// this function ready the Display Buttons (analog pin)
// the values from analogRead are due tu a Voltage Divider
inline byte readButtons() {
  int c = analogRead(BTN_PIN);
 
  if(c > 1000) {
    return 0;
  } else if(c < 650 && c > 630) {
    return 1;   // select
  } else if(c < 420 && c > 370) {
    return 2;   // left
  } else if(c < 280 && c > 200) {
    return 3;   // down
  }

  return 4;     // up
}

// switch the output Relaid on/off
void set_output(boolean on) {
  if(on) {
    digitalWrite(A4, LOW);
  } else {
    digitalWrite(A4, HIGH);
  }
  outputOn = on;
}

// switch the LDC Backlight on/off
void lcd_backlight(boolean on) {
  if(on) {
    lcdbacklight=true;
    digitalWrite(LCD_BACKLIGHT, HIGH);
  } else {
    lcdbacklight=false;
    digitalWrite(LCD_BACKLIGHT, LOW);
  }
}

bool get_lcd_backlight(){
  return lcdbacklight;
}

// print a Mifare UID at current LDC position
void lcd_print_uid(MFRC522::Uid *uid) {
  for (byte i=0; i < uid->size; i++) {
    lcd.print(uid->uidByte[i] < 0x10 ? " 0" : " ");
    lcd.print(uid->uidByte[i], HEX);
  }
}

// gives index of stored card uid if any, otherwise -1
int check_uid(MFRC522::Uid *uid) {
  MFRC522::Uid uid2;

  for(byte i=0; i < 1+EEP_CLIENT_MAX; i++) {   
    uid2 = get_uid(i, EEP_ADDR_START);

    if(compare_uids(uid, &uid2)) {
      return i;
    }
  }
  
  return -1;
}

boolean compare_uids(MFRC522::Uid *uid1, MFRC522::Uid *uid2) {

  if(uid1->size != uid2->size) {
      return false;
  }

  for(byte j=0;j<uid1->size;j++) {
    if(uid1->uidByte[j] != uid2->uidByte[j]) {
        return false;
    }
  }

  return true;
}

// get a uid from EEPROM at given index + start Address
MFRC522::Uid get_uid(byte index, int startAddress) {
  MFRC522::Uid uid;
   
  int address = startAddress + index * EEP_ADDR_UID_INCREMENT;
  uid.size = 0;
  EEPROM.get(address, uid);
  return uid;    
}

// delete a UID at the given index + start Address
void delete_uid(int index, int startAddress) {

  int address = startAddress + index * EEP_ADDR_UID_INCREMENT;
  
  for(byte i=0; i < EEP_ADDR_UID_INCREMENT; i++) {
    EEPROM.write(address+i, 0);
  }  
}

// store the master UID at first address of EEPROM
void save_master_uid(MFRC522::Uid *uid) {
  EEPROM.put(EEP_ADDR_START, *uid);
}


boolean save_client_uid(MFRC522::Uid *uid) {
  byte index = EEP_CLIENT_MAX;

  // try to find a free slot in EEPROM
  for(byte i=0; i<EEP_CLIENT_MAX; i++) {

    // we rely on the fact that uid.size is the first byte of the struct, so we can scan faster
    byte value = EEPROM.read(EEP_ADDR_START + (i+1)*EEP_ADDR_UID_INCREMENT);

    // a empty slot is found if size is 0 or 0xff which is EEPROM default value
    if(value == 0 || value == 0xff) {
      index = i;
      break;
    }
  }
  
  if(index == EEP_CLIENT_MAX) {
    return false;
  }

  // address is START + Master Slot + Index*Increment
  int address = EEP_ADDR_START + EEP_ADDR_UID_INCREMENT + index * EEP_ADDR_UID_INCREMENT;
  EEPROM.put(address, *uid);
  return true;
}


void add_log(MFRC522::Uid *uid) {

  MFRC522::Uid temp;

  //TODO: rather than moving the log every time around, we could
  // use a pointer the the start index and just increment this and append
  // the log a position startindex-1 und decrement the index
  
  // move all entries one back
  for(byte i=EEP_ADDR_LOG_LENGTH - 1; i> 0; i--) {    
    temp.size = 0;
    
    EEPROM.get(EEP_ADDR_LOG_START + (i - 1)  * EEP_ADDR_UID_INCREMENT, temp);
    
    if(temp.size != 0 && temp.size != 255) {    
      EEPROM.put(EEP_ADDR_LOG_START + i * EEP_ADDR_UID_INCREMENT, temp);  
    }    
  }

  EEPROM.put(EEP_ADDR_LOG_START, *uid);
}

// a debug function for showing all UID from EEPROM over Serial
void dump_uid(byte count, int address) {
  MFRC522::Uid uid;
  
  for(byte i=0; i< count; i++) {
    uid = get_uid(i, address);

    Serial.print("slot ");
    if(i < 10) Serial.print(" ");
    Serial.print(i);
    Serial.print(":");
    for (byte j=0;j<10;j++) {
      Serial.print(uid.uidByte[j] < 0x10 ? " 0" : " ");
      Serial.print(uid.uidByte[j], HEX);
    }
    Serial.println(" ");
  }  
}