/*
Took care of that damn blinking!

Used LC_baseTools for low level goodies and made up a
class that holds the text as a ring of beads.

Oh, and this version is NON BLOCKING.

For document on LC_baseTools : 
https://github.com/leftCoast/LC_libraryDocs/blob/main/LC_libraries.pdf
*/

#include <LiquidCrystal_I2C.h>
#include <lists.h>
#include <strTools.h>
#include <timeObj.h>

// ****************   class aChar   ****************


class aChar : public linkListObj {

  public:
          aChar(char inChar);
  virtual ~aChar();

          char  getChar(void);

          char  ourChar;
};

aChar::aChar(char inChar) { ourChar = inChar; }

aChar::~aChar() {  }

char aChar::getChar(void) { return ourChar; }



// ***************  class charRing   ***************


class  charRing : public linkList {

  public:
          charRing(const char* inStr);
  virtual ~charRing(void);

  char* getSubstr(int offset,int nunChars);

        char* ourStr;
        char* returnStr;
};


charRing::charRing(const char* inStr) {

  aChar*  newChar;
  int     i;

  returnStr = NULL;
  heapStr(&returnStr,inStr);          // Q&D way to get string allocated.
  if (returnStr) {                    // We got it?
    i = 0;                            // Start building the loop.
    while(inStr[i]) {                 // For every non-null char..
      newChar = new aChar(inStr[i]);  // Create a node for it and stuff it in.
      addToEnd(newChar);              // Add the new node to our list.
      i++;                            // Don't forget to bump i.
    }                                 //      
    newChar->setNext(theList);        // Make it a loop.
  }                                   //
}


// Little tricky here. We made it into a ring so no NULL
// at the end to know where to stop.
charRing::~charRing(void) {
  
  aChar*  trace;

  freeStr(&returnStr);                                    // Knock this out first.
  trace = (aChar*)theList;                                // Grab at the ring..
  if (trace) {                                            // Got a ring?
    while(trace && trace->getNext()!=(aChar*)theList) {   // While we have a ring and this guys't not pointint at it too..
      trace = (aChar*)trace->getNext();                   // Move up the ring one..
    }                                                     //
    if (trace) {                                          // If we popped out with trace!=NULL? We found the end.
      trace->setNext(NULL);                               // Now the auto destructor shoudld work.
    }
  }
}

char* charRing::getSubstr(int offset,int numChars) {

  aChar*  trace;

  if (returnStr && numChars) {              // Input make sense?
    trace = (aChar*)theList;                // Make a grab at the bead we're holding.
    while(trace && offset>0) {              // While we have a bead and + offset..
      trace = (aChar*)(trace->getNext());   // Move to th enext bead.
      offset--;                             // bump down the offset.
    }                                       //
    theList = trace;                        // Move what we are holding to this bead.
    for(int i=0;i<numChars;i++) {           // Setup for substring copy.
      returnStr[i] = trace->getChar();      // Start fiulling returnStr.
      returnStr[i+1] = '\0';                // Pop a endstring after each write. (Lazy)
      trace = (aChar*)(trace->getNext());   // Move to next bead.
    }                                       // By now the substring is ready.
  }                                         //
  return returnStr;                         // Hand it over to the user.
}



// ***************  Your sketch   ***************


char                firstLine[16] = "Static 1st line";
char                secondLine[] = "                Scrolling text on second line";
charRing            ourScroller(secondLine);                    // The set of string beads.
timeObj             scrollTimer(250);                           // Wait time per letter.
LiquidCrystal_I2C   lcd(0x27, 16, 2);                           // The LCD.

void setup() {

  lcd.init();             // Fire up the LCD.
  lcd.backlight();        // And the  backlight.
  lcd.print(firstLine);   // First line is static. So print it once.
}

void loop() {
  
  char* subsetStr;

  if (scrollTimer.ding()) {                     // If the timer went off..
    lcd.setCursor(0, 1);                        // Position ourselselves at the second line.
    subsetStr = ourScroller.getSubstr(1,16);    // Offset the chars by one and give me 16 of 'em.
    lcd.print(subsetStr);                       // Print that subset.
    scrollTimer.start();                        // Restart the timer.
  }
}