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

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET    -1
#define SCREEN_ADDRESS 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define ADC_PIN 34
#define NUM_SAMPLES 20
#define X0 15
#define Y0 16
#define GRAPH_WIDTH 113 //SCREEN_WIDTH-X0

float voltageSamples[NUM_SAMPLES];
float voltageHistory[GRAPH_WIDTH];
int sampleIndex = 0;
int historyIndex = 0;

void setup() {
  Serial.begin(115200);
  // initialize OLED display with I2C address 0x3C
  if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
    Serial.println(F("failed to start SSD1306 OLED"));
    while (1);
  }

  //delay(2000);         // wait two seconds for initializing
  display.clearDisplay(); // clear display
  display.setTextSize(1);         // set text size
  display.setTextColor(WHITE);    // set text color

}

void loop() {
  static unsigned long lastSampleTime = 0, lastAverageTime = 0;
  unsigned long currentTime = millis();

  if (currentTime - lastSampleTime >= 50) { // 20 samples per second
    lastSampleTime = currentTime;
    voltageSamples[sampleIndex] = analogRead(ADC_PIN) * (3.3 / 4095.0); // Convert ADC value to voltage
    sampleIndex = (sampleIndex + 1) % NUM_SAMPLES;
  //}

  //if (currentTime - lastAverageTime >= 1000) { // 1 sample per second  //va muy lento
  //  lastAverageTime = currentTime;
    float averageVoltage = 0;  //calcula la media de 20 valores
    for (int i = 0; i < NUM_SAMPLES; i++) {
      averageVoltage += voltageSamples[i];
    }
    averageVoltage /= NUM_SAMPLES;

    voltageHistory[historyIndex] = averageVoltage;
    historyIndex = (historyIndex + 1) % GRAPH_WIDTH;

    display.clearDisplay();
    display.setCursor(0, 0);
    display.print("Voltaje: " + String(averageVoltage, 2) + " V");

   //dibuja eje X y Y
    display.drawLine(0, SCREEN_HEIGHT-7 , SCREEN_WIDTH-1 , SCREEN_HEIGHT-7, WHITE);
    display.drawLine(X0, SCREEN_HEIGHT-7, X0, Y0, WHITE);
    // Draw graph, margen izq 25, margen superior 16, margen inferior 7
    for (int x = 0; x < GRAPH_WIDTH; x++) {
      int index = (historyIndex + x) % GRAPH_WIDTH;
      int y = map(voltageHistory[index] * 100, 0, 330, SCREEN_HEIGHT-7, Y0);
      display.drawPixel(x+X0, y, SSD1306_WHITE);
  }
   display.display();
  }
}