#include <SD.h>
#include <ezButton.h>

File file;

ezButton next(2);
ezButton prev(3);
ezButton select_book(4); 
ezButton open_book(5);

// keeps track of which book is to be read 
int book_num = 0;

//checks if the book should be opened or not.
int book_state = 0;

// flag to avoid reptation of the currently selected book
int prev_book = -1;


void setup() 
{
    Serial.begin(9600);
    if (!SD.begin())
        Serial.println("SD card not detected");
    else 
        Serial.println("SD card detected");
    
    // file = SD.open("harry.txt" , FILE_READ);
    // Serial.print("Total Characters: ");
    // Serial.println(file.size());

    // if(file)
    // {
    //     Serial.println("Harry Potter");
    //     delay(2000);
    //     while (file.available())
    //     {
    //         char data = file.read();
    //         Serial.print(data);
    //     }
    //     Serial.println();
    //     file.close();
    // }
    // Serial.println("File read successfully");

    next.setDebounceTime(50);
    prev.setDebounceTime(50);
    select_book.setDebounceTime(50);
    open_book.setDebounceTime(50);
}

void loop() 
{
    next.loop();
    prev.loop();
    select_book.loop();
    open_book.loop();

    if (next.isPressed())
          book_num++;
    else if (prev.isPressed())
          book_num--;
    else if (select_book.isPressed())
    {
          // changes values to restart after opening a book
          book_state = 0;
          prev_book = -1;
    }
    else if(open_book.isPressed()) 
    {
          // changes value of the variable to enable book opening in the read_book() 
          book_state = 1;
    } 
    // makes sure doesn't go past 0 or 1 as only 2 books present.
    book_num = constrain(book_num,0,1);

    //checks which book is selected
    check_book();

    // reads book content
    read_book();
}

void check_book()
{
  // to avoid repeative printing of book name
  if (prev_book != book_num)
  {
      prev_book = book_num;
      if (book_num)
         Serial.println("Think and Grow Rich!");
      else
         Serial.println("Harry Potter!");
  }
}

void read_book()
{
   if(book_state)
   {
      if(book_num)
      {
         file= SD.open("think.txt",FILE_READ);
      }
      else
      {
         file= SD.open("harry.txt",FILE_READ);
      }

      String display_text="";
      if(file)
      {
          while(file.available())
          {
              char data=file.read();
              Serial.print(data);
          }
      }
   } 
   file.close();
}