#define ENCODER_CLK 16
#define ENCODER_DT  4
#define ENCODER_BTN 15
#define SDA         12
#define SCL         13
#define LED1        14
#define LED2        27
#define LED3        26
#define LED4        25

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27, 20, 4);

int Menu = 1;
int MenuUp = 0;
int MenuDown = 0; 

int StateBTN = 1;
int led1 = 0;
int led2 = 0;
int led3 = 0;
int led4 = 0;

void setup() {
  Serial.begin(9600);
  Wire.begin(SDA, SCL);
  lcd.init();
  lcd.backlight();
  pinMode(ENCODER_CLK, INPUT);
  pinMode(ENCODER_DT, INPUT);
  pinMode(ENCODER_BTN, INPUT_PULLUP);
  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);
  pinMode(LED3, OUTPUT);
  pinMode(LED4, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(ENCODER_CLK), readEncoder, FALLING);
  Serial.println("Begin");
  updateMenu();
}

void readEncoder() {
  int dtValue = digitalRead(ENCODER_DT);
  if (dtValue == HIGH) {
    Serial.println("Rotated clockwise ⏩");
    MenuUp=1;
  }
  if (dtValue == LOW) {
    Serial.println("Rotated counterclockwise ⏪");
    MenuDown=1;
  }
}
void updateMenu() {
  switch (Menu) {
    case 0:
      Menu = 1;
      break;
    case 1:
      lcd.clear();
      lcd.print(">LED1");
      lcd.setCursor(0, 1);
      lcd.print(" LED2");
      action1();
      break;
    case 2:
      lcd.clear();
      lcd.print(" LED1");
      lcd.setCursor(0, 1);
      lcd.print(">LED2");
      break;
    case 3:
      lcd.clear();
      lcd.print(">LED3");
      lcd.setCursor(0, 1);
      lcd.print(" LED4");
      break;
    case 4:
      lcd.clear();
      lcd.print(" LED3");
      lcd.setCursor(0, 1);
      lcd.print(">LED4");
      break;
    case 5:
      Menu = 4;
      break;
  }
}

void loop() {
  if (MenuUp){
    MenuUp=0;
    Menu++;
    updateMenu();
    delay(100);
  }
  if (MenuDown){
    MenuDown=0;
    Menu--;
    updateMenu();
    delay(100);
  }
  if (digitalRead(ENCODER_BTN) == LOW) {
    StateBTN = !StateBTN;
    Serial.println(StateBTN);
    executeAction();
    delay(1000);
  }
  delay(10);
}

void executeAction() {
  switch (Menu) {
    case 1:
      action1();
      break;
    case 2:
      action2();
      break;
    case 3:
      action3();
      break;
    case 4:
      action4();
      break;
  }
}

void action1() {
if (StateBTN == LOW) led1 = HIGH;
  else led1 = LOW;
digitalWrite(LED1, led1);
}

void action2() {
if (StateBTN == LOW) led2 = HIGH;
  else led2 = LOW;
digitalWrite(LED2, led2);
}

void action3() {
if (StateBTN == LOW) led3 = HIGH;
  else led3 = LOW;
digitalWrite(LED3, led3);
}

void action4() {
if (StateBTN == LOW) led4 = HIGH;
  else led4 = LOW;
digitalWrite(LED4, led4);
}