#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Keypad.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

int w, h = 10;

const byte ROWS = 4;
const byte COLS = 4;

char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};

byte rowPins[ROWS] = {23, 15, 3, 4}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {19, 18, 5, 2}; //connect to the column pinouts of the keypad

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

String temp;
String inputString;
bool capslock;


void setup() {
  Serial.begin(115200);
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.clearDisplay();
  display.setTextColor(WHITE);
  display.setTextSize(2);
  display.setCursor(w, h);
  display.println("Type something: ");
  display.display();
}

void loop() {
  char key = keypad.getKey();

  if (key != NO_KEY && key != 'A' && key != 'B' && key != 'C' && key != 'D' && key != '#' && key != '*') {
      
      temp += key;

  }

  if (key == 'A'){
    capslockButton();
    display.clearDisplay();
    display.setCursor(w, h);
    if (capslock == true){
      display.println("CAPS: ON");
    }  
    else {
      display.println("CAPS: OFF");
    } 
    display.display();
    delay(100);
  }

  if (key != NO_KEY && key == 'B') {
    key = ' ';
    inputString += key;
    display.clearDisplay();
    display.setCursor(w, h);
    display.println(inputString);
    display.display();
    delay(100);
  }

  if (key != NO_KEY && key == 'C') {
    if(inputString.length() > 0) {
      int lastIndex = inputString.length() - 1;
      inputString.remove(lastIndex);
      display.clearDisplay();
      display.setCursor(w, h);
      display.println(inputString);
      display.display();
    }

    delay(100);
  }

  if (key != NO_KEY && key == 'D') {
    key = '\n';
    inputString += key;
    display.clearDisplay();
    display.setCursor(w, h);
    display.println(inputString);
    display.display();
    delay(100);
  }

  if (key != NO_KEY && key == '#'){
    alphabet();
    inputString += temp;
    temp.remove(0, temp.length());
    display.clearDisplay();
    display.setTextSize(2);
    display.setCursor(w, h);
    display.println(inputString);
    display.display();
    delay(100);
  }
}

void alphabet(){
  if (temp == "11" && capslock == false){
    temp = 'a';
  }
  if (temp == "11" && capslock == true){
    temp = 'A';
  }
  if (temp == "111" && capslock == false){
    temp = 'b';
  }
  if (temp == "111" && capslock == true){
    temp = 'B';
  }
  if (temp == "1111" && capslock == false){
    temp = 'c';
  }
  if (temp == "1111" && capslock == true){
    temp = 'C';
  }
  if (temp == "22" && capslock == false){
    temp = 'd';
  }
  if (temp == "22" && capslock == true){
    temp = 'D';
  }
  if (temp == "222" && capslock == false){
    temp = 'e';
  }
  if (temp == "222" && capslock == true){
    temp = 'E';
  }
  if (temp == "2222" && capslock == false){
    temp = 'f';
  }
  if (temp == "2222" && capslock == true){
    temp = 'F';
  }
  if (temp == "33" && capslock == false){
    temp = 'g';
  }
  if (temp == "33" && capslock == true){
    temp = 'G';
  }
  if (temp == "333" && capslock == false){
    temp = 'h';
  }
  if (temp == "333" && capslock == true){
    temp = 'H';
  }
  if (temp == "3333" && capslock == false){
    temp = 'i';
  }
  if (temp == "3333" && capslock == true){
    temp = 'I';
  }
  if (temp == "44" && capslock == false){
    temp = 'j';
  }
  if (temp == "44" && capslock == true){
    temp = 'J';
  }
  if (temp == "444" && capslock == false){
    temp = 'k';
  }
  if (temp == "444" && capslock == true){
    temp = 'K';
  }
  if (temp == "4444" && capslock == false){
    temp = 'l';
  }
  if (temp == "4444" && capslock == true){
    temp = 'L';
  }
  if (temp == "55" && capslock == false){
    temp = 'm';
  }
  if (temp == "55" && capslock == true){
    temp = 'M';
  }
  if (temp == "555" && capslock == false){
    temp = 'n';
  }
  if (temp == "555" && capslock == true){
    temp = 'N';
  }
  if (temp == "5555" && capslock == false){
    temp = 'o';
  }
  if (temp == "5555" && capslock == true){
    temp = 'O';
  }
  if (temp == "66" && capslock == false){
    temp = 'p';
  }
  if (temp == "66" && capslock == true){
    temp = 'P';
  }
  if (temp == "666" && capslock == false){
    temp = 'q';
  }
  if (temp == "666" && capslock == true){
    temp = 'Q';
  }
  if (temp == "6666" && capslock == false){
    temp = 'r';
  }
  if (temp == "6666" && capslock == true){
    temp = 'R';
  }
  if (temp == "66666" && capslock == false){
    temp = 's';
  }
  if (temp == "66666" && capslock == true){
    temp = 'S';
  }
  if (temp == "77" && capslock == false){
    temp = 't';
  }
  if (temp == "77" && capslock == true){
    temp = 'T';
  }
  if (temp == "777" && capslock == false){
    temp = 'u';
  }
  if (temp == "777" && capslock == true){
    temp = 'U';
  }
  if (temp == "7777" && capslock == false){
    temp = 'v';
  }
  if (temp == "7777" && capslock == true){
    temp = 'V';
  }
  if (temp == "88" && capslock == false){
    temp = 'w';
  }
  if (temp == "88" && capslock == true){
    temp = 'W';
  }
  if (temp == "888" && capslock == false){
    temp = 'x';
  }
  if (temp == "888" && capslock == true){
    temp = 'X';
  }
  if (temp == "8888" && capslock == false){
    temp = 'y';
  }
  if (temp == "8888" && capslock == true){
    temp = 'Y';
  }
  if (temp == "88888" && capslock == false){
    temp = 'z';
  }
  if (temp == "88888" && capslock == true){
    temp = 'Z';
  }
  if (temp == "99"){
    temp = '#';
  }
}

void capslockButton() {
  capslock = !capslock;
}