#include <EEPROM.h>


int items_counter = 0;
int lookup_table_ini_pos = EEPROM.length() - 256;
int REG_SIZE = 16;
int REGID_SIZE = 7;


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);

  // put your setup code here, to run once:
  // for (int i = 0 ; i < EEPROM.length() ; i++) EEPROM.write(i, 0);
  //for (int i = 0 ; i < 255 ; i++) EEPROM.write(i, 0);

  while (!Serial);

  for (int i = 1; i <= 256; i++)
    if (i <= 16)
      EEPROM.write( (EEPROM.length() - i) , 1);
    else {
      EEPROM.write( (EEPROM.length() - i) , 0);
      Serial.println((EEPROM.length() - i));
    }
}


void print_positions_marked() {
  for (int i = 0; i < 256; i++) {
    Serial.print(lookup_table_ini_pos + i);
    Serial.print(" (");
    Serial.print(i);
    Serial.print(") ");
    Serial.print(" : ");
    Serial.println( EEPROM.read(lookup_table_ini_pos + i) );
  }
}

int capture_and_use_first_clean_pos() {
  for (int i = 0; i <= 240; i++) {
/*     Serial.print("posicao: ");
    Serial.print(i);
    Serial.print("val: ");
    Serial.println(EEPROM.read(lookup_table_ini_pos + i)); */
    if (EEPROM.read(lookup_table_ini_pos + i) == 0) {
      EEPROM.write(lookup_table_ini_pos + i, 1);
      return i * REG_SIZE;
    }
  }
}


void write_string_to_eeprom(const String &strToWrite)
{
  if (!update_items_counter(1)) {
    Serial.println("item cannot be added!");
    return;
  }
  int clean_pos = capture_and_use_first_clean_pos();
/*   Serial.print(strToWrite);
  Serial.print(" : ");
  Serial.println(clean_pos); */
  
  for (int i = 0; i < REG_SIZE; i++)
    EEPROM.write(clean_pos + i, strToWrite[i]);
}


String read_string_from_eeprom(int addrOffset, int ssize)
{
  char data[ssize + 1];
  for (int i = 0; i < ssize; i++)
  {
    data[i] = EEPROM.read(addrOffset + i);
  }
  data[ssize] = '\0';
  return String(data);
}


bool update_items_counter(byte n) {
  if (items_counter == 0 && n < 0) {
    Serial.println("memory is already empty");
    return false;
  }
  if (items_counter == 240 && n > 0) {
    Serial.println("full memory!");
    return false;
  }
  items_counter += n;
  return true;
}



int delete_string_from_eeprom(const String &s) {  
  int pos = capture_string_position(s);

  if (pos == -1) {
    Serial.println("item not found");
    return pos;
  }
  int s_pos =  pos / REG_SIZE;

  update_items_counter(-1);
  EEPROM.write(lookup_table_ini_pos + s_pos, 0);
  return pos;
}


int capture_string_position(const String &s) {
  for (int i = 0; i <= 240; i++) {
    int has_s = EEPROM.read(lookup_table_ini_pos + i);
    if (has_s) {
      String aux = read_string_from_eeprom(i * REG_SIZE, s.length());
      if (aux == s)
        return i * REG_SIZE;
    }
  }
  return -1;
}


String read_name() {
  String name = "";
  while (name.length() < 9) {
    if(Serial.available()){
      char data_in = Serial.read();
        name += (data_in);  
        Serial.println(data_in);
    }
  }
  Serial.flush();
  return name;
}


void add() {
  // read tag id
  String tagID = "1234567";

  // check if already exists
  int tagID_pos = capture_string_position(tagID);
  Serial.println( tagID_pos );

  if (tagID_pos != -1) {
    Serial.println("tag already exists, continue to change your username: ");
    delete_string_from_eeprom(tagID);
  }
  // read username
  String name = read_name();
  
  // add tag to registers
  write_string_to_eeprom(tagID + name);
}

int i = 1;
void loop() {
  // put your main code here, to run repeatedly:
  if (i == 1) {

  String r = "1234567luizpaulo";
  Serial.println(r);

  write_string_to_eeprom(r);
  
  String z = read_string_from_eeprom(0, REG_SIZE);
  Serial.println(z);
  
  String b = "7654321luizpaulo";
  write_string_to_eeprom(b);

  int p = delete_string_from_eeprom("bbbgggiiijjjkkkl");
  Serial.print("luizaqui");
  Serial.println(p);
  Serial.println("----");

  String c = "7654321pauloluiz";
  write_string_to_eeprom(c);
  Serial.println(read_string_from_eeprom(0, REG_SIZE));

  write_string_to_eeprom(r);

  add();

  print_positions_marked();
  
  String ss = "1234567ziuloluap";
  Serial.println( read_string_from_eeprom(capture_string_position(ss),  REG_SIZE));
  i = 2;
  }
}