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

#define AUDIO_IN 16
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define SAMPLES      64  // Number of samples to take for FFT
#define BANDS        15  // Number of frequency bands
#define BAR_HEIGHT   64  //53 pixel

arduinoFFT FFT = arduinoFFT();

double vReal[SAMPLES];
double vImag[SAMPLES];

byte audio_bar_height[15]; // sizes for the individual bars
byte audio_bar_peak[15]; // positions for the individual peaks (lines over the bars)

float heightAdjust =  0.3;

void setup() {
  randomSeed(analogRead(0));
  Serial.begin(115200);
  Wire.begin(33, 35);

  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for (;;);
  }

  display.fillScreen(0);
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.cp437(true);
}

void loop() {
  for (int i = 0; i < SAMPLES; i++) {
    vReal[i] = random(1024);// analogRead(AUDIO_IN);
    vImag[i] = 0;
  }

  FFT.Windowing(vReal, SAMPLES, FFT_WIN_TYP_HAMMING, FFT_FORWARD);
  FFT.Compute(vReal, vImag, SAMPLES, FFT_FORWARD);
  FFT.ComplexToMagnitude(vReal, vImag, SAMPLES);

  display.clearDisplay();
for (int i = 0; i < BANDS; i++) {
    int bandStart = (i * SAMPLES) / BANDS;
    int bandEnd = ((i + 1) * SAMPLES) / BANDS;
    
    double sum = 0;
    for (int j = bandStart; j < bandEnd; j++) {
        sum += vReal[j];
    }

    int averageMagnitude = sum / (bandEnd - bandStart+1)*heightAdjust;
   
    audio_bar_height[i] = map(averageMagnitude, 0, 1023, 0, BAR_HEIGHT);
    
    // Adjust the peak value with heightAdjust
 
    //audio_bar_peak[i] = audio_bar_height[i];

    // calculate the peak position
    if (audio_bar_peak[i] < audio_bar_height[i]) {
        audio_bar_peak[i] = audio_bar_height[i];
    } else if (audio_bar_peak[i] > audio_bar_height[i]) {
        audio_bar_peak[i]--; // slowly move the peak down, one pixel every frame
         display.drawFastHLine(5 + i * 8, BAR_HEIGHT - audio_bar_peak[i], 5, SSD1306_WHITE); // draw peak
    }

   
    display.fillRect(5 + i * 8, BAR_HEIGHT - audio_bar_height[i], 5, audio_bar_height[i], SSD1306_WHITE); // draw bar
}

  display.display();
}