// Digital Relay Full Adder 
// (c) Torsten Jaeger <www.spassantechnik.de> 2024

#include <Wire.h> 
#include <SimpleKeypad.h>
#include <LiquidCrystal_I2C.h>

const int adder_input_a = A1;
const int adder_input_b = A2;
const int adder_carry_in = A3;
const int adder_sum = 10;
const int adder_carry_out = 11;

const byte nb_rows = 4;                         // four rows
const byte nb_cols = 4;                         // four columns
char key_chars[nb_rows][nb_cols] = {            // The symbols of the keys
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[nb_rows] = {9, 8, 7, 6};           // The pins where the rows are connected
byte colPins[nb_cols] = {5, 4, 3, 2};           // The pins where the columns are connected

int potpin = 0;  // analog pin used to connect the potentiometer
int potval;    // variable to read the value from the analog pin

char cursorBlink = 0;
unsigned long previousMillis = 0;

byte adder_input_a_state = 0;
byte adder_input_b_state = 0;
byte adder_carry_in_state = 0;
byte adder_sum_state = 0;
byte adder_carry_out_state = 0;

byte current_input_row = 0;
byte current_input_column[2] = { 19, 19 };

char input_number[2][20] = { "", "" };
int calculated_summ = 0;

SimpleKeypad kp1((char*)key_chars, rowPins, colPins, nb_rows, nb_cols);   // New keypad called kp1
LiquidCrystal_I2C lcd(0x27,20,4);  // set the LCD address to 0x27 for a 16 chars and 2 line display

void setup() {
  lcd.init();                      // initialize the lcd 
  Serial.begin(9600);
  Serial.println("Press any key on the keypad and it will show up here :");

  // Setup Welcome Screen
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("A: ");
  lcd.setCursor(0,1);
  lcd.print("B: ");
  lcd.setCursor(0,2);
  lcd.print("--------------------");
  lcd.setCursor(0,3);
  lcd.print("S: ");

  // full adder
  pinMode(adder_input_a, OUTPUT);
  pinMode(adder_input_b, OUTPUT);
  pinMode(adder_carry_in, OUTPUT);
  pinMode(adder_sum, INPUT);
  pinMode(adder_carry_out, INPUT);
}

void loop() 
{
  unsigned long currentMillis = millis();

  potval = analogRead(potpin);                  // reads the value of the potentiometer (value between 0 and 1023)
  potval = map(potval, 0, 1023, 0, 255);           // scale it to use it with the servo (value between 0 and 180)  
  //lcd.setCursor(0, 1);
  //lcd.print("Poti: ");
  //lcd.print(potval);
  //lcd.print("  ");

  adder_sum_state = digitalRead(adder_sum);
  adder_carry_out_state = digitalRead(adder_carry_out);

  // blinking cursor
  if (currentMillis - previousMillis >= 350) {
    previousMillis = currentMillis;
    if (cursorBlink) {
      lcd.setCursor(19, current_input_row);
      lcd.print("#");
      cursorBlink = 0;
    } else {
      lcd.setCursor(19, current_input_row);
      lcd.print(input_number[current_input_row][19-current_input_column[current_input_row]-1]);
      cursorBlink = 1;
    }
  }

  //lcd.setCursor(0, 0);
  //lcd.print("SUM: ");
  //lcd.print(adder_sum_state);
  //lcd.print(" / C-OUT: ");
  //lcd.print(adder_carry_out_state);

  char key = kp1.getKey();  // The getKey function scans the keypad every 10 ms and returns a key only one time, when you start pressing it
  if (key) {                        
    Serial.println(key);            
    //lcd.setCursor(0, 2);
    //lcd.print("Key: ");
    //lcd.print(key);

    //lcd.setCursor(current_input_column, current_input_row);
    //lcd.print(key);
    //input_number[current_input_row][20-current_input_column] = key;

    if (key == 'C') {
      for (int i = 0; i < 20; i++) {
        input_number[current_input_row][i] = {""};
      }
      lcd.setCursor(2, current_input_row);
      lcd.print("                  ");
      current_input_column[current_input_row] = 19;
    }

    if (current_input_column[current_input_row] > 2 && key != 'A' && key != 'B' && key != 'C' && key != 'D' && key != '*' && key != '#') {
      input_number[current_input_row][20-current_input_column[current_input_row]-1] = key;
      current_input_column[current_input_row]--;

      Serial.print("Number: ");
      for (int i = 0; i < 19-current_input_column[current_input_row]+1; i++) {
        Serial.print(input_number[current_input_row][i-1]);
        //if (input_number[current_input_row][i-1] != "*") {
          lcd.setCursor(current_input_column[current_input_row]+i, current_input_row);
          lcd.print(input_number[current_input_row][i-1]);
        //}
      }
      Serial.println("");
    }

    if (key == '#') {
      if (current_input_row == 0) {
        lcd.setCursor(19, current_input_row);
        lcd.print(input_number[current_input_row][19-current_input_column[current_input_row]-1]);
        current_input_row++;
      }
    }

    if (key == 'A') {
      if (current_input_row == 1) {
        lcd.setCursor(19, current_input_row);
        lcd.print(input_number[current_input_row][19-current_input_column[current_input_row]-1]);
        current_input_row--;
      }
    }

    if (key == 'B') {
      if (current_input_row == 0) {
        lcd.setCursor(19, current_input_row);
        lcd.print(input_number[current_input_row][19-current_input_column[current_input_row]-1]);
        current_input_row++;
      }
    }

    //if (key == 'A') {
    //  if (adder_input_a_state) {
    //    analogWrite(adder_input_a, 0);
    //    adder_input_a_state = 0;
    //  } else {
    //    analogWrite(adder_input_a, 255);
    //    adder_input_a_state = 1;
    //  }
    //}
    //if (key == 'B') {
    //  if (adder_input_b_state) {
    //    analogWrite(adder_input_b, 0);
    //    adder_input_b_state = 0;
    //  } else {
    //    analogWrite(adder_input_b, 255);
    //    adder_input_b_state = 1;
    //  }
    //}
    //if (key == 'C') {
    //  if (adder_carry_in_state) {
    //    analogWrite(adder_carry_in, 0);
    //    adder_carry_in_state = 0;
    //  } else {
    //    analogWrite(adder_carry_in, 255);
    //    adder_carry_in_state = 1;
    //  }
    //}

    //delay(500);

    //lcd.setCursor(0, 3);
    //lcd.print("A: ");
    //lcd.print(adder_input_a_state);
    //lcd.print(" B: ");
    //lcd.print(adder_input_b_state);
    //lcd.print(" C-IN: ");
    //lcd.print(adder_carry_in_state);

  }

}