzState ? HIGH : LOW);
    }
  } else {
    digitalWrite(buzzerPin, LOW); // Ensure buzzer is OFF when not active
  }

  // No need for delay here
}

// Function to handle IR remote input
void handleIRRemote() {
  // Check if an IR signal is available
  if (IrReceiver.decode()) {
    Serial.print("IR Code Received: ");
    Serial.print(IrReceiver.decodedIRData.command, HEX);
    Serial.print(" (HEX), ");
    Serial.print(IrReceiver.decodedIRData.command);
    Serial.println(" (DEC)");

    // Use the actual received code
    uint8_t receivedCommand = IrReceiver.decodedIRData.command;

    // Handle the command
    switch (receivedCommand) {
      case 0xA2: // Replace 0xA2 with the actual code from your remote
        alarmEnabled = !alarmEnabled; // Toggle alarm state

        // When alarm is toggled, reset alarm state
        digitalWrite(ledPin, LOW);    // Turn OFF LED
        buzzerActive = false;         // Deactivate the buzzer
        digitalWrite(buzzerPin, LOW); // Ensure buzzer is OFF
        buzzState = false;            // Reset buzz state

        if (alarmEnabled) {
          lcd.setCursor(0, 0);
          lcd.print("Fire Alarm Ready");
          lcd.setCursor(0, 1);
          lcd.print("                "); // Clear any old messages
          Serial.println("Alarm Enabled");
        } else {
          lcd.setCursor(0, 0);
          lcd.print("Alarm is OFF    ");
          lcd.setCursor(0, 1);
          lcd.print("ALARM DISABLED  ");
          Serial.println("Alarm Disabled");
        }
        break;

      default:
        lcd.setCursor(0, 0);
        lcd.print("Unknown Command ");
        Serial.println("Unknown IR Command Received");
        break;
    }

    IrReceiver.resume(); // Prepare to receive the next signal
  }
}