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

// Constants and Pin Definitions
#define DHTTYPE DHT22         // Define DHT type
#define TRIG_PIN 10           // Ultrasonic sensor trigger pin
#define ECHO_PIN 11           // Ultrasonic sensor echo pin
#define SERVO_PIN 9           // Servo motor control pin
#define NUM_SENSORS 4         // Number of DHT22 sensors
#define DISTANCE_OFFSET 50.0  // Offset for waterway depth in cm
#define WATERWAY_WIDTH 50.0   // Waterway width in cm
#define VELOCITY 100.0        // Waterway flow velocity in cm/s (1 m/s)

// DHT sensor pins and objects
const int dhtPins[NUM_SENSORS] = {2, 3, 4, 5};
DHT dht[NUM_SENSORS] = {
  DHT(dhtPins[0], DHTTYPE), 
  DHT(dhtPins[1], DHTTYPE), 
  DHT(dhtPins[2], DHTTYPE), 
  DHT(dhtPins[3], DHTTYPE)
};

// LCD and Servo
LiquidCrystal_I2C lcd(0x27, 20, 4);  // LCD with I2C address 0x27
Servo myServo;

void setup() {
  Serial.begin(9600);
  
  // Initialize the LCD with 20 columns and 4 rows
  lcd.begin(20, 4);
  lcd.backlight();

  // Initialize DHT sensors
  for (int i = 0; i < NUM_SENSORS; i++) {
    dht[i].begin();
  }

  // Set up ultrasonic sensor pins
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  // Attach servo motor
  myServo.attach(SERVO_PIN);

  // Display welcome message on LCD
  lcd.print("Irrigation System");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Calculate average humidity and temperature
  float avgHumidity = calculateAverageHumidity();
  float avgTemp = calculateAverageTemperature();

  // Calculate water elevation and discharge
  float waterElevation = calculateWaterElevation();
  float dischargeQ = calculateWaterDischarge(waterElevation);

  // Display data on LCD
  displayData(avgHumidity, avgTemp, dischargeQ);

  // Control servo based on average humidity
  controlServo(avgHumidity);

  // Delay between loop iterations
  delay(2000);
}

// Function to calculate average humidity from DHT22 sensors
float calculateAverageHumidity() {
  float humiditySum = 0.0;
  int validReadings = 0;

  for (int i = 0; i < NUM_SENSORS; i++) {
    float h = dht[i].readHumidity();
    if (!isnan(h)) {  // Only add valid readings
      humiditySum += h;
      validReadings++;
    }
  }

  return (validReadings > 0) ? (humiditySum / validReadings) : 0;
}

// Function to calculate average temperature from DHT22 sensors
float calculateAverageTemperature() {
  float tempSum = 0.0;
  int validReadings = 0;

  for (int i = 0; i < NUM_SENSORS; i++) {
    float t = dht[i].readTemperature();
    if (!isnan(t)) {  // Only add valid readings
      tempSum += t;
      validReadings++;
    }
  }

  return (validReadings > 0) ? (tempSum / validReadings) : 0;
}

// Function to measure distance using HC-SR04 ultrasonic sensor
float getDistance() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  long duration = pulseIn(ECHO_PIN, HIGH);
  float distance = duration * 0.034 / 2;  // Convert to cm
  return distance;
}

// Function to calculate water elevation based on distance measurement
float calculateWaterElevation() {
  float distance = getDistance();
  return DISTANCE_OFFSET - distance;  // Water elevation in cm
}

// Function to calculate water discharge (Q) in liters per second
float calculateWaterDischarge(float elevation) {
  float crossSectionArea = elevation * WATERWAY_WIDTH;  // Area in cm^2
  return (crossSectionArea * VELOCITY) / 1000;          // Convert to liters per second
}

// Function to display data on LCD
void displayData(float humidity, float temperature, float discharge) {
  lcd.clear();
  
  lcd.setCursor(0, 0);
  lcd.print("Humidity: ");
  lcd.print(humidity, 1);
  lcd.print("%");

  lcd.setCursor(0, 1);
  lcd.print("Temp: ");
  lcd.print(temperature, 1);
  lcd.print(" C");

  lcd.setCursor(0, 2);
  lcd.print("Water Q: ");
  lcd.print(discharge, 1);
  lcd.print(" lt/s");
}

// Function to control servo position based on humidity
void controlServo(float humidity) {
  if (humidity < 70) {
    myServo.write(90);  // Open position
  } else {
    myServo.write(0);   // Close position
  }
}