#include <EEPROM.h>
#include <ELClientWebServer.h>

#define MAGIC 0xABEF
#define MAX_STR_LEN  32

// EEPROM content 
#define EEPROM_POS_MAGIC          0
#define EEPROM_POS_FIRST_NAME     (EEPROM_POS_MAGIC + 2)
#define EEPROM_POS_LAST_NAME      (EEPROM_POS_FIRST_NAME + MAX_STR_LEN)
#define EEPROM_POS_AGE            (EEPROM_POS_LAST_NAME + MAX_STR_LEN)
#define EEPROM_POS_GENDER         (EEPROM_POS_AGE+1)
#define EEPROM_POS_NOTIFICATIONS  (EEPROM_POS_GENDER+1)

// write a string to EEPROM
void userWriteStr(char * str, int ndx)
{
  for(uint8_t i=0; i < MAX_STR_LEN-1; i++)
  {
    EEPROM.update(ndx + i, str[i]);
    if( str[i] == 0 )
      break;
  }
  EEPROM.update(ndx + MAX_STR_LEN - 1, 0);
}


// read a string from EEPROM
void userReadStr(char * str, int ndx)
{
  for(uint8_t i=0; i < MAX_STR_LEN; i++)
  {
    str[i] = EEPROM[ndx + i];
  }
}


// setting the value of a field
//
// handle data as fast as possible
// - huge HTML forms can arrive in multiple packets
// - if this method is slow, UART receive buffer may overrun
void userSetFieldCb(const char * field)
{
  String fld = field;
  if( fld == F("first_name"))
    userWriteStr(webServer.getArgString(), EEPROM_POS_FIRST_NAME);
  else if( fld == F("last_name"))
    userWriteStr(webServer.getArgString(), EEPROM_POS_LAST_NAME);
  else if( fld == F("age"))
    EEPROM.update(EEPROM_POS_AGE, (uint8_t)webServer.getArgInt());
  else if( fld == F("gender"))
  {
    String gender = webServer.getArgString();
    EEPROM.update(EEPROM_POS_GENDER, (gender == F("male")) ? 'm' : 'f');
  }
  else if( fld == F("notifications"))
    EEPROM.update(EEPROM_POS_NOTIFICATIONS, webServer.getArgBoolean());
}

// called at page loading
void userLoadCb(const char * url)
{
  char buf[MAX_STR_LEN];
  userReadStr( buf, EEPROM_POS_FIRST_NAME );
  webServer.setArgString(F("first_name"), buf);
  userReadStr( buf, EEPROM_POS_LAST_NAME );
  webServer.setArgString(F("last_name"), buf);
  webServer.setArgInt(F("age"), (uint8_t)EEPROM[EEPROM_POS_AGE]);
  webServer.setArgString(F("gender"), (EEPROM[EEPROM_POS_GENDER] == 'm') ? F("male") : F("female"));
  webServer.setArgBoolean(F("notifications"), EEPROM[EEPROM_POS_NOTIFICATIONS] != 0);
}

// initialization
void userInit()
{
  uint16_t magic;
  EEPROM.get(EEPROM_POS_MAGIC, magic);

  if( magic != MAGIC ) // EEPROM is uninitialized?
  {
    magic = MAGIC;
    // set default values
    EEPROM.put(EEPROM_POS_MAGIC, magic);
    EEPROM.update(EEPROM_POS_FIRST_NAME, 0);
    EEPROM.update(EEPROM_POS_LAST_NAME, 0);
    EEPROM.update(EEPROM_POS_AGE, 0);
    EEPROM.update(EEPROM_POS_GENDER, 'f');
    EEPROM.update(EEPROM_POS_NOTIFICATIONS, 0);
  }

  URLHandler *userPageHandler = webServer.createURLHandler(F("/User.html.json"));
  userPageHandler->setFieldCb.attach(userSetFieldCb);
  userPageHandler->loadCb.attach(userLoadCb);
}