#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#include <RTClib.h>

// Pin configuration
#define DHTPIN 2
#define MQ2PIN 8 // Digital pin for MQ2 sensor
#define BUZZERPIN 3
#define BUTTON1PIN 4
#define BUTTON2PIN 5
#define BUTTON3PIN 6

// DHT setup
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);

// LCD setup
LiquidCrystal_I2C lcd(0x27, 20, 4); // Adjust the address if needed

// RTC setup
RTC_DS3231 rtc;

// Thresholds
const int temperatureThresholds[] = {80, 85, 95}; // Example thresholds, replace as needed
const int MQ2Threshold = 500;

// Variables
int currentPage = 1;
unsigned long lastButtonPress = 0;
const unsigned long debounceDelay = 200;
bool buzzerActive = false;
bool buzzerMQ2Active = false;
unsigned long buzzerStartTime = 0;
int currentThresholdIndex = 0;
unsigned long lastHourlyBeep = 0;

// Cached sensor values to reduce unnecessary updates
float cachedTemperature = NAN;
float cachedHumidity = NAN;
int cachedMQ2Value = -1;
DateTime cachedTime;

// Function declarations
void updateDisplay(float temperature = NAN, float humidity = NAN, int mq2Value = -1);
void togglePage();
void manageBuzzer(float temperature, int mq2Value);
void checkHourlyBeep();
void scrollPresets();
bool detectSensor(int pin);
bool checkAndUpdate(float& cache, float newValue);
bool checkAndUpdate(int& cache, int newValue);
bool checkAndUpdate(DateTime& cache, DateTime newValue);
String formatTime12Hour(DateTime now);
void displayWelcomeMessage();

// Setup function
void setup() {
  // Initialize the LCD
  lcd.begin(20, 4); // Specify the number of columns and rows
  lcd.backlight();  // Turn on the backlight

  // Initialize the DHT sensor
  dht.begin();

  // Initialize the RTC
  if (!rtc.begin()) {
    lcd.print("RTC failed");
    while (1);
  }

  // Set pin modes
  pinMode(MQ2PIN, INPUT);
  pinMode(BUZZERPIN, OUTPUT);
  pinMode(BUTTON1PIN, INPUT_PULLUP);
  pinMode(BUTTON2PIN, INPUT_PULLUP);
  pinMode(BUTTON3PIN, INPUT_PULLUP);

  // Display welcome message
  displayWelcomeMessage();

  // Display initial page
  updateDisplay();
}

void loop() {
  // Read button states
  if (digitalRead(BUTTON1PIN) == LOW) {
    delay(debounceDelay); // Debounce delay
    if (digitalRead(BUTTON1PIN) == LOW) {
      tone(BUZZERPIN, 250); // Sound buzzer for 0.5 seconds
      delay(500);
      noTone(BUZZERPIN);
      togglePage();
    }
  }

  if (digitalRead(BUTTON2PIN) == LOW) {
    delay(debounceDelay); // Debounce delay
    if (digitalRead(BUTTON2PIN) == LOW) {
      tone(BUZZERPIN, 250); // Sound buzzer for 0.5 seconds
      delay(500);
      noTone(BUZZERPIN);
      lcd.clear(); // Clear the display
    }
  }

  if (digitalRead(BUTTON3PIN) == LOW) {
    delay(debounceDelay); // Debounce delay
    if (digitalRead(BUTTON3PIN) == LOW) {
      tone(BUZZERPIN, 250); // Sound buzzer for 0.5 seconds
      delay(500);
      noTone(BUZZERPIN);
      scrollPresets(); // Scroll through presets
    }
  }

  // Read sensors
  float temperature = dht.readTemperature(true); // Temperature in Fahrenheit
  float humidity = dht.readHumidity();
  int mq2Value = digitalRead(MQ2PIN);

  // Check if sensor values have changed
  bool tempChanged = checkAndUpdate(cachedTemperature, temperature);
  bool humidityChanged = checkAndUpdate(cachedHumidity, humidity);
  bool mq2Changed = checkAndUpdate(cachedMQ2Value, mq2Value);
  bool timeChanged = checkAndUpdate(cachedTime, rtc.now());

  // Update display only if values have changed
  if (tempChanged || humidityChanged || mq2Changed || timeChanged) {
    updateDisplay(cachedTemperature, cachedHumidity, cachedMQ2Value);
  }

  // Check thresholds and manage buzzer
  manageBuzzer(cachedTemperature, cachedMQ2Value);

