// Resources:
// [Consul 262.4 Converter] https://deskthority.net/viewtopic.php?t=26908
// [Consul 262.5 manual in CS] http://www.sapi.cz/prislusenstvi/c262-5.php#odkazp4

#include <TimerOne.h>

// pinout config
const int pinData = 6; // out, host data
const int pinStatus = 7; // in, host status
const int clockPin = 5; // out, kbd clock
const int dataPin = 3; // in, kbd data
const int outPin = 4; // out, kbd led

// constant config
const int slaveClockDivider = 8;
const int timerDelay = 520 / slaveClockDivider;

// variables
volatile int slaveClockStep = 0;
char m[255];
volatile int data = 0;
int test = 0;
volatile int counter = 0;
int numbits = 10;

// MODS >>>
// [1] send debug scancode information to serial port
bool modConsoleLog = true;
// <<< MODS

// ----------
// KBD Output
// ----------
volatile long lastChange = 0;
volatile int x = 0;
volatile int dataWord = 0;
volatile int dataState = 0;
volatile int dataDelay = 0;
volatile int packetDelay = 0;
volatile int packetTail = 0;

volatile bool nextKeyReady = false;
volatile byte nextKey = 0;

void typeKey(byte key) {
    nextKey = key;
    nextKeyReady = true;
    //Serial.print("Typing key "); Serial.println((int) key);
}
    
void sendKey(byte key) { 
    dataWord = key;
    dataState = 8;
    dataDelay = 0;
    packetDelay = 0;
    packetTail = 15;
    //Serial.print("Sending key "); Serial.println((int) key);
}

void onHostStatusChange() {
  long timeNow = millis();
  long changeDiff = timeNow - lastChange;
  lastChange = timeNow;
  if (changeDiff >= 10 && nextKeyReady) {
      nextKeyReady = false;
      sendKey(nextKey);
      Timer1.start(); // synchronize with the host
      slaveClockStep = 0;
  }
}

void onHostClockCycle(void)
{
  int dataBit = HIGH;
  if (packetDelay > 0) {
    packetDelay--;
  } else if (dataDelay > 0) {
    dataDelay--;
    dataBit = LOW;
  } else if (dataState > 0) {
    int bitToSend = (dataWord >> (dataState - 1)) & 1;
    dataBit = !bitToSend ? LOW : HIGH;
    dataState--;
  } else if (packetTail > 0) {
    packetTail--;
    dataBit = LOW;
  } else {
  }
  digitalWrite(pinData, dataBit);
}

// ---------
// KBD Input
// ---------
const int receivingSteps = 16;
volatile int clockStep = 0;
volatile int receivingStep = 0;
volatile int receivingData = 0;
volatile int receivingBit = 0;

void onSlaveClockInterrupt() {
  clockStep = (clockStep + 1) % 2;
  int clockValue = (clockStep % 2)  ? HIGH : LOW;
  digitalWrite(clockPin, clockValue);
  int dataBit = digitalRead(dataPin);
  if (clockValue == LOW) {
    if (receivingData == 0 && dataBit == LOW) {
      receivingData = 1;
      receivingStep = 0;
      receivingBit = 0;
      test = 0;
      digitalWrite(outPin, HIGH);
    } else if (receivingData == 1) {
      receivingStep++;
      digitalWrite(outPin, HIGH);
    }
    if (receivingData == 1 && test == 0) {
      test = 1;
      receivingBit += dataBit  == HIGH ? 1 : 0;
      if (receivingStep >= receivingSteps) {
        if (counter <= 8) {
          data = data >> 1;
          if (receivingBit > receivingSteps / 2) {
            bitSet(data, 7);
          }
        }
        counter++;
        receivingStep = 0;
        receivingBit = 0;
          digitalWrite(outPin, LOW);
        if (counter >= numbits) {
          receivingData = 0;
        }  
      }
    }
  }
  if (clockValue == HIGH && test == 1) {
    test = 0;
  }
}

