#include "alphabet.h" //separate library containing all capital letters and a ' ' drawn in the 8x8 grid.
#include <EEPROM.h>

int length = 16; //global variable at length of my name. rewritten if user enters something in serial monitor
String input = "ALEXANDRA IRVINE"; //my name. rewritten to user entry
int number; //global variable to determine which letter to print
int buttonPin = 2; //buttonPin declared as pin 2, this is the first priority hardware interrupt for Arduino Mega
volatile int start = 0; //global variable saving button push time in millis
volatile int finish = 0; //global variable saving button release time in millis

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("Please enter input: "); //opens serial monitor and prompts user to enter something
  pinMode(buttonPin, INPUT_PULLUP); //assigns pin 2 to input_pullup which inverts the highs and lows read. more reliable than just input
  attachInterrupt(digitalPinToInterrupt(buttonPin), interrupt, CHANGE); //attaches hardware interrupt to pin 2 when button state changes

  for (int initialrow = 23; initialrow < 38; initialrow += 2) { //initialises all row pins for LED matrix
    pinMode(initialrow, OUTPUT);
    digitalWrite(initialrow, LOW);
  }

  for (int initialcolumn = 39; initialcolumn < 54; initialcolumn += 2) { //initialises all column pins for LED matrix
    pinMode(initialcolumn, OUTPUT);
    digitalWrite(initialcolumn, HIGH);
  }
}

void loop() {
  // put your main code here, to run repeatedly:

  if (Serial.available() == 0) { //does nothing if there is no input
  }

  if (Serial.available() > 0) { //if user inputs something into serial monitor...
    input = Serial.readString(); //saves input as global string variable input
    length = input.length() - 1; //finds length of input, minus 1 to get addresses of EEPROM correct
    for (int b = 0; b < length; b++) { //writes input to EEPROM for length of input one letter at a time
      EEPROM.write(b, input.charAt(b));
    }
    Serial.print("Now printing "); //confirms that it is now printing the user input. Waits until prior input has finished printing
    Serial.println(input);

  }
  input.toUpperCase(); //converts input to uppercase for switch statement

  for (int a = 0; a < length; a++) { //turns input into numbers for the alphabet library and prints them on LED matrix
    char letter = input[a]; //reads one letter of input at a time

    switch (letter) { //based on letter, chooses the corresponding number for that letter inside alphabet library

      case 'A': //eg. if letter is A, will make number = 0.
        number = 0;
        break;
      case 'B':
        number = 1;
        break;
      case 'C':
        number = 2;
        break;
      case 'D':
        number = 3;
        break;
      case 'E':
        number = 4;
        break;
      case 'F':
        number = 5;
        break;
      case 'G':
        number = 6;
        break;
      case 'H':
        number = 7;
        break;
      case 'I':
        number = 8;
        break;
      case 'J':
        number = 9;
        break;
      case 'K':
        number = 10;
        break;
      case 'L':
        number = 11;
        break;
      case 'M':
        number = 12;
        break;
      case 'N':
        number = 13;
        break;
      case 'O':
        number = 14;
        break;
      case 'P':
        number = 15;
        break;
      case 'Q':
        number = 16;
        break;
      case 'R':
        number = 17;
        break;
      case 'S':
        number = 18;
        break;
      case 'T':
        number = 19;
        break;
      case 'U':
        number = 20;
        break;
      case 'V':
        number = 21;
        break;
      case 'W':
        number = 22;
        break;
      case 'X':
        number = 23;
        break;
      case 'Y':
        number = 24;
        break;
      case 'Z':
        number = 25;
        break;
      case ' ':
        number = 26;
        break;
      default:
        number = 27;
        break;
    }

    int timer = finish - start; //calculates how long button was held based on global variables finish and start

    if (timer > 2000) { //if button held longer than two seconds, will print the input from left to right

      for (int border = 6 ; border > -6; border--) { //sets border between letters and printing direction. decreases with each increment so scrolls left to right

        for (int column = 7; column >= 0 ; column--) { //selects the column within alphabet for each letter

          if (column + border <= 8 && column + border >= 0) { //when border and selected column are within 0 and 8, will print the letter

            digitalWrite(37, alphabet_display[number][7][column + border]); //letter,row,column within alphabet library
            digitalWrite(35, alphabet_display[number][6][column + border]);
            digitalWrite(33, alphabet_display[number][5][column + border]);
            digitalWrite(31, alphabet_display[number][4][column + border]);
            digitalWrite(29, alphabet_display[number][3][column + border]);
            digitalWrite(27, alphabet_display[number][2][column + border]);
            digitalWrite(25, alphabet_display[number][1][column + border]);
            digitalWrite(23, alphabet_display[number][0][column + border]);


            digitalWrite((39 + 2 * column ), LOW); //creates a fast flashing of columns between movements so letters look like they are constantly on
            delay(1); //short delay makes it look like the whole letter is moving instead of one column of the letter at a time
            digitalWrite((39 + 2 * column ), HIGH);
          }
        }
        delay(50); //sets speed of scroll
      }
    }

    if (timer <= 2000) { //if button held for less than two seconds, letters will scroll right to left
      for (int border = -6 ; border < 6; border++) { //sets border between letters and printing direction. increases with each increment so scrolls right to left

        for (int column = 7; column >= 0 ; column--) { //selects the column within alphabet for each letter

          if (column + border <= 8 && column + border >= 0) { //when border and selected column are within 0 and 8, will print the letter

            digitalWrite(37, alphabet_display[number][7][column + border]); //letter,row,column within alphabet library
            digitalWrite(35, alphabet_display[number][6][column + border]);
            digitalWrite(33, alphabet_display[number][5][column + border]);
            digitalWrite(31, alphabet_display[number][4][column + border]);
            digitalWrite(29, alphabet_display[number][3][column + border]);
            digitalWrite(27, alphabet_display[number][2][column + border]);
            digitalWrite(25, alphabet_display[number][1][column + border]);
            digitalWrite(23, alphabet_display[number][0][column + border]);


            digitalWrite((39 + 2 * column ), LOW); //creates a fast flashing of columns between movements so letters look like they are constantly on
            delay(1); //short delay makes it look like the whole letter is moving instead of one column of the letter at a time
            digitalWrite((39 + 2 * column ), HIGH);
          }
        }
        delay(50); //sets speed of scroll
      }
    }
  }
}


void interrupt() { //hardware interrupt function is called when button is pressed and released
  int test = digitalRead(buttonPin); //sees if button has been pressed or released

  if (test == HIGH) { //if test is high, button has been released.
    finish = millis(); //saves release millis value to global variable finish so it can be used in loop function
    //Serial.println("finish");
  }

  if (test == LOW) { //if test is low, button has been pressed
    start = millis(); //saves press millis value to global variable finish so it can be used in loop function.
    //Serial.print("Start: ");

  }
}