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

// Pin Definitions
#define DHTPIN 8
#define FAN_PIN_1 6
#define FAN_PIN_2 9
#define MQ_SENSOR_PIN A0 // Analog pin for the MQ sensor
#define UP_PIN 12
#define DOWN_PIN 11 // Changed DOWN_PIN to 11 to avoid conflict with FAN_PIN_1
#define ENTER_PIN 13

// DHT Sensor Type
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

// LCD Configuration
LiquidCrystal_I2C lcd(0x27, 20, 4);

// Global Variables
int currentPage = 0;
int humiditySetPoint = 62;
int autoFlushIntervalOption = 1; // Default auto flush interval option (12 hours)
int autoFlushTime = 5;           // Default auto flush time
bool fansOn = false;
unsigned long fanOnTime = 0;
const unsigned long fanInterval = 300000; // 5 minutes
unsigned long systemStartTime = 0; // Track the time when the system started
unsigned long lastUpdate = 0; // Track the time of the last update
bool upPressed = false;
bool downPressed = false;
bool enterPressed = false;
bool needScreenRefresh = true;

// Debounce Variables
unsigned long lastDebounceTime = 0; 
const unsigned long debounceDelay = 50; // debounce delay in milliseconds

void updateFanStatus(float humidity); // Declaration of updateFanStatus function

void setup() {
  Serial.begin(9600);
  dht.begin();
  lcd.init();
  lcd.backlight();

  // Initialize Button Pins
  pinMode(UP_PIN, INPUT_PULLUP);
  pinMode(DOWN_PIN, INPUT_PULLUP);
  pinMode(ENTER_PIN, INPUT_PULLUP);

  // Initialize Fan Pins
  pinMode(FAN_PIN_1, OUTPUT);
  pinMode(FAN_PIN_2, OUTPUT);
  digitalWrite(FAN_PIN_1, LOW);
  digitalWrite(FAN_PIN_2, LOW);

  systemStartTime = millis();
  lastUpdate = millis(); // Initialize last update time

  // Display Initial Screen
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(" ------------------");
  lcd.setCursor(0, 1);
  lcd.print("|     CureOs       |");
  lcd.setCursor(0, 2);
  lcd.print("|      v1.5        |");
  lcd.setCursor(0, 3);
  lcd.print(" ------------------ ");
  delay(1500); // Wait for 1.5 seconds
  lcd.clear();
}

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

  // Update the display values every second if on the home page
  if (currentPage == 0 && currentMillis - lastUpdate >= 1000) {
    lastUpdate = currentMillis;

    float humidity = dht.readHumidity();
    float temperature = dht.readTemperature();
    int co2Level = analogRead(MQ_SENSOR_PIN);

    // Display updated values on the home page
    lcd.setCursor(10, 0);
    lcd.print(humidity, 1); // Display humidity with 1 decimal point
    lcd.print("%");
    lcd.setCursor(6, 1);
    lcd.print(temperature, 1); // Display temperature with 1 decimal point
    lcd.print("c");
    lcd.setCursor(5, 2);
    lcd.print(co2Level); // Display CO2 level
    lcd.print(" ppm");
  }

  handleButtonPresses();

  float humidity = dht.readHumidity();
  updateFanStatus(humidity); // Update the status of fans based on humidity

  unsigned long elapsedTime = currentMillis - systemStartTime;
  unsigned long interval = autoFlushIntervalOption * 12 * 3600UL * 1000UL; // Convert hours to milliseconds
  if (elapsedTime >= interval && !fansOn) {
    digitalWrite(FAN_PIN_1, HIGH);
    digitalWrite(FAN_PIN_2, HIGH);
    fansOn = true;
    fanOnTime = currentMillis; // Record the time when fans turned on
  }

  if (fansOn && (currentMillis - fanOnTime >= autoFlushTime * 60000)) {
    digitalWrite(FAN_PIN_1, LOW);
    digitalWrite(FAN_PIN_2, LOW);
    fansOn = false;
    systemStartTime = currentMillis; // Reset the system start time for the next interval
  }

  if (needScreenRefresh) {
    if (currentPage == 0) { // Only display home page if not in menu
      displayHomePage();
    } else {
      displayMenuPage();
    }
    needScreenRefresh = false;
  }
}

