#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C oLcd(0x3F, 16, 2);


// Rotary Encoder Inputs
#define CLK PB4
#define DT PB5
#define BTN PA15

int counter = 0;
int currentStateCLK;
int lastStateCLK;
String currentDir = "";
unsigned long lastButtonPress = 0;

void setup() {
  // Set encoder pins as inputs
  pinMode(CLK, INPUT);
  pinMode(DT, INPUT);
  pinMode(BTN, INPUT_PULLUP);

  // Read the initial state of CLK
  lastStateCLK = digitalRead(CLK);

  oLcd.init();
  oLcd.backlight();
  oLcd.setCursor(0, 0);

  attachInterrupt(CLK, updateEncoder, CHANGE);
  attachInterrupt(DT, updateEncoder, CHANGE);
  attachInterrupt(BTN, updateBtnPressed, CHANGE);
}

void loop() {
}

void updateEncoder(){
  // Read the current state of CLK
  currentStateCLK = digitalRead(CLK);

  // If last and current state of CLK are different, then pulse occurred
  // React to only 1 state change to avoid double count
  if (currentStateCLK != lastStateCLK  && currentStateCLK == 1){

    // If the DT state is different than the CLK state then
    // the encoder is rotating CCW so decrement
    if (digitalRead(DT) != currentStateCLK) {
      counter --;
      currentDir ="CCW";
    } else {
      // Encoder is rotating CW so increment
      counter ++;
      currentDir ="CW";
    }
    oLcd.clear();
    oLcd.print("Direction: ");
    oLcd.print(currentDir);
    oLcd.setCursor(0, 1);
    oLcd.print("Counter: ");
    oLcd.print(counter);
  }

  // Remember last CLK state
  lastStateCLK = currentStateCLK;
}

void updateBtnPressed() {
  int btnState = digitalRead(BTN);

  if (btnState == LOW) {
    if (millis() - lastButtonPress > 50) {
        oLcd.clear();
        oLcd.print("Button pressed!");
    }
    lastButtonPress = millis();
  }
}