#include <Arduino.h>
#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

#define CLK_PIN 32
#define DT_PIN 33
#define SW_PIN 34
#define DAC_PIN 25  // Virtual DAC output pin

#define ENCODER_STEPS 4
#define MAX_VALUE 127
#define MIN_VALUE 0
#define MIDDLE_VALUE 64

#define DEBOUNCE_TIME 20  // Reduced debounce time to 20ms

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

volatile int32_t encoderPosition = MIDDLE_VALUE * ENCODER_STEPS;
volatile uint8_t encoderState = 0;
volatile bool updateDisplay = false;

int32_t getEncoderValue() {
  return constrain(encoderPosition / ENCODER_STEPS, MIN_VALUE, MAX_VALUE);
}

void IRAM_ATTR handleEncoder() {
  static const int8_t encoderStates[] = {0, -1, 1, 0, 1, 0, 0, -1, -1, 0, 0, 1, 0, 1, -1, 0};
  encoderState = ((encoderState << 2) | (digitalRead(CLK_PIN) << 1) | digitalRead(DT_PIN)) & 0x0F;
  int8_t change = encoderStates[encoderState];
  if (change != 0) {
    encoderPosition += change;
    encoderPosition = constrain(encoderPosition, MIN_VALUE * ENCODER_STEPS, MAX_VALUE * ENCODER_STEPS);
    updateDisplay = true;
  }
}

void setup() {
  Serial.begin(115200);
  Wire.begin();

  pinMode(CLK_PIN, INPUT_PULLUP);
  pinMode(DT_PIN, INPUT_PULLUP);
  pinMode(SW_PIN, INPUT_PULLUP);
  pinMode(DAC_PIN, OUTPUT);

  attachInterrupt(digitalPinToInterrupt(CLK_PIN), handleEncoder, CHANGE);
  attachInterrupt(digitalPinToInterrupt(DT_PIN), handleEncoder, CHANGE);

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

  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("KY-040 Test");
  display.display();
  delay(2000);
}

void loop() {
  static uint32_t lastDebounceTime = 0;
  static int lastButtonState = HIGH;
  int buttonState = digitalRead(SW_PIN);

  if (buttonState != lastButtonState) {
    lastDebounceTime = millis();
  }

  if ((millis() - lastDebounceTime) > DEBOUNCE_TIME) {
    if (buttonState == LOW) {
      encoderPosition = MIDDLE_VALUE * ENCODER_STEPS;
      updateDisplay = true;
      Serial.println("Button pressed, reset to middle position");
    }
  }

  lastButtonState = buttonState;

  if (updateDisplay) {
    int encoderValue = getEncoderValue();
    float voltage = map(encoderValue, MIN_VALUE, MAX_VALUE, 0, 1000) / 100.0;  // 0-10V range

    // Set virtual DAC output
    int dacValue = map(encoderValue, MIN_VALUE, MAX_VALUE, 0, 255);
    analogWrite(DAC_PIN, dacValue);

    display.clearDisplay();
    display.setTextSize(2);
    display.setCursor(0, 0);
    display.print("Value: ");
    display.println(encoderValue);
    
    display.setTextSize(3);
    display.setCursor(0, 30);
    display.print(voltage, 2);
    display.println("V");
    
    display.display();

    Serial.printf("Encoder: %d, Voltage: %.2fV, DAC: %d\n", encoderValue, voltage, dacValue);
    
    updateDisplay = false;
  }
}