#include <Wire.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

// OLED display width and height, in pixels
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET    -1 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Data wire for DS18B20 is connected to GPIO 4
#define ONE_WIRE_BUS 4

// Analog pin for IR sensor (simulated as TDS sensor)
const int tdsSensorPin = 35;

// Setup a oneWire instance to communicate with any OneWire devices
OneWire oneWire(ONE_WIRE_BUS);

// Pass oneWire reference to DallasTemperature library
DallasTemperature sensors(&oneWire);

void setup() {
  // Initialize serial communication
  Serial.begin(115200);

  // Initialize I2C communication with specified SDA and SCL pins
  Wire.begin(32, 33);

  // Initialize the OLED display
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3C for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }

  // Clear the buffer
  display.clearDisplay();

  // Set text size and color
  display.setTextSize(1);      
  display.setTextColor(SSD1306_WHITE);

  // Display static text
  display.setCursor(0, 10);     // Start at top-left corner
  display.println(F("Hello, World!"));

  // Update the display with the new data
  display.display();

  // Start up the DS18B20 library
  sensors.begin();
}

void loop() {
  // Request temperature readings
  sensors.requestTemperatures();
  
  // Fetch temperature in Celsius
  float temperatureC = sensors.getTempCByIndex(0);

  // Read the analog value from the IR sensor (simulated as TDS sensor)
  int analogValue = analogRead(tdsSensorPin);
  
  // Convert the analog value to voltage (ESP32 has 12-bit ADC, 0-4095 range)
  float voltage = analogValue * (3.3 / 4095.0);

  // Convert voltage to TDS (Total Dissolved Solids)
  // This conversion formula will be a placeholder; in a real TDS sensor, you would use a specific conversion
  float tdsValue = voltage * 500.0; // Example conversion factor
  
  // Calculate electrical conductivity (EC)
  // EC is often directly related to TDS, a common approximation: EC (uS/cm) = TDS (ppm) * 2
  float ecValue = tdsValue * 2;

  // Display temperature and EC on Serial Monitor
  Serial.print("Temperature: ");
  Serial.print(temperatureC);
  Serial.print(" °C, ");
  Serial.print("EC: ");
  Serial.print(ecValue);
  Serial.println(" uS/cm");

  // Display temperature and EC on the OLED display
  display.clearDisplay();
  display.setCursor(0, 0);
  display.setTextSize(1);
  display.println(F("Hello, World!"));
  display.setCursor(0, 20);
  display.print(F("Temp: "));
  display.print(temperatureC);
  display.println(F(" C"));
  display.setCursor(0, 40);
  display.print(F("EC: "));
  display.print(ecValue);
  display.println(F(" uS/cm"));
  display.display();

  // Wait for a bit before the next reading
  delay(1000);
}