int led = 13;  // led to use for output (13 is built-in)

int dit_delay = 200;           // length of a dit in ms
int dah_delay = dit_delay * 3; // length of a dah in ms

// dit() and dat() already include dit_delay
int letter_delay = dah_delay - dit_delay;

// letters already include letter delay
int word_delay   = dit_delay * 7 - letter_delay;

// send a dit
void dit() {

  Serial.print(".");

  digitalWrite(led, HIGH);
  delay(dit_delay);

  digitalWrite(led, LOW);
  delay(dit_delay);
}

// send a dah
void dah() {
  Serial.print("-");
  digitalWrite(led, HIGH);
  delay(dah_delay);

  digitalWrite(led, LOW);
  delay(dit_delay);
}

void morse_S() {
  Serial.print("Morse Letter 'S' ");
  dit(); dit(); dit();
  pause_letter();
}

void morse_O() {
  Serial.print("Morse Letter 'O' ");
  dah(); dah(); dah();
  pause_letter();
}

void morse_SOS() {

  morse_S(); morse_O(); morse_S();
  delay(dit_delay * 6);
  pause_word();
}

// Send single digit n in morse code. Fails if n > 9
void morse_digit(int n) {
  Serial.print("morse_digit(");
  Serial.print(n);
  Serial.println(")");

  if (n == 0) {
    dah(); dah(); dah(); dah(); dah();
  }
  if (n == 1) {
    dit(); dah(); dah(); dah(); dah();
  }
  if (n == 2) {
    dit(); dit(); dah(); dah(); dah();
  }
  if (n == 3) {
    dit(); dit(); dit(); dah(); dah();
  }
  if (n == 4) {
    dit(); dit(); dit(); dit(); dah();
  }
  if (n == 5) {
    dit(); dit(); dit(); dit(); dit();
  }
  if (n == 6) {
    dah(); dit(); dit(); dit(); dit();
  }
  if (n == 7) {
    dah(); dah(); dit(); dit(); dit();
  }
  if (n == 8) {
    dah(); dah(); dah(); dit(); dit();
  }
  if (n == 9) {
    dah(); dah(); dah(); dah(); dit();
  }

  if (n > 9) {
    if (n == 10) {
      send_A();
    }

    if (n == 11) {
      send_B();
    }

    if (n == 12) {
      send_C();
    }

    if (n == 13) {
      send_D();
    }

    if (n == 14) {
      send_E();
    }

    if (n == 15) {
      send_F();
    }
  }


  pause_letter();
}

//Send Letter A
void send_A() {
  Serial.println("Sending A");
  dit(); dah();
}

//Send Letter B
void send_B() {
  Serial.println("Sending B");
  dah(); dit(); dit(); dit();
}

//Send Letter C
void send_C() {
  Serial.println("Sending C");
  dah(); dit(); dah(); dit();
}

//Send Letter D
void send_D() {
  Serial.println("Sending D");
  dah(); dit(); dit();
}

//Send Letter E
void send_E() {
  Serial.println("Sending E");
  dit();
}

void send_F() {
  Serial.println("Sending F");
  dit(); dit(); dah(); dit();
}

//Adds a pause between two letters
void pause_letter() {
  Serial.println("");
  delay(letter_delay);
}

//Adds a pause between two words
void pause_word() {
  delay(word_delay);
}

//Morses given number n with base 10
void morse_decimal(int n) {
  if (n >= 10) {
    morse_decimal(n / 10);
  }
  morse_digit(n % 10); //what would happen if we add this call at the top?
}

//Morse number n with binary base
void morse_binary(int n) {
  if (n >= 2) {
    morse_binary(n / 2);
  }
  morse_digit(n % 2);
}

//Morse number n encoded in base base
void morse_base(int n, int base) {
  Serial.print("Sending number ");
  Serial.print(n);
  Serial.print(" to base ");
  Serial.print(base);
  Serial.println(".");

  if (n >= base) {
    morse_base(n / base, base);
  }
  morse_digit(n % base);
}

void setup() {
  // Transfer at 9600 bits/s
  Serial.begin(9600);

  // Configure LED as output
  pinMode(led, OUTPUT);
}

void loop() {

  morse_base(31, 16);

  pause_word();
}