#include <SPI.h>
#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <Fonts/FreeSerif9pt7b.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3D ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
void setup() {
  Serial.begin(9600);
  display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS);
  display.setTextSize(1);
  display.setTextColor(WHITE);
  display.setTextWrap(true);

  int wrapline = 21; // character limit for one line
  // initialising example string
  char s[1000] = "Arduino was born at the Ivrea Interaction Design Institute as an easy tool for fast prototyping, aimed at students without a background in electronics and programming. As soon as it reached a wider community, the Arduino board started changing to adapt to new needs and challenges, differentiating its offer from simple 8-bit boards to products for IoT applications, wearable, 3D printing, and embedded environments. All Arduino boards are completely open-source, empowering users to build them independently and eventually adapt them to their particular needs. The software, too, is open-source, and it is growing through the contributions of users worldwide.";
  int i, k, wraploc, lastwrap;

  lastwrap = 0; // saves character index after most recent line wrap
  wraploc = 0; // used to find the location for next word wrap
  int lastchar = 0;
  // wrapping text
  for (i = 0; s[i] != '\0'; ++i, ++wraploc) {

    if (wraploc >= wrapline) {
      for (k = i; k > 0; --k) {
        // make sure word wrap doesn't overflow past maximum length
        if (k - lastwrap <= wrapline && s[k] == ' ') {
          s[k] = '\n'; // adding line breaks at the end of a line
          lastwrap = k + 1;
          break;
        }
      }
      wraploc = i - lastwrap;
    }
    lastchar = i + 1; // getting the position of last character
  } // end main loop

  // transferring to 2d array
  s[lastchar] = '\n'; // adding line break to the end of it
  char ss[80][50];//2d char array
  k = 0; // initliaze line counter for 2d array
  int j = 0; // initialize character counter for 2d array
  int row[200] = {0}; // array that stores number of elements per line
  int lines = 0; // stores number of lines in total

  for (i = 0; s[i] != '\0'; i++) //going through every character
  {
    if (s[i] != '\n') // checking if end of line
    {
      ss[k][j] = s[i]; // forming one line
      j++;
      row[k] = row[k] + 1; // counting characters per line
    }
    else
    {
      ss[k][j] = '\n';
      k++;// going to next line
      j = 0;
      lines++;//counting the number of lines
    }
  }
  // 2D Array SS now has the word wrapped string stored linewise
  int lastline = 7;// line 1 to 8 need to be printed first
  char final[180];
  k = 0;
  int y = 0; // character index for char final[] that needs to be printed
  while (k <= lastline) // loop to select lines (ex 1...7)
  {
    for (j = 0; j < row[k] + 1; j++) // loop to assign characters from 2D array and create a string
    {
      final[y] = ss[k][j];// Printing Line 1 to 8 first and then scrolling will start after an appropriate delay wherein the user can read the first line
      y++;
    }
    k++;// incrementing line lower limit
  }
  display.clearDisplay();
  display.display();
  display.setCursor(0, 0);
  display.print(final);// printing the first 8 lines
  display.display();
  delay(1000);
  int upper = 0; // variable to get number of pixels to scroll up(-ve number)
  lines = lines - 1; // ensuring that last line is still visible(-8 if we want all of the last 8 lines to be display, -1 if only last line needed to be displayed)
  if (lines > 8) // checking to see if scrolling needs to be done or not
  {

    upper = lines * 8; // calculating number of pixels needed for lowest line to be at (0,0) cursor position
    i = 0;
    for (i = 0; i >= -upper; i--) // printing each line furhter up
    {
      display.setCursor(0, i); // printing pixel by pixel
      display.clearDisplay();
      display.print(s);
      display.display();
      delay(0);
    }
  }
  delay(100000);
}

void loop() {}