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

  if ((currentMillis - lastDebounceTime) > debounceDelay) {
    if (digitalRead(UP_PIN) == LOW && !upPressed) {
      upPressed = true;
      handleUpButton();
      needScreenRefresh = true;
      lastDebounceTime = currentMillis;
    } else if (digitalRead(UP_PIN) == HIGH && upPressed) {
      upPressed = false;
    }

    if (digitalRead(DOWN_PIN) == LOW && !downPressed) {
      downPressed = true;
      handleDownButton();
      needScreenRefresh = true;
      lastDebounceTime = currentMillis;
    } else if (digitalRead(DOWN_PIN) == HIGH && downPressed) {
      downPressed = false;
    }

    if (digitalRead(ENTER_PIN) == LOW && !enterPressed) {
      enterPressed = true;
      handleEnterButton();
      needScreenRefresh = true;
      lastDebounceTime = currentMillis;
    } else if (digitalRead(ENTER_PIN) == HIGH && enterPressed) {
      enterPressed = false;
    }
  }
}

void handleUpButton() {
  switch (currentPage) {
    case 1:
      humiditySetPoint++;
      if (humiditySetPoint > 90) humiditySetPoint = 90; // Adjusted maximum humidity set point to 90%
      break;
    case 2:
      autoFlushIntervalOption++;
      if (autoFlushIntervalOption > 3) autoFlushIntervalOption = 3; // Maximum option is 36 hours
      break;
    case 3:
      autoFlushTime += 5; // Increment flush time by 5 minutes
      if (autoFlushTime > 15) autoFlushTime = 15;
      break;
  }
}

void handleDownButton() {
  switch (currentPage) {
    case 1:
      humiditySetPoint--;
      if (humiditySetPoint < 55) humiditySetPoint = 55;
      break;
    case 2:
      autoFlushIntervalOption--;
      if (autoFlushIntervalOption < 1) autoFlushIntervalOption = 1; // Minimum option is 12 hours
      break;
    case 3:
      autoFlushTime -= 5; // Decrement flush time by 5 minutes
      if (autoFlushTime < 1) autoFlushTime = 1;
      break;
  }
}

void handleEnterButton() {
  static bool menuCycled = true; // Track if the menu has cycled at least once
  if (currentPage < 3) { // Change 3 to the total number of menu pages
    currentPage++;
  }
  else {
    if (menuCycled) {
      currentPage = 0; // Return to home page after cycling through the menu
    } else {
      currentPage = 1; // Start from the first menu page
      menuCycled = true; // Mark that the menu has cycled at least once
    }
  }
}

void displayHomePage() {
  lcd.setCursor(0, 0);
  lcd.print("Humidity: ");
  lcd.setCursor(10, 0);
  lcd.print(dht.readHumidity(), 1); // Display humidity with 1 decimal point
  lcd.print("%");
  
  lcd.setCursor(0, 1);
  lcd.print("Temp: ");
  lcd.setCursor(6, 1);
  lcd.print(dht.readTemperature(), 1); // Display temperature with 1 decimal point
  lcd.print("c");
  
  lcd.setCursor(0, 2);
  lcd.print("CO2: ");
  lcd.setCursor(5, 2);
  lcd.print(analogRead(MQ_SENSOR_PIN)); // Read CO2 level from MQ sensor
  lcd.print(" ppm");

  lcd.setCursor(0, 3);
  if (fansOn) {
    lcd.print("*FANS ON*");
  } else {
    lcd.print("          "); // Clear the line if fans are off
  }
}

void displayMenuPage() {
  if (currentPage != 0) {
    lcd.clear();
    lcd.setCursor(0, 0);
    switch (currentPage) {
      case 1:
        lcd.print("Humidity Set Point");
        lcd.setCursor(0, 2);
        lcd.print("-  ");
        lcd.print(humiditySetPoint);
        lcd.print("%");
        break;
      case 2:
        lcd.print("Auto Flush Interval");
        lcd.setCursor(0, 2);
        lcd.print("- ");
        lcd.print(autoFlushIntervalOption * 12);
        lcd.print(" hrs");
        break;
      case 3:
        lcd.print("Auto Flush Time");
        lcd.setCursor(0, 2);
        lcd.print("- ");
        lcd.print(autoFlushTime);
        lcd.print(" mins");
        break;
    }
  }
}

void updateFanStatus(float humidity) {
  // Calculate the humidity thresholds for turning the fans on and off
  float humidityOnThreshold = humiditySetPoint;
  float humidityOffThreshold = humiditySetPoint - 3; // 3% below the set point

  // Check if humidity is above the ON threshold
  if (humidity >= humidityOnThreshold) {
    digitalWrite(FAN_PIN_1, HIGH);
    digitalWrite(FAN_PIN_2, HIGH);
    fansOn = true;
  } 
  // Check if humidity is below the OFF threshold and fans are currently on
  else if (humidity < humidityOffThreshold && fansOn) {
    digitalWrite(FAN_PIN_1, LOW);
    digitalWrite(FAN_PIN_2, LOW);
    fansOn = false;
  }
  // If humidity is between the ON and OFF thresholds or above the OFF threshold but fans are already off, do nothing
}