#include <Adafruit_NeoPixel.h>

// --- NEOPIXEL CONFIGURATION ---
#define LED_PIN         6       // Which pin on the Arduino is connected to the NeoPixels.
#define NUM_LEDS        60      // The number of LEDs in your strip.

// --- VU METER CONFIGURATION ---
#define ANALOG_PIN      A0      // The microphone's analog output is connected to this pin.
#define SAMPLES         100     // How many samples to take to determine the sound level.

// --- CALIBRATION ---
// These values will need to be adjusted for your specific microphone and environment.
// See the "How to Calibrate" section below.
#define NOISE           10      // A baseline noise level. Anything below this is considered silence.
#define MAX_LEVEL       500     // The maximum peak-to-peak signal you expect.

// Create a NeoPixel object
Adafruit_NeoPixel strip = Adafruit_NeoPixel(NUM_LEDS, LED_PIN, NEO_GRB + NEO_KHZ800);

int peak = 0; // Stores the peak LED position
unsigned long peak_millis = 0; // Timestamp for when the peak was last updated
#define PEAK_FALL_DELAY 30 // How many milliseconds before the peak falls one step

void setup() {
  Serial.begin(9600); // For debugging and calibration
  strip.begin();      // Initialize the NeoPixel strip
  strip.show();       // Initialize all pixels to 'off'
  strip.setBrightness(150); // Set brightness (0-255). 150 is a good starting point.
}

void loop() {
  unsigned int signalMax = 0;
  unsigned int signalMin = 1024;
  unsigned int sample;

  // 1. COLLECT SAMPLES
  // Find the peak-to-peak amplitude of the audio signal over a short period.
  for (int i = 0; i < SAMPLES; i++) {
    sample = analogRead(ANALOG_PIN);
    if (sample < 1024) { // Guard against spurious readings
      if (sample > signalMax) {
        signalMax = sample; // Save the maximum value
      } else if (sample < signalMin) {
        signalMin = sample; // Save the minimum value
      }
    }
  }

  // 2. CALCULATE PEAK-TO-PEAK AMPLITUDE
  // This is a better measure of volume than a single reading.
  int p2p_level = signalMax - signalMin;

  // Optional: Apply some smoothing to make the display less "jumpy"
  // This is a simple low-pass filter.
  static int last_level = 0;
  p2p_level = (last_level * 0.7) + (p2p_level * 0.3);
  last_level = p2p_level;

  // For calibration, uncomment the line below:
  // Serial.println(p2p_level);

  // 3. MAP THE AUDIO LEVEL TO THE NUMBER OF LEDS
  // Subtract the noise floor and constrain the value.
  int level = map(p2p_level, NOISE, MAX_LEVEL, 0, NUM_LEDS);
  level = constrain(level, 0, NUM_LEDS);

  // 4. UPDATE THE PEAK INDICATOR
  if (level > peak) {
    peak = level;
    peak_millis = millis(); // Reset the peak fall timer
  }

  // 5. DRAW THE VU METER BAR
  for (int i = 0; i < NUM_LEDS; i++) {
    if (i < level) {
      // Create a color gradient from green to red.
      // Hue values: 0 = Red, 85 = Green. We map from green to red.
      int hue = map(i, 0, NUM_LEDS - 1, 85, 0);
      strip.setPixelColor(i, strip.ColorHSV(hue * 256));
    } else {
      // Turn off LEDs beyond the current level
      strip.setPixelColor(i, strip.Color(0, 0, 0));
    }
  }

  // 6. DRAW THE PEAK PIXEL
  // Draw the peak pixel in a distinct color (e.g., white or blue)
  if (peak > 0 && peak < NUM_LEDS) {
    strip.setPixelColor(peak, strip.Color(200, 200, 255)); // A light blueish-white
  }

  // 7. SHOW THE CHANGES ON THE STRIP
  strip.show();

  // 8. MAKE THE PEAK FALL
  // After a short delay, make the peak LED fall by one position.
  if (millis() - peak_millis > PEAK_FALL_DELAY) {
    if (peak > 0) {
      peak--;
    }
    peak_millis = millis(); // Reset the timer for the next fall step
  }
}