/*
Copyright (c) 2017 Theo Arends.  All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

- Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/

const char JSON_SNS_TEMPHUM[] PROGMEM =
  "%s, \"%s\":{\"Temperature\":%s, \"Humidity\":%s}";

/*********************************************************************************************\
 * Watchdog extension (https://github.com/esp8266/Arduino/issues/1532)
\*********************************************************************************************/

Ticker tickerOSWatch;

#define OSWATCH_RESET_TIME 30

static unsigned long osw_last_loop;
byte osw_flag = 0;

#ifndef USE_WS2812_DMA  // Collides with Neopixelbus but solves exception
void osw_osWatch() ICACHE_RAM_ATTR;
#endif  // USE_WS2812_DMA

void osw_osWatch()
{
  unsigned long t = millis();
  unsigned long last_run = abs(t - osw_last_loop);

#ifdef DEBUG_THEO
  char log[LOGSZ];
  snprintf_P(log, sizeof(log), PSTR("osWatch: FreeRam %d, rssi %d, last_run %d"), ESP.getFreeHeap(), WIFI_getRSSIasQuality(WiFi.RSSI()), last_run);
  addLog(LOG_LEVEL_DEBUG, log);
#endif  // DEBUG_THEO
  if(last_run >= (OSWATCH_RESET_TIME * 1000)) {
    addLog_P(LOG_LEVEL_INFO, PSTR("osWatch: Warning, loop blocked. Restart now"));
    rtcMem.osw_flag = 1;
    RTC_Save();
//    ESP.restart();  // normal reboot 
    ESP.reset();  // hard reset
  }
}

void osw_init()
{
  osw_flag = rtcMem.osw_flag;
  rtcMem.osw_flag = 0;
  osw_last_loop = millis();
  tickerOSWatch.attach_ms(((OSWATCH_RESET_TIME / 3) * 1000), osw_osWatch);
}

void osw_loop()
{
  osw_last_loop = millis();
//  while(1) delay(1000);  // this will trigger the os watch
}

String getResetReason()
{
  char buff[32];
  if (osw_flag) {
    strcpy_P(buff, PSTR("Blocked Loop"));
    return String(buff);
  } else {
    return ESP.getResetReason();
  }
}

#ifdef DEBUG_THEO
void exception_tst(byte type)
{
/*    
Exception (28):
epc1=0x4000bf64 epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000007 depc=0x00000000

ctx: cont 
sp: 3fff1f30 end: 3fff2840 offset: 01a0

>>>stack>>>
3fff20d0:  202c3573 756f7247 2c302070 646e4920
3fff20e0:  40236a6e 7954202c 45206570 00454358
3fff20f0:  00000010 00000007 00000000 3fff2180
3fff2100:  3fff2190 40107bfc 3fff3e4c 3fff22c0
3fff2110:  40261934 000000f0 3fff22c0 401004d8
3fff2120:  40238fcf 00000050 3fff2100 4021fc10
3fff2130:  3fff32bc 4021680c 3ffeade1 4021ff7d
3fff2140:  3fff2190 3fff2180 0000000c 7fffffff
3fff2150:  00000019 00000000 00000000 3fff21c0
3fff2160:  3fff23f3 3ffe8e08 00000000 4021ffb4
3fff2170:  3fff2190 3fff2180 0000000c 40201118
3fff2180:  3fff21c0 0000003c 3ffef840 00000007
3fff2190:  00000000 00000000 00000000 40201128
3fff21a0:  3fff23f3 000000f1 3fff23ec 4020fafb
3fff21b0:  3fff23f3 3fff21c0 3fff21d0 3fff23f6
3fff21c0:  00000000 3fff23fb 4022321b 00000000

Exception 28: LoadProhibited: A load referenced a page mapped with an attribute that does not permit loads
Decoding 14 results
0x40236a6e: ets_vsnprintf at ?? line ?
0x40107bfc: vsnprintf at C:\Data2\Arduino\arduino-1.8.1-esp-2.3.0\portable\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266/libc_replacements.c line 387
0x40261934: bignum_exptmod at ?? line ?
0x401004d8: malloc at C:\Data2\Arduino\arduino-1.8.1-esp-2.3.0\portable\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266\umm_malloc/umm_malloc.c line 1664
0x40238fcf: wifi_station_get_connect_status at ?? line ?
0x4021fc10: operator new[](unsigned int) at C:\Data2\Arduino\arduino-1.8.1-esp-2.3.0\portable\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266/abi.cpp line 57
0x4021680c: ESP8266WiFiSTAClass::status() at C:\Data2\Arduino\arduino-1.8.1-esp-2.3.0\portable\packages\esp8266\hardware\esp8266\2.3.0\libraries\ESP8266WiFi\src/ESP8266WiFiSTA.cpp line 569
0x4021ff7d: vsnprintf_P(char*, unsigned int, char const*, __va_list_tag) at C:\Data2\Arduino\arduino-1.8.1-esp-2.3.0\portable\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266/pgmspace.cpp line 146
0x4021ffb4: snprintf_P(char*, unsigned int, char const*, ...) at C:\Data2\Arduino\arduino-1.8.1-esp-2.3.0\portable\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266/pgmspace.cpp line 146
0x40201118: atol at C:\Data2\Arduino\arduino-1.8.1-esp-2.3.0\portable\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266/core_esp8266_noniso.c line 45
0x40201128: atoi at C:\Data2\Arduino\arduino-1.8.1-esp-2.3.0\portable\packages\esp8266\hardware\esp8266\2.3.0\cores\esp8266/core_esp8266_noniso.c line 45
0x4020fafb: mqttDataCb(char*, unsigned char*, unsigned int) at R:\Arduino\Work-ESP8266\Theo\sonoff\sonoff-4\sonoff/sonoff.ino line 679 (discriminator 1)
0x4022321b: pp_attach at ?? line ?

