#define POT_PIN A0            // Analog pin for the potentiometer
#define OUT_PIN 9             // PWM output pin
#define NUM_READINGS 100      // Number of readings for smoothing
#define CALIBRATION_TIME 5000  // Calibration period in milliseconds (1 minute)

int calibratedMin = 1023;     // To store the minimum reading during calibration
int calibratedMax = 0;        // To store the maximum reading during calibration
bool calibrationDone = false; // Flag to indicate calibration is complete
unsigned long calibrationStartTime;  // To mark when calibration starts

// Running average variables for normal operation
int readings[NUM_READINGS];
int index = 0;
long total = 0;              // Use long to avoid overflow
float sens = 1;           // Sensitivity factor

void setup() {
  Serial.begin(9600);
  pinMode(OUT_PIN, OUTPUT);
  
  // Start calibration timing.
  calibrationStartTime = millis();
  
  // Do an initial reading to initialize variables.
  int initial = analogRead(POT_PIN);
  calibratedMin = initial;
  calibratedMax = initial;
  
  // Also initialize the running average buffer.
  total = (long)initial * NUM_READINGS;
  for (int i = 0; i < NUM_READINGS; i++) {
    readings[i] = initial;
  }
}

void loop() {
  unsigned long elapsed = millis() - calibrationStartTime;
  
  if (!calibrationDone) {
    // Calibration mode: during the first minute, update calibrated min and max.
    int reading = analogRead(POT_PIN);
    
    // Update calibration bounds.
    if (reading < calibratedMin) {
      calibratedMin = reading;
    }
    if (reading > calibratedMax) {
      calibratedMax = reading;
    }
    
    // Debug: print calibration progress.
    Serial.print("Calibrating... ");
    Serial.print("Elapsed: ");
    Serial.print(elapsed);
    Serial.print(" ms, Min: ");
    Serial.print(calibratedMin);
    Serial.print(", Max: ");
    Serial.println(calibratedMax);
    
    // Check if calibration time is complete.
    if (elapsed >= CALIBRATION_TIME) {
      calibrationDone = true;
      Serial.println("Calibration complete!");
      Serial.print("Final Calibrated Min: ");
      Serial.print(calibratedMin);
      Serial.print(", Max: ");
      Serial.println(calibratedMax);
      
      // Optionally, reset the running average buffer with the current reading.
      int current = analogRead(POT_PIN);
      total = (long)current * NUM_READINGS;
      for (int i = 0; i < NUM_READINGS; i++) {
        readings[i] = current;
      }
    }
    
    delay(10);  // Small delay for stable calibration readings
  } else {
    // Normal operation: use running average and sensitivity check.
    int reading = analogRead(POT_PIN);
    
    // Compute the current running average.
    int avgReading = total / NUM_READINGS;
    
    // If the new reading is significantly lower than the average (scaled by sens),
    // reset the running average buffer to the new reading.
    if (reading <= (avgReading * sens)) {
      total = (long)reading * NUM_READINGS;
      for (int i = 0; i < NUM_READINGS; i++) {
        readings[i] = reading;
      }
      avgReading = reading;
    } else {
      // Update running total: subtract the oldest reading and add the new reading.
      total = total - readings[index] + reading;
      readings[index] = reading;
      index = (index + 1) % NUM_READINGS;
      avgReading = total / NUM_READINGS;
    }
    
    // Map the averaged reading from the calibrated range to a PWM value (0–255).
    int pwmValue = map(avgReading, calibratedMin, calibratedMax, 0, 255);
    pwmValue = constrain(pwmValue, 0, 255);
    
    // Output the PWM signal.
    analogWrite(OUT_PIN, pwmValue);
    
    // Debug output.
    Serial.print("Reading: ");
    Serial.print(reading);
    Serial.print(" | Avg: ");
    Serial.print(avgReading);
    Serial.print(" | PWM: ");
    Serial.println(pwmValue);
    
    delay(50);
  }
}