/*

*/

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

LiquidCrystal_I2C lcd(0x27, 20, 4); //*************

const byte button_set    = A0;
const byte button_up     = A1;
const byte button_down   = A2;
const byte button_cancel = A3;


void setup() {
  //SPI.begin();   // LCD pin A4,A5
  Serial.begin(115200);
  lcd.begin(4,20);
  lcd.backlight(); delay(1000); 

  pinMode(button_set,    INPUT_PULLUP);
  pinMode(button_up,     INPUT_PULLUP);
  pinMode(button_down,   INPUT_PULLUP);
  pinMode(button_cancel, INPUT_PULLUP);

}


void loop() {
  boolean Display   = true;  //*****
  boolean ButtonSet = false; //**********

  if(Display == true){ 
    Display = false;
    lcd.setCursor(0,0); lcd.print("LCD 16x2 MENU       ");
    lcd.setCursor(0,1); lcd.print("Font Display        ");
                                //"01234567890123456789"
  }

  if(digitalRead(button_set) == 0){  //0
    delay(100);  
    if(digitalRead(button_set) == 0){
      if(ButtonSet == false){
        ButtonSet = true;        //*******
        Select_MENU();
      }
    }

  } else {
      ButtonSet = false;
    } 
}

////////////////////////////////////////////////////////////////
void Select_MENU()
{
  boolean Display     = true;    //*********true
  //boolean Display     = false;   
  //boolean Exit        = true;  
  boolean Exit        = false;   //********false

  boolean ButtonSet   = true;  //*********true
  boolean ButtonUp    = false;
  boolean ButtonDown  = false;
  boolean ButtonCancel  = false;

  byte Menu = 0;            // "01234567890123456789" 
  const String MenuText[4] = { "1: Menu 1 .........0",
                               "2: Menu 2 .........1",
                               "3: Menu 3 .........2",
                               "4: Menu 4 .........3" }; 

////////////////////////////////////////////////////////////////////
  //Serial.println(ButtonSet); //****** 
  while (Exit == false) {
    if(Display == true) {
      lcd.setCursor(0, 0);  lcd.print("SELECT MENU 1-4     ");
      lcd.setCursor(0, 1);  lcd.print(MenuText[Menu]); //************
    }

// *** Set
      if(digitalRead(button_set) == 0){ 
        delay(10);  //Serial.println(ButtonSet); // *** ButtonSet=true 
          if(digitalRead(button_set) == 0){
            if (ButtonSet == false){    // *** ButtonSet=true   **not select menu 1
              ButtonSet = true;
              //***************************
              //Serial.println(Menu);
              switch(Menu){
                case 0: Serial.println("1: Menu 1 .........0"); 
                        lcd_menu1(); // add command
                break;
                case 1: Serial.println("2: Menu 2 .........1");
                        // add command
                break;
                case 2: Serial.println("3: Menu 3 .........2");
                        // add command
                break;
                case 3: Serial.println("4: Menu 4 .........3"); 
                        // add command
                break;
              }
            }
          }
      } else {
          ButtonSet  = false; 
        }
// *** Up
      if(digitalRead(button_up) == 0){
        delay(100);        
          if(digitalRead(button_up) == 0){
            if (ButtonUp == false){
              ButtonUp = true;
            }  
              if(Menu <= 2){
                Menu++;  //Serial.println(Menu);
              } else Menu = 3;
          }
      } else {
          ButtonUp  = false;
        }
// *** Down
      if(digitalRead(button_down) == 0){
        delay(100);        
          if(digitalRead(button_down) == 0){
            if (ButtonDown == false){
              ButtonDown = true;
              //*****
              if(Menu >= 1){
                Menu--;      //Serial.println(Menu);
              } else Menu = 0;
            } 
         } else {
            ButtonDown  = false;
           }
      }    
// *** Cancle
      if(digitalRead(button_cancel) == 0){
        delay(100);
          if(digitalRead(button_cancel) == 0){
            if (ButtonCancel == false){
              ButtonCancel = true;
              Exit = true;
              //Display = true;
            }
          }
      } else {
          ButtonCancel  = false;
        }        
    } // while ...
  delay(100);
}

////////////////////////
void lcd_menu1()
{
  lcd.setCursor(0, 3); lcd.print("Add command menu 1");
}

// https://www.youtube.com/watch?v=fuL3fRTxCuk&t=949s