#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <RTClib.h>
#include <DHT.h>
#include <WiFi.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>

#define DHTPIN D2
#define DHTTYPE DHT22
#define MQ135_PIN A0
#define FAN_PIN D9
#define LAMP_PIN D10

const char* ssid = "STES GROUP";
const char* password = "Stesgroup@20";

const char* serverName = "https://fabacademy-airquality-monitoring.onrender.com/sensordata";

DHT dht(DHTPIN, DHTTYPE);
RTC_DS3231 rtc;
LiquidCrystal_I2C lcd(0x27, 20, 4); // Adjust the address if needed

float Ro = 30.7;           // Initial Ro value, which will be calibrated
float RL = 10.0;           // Load resistance on the board
float cleanAirFactor = 3.6; // Sensor's Rs/Ro ratio in clean air

unsigned long lastTime = 0;
unsigned long timerDelay = 180000; // 180 seconds

void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  dht.begin();

  if (!rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }

  if (rtc.lostPower()) {
    rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
  }

  Ro = calibrateMQ135(); // Calibrate MQ135 sensor

  pinMode(FAN_PIN, OUTPUT);
  pinMode(LAMP_PIN, OUTPUT);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }

  Serial.println("Connected to WiFi");
}

void loop() {
  DateTime now = rtc.now();

  float sensorResistance = getResistance();
  float ratio = sensorResistance / Ro;

  // Estimate gas concentrations
  float co2 = calculateCO2(ratio);
  float no2 = calculateNO2(ratio);
  float nh3 = calculateNH3(ratio);

  // Read DHT22 sensor
  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  // Display on LCD
  lcd.setCursor(0, 0);
  lcd.print("Time: ");
  lcd.print(now.hour(), DEC);
  lcd.print(':');
  lcd.print(now.minute(), DEC);
  lcd.print(':');
  lcd.print(now.second(), DEC);

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

  lcd.setCursor(0, 2);
  lcd.print("CO2: ");
  lcd.print(co2);
  lcd.print(" ppm");

  lcd.setCursor(0, 3);
  lcd.print("NO2: ");
  lcd.print(no2);
  lcd.print(" ppm");

  lcd.setCursor(0, 4);
  lcd.print("NH3: ");
  lcd.print(nh3);
  lcd.print(" ppm");

  lcd.setCursor(0, 5);
  lcd.print("Temp: ");
  lcd.print(temperature);
  lcd.print(" C");

  lcd.setCursor(0, 6);
  lcd.print("Humidity: ");
  lcd.print(humidity);
  lcd.print(" %");

  // Control actuators based on time
  if ((now.hour() > 18 || (now.hour() == 18 && now.minute() >= 30)) && now.hour() < 24) {
    digitalWrite(FAN_PIN, HIGH);
    digitalWrite(LAMP_PIN, HIGH);
  } else {
    digitalWrite(FAN_PIN, LOW);
    digitalWrite(LAMP_PIN, LOW);
  }

  // Send data to server every 60 seconds
  if (WiFi.status() == WL_CONNECTED && (millis() - lastTime) > timerDelay) {
    HTTPClient http;
    http.begin(serverName);
    http.addHeader("Content-Type", "application/json");

    StaticJsonDocument<200> doc;
    doc["NO2"] = round(no2 * 100) / 100.0;
    doc["CO2"] = round(co2 * 100) / 100.0;
    doc["NH3"] = round(nh3 * 100) / 100.0;
    doc["humidity"] = round(humidity * 100) / 100.0;
    doc["temperature"] = round(temperature * 100) / 100.0;
    doc["deviceId"] = "1";

    String jsonData;
    serializeJson(doc, jsonData);

    int httpResponseCode = http.POST(jsonData);

    if (httpResponseCode > 0) {
      String response = http.getString();
      Serial.println(httpResponseCode);
      Serial.println(response);
    } else {
      Serial.print("Error on sending POST: ");
      Serial.println(httpResponseCode);
    }

    http.end();
    lastTime = millis();
  }

  delay(1000); // Update every second
}

// Calculate resistance of the sensor
float getResistance() {
  int sensorValue = analogRead(MQ135_PIN);
  float voltage = sensorValue / 4095.0 * 3.3;
  float resistance = (3.3 - voltage) * RL / voltage;
  return resistance;
}

// Calibrate the MQ135 sensor
float calibrateMQ135() {
  float val = 0;

  for (int i = 0; i < 50; i++) {
    val += getResistance();
    delay(100);
  }
  val = val / 50.0;
  return val / cleanAirFactor;
}

// Placeholder functions for gas concentration calculations
float calculateCO2(float ratio) {
  // Use the appropriate formula based on the MQ135 datasheet
  return pow(10, ((-0.42 * log10(ratio)) + 1.92));
}

float calculateNO2(float ratio) {
  // Use the appropriate formula based on the MQ135 datasheet
  return pow(10, ((-0.71 * log10(ratio)) + 0.98));
}

float calculateNH3(float ratio) {
  // Use the appropriate formula based on the MQ135 datasheet
  return pow(10, ((-0.57 * log10(ratio)) + 1.53));
}