#include <LiquidCrystal_I2C.h>

#define I2C_ADDR    0x27
#define LCD_COLUMNS 20
#define LCD_LINES   4

LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

String menutitle = "Menu Title";
String linearray[]={"menu1", "menu2", "menu3", "menu4", "menu5", "menu6"};
int currentcursorpos=0;
int linearraylen = sizeof(linearray)/sizeof(linearray[0]);//Serial.print("Arraylen ");Serial.println(arraylen);
///////////////////////////////////////////
void setup() {
  Serial.begin(9600);
  // Init
  lcd.init();
  lcd.backlight();  
}
////////////////////////////////////////////
void loop() {
  
  displaylcdmenu(menutitle, linearray, currentcursorpos, linearraylen);

  //TESTING CHANGING CURSOR POS EVERY 3 SECONDS
  currentcursorpos++;if (currentcursorpos==6) currentcursorpos=0;
  Serial.println(currentcursorpos);
  delay(5000);
}

//////////////////////////////////////////////
void displaylcdmenu(String _menutitle, String _linearray[], int _cpos, int _linearraylen){
  int arraylen = _linearraylen;//sizeof(_linearray)/sizeof(_linearray[0]);
  //Serial.print("Arraylen ");Serial.println(arraylen);
  
  int scrl=0;
  while(_cpos>scrl+2) {scrl++;}
  while(_cpos<scrl) {scrl--;}

  _menutitle="** "+_menutitle+" **";
  int offset = (20-(_menutitle.length()))/2;

  lcd.clear();
  //lcd.setCursor(offset, 0);lcd.print(_menutitle);

  for(int n=0;n<4;n++){
    if (n==0){
      lcd.setCursor(offset, 0);
      lcd.print(_menutitle);
    }else{
      char crsr=' ';
      if (n==_cpos-scrl+1)  crsr='>'; 
      char scrlarrow='|';//tbd logic for up and dn arrows on line 1 and 3
      if((n==1) && (scrl>0) )scrlarrow='A';
      if((n==3) && !(arraylen-3==scrl))scrlarrow='V';
      lcd.setCursor(0, n);lcd.print(crsr+_linearray[(n-1)+scrl]);
      lcd.setCursor(19, n);lcd.print(scrlarrow);
    }
  }
}
////////////////////////////////////////////////
/*
  // Print something
  lcd.setCursor(3, 0);
  lcd.print("Hello, world!");
  lcd.setCursor(2, 1);
  lcd.print("Wokwi Online IoT");
  lcd.setCursor(5, 2);
  lcd.print("Simulator");
  lcd.setCursor(7, 3);
  lcd.print("Enjoy!");
  delay(3000);
  lcd.setCursor(7, 3);
  lcd.print("      "); 
  lcd.clear();
  
  uvolt = 200.4;
  ufreq = 50.0;
  evolt = 220.4;
  efreq = 51.0;
  displayparams();

//////////////////////////
///////////////////////////////////////////
void displayparams(){
   //Parameters  
  for (int n=0; n<LCD_LINES; n++){
    lcd.setCursor(0, n);dispLines[n];
    //lcd.setCursor(0, n);dispLines[n+lcdScrl];
  }
  //Values
  lcd.setCursor(10, 0);lcd.print(uvolt);
  lcd.setCursor(10, 1);lcd.print(ufreq);
  lcd.setCursor(10, 2);lcd.print(evolt);
  lcd.setCursor(10, 3);lcd.print(efreq); 
  //Units
  lcd.setCursor(17, 0);lcd.print(" V");
  lcd.setCursor(17, 1);lcd.print(" Hz");
  lcd.setCursor(17, 2);lcd.print(" V");
  lcd.setCursor(17, 3);lcd.print(" Hz"); 

}

*/