// 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;
const int pinStatus = 7;
const int clockPin = 5;
const int dataPin = 3;
const int outPin = 4;
const int speakerPin = 6;

// constant config
const int slaveClockDivider = 16;
const int timerDelay = 530 / 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;
// [2] play speaker sounds of keys
bool modKeySounds = 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;
}
    
void sendKey(byte key) { 
    dataWord = key;
    dataState = 8;
    dataDelay = 0;
    packetDelay = 0;
    packetTail = 15;
    //Timer1.initialize(timerDelay);
    //Timer1.start();
}

void onHostStatusChange() {
  long timeNow = millis();
  long changeDiff = timeNow - lastChange;
  lastChange = timeNow;
  if (changeDiff >= 10 && nextKeyReady) {
      nextKeyReady = false;
      sendKey(nextKey);
  }
}

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 {
    //Timer1.stop();
  }
  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() {
}

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;
  if (modConsoleLog) {
    Serial.print("Key: <"); Serial.print(int(key)); Serial.print("> ");
  }
  char keyChar = translateKeyToChar(key);

  #ifdef KEYBOARD
  Keyboard.press(keyChar);
  delay(10);
  Keyboard.release(keyChar);
  #endif
    
  if (modConsoleLog) {
    Serial.print("Press: ");
    printChar(keyChar);
  }
}

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

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

// ----
// 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);
  //Timer1.stop();

  Serial.println("Keyboard ready");
  tone(speakerPin, 80, 50);
}

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);
    if (modKeySounds) tone(speakerPin, 60 + int(data), 25);
    data = B0;
    counter = 0;
  }
}