#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <SoftwareSerial.h>

#define OLED_RESET -1
#define SCREEN_WIDTH 128    // OLED display width, in pixels
#define SCREEN_HEIGHT 64    // OLED display height, in pixels
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define sensorPin A0

#define RE 8
#define DE 7

const byte nitro[] = {0x01, 0x03, 0x00, 0x1e, 0x00, 0x01, 0xe4, 0x0c};
const byte phos[] = {0x01, 0x03, 0x00, 0x1f, 0x00, 0x01, 0xb5, 0xcc};
const byte pota[] = {0x01, 0x03, 0x00, 0x20, 0x00, 0x01, 0x85, 0xc0};

byte values[11];
SoftwareSerial mod(2, 3);

void setup() {
    Serial.begin(9600);
    mod.begin(9600);
    pinMode(RE, OUTPUT);
    pinMode(DE, OUTPUT);

    display.begin(SSD1306_SWITCHCAPVCC, 0x3C); // Initialize with the I2C addr 0x3C (128x64)
    display.clearDisplay();
    display.setCursor(25, 15);
    display.setTextSize(1);
    display.setTextColor(WHITE);
    display.println("NPK Sensor");
    display.setCursor(25, 35);
    display.setTextSize(1);
    display.print("Initializing...");
    display.display();
    delay(3000);
}

void loop() {
    int soilMoistureValue = analogRead(sensorPin);
    int soilMoisturePercent = map(soilMoistureValue, 0, 1023, 0, 100);

    byte nitrogenValue = readSensor(nitro);
    byte phosphorusValue = readSensor(phos);
    byte potassiumValue = readSensor(pota);

    Serial.print("Nitrogen: ");
    Serial.print(nitrogenValue);
    Serial.println(" mg/kg");
    Serial.print("Phosphorus: ");
    Serial.print(phosphorusValue);
    Serial.println(" mg/kg");
    Serial.print("Potassium: ");
    Serial.print(potassiumValue);
    Serial.println(" mg/kg");
    delay(2000);

    display.clearDisplay();

    display.setTextSize(1);
    display.setCursor(0, 0);
    display.println("Embedded Systems Lab");
    display.println("Araf Sourov Mahid");
    display.print("Soil Moisture: ");
    display.print(soilMoisturePercent);
    display.println("%");

    display.setTextSize(2);
    display.setCursor(0, 20);
    display.print("N: ");
    display.print(nitrogenValue);
    display.setTextSize(1);
    display.print(" mg/kg");

    display.setTextSize(2);
    display.setCursor(0, 40);
    display.print("P: ");
    display.print(phosphorusValue);
    display.setTextSize(1);
    display.print(" mg/kg");

    display.setTextSize(2);
    display.setCursor(0, 60);
    display.print("K: ");
    display.print(potassiumValue);
    display.setTextSize(1);
    display.print(" mg/kg");

    display.display();
}

byte readSensor(const byte *command) {
    digitalWrite(DE, HIGH);
    digitalWrite(RE, HIGH);
    delay(10);
    byte returnValue = 0;
    if (mod.write(command, 8) == 8) {
        digitalWrite(DE, LOW);
        digitalWrite(RE, LOW);
        for (byte i = 0; i < 7; i++) {
            values[i] = mod.read();
            Serial.print(values[i], HEX);
        }
        Serial.println();
        returnValue = values[4];
    }
    return returnValue;
}