#include <LiquidCrystal_I2C.h>

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

const int potassiumSensorPin = A0;  // Potassium sensor analog pin
const int nitrogenSensorPin = A1;   // Nitrogen sensor analog pin
const int phosphorusSensorPin = A2; // Phosphorus sensor analog pin
const int ledPin = 4;               // LED connected to digital pin 4

// Thresholds in ppm
const int potassiumThreshold = 200; // ppm
const int nitrogenThreshold = 500;  // ppm
const int phosphorusThreshold = 300; // ppm

// Mapping range
const int sensorMin = 0;   // sensor minimum, representing 0 ppm
const int sensorMax = 1023; // sensor maximum, representing 1000 ppm

unsigned long previousMillis = 0;   // will store last time the nutrients were updated
const long interval = 10000;        // interval at which to update the nutrient readings (10 seconds)

void setup() {
  lcd.init();                       // Start the LCD
  lcd.backlight();

  pinMode(potassiumSensorPin, INPUT);
  pinMode(nitrogenSensorPin, INPUT);
  pinMode(phosphorusSensorPin, INPUT);
  pinMode(ledPin, OUTPUT);          // Set the LED pin as output
  digitalWrite(ledPin, LOW);        // Start with the LED off
}

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

  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis;
    
    // Read the value from the potentiometers
    int potassiumLevel = analogRead(potassiumSensorPin);
    int nitrogenLevel = analogRead(nitrogenSensorPin);
    int phosphorusLevel = analogRead(phosphorusSensorPin);

    // Map the potentiometer value to a ppm range (0 - 1000 ppm for example)
    int potassiumPPM = map(potassiumLevel, sensorMin, sensorMax, 0, 1000);
    int nitrogenPPM = map(nitrogenLevel, sensorMin, sensorMax, 0, 1000);
    int phosphorusPPM = map(phosphorusLevel, sensorMin, sensorMax, 0, 1000);

    // Clear the LCD and set the cursor to the beginning
    lcd.clear();
    lcd.setCursor(0, 0);

    // Display the current simulated nutrient levels
    lcd.print("K: ");
    lcd.print(potassiumPPM);
    lcd.print(" N: ");
    lcd.print(nitrogenPPM);
    lcd.print(" P: ");
    lcd.print(phosphorusPPM);

    // Check if any nutrient level is below the threshold and turn on the LED if so
    if (potassiumPPM < potassiumThreshold || nitrogenPPM < nitrogenThreshold || phosphorusPPM < phosphorusThreshold) {
      digitalWrite(ledPin, HIGH);
    } else {
      digitalWrite(ledPin, LOW);
    }
  }
}