#include <LiquidCrystal_I2C.h>

#define LCD_ADDR 0x27
#define LCD_COLUMNS 16
#define LCD_ROWS 2

#define ENCODER_CLK 3
#define ENCODER_DT  4
#define ENCODER_BTN 2

LiquidCrystal_I2C lcd(LCD_ADDR, LCD_COLUMNS, LCD_ROWS);

int count = 0;

const unsigned long interval_lcd = 100;

char buffer_line_1 [16];
char buffer_line_2 [16];

void setup() {
  Serial.begin(115200);
  pinMode(ENCODER_CLK, INPUT);
  pinMode(ENCODER_DT, INPUT);
  pinMode(ENCODER_BTN, INPUT_PULLUP);
  pinMode(LED_BUILTIN, OUTPUT);
  
  attachInterrupt(digitalPinToInterrupt(ENCODER_CLK), readEncoder, FALLING);
  attachInterrupt(digitalPinToInterrupt(ENCODER_BTN), readButton, CHANGE);

  lcd.begin(16,2);
  lcd.init();
  lcd.backlight();
}

void readEncoder() {
  int dtValue = digitalRead(ENCODER_DT);
  if (dtValue == HIGH) {
    ++count;
    if (count > 359){count = 0;}
    Serial.print("Rotated cw Count = ");
    Serial.println(count);
  }
  if (dtValue == LOW) {
    --count;
    if (count < 0){count = 359;}
    Serial.print("Rotated ccw Count = ");
    Serial.println(count);
  }
}
// for test
void readButton(){
  int swValue = digitalRead(ENCODER_BTN);
  if (swValue == HIGH){
    Serial.println("Button up");
  } else {
    Serial.println("Button down");
  }
}

void loop() {
  static unsigned long previousMillis_lcd = 0;
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis_lcd >= interval_lcd) {
    sprintf(buffer_line_1,"Position %3d",count);
    lcd.setCursor(0,0);
    lcd.print(buffer_line_1);
  }
  if (digitalRead(ENCODER_BTN) == LOW) {
    digitalWrite(LED_BUILTIN, HIGH);
    sprintf(buffer_line_2,"Button down");
    lcd.setCursor(0,1);
    lcd.print(buffer_line_2);
  } else {
    digitalWrite(LED_BUILTIN, LOW);
    sprintf(buffer_line_2,"Button up  ");
    lcd.setCursor(0,1);
    lcd.print(buffer_line_2);
  } 
}