void setupKeyMapping() {
    m[0] = 0;
    m[223] = ' '; // Spacebar
    // top row special
    m[63] = 0x12; // ?? Setup
    m[62] = 'j'; // up
    m[61] = 'k'; // down
    m[59] = 'h'; // left
    m[60] = 'l'; // right 
    // top numbers row
    m[228] = 0x1B; // ESC
    m[206] = '1';
    m[205] = '2';
    m[204] = '3';
    m[203] = '4';
    m[202] = '5';
    m[201] = '6';
    m[200] = '7';
    m[199] = '8';
    m[198] = '9';
    m[207] = '0';
    m[210] = '-';
    m[161] = '^';
    m[0] = ' '; // Empty cap
    m[247] = 0x08; // Backspace
    m[56] = 0x10; // Break
     // top letter row
    m[246] = '\t';
    m[142] = 'q';
    m[142+32] = 'Q';
    m[136] = 'w';
    m[136+32] = 'W';
    m[154] = 'e';
    m[154+32] = 'E';
    m[141] = 'r';
    m[141+32] = 'R';
    m[139] = 't';
    m[139+32] = 'T';
    m[134] = 'y';
    m[134+32] = 'Y';
    m[138] = 'u';
    m[138+32] = 'U';
    m[150] = 'i';
    m[150+32] = 'I';
    m[144] = 'o';
    m[144+32] = 'O';
    m[143] = 'p';
    m[143+32] = 'P';
    m[191] = '@';
    m[164] = '[';
    m[245] = 0x0A;
    m[128] = 0x7F;
    // middle letter row
    /*
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    m[] = '';
    /**/
}

char translateKeyToChar(int key) {
  if (sizeof(m) <= key) {
    return 0;
  }
  return m[key];
}

void printChar(char keyChar) {
  Serial.print("'"); Serial.print(keyChar); Serial.print("' (");  Serial.print(int(keyChar)); Serial.println(")");
}

void processKbdByte(int data) {
  int key = data;
  char keyChar = translateKeyToChar(key);

  if (modConsoleLog) {
    Serial.print("Key: <"); Serial.print(int(key)); Serial.print("> ");
    Serial.print("Char: "); printChar(keyChar);
  }
  
  #ifdef KEYBOARD
  Keyboard.press(keyChar);
  delay(10);
  Keyboard.release(keyChar);
  #endif

  typeKey(keyChar);
}

// ----------------------
// Input and Output Merge
// ----------------------
void onTimerInterrupt()
{
  onSlaveClockInterrupt();

  if (slaveClockStep == 0) {
      onHostClockCycle();
  }
  slaveClockStep = (slaveClockStep + 1) % slaveClockDivider;
}

// ----
// Main
// ----
void setup(void)
{
  Serial.begin(9600);
  
  setupKeyMapping();
  
  pinMode(pinData, OUTPUT);
  pinMode(dataPin, INPUT);
  pinMode(outPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
  pinMode(pinStatus, INPUT_PULLUP);

  digitalWrite(pinData, HIGH);
  digitalWrite(outPin, LOW);

  attachInterrupt(digitalPinToInterrupt(pinStatus), onHostStatusChange, CHANGE);
  
  Timer1.initialize(timerDelay);
  Timer1.attachInterrupt(onTimerInterrupt);

  Serial.println("Keyboard ready");
}

void loop(void)
{
  // type key from serial
  if (!nextKeyReady && Serial.available() > 0) {
      long key = Serial.parseInt(SKIP_ALL);
      if (key != 0) {
	typeKey(key);
      }
  }
  /**/
  
  // type key from keyboard
  if (counter >= numbits) {
    processKbdByte(data);
    data = B0;
    counter = 0;
  }
  /**/

  /*/ auto-type test
  delay(500);
  typeKey('B');
  /**/
}