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

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

// OLED reset pin (if required)
#define OLED_RESET -1
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Fuel sensor pin
const int fuelSensorPin = A0;

// Resistance values (in ohms)
const float fullResistance = 20.0;
const float emptyResistance = 220.0;

// Voltage divider reference resistor value (in ohms)
const float referenceResistor = 1000.0; // Example: 1k ohm resistor

// Variables for averaging
const int numReadings = 60; // Number of readings for 1-minute average
float readings[numReadings];
int readIndex = 0;
float total = 0;
float average = 0;

void setup() {
  // Initialize Serial Monitor
  Serial.begin(9600);

  // Initialize the OLED display
  }

  // Clear and display a welcome message
  display.clearDisplay();
  display.setTextSize(1);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("Fuel Level Monitor");
  display.display();
  delay(2000);

  // Initialize readings array
  for (int i = 0; i < numReadings; i++) {
    readings[i] = 0;
  }
}

void loop() {
  // Read the analog value from the sensor
  int sensorValue = analogRead(fuelSensorPin);

  // Convert the analog value to resistance
  float voltage = sensorValue * (5.0 / 1023.0); // Assuming 5V reference
  float resistance = (referenceResistor * (5.0 - voltage)) / voltage;

  // Map the resistance to a fuel level percentage
  float fuelLevel = map(resistance, fullResistance, emptyResistance, 100, 0);
  fuelLevel = constrain(fuelLevel, 0, 100); // Ensure the value stays within 0-100%

  // Update the readings array for averaging
  total -= readings[readIndex];        // Subtract the oldest reading
  readings[readIndex] = fuelLevel;    // Store the new reading
  total += readings[readIndex];       // Add the new reading to the total
  readIndex = (readIndex + 1) % numReadings; // Advance to the next position

  // Calculate the average
  average = total / numReadings;

  // Print the values to the Serial Monitor
  Serial.print("Resistance (Ohms): ");
  Serial.print(resistance);
  Serial.print(" | Fuel Level (%): ");
  Serial.print(fuelLevel);
  Serial.print(" | Average Fuel Level (%): ");
  Serial.println(average);

  // Display the fuel level on the OLED
  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println("Fuel Level Monitor");

  display.setTextSize(2);
  display.setCursor(0, 20);
  display.print("Fuel: ");
  display.print(average);
  display.println("%");

  display.display();

  // Small delay for readability
  delay(1000);
}