#include <USBComposite.h>

int key_L1 = 4; // braille dot 1 - binary 32
int key_L2 = 5; // dot 2 - binary 16
int key_L3 = 6; // dot 3 - binary 8
int key_R1 = 7; // dot 4 - binary 4
int key_R2 = 8; // dot 5 - binary 2
int key_R3 = 9; // dot 6 - binary 1

int key_SPACE = 10;
int key_SHIFT = 11;  // TODO: probably should support differentiation of L/R shift

/*
    the keyMap uses a braille alphabet (6-bit values) from ASCII Braille

  // TODO: add other keyMaps for other braille or alternative
  // chording/encoding systems
*/
char keyMap[65];
int lastKey = -1;

USBHID HID;
HIDKeyboard Keyboard(HID);

void setup() {
  pinMode(key_L1, INPUT_PULLUP);
  pinMode(key_L2, INPUT_PULLUP);
  pinMode(key_L3, INPUT_PULLUP);
  pinMode(key_R1, INPUT_PULLUP);
  pinMode(key_R2, INPUT_PULLUP);
  pinMode(key_R3, INPUT_PULLUP);

  // TODO: there is probably a more RAM-saving way to do this with #DEFINE or
  //       similar preprocessor magic
  keyMap[0] = ' ';
  keyMap[0b100] = '@';
  keyMap[0b100000] = 'a';
  keyMap[0b110000] = 'b';
  keyMap[0b100100] = 'c';
  keyMap[0b100110] = 'd';
  keyMap[0b100010] = 'e';
  keyMap[0b110100] = 'f';
  keyMap[0b110110] = 'g';
  keyMap[0b110010] = 'h';
  keyMap[0b10100] = 'i';
  keyMap[0b10110] = 'j';
  keyMap[0b101000] = 'k';
  keyMap[0b111000] = 'l';
  keyMap[0b101100] = 'm';
  keyMap[0b101110] = 'n';
  keyMap[0b101010] = 'o';
  keyMap[0b111100] = 'p';
  keyMap[0b111110] = 'q';
  keyMap[0b111010] = 'r';
  keyMap[0b11100] = 's';
  keyMap[0b11110] = 't';
  keyMap[0b101001] = 'u';
  keyMap[0b111001] = 'v';
  keyMap[0b10111] = 'w';
  keyMap[0b101101] = 'x';
  keyMap[0b101111] = 'y';
  keyMap[0b101011] = 'z';
  keyMap[0b10101] = '[';
  keyMap[0b110011] = '\\';
  keyMap[0b110111] = ']';
  keyMap[0b110] = '^';
  keyMap[0b111] = '_';

  keyMap[0b11101] = '!';
  keyMap[0b10] = '"';
  keyMap[0b1111] = '#';
  keyMap[0b110101] = '$';
  keyMap[0b100101] = '%';
  keyMap[0b111101] = '&';
  keyMap[0b1000] = '\'';
  keyMap[0b111011] = '(';
  keyMap[0b11111] = ')';
  keyMap[0b100001] = '*';
  keyMap[0b1101] = '+';
  keyMap[0b1] = ',';
  keyMap[0b1001] = '-';
  keyMap[0b101] = '.';
  keyMap[0b1100] = '/';
  keyMap[0b1011] = '0';
  keyMap[0b10000] = '1';
  keyMap[0b11000] = '2';
  keyMap[0b10010] = '3';
  keyMap[0b10011] = '4';
  keyMap[0b10001] = '5';
  keyMap[0b11010] = '6';
  keyMap[0b11011] = '7';
  keyMap[0b11001] = '8';
  keyMap[0b1010] = '9';
  keyMap[0b100011] = ':';
  keyMap[0b11] = ';';
  keyMap[0b110001] = '<';
  keyMap[0b111111] = '=';
  keyMap[0b1110] = '>';
  keyMap[0b100111] = '?';


  HID.begin(HID_KEYBOARD);
  while (!USBComposite);
  Keyboard.begin();
}

void loop() {
  int key = -1;

  if (digitalRead(key_L1) == LOW) {
    key += 32;
  }
  if (digitalRead(key_L2) == LOW) {
    key += 16;
  }
  if (digitalRead(key_L3) == LOW) {
    key += 8;
  }
  if (digitalRead(key_R1) == LOW) {
    key += 4;
  }
  if (digitalRead(key_R2) == LOW) {
    key += 2;
  }
  if (digitalRead(key_R3) == LOW) {
    key += 1;
  }

  if (digitalRead(key_SPACE) == LOW) {
    key = 0;
  }

  if ((key != lastKey) && (key != -1)) {

      char key_out = keyMap[key];

      // check for shift
      // TODO: either use STD::TOUPPER or make this more proper for extended chars
      if (digitalRead(key_SHIFT) == LOW) {
        key_out &= ~' ';
      }

      // TODO: send proper keydown and keyup so key-repeat works on OS level.
      Keyboard.print(key_out);
  }

  lastKey = key;
  delay(100);
}