  // Check hourly beep
  checkHourlyBeep();

  delay(500); // Update every 0.5 seconds
}

void togglePage() {
  currentPage = (currentPage == 1) ? 2 : 1;
  lcd.clear(); // Clear the display to avoid overlapping content
  updateDisplay(); // Update display based on the new page
}

void manageBuzzer(float temperature, int mq2Value) {
  unsigned long currentTime = millis();

  if (temperature > temperatureThresholds[currentThresholdIndex]) {
    if (!buzzerActive) {
      buzzerActive = true;
      buzzerStartTime = currentTime;
    }
    
    if (buzzerActive && (currentTime - buzzerStartTime >= 1000)) {
      tone(BUZZERPIN, 1000); // 1 kHz frequency
      delay(1000); // Buzzer on for 1 second
      noTone(BUZZERPIN);
      delay(4000); // Wait for 4 seconds
      buzzerStartTime = millis(); // Reset buzzer start time
    }
  } else {
    noTone(BUZZERPIN);
    buzzerActive = false;
  }

  if (mq2Value > MQ2Threshold) {
    if (!buzzerMQ2Active) {
      buzzerMQ2Active = true;
      buzzerStartTime = currentTime;
    }
    
    if (buzzerMQ2Active && (currentTime - buzzerStartTime >= 1500)) {
      tone(BUZZERPIN, 1000); // 1 kHz frequency
      delay(1500); // Buzzer on for 1.5 seconds
      noTone(BUZZERPIN);
      delay(3500); // Wait for 3.5 seconds
      buzzerStartTime = millis(); // Reset buzzer start time
    }
  } else {
    noTone(BUZZERPIN);
    buzzerMQ2Active = false;
  }
}

void checkHourlyBeep() {
  DateTime now = rtc.now();
  unsigned long currentTime = millis();
  
  if (now.minute() == 0 && now.second() == 0) { // On the hour
    if (currentTime - lastHourlyBeep >= 3600000) { // 1 hour in milliseconds
      tone(BUZZERPIN, 1000); // Beep for 0.75 seconds
      delay(750);
      noTone(BUZZERPIN);
      lastHourlyBeep = currentTime; // Update the last beep time
    }
  }
}

void updateDisplay(float temperature, float humidity, int mq2Value) {
  DateTime now = rtc.now();

  if (currentPage == 1) {
    lcd.setCursor(0, 0);
    lcd.print("Temp: ");
    if (isnan(temperature)) {
      lcd.print("NA");
    } else {
      lcd.print(temperature);
      lcd.print(" F   ");
    }

    lcd.setCursor(0, 1);
    lcd.print("Humidity: ");
    if (isnan(humidity)) {
      lcd.print("NA     ");
    } else {
      lcd.print(humidity);
      lcd.print(" %   ");
    }

    lcd.setCursor(0, 2);
    lcd.print("MQ2 Value: ");
    if (mq2Value == LOW) {
      lcd.print("NA");
    } else {
      lcd.print(mq2Value);
      lcd.print("       ");
    }

    lcd.setCursor(0, 3);
    lcd.print("Time: ");
    lcd.print(formatTime12Hour(now));
  } else if (currentPage == 2) {
    lcd.setCursor(0, 0);
    lcd.print("Time: ");
    lcd.print(formatTime12Hour(now));

    lcd.setCursor(0, 1);
    lcd.print("Date: ");
    lcd.print(now.month());
    lcd.print("/");
    lcd.print(now.day());
    lcd.print("/");
    lcd.print(now.year());

    lcd.setCursor(0, 2);
    lcd.print("Preset Temp: ");
    lcd.print(temperatureThresholds[currentThresholdIndex]);

    lcd.setCursor(0, 3);
    lcd.print("Temp: ");
    if (isnan(temperature)) {
      lcd.print("NA");
    } else {
      lcd.print(temperature);
      lcd.print(" F");
    }
  }
}

String formatTime12Hour(DateTime now) {
  String period = "AM";
  int hour = now.hour();
  if (hour >= 12) {
    period = "PM";
    if (hour > 12) {
      hour -= 12;
    }
  } else if (hour == 0) {
    hour = 12;
  }
  String formattedTime = String(hour) + ":" + String(now.minute()) + " " + period;
  return formattedTime;
}

void scrollPresets() {
  currentThresholdIndex = (currentThresholdIndex + 1) % (sizeof(temperatureThresholds) / sizeof(temperatureThresholds[0]));
  updateDisplay(cachedTemperature, cachedHumidity, cachedMQ2Value);
}

bool detectSensor(int pin) {
  return digitalRead(pin) != LOW; // Adjust according to your sensor's logic
}

bool checkAndUpdate(float& cache, float newValue) {
  if (cache != newValue) {
    cache = newValue;
    return true;
  }
  return false;
}

bool checkAndUpdate(int& cache, int newValue) {
  if (cache != newValue) {
    cache = newValue;
    return true;
  }
  return false;
}

bool checkAndUpdate(DateTime& cache, DateTime newValue) {
  if (cache.unixtime() != newValue.unixtime()) {
    cache = newValue;
    return true;
  }
  return false;
}

void displayWelcomeMessage() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Welcome to your");
  lcd.setCursor(0, 1);
  lcd.print("Smart 3D Enclose");
  lcd.setCursor(0, 2);
  lcd.print("Version 1.0.0");
  delay(5000); // Display for 5 seconds
  lcd.clear();
}