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

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

// DHT Sensor setup (using DHT22)
#define DHTPIN 2
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

// Rotary Encoder Pins
#define ENCODER_CLK 5
#define ENCODER_DT  6
#define ENCODER_SW  7

// Sensor Pins
const int mq2Pin = A0;
const int dcMotorPin = 9;  // DC motor control pin (PWM)

// Button Pins
const int button1 = 3;  // Page switch button
const int button2 = 4;  // Refresh/clear button

int currentPage = 1;
bool buzzerMuted = false;
unsigned long lastChangeTime = 0;
unsigned long debounceDelay = 250; // Time between page changes (in milliseconds)
unsigned long lastUpdateTime = 0; // Tracks last update time for auto-refresh
const unsigned long updateInterval = 2000; // Refresh interval (2 seconds)

// Temperature Thresholds (Preset values)
float temperatureThresholds[] = {75.0, 80.0, 85.0, 90.0}; // Thresholds for fan to activate
int currentThresholdIndex = 0;

// MQ2 Threshold Presets (Low, Medium, High)
int mq2Thresholds[] = {200, 400, 600};  // Adjust these based on your sensor's output range
int currentMq2ThresholdIndex = 0;

// Create Encoder instance
Encoder enc(ENCODER_CLK, ENCODER_DT);

// DC motor speed control
int motorSpeed = 0;  // Motor speed from 0 to 255

void setup() {
    lcd.init();
    lcd.backlight();
    
    pinMode(mq2Pin, INPUT);
    pinMode(dcMotorPin, OUTPUT);
    
    pinMode(button1, INPUT_PULLUP);
    pinMode(button2, INPUT_PULLUP);
    pinMode(ENCODER_SW, INPUT_PULLUP);  // SW button for Rotary Encoder

    dht.begin();
}

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

    // Read temperature, humidity, and MQ2 sensor values
    float temperature = dht.readTemperature(true);
    float humidity = dht.readHumidity();
    int mq2Value = analogRead(mq2Pin);

    // Handle button presses for page navigation
    if (digitalRead(button1) == LOW) {
        currentPage++;
        if (currentPage > 4) currentPage = 1;
        delay(200);  // Debounce delay
    }

    // Manual refresh with Button 2
    if (digitalRead(button2) == LOW) {
        lcd.clear();  // Clear the display for manual refresh
        updateDisplay(temperature, humidity, mq2Value); // Force update
        delay(200);  // Debounce delay
    }

    // Read rotary encoder values for controlling parameters
    long newPosition = enc.read();
    if (newPosition != 0 && (currentMillis - lastChangeTime >= debounceDelay)) {
        if (currentPage == 2) {
            // Adjust temperature threshold
            currentThresholdIndex += (newPosition > 0) ? 1 : -1;
            if (currentThresholdIndex > 3) currentThresholdIndex = 0;
            if (currentThresholdIndex < 0) currentThresholdIndex = 3;
        } else if (currentPage == 3) {
            // Adjust MQ2 threshold
            currentMq2ThresholdIndex += (newPosition > 0) ? 1 : -1;
            if (currentMq2ThresholdIndex > 2) currentMq2ThresholdIndex = 0;
            if (currentMq2ThresholdIndex < 0) currentMq2ThresholdIndex = 2;
        } else if (currentPage == 4) {
            // Control DC motor speed
            motorSpeed += (newPosition > 0) ? 10 : -10;
            if (motorSpeed > 255) motorSpeed = 255;
            if (motorSpeed < 0) motorSpeed = 0;
        }
        enc.write(0);  // Reset encoder position after change
        lastChangeTime = currentMillis;  // Update last change time
    }

    // **Automatic display refresh every 2 seconds**
    if (currentMillis - lastUpdateTime >= updateInterval) {
        updateDisplay(temperature, humidity, mq2Value);
        lastUpdateTime = currentMillis;  // Reset update timer
    }

    // Control fan based on temperature
    if (temperature > temperatureThresholds[currentThresholdIndex]) {
        analogWrite(dcMotorPin, motorSpeed);
    } else {
        analogWrite(dcMotorPin, 0);
    }
}

void updateDisplay(float temperature, float humidity, int mq2Value) {
    static int previousPage = -1;
    if (currentPage != previousPage) {
        lcd.clear();
        previousPage = currentPage;
    }

    lcd.setCursor(0, 3);
    lcd.print("Page ");
    lcd.print(currentPage);

    // Page 1: Sensor Data
    if (currentPage == 1) {
        lcd.setCursor(0, 0);
        lcd.print("Temp: ");
        lcd.print(isnan(temperature) ? "NA" : String(temperature) + " F");

        lcd.setCursor(0, 1);
        lcd.print("Hum: ");
        lcd.print(isnan(humidity) ? "NA" : String(humidity) + " %");

        lcd.setCursor(0, 2);
        lcd.print("MQ2 Value: ");
        lcd.print(mq2Value);
    } 
    
    // Page 2: Uptime & Threshold
    else if (currentPage == 2) {
        unsigned long uptimeSeconds = millis() / 1000;
        unsigned long uptimeMinutes = uptimeSeconds / 60;
        unsigned long uptimeHours = uptimeMinutes / 60;

        lcd.setCursor(0, 0);
        lcd.print("Uptime: ");
        lcd.print(uptimeHours);
        lcd.print("h ");
        lcd.print(uptimeMinutes % 60);
        lcd.print("m ");
        lcd.print(uptimeSeconds % 60);
        lcd.print("s");

        lcd.setCursor(0, 1);
        lcd.print("Preset Temp: ");
        lcd.print(temperatureThresholds[currentThresholdIndex]);

        lcd.setCursor(0, 2);
        lcd.print("Temp: ");
        lcd.print(isnan(temperature) ? "NA" : String(temperature) + " F");
    } 
    
    // Page 3: Buzzer control and MQ2 threshold
    else if (currentPage == 3) {
        lcd.setCursor(0, 0);
        lcd.print("Buzzer: ");
        lcd.print(buzzerMuted ? "Muted" : "Active");

        lcd.setCursor(0, 1);
        lcd.print("MQ2 Threshold: ");
        lcd.print(mq2Thresholds[currentMq2ThresholdIndex]);

        if (mq2Value > mq2Thresholds[currentMq2ThresholdIndex] && !buzzerMuted) {
            // Activate buzzer (add your buzzer control logic here)
        }
    } 
    
    // Page 4: DC Motor Speed Control
    else if (currentPage == 4) {
        lcd.setCursor(0, 0);
        lcd.print("DC Motor Speed:");
        lcd.setCursor(0, 1);
        lcd.print(motorSpeed);
    }
}