#define RS 13
#define E 12
/*
You can read data from LCDs, however
In this tutorial I'm only writing to it
Thus, RW pin is set to ground (Write)
and not defined
*/


// const int d0 = 0;
// const int d1 = 1;
// const int d2 = 2;
// const int d3 = 3;
// const int d4 = 4;
// const int d5 = 5;
// const int d6 = 6;
// const int d7 = 7;

/*
You can set and use every pin individually
but you don't need to specify each pin when
doing direct port manipulation

i.e. PORTD = 0X93
0x93 -> 10010011
|
v
d7 d6 d5 d4 d3 d2 d1 d0
1  0  0  1  0  0  1  1

For PORTS and Pinouts:
https://docs.arduino.cc/static/6ec5e4c2a6c0e9e46389d4f6dc924073/4ef49/Pinout-UNOrev3_latest.png
*/

byte customChar[] = {
  B00100,
  B00100,
  B00100,
  B11111,
  B00100,
  B00100,
  B00100,
  B00100
};

void setup() {
  //Setting all PORT D as OUTPUT

  DDRD = 0XFF;

  pinMode(RS, OUTPUT);
  pinMode(E, OUTPUT);

  /*
  RS LOW -> Command mode
  In this mode, the LCD interprets the
  data as a command
  */
  digitalWrite(RS, LOW);

  // 00001111 -> 0x0F Turn on Screen with Blinking Cursor

  //Method without Port manipulation
  // digitalWrite(d7, LOW);
  // digitalWrite(d6, LOW);
  // digitalWrite(d5, LOW);
  // digitalWrite(d4, LOW);
  // digitalWrite(d3, HIGH);
  // digitalWrite(d2, HIGH);
  // digitalWrite(d1, HIGH);
  // digitalWrite(d0, HIGH);

  PORTD = 0X0F;

  /*
  Toggles the Enable pin,
  the Display reads the data then
  Enable pin is toggle again to LOW
  */
  readSentData();
  sendCustomCharacter();
  printCharacter(0); // Display the custom character at index 0


}

void loop() {
  ;
}

/*
Commented out portion (using old method; no port manipulation)
is bitwise mapping, basically you turn the character into
an int, then get the n bit and check if that n bit is 1 (HIGH)
or 0 (LOW)

Example with 2nd bit:

'a' -> int('a') -> 01100001
01100001 >> 2
Index 2 bit (right to left, starting at index 0) is 0
01100001 >> 2 & 1 -> 0 & 1 -> 0
Sets the pin to LOW

This step is not needed because all the pins are
in a PORT, so all the bits get set to the corresponding
pin when you set the port to (int)character
*/
void printCharacter(char character) {
  // Check if the character is a custom character
  if (character >= 0 && character <= 7) {
    // Custom character, send its index as data
    digitalWrite(RS, HIGH);
    PORTD = 0x80 | (character << 3); // Set D7-D3 to the custom character index
    readSentData();
  } else {
    // Standard ASCII character
    digitalWrite(RS, HIGH);

    // Set the data bits based on the ASCII value of the character
    PORTD = (int) character;
    readSentData();
  }
}


/*
Basic function for printing a string
Iterates through a string and prints each character
If the character is a \n (newline) or the string is
longer than 16 it prints in the second line

secondLineIndexStart is needed because in the case of
a \n, the second line shouldn't start on the 16 index
of the string

*/
void printString(String stringToPrint) {

  int stringSize = stringToPrint.length();
  bool doNewLine = false;

  int secondLineIndexStart = 16;
  int secondLineIndexEnd = stringSize;

  for (int i = 0; i < 16; i++) {
    if (stringToPrint[i] == '\n') {
      doNewLine = true;
      secondLineIndexStart = i + 1;
      break;
    }
    printCharacter(stringToPrint[i]);
  }

  if (stringSize > 16 || doNewLine) {
    digitalWrite(RS, LOW);

    //Move to second line index 0 (Digit after C determines Index -> [C0 - CF])
    PORTD = 0XC0;
    readSentData();

    for (int i = secondLineIndexStart; i < secondLineIndexEnd; i++) {
      printCharacter(stringToPrint[i]);
    }
  }
}

void readSentData() {
  digitalWrite(E, HIGH);
  digitalWrite(E, LOW);
}

void sendCustomCharacter() {
  // Set CGRAM address to start (usually 0x40)
  digitalWrite(RS, LOW);
  PORTD = 0x40;
  readSentData();

  // Set RS to HIGH for data mode
  digitalWrite(RS, HIGH);

  // Send custom character pattern data to CGRAM
  for (int i = 0; i < 8; i++) {
    PORTD = customChar[i];
    readSentData();
  }

  // Move the cursor back to the display RAM
  digitalWrite(RS, LOW);
  PORTD = 0x80; // Move to the beginning of the display
  readSentData();
}