#include <Keypad.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,16,2);  // set the LCD address to 0x27 for a 16 chars and 2 line display

int a = 0;
int b = 0;
int c = 0;
int display = 0;
boolean ADD = false;
boolean SUB = false;
boolean MUX = false;

int next = 0;

const byte ROW_NUM = 4; //four rows
const byte COLUMN_NUM = 4; //four columns

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

byte pin_rows[] = {13, 12, 11, 10};
byte pin_column[] = {9, 8, 7, A2};

Keypad keypad = Keypad( makeKeymap(keys), pin_rows, pin_column, ROW_NUM, COLUMN_NUM );
void setup()
{
 Serial.begin(9600);
lcd.init();                      // initialize the lcd 
lcd.init();
// Print a message to the LCD.
lcd.backlight();
 Serial.println("====== Clavier pret ======");
}
void loop()
{
char key = keypad.getKey();
 toucherBouton(key);
}


void toucherBouton(char key)
{
 if (key == '1'){ // Bouton S1 enfoncé
 num_1(); 
  if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 
 if (key == '2'){ // Bouton S2 enfoncé
 num_2();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 
 if (key == '3'){ // Bouton S3 enfoncé
 num_3();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 
 if (key == '4'){ // Bouton S4 enfoncé
 num_4();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 
 if (key == '5'){ // Bouton S5 enfoncé
 num_5();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 
 if (key == '6'){ // Bouton S6 enfoncé
 num_6();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 
 if (key == '7'){ // Bouton S7 enfoncé
 num_7();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
}
 
 if (key == '8'){ // Bouton S8 enfoncé
 num_8();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 
 if (key == '9'){ // Bouton S9 enfoncé
 num_9();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 if (key == '0'){ // Bouton S10 enfoncé
 num_0();
 if(ADD == true && MUX == false){
    addition();
  }
  if(ADD == false && MUX == true){
    multiplication();
  }
 }
 
 if (key == 'A'){ // Bouton S11 enfoncé
  if(MUX == false){
    add();
    ADD = true;
  }
 }
 
 if (key == 'B'){ // Bouton S12 enfoncé
  if(ADD == false){
    mux();
    MUX = true;
  }
 }

 if (key == 'C'){// Bouton S13 enfoncé
  reset_num();
 }
}

void num_nothing(){
  lcd.clear();
  delay(1);               // wait for a second
}

void num_0(){
  if(display == 0) lcd.print("0");
  if(next == 1 && ADD == true || MUX == true) b = 0;
  if(next == 0){
    a = 0;
    display = 1;
  } 
  next = 1;
  delay(1);               // wait for a second
}

void num_1(){
  if(display == 0) lcd.print("1");
  if(next == 1 && ADD == true || MUX == true) b = 1;
  if(next == 0){
    a = 1;
    display = 1;
  } 
  next = 1;  
  delay(1);
}

void num_2(){
  if(display == 0) lcd.print("2");
  if(next == 1 && ADD == true || MUX == true) b = 2;
  if(next == 0){
    a = 2;
    display = 1;
  } 
  next = 1;
  delay(1);               // wait for a second
}

void num_3(){
  if(display == 0) lcd.print("3");
  if(next == 1 && ADD == true || MUX == true) b = 3;
  if(next == 0){
    a = 3;
    display = 1;
  } 
  next = 1;   
  delay(1);               // wait for a second
}

void num_4(){
  if(display == 0) lcd.print("4");
  if(next == 1 && ADD == true || MUX == true) b = 4;
  if(next == 0){
    a = 4;
    display = 1;
  }     
  next = 1;
  delay(1);               // wait for a second
}

void num_5(){
  if(display == 0) lcd.print("5");
  if(next == 1 && ADD == true || MUX == true) b = 5;
  if(next == 0){
    a = 5;
    display = 1;
  }   
  next = 1;  
  delay(1);               // wait for a second
}

void num_6(){
  if(display == 0) lcd.print("6");
  if(next == 1 && ADD == true || MUX == true) b = 6;
  if(next == 0){
    a = 6;
    display = 1;
  } 
  next = 1;
  delay(1);  
}

void num_7(){
  if(display == 0) lcd.print("7");
  if(next == 1 && ADD == true || MUX == true) b = 7;
  if(next == 0){
    a = 7;
    display = 1;
  }   
  next = 1;
  delay(1);               // wait for a second
}

void num_8(){
  if(display == 0) lcd.print("8");
  if(next == 1 && ADD == true || MUX == true) b = 8;
  if(next == 0){
    a = 8;
    display = 1;
  }    
  next = 1;
  delay(1);               // wait for a second
 
}

void num_9(){
  if(display == 0) lcd.print("9");
  if(next == 1 && ADD == true || MUX == true) b = 9;
  if(next == 0){
    a = 9;
    display = 1;
  } 
  next = 1;
  delay(1);               // wait for a second
}

void add(){
   lcd.print(" + ");
   display = 0;  
   delay(1);               // wait for a second
}

void mux(){
   lcd.print(" x ");
   display = 0; 
   delay(1);               // wait for a second
}

void reset_num(){
 a = 0;
 b = 0;
 c = 0;
 display = 0;
 next = 0;
 ADD = false;
 MUX = false;
 num_nothing();
}

void addition(){
  c = a + b;
  lcd.print(" = ");
  lcd.print(c);
  next = 0;
  delay(3000);
  reset_num();
}

void multiplication(){
  c = a * b;
  lcd.print(" = ");
  lcd.print(c);
  next = 0;
  delay(3000);
  reset_num();
}