00:00:08 MQTT: tele/sonoff/INFO3 = {"Started":"Fatal exception:28 flag:2 (EXCEPTION) epc1:0x4000bf64 epc2:0x00000000 epc3:0x00000000 excvaddr:0x00000007 depc:0x00000000"}
*/
  if (type == 1) {
    char svalue[10];
    snprintf_P(svalue, sizeof(svalue), PSTR("%s"), 7);  // Exception 28 as number in string (7 in excvaddr)
  }
/*
14:50:52 osWatch: FreeRam 25896, rssi 68, last_run 0
14:51:02 osWatch: FreeRam 25896, rssi 58, last_run 0
14:51:03 CMND: exception 2
14:51:12 osWatch: FreeRam 25360, rssi 60, last_run 8771
14:51:22 osWatch: FreeRam 25360, rssi 62, last_run 18771
14:51:32 osWatch: FreeRam 25360, rssi 62, last_run 28771
14:51:42 osWatch: FreeRam 25360, rssi 62, last_run 38771
14:51:42 osWatch: Warning, loop blocked. Restart now
*/
  if (type == 2) {
    while(1) delay(1000);  // this will trigger the os watch
  }
}
#endif  // DEBUG_THEO

/*********************************************************************************************\
 * General
\*********************************************************************************************/

boolean parseIPx(char* str, uint16_t len, uint32_t* addr)
{
  uint8_t *part = (uint8_t *)addr;
  byte i;

  if (!len) return false;
  *addr = 0;
  for (i = 0; i <= len; i++) if (*(str +i) == ',') *(str +i) = '.';
  for (i = 0; i < 4; i++) {
    part[i] = strtoul(str, NULL, 10);        // Convert byte
    str = strchr(str, '.');
    if (str == NULL || *str == '\0') break;  // No more separators, exit
    str++;                                   // Point to next character after separator
  }
  return (i == 3);
}

boolean parseIP(uint32_t* addr, const char* str)
{
  uint8_t *part = (uint8_t*)addr;
  byte i;

  *addr = 0;
  for (i = 0; i < 4; i++) {
    part[i] = strtoul(str, NULL, 10);        // Convert byte
    str = strchr(str, '.');
    if (str == NULL || *str == '\0') break;  // No more separators, exit
    str++;                                   // Point to next character after separator
  }
  return (i == 3);
}

/*********************************************************************************************\
 * Wifi
\*********************************************************************************************/

#define WIFI_CONFIG_SEC   60   // seconds before restart
#define WIFI_MANAGER_SEC  120  // seconds before restart
#define WIFI_CHECK_SEC    20   // seconds
#define WIFI_RETRY_SEC    30   // seconds

uint8_t _wificounter, _wifiretry, _wifistatus, _wpsresult, _wificonfigflag = 0, _wifiConfigCounter = 0;

int WIFI_getRSSIasQuality(int RSSI)
{
  int quality = 0;

  if (RSSI <= -100) {
    quality = 0;
  } else if (RSSI >= -50) {
    quality = 100;
  } else {
    quality = 2 * (RSSI + 100);
  }
  return quality;
}

boolean WIFI_configCounter()
{
  if (_wifiConfigCounter) _wifiConfigCounter = WIFI_MANAGER_SEC;
  return (_wifiConfigCounter);
}

extern "C" {
#include "user_interface.h"
}

void WIFI_wps_status_cb(wps_cb_status status);

void WIFI_wps_status_cb(wps_cb_status status)
{
  char log[LOGSZ];

/* from user_interface.h:
  enum wps_cb_status {
    WPS_CB_ST_SUCCESS = 0,
    WPS_CB_ST_FAILED,
    WPS_CB_ST_TIMEOUT,
    WPS_CB_ST_WEP,      // WPS failed because that WEP is not supported
    WPS_CB_ST_SCAN_ERR, // can not find the target WPS AP
  };
*/

  _wpsresult = status;
  if (_wpsresult == WPS_CB_ST_SUCCESS) {
    wifi_wps_disable();
  } else {
    snprintf_P(log, sizeof(log), PSTR("WPSconfig: FAILED with status %d"), _wpsresult);
    addLog(LOG_LEVEL_DEBUG, log);
    _wifiConfigCounter = 2;
  }
}

boolean WIFI_WPSConfigDone(void)
{
  return (!_wpsresult);
}

boolean WIFI_beginWPSConfig(void)
{
  _wpsresult = 99;
  if (!wifi_wps_disable()) return false;
  if (!wifi_wps_enable(WPS_TYPE_PBC)) return false;  // so far only WPS_TYPE_PBC is supported (SDK 2.0.0)
  if (!wifi_set_wps_cb((wps_st_cb_t) &WIFI_wps_status_cb)) return false;
  if (!wifi_wps_start()) return false;
  return true;
}

void WIFI_config(uint8_t type)
{
  if (!_wificonfigflag) {
    if (type == WIFI_RETRY) return;
#ifdef USE_EMULATION
    UDP_Disconnect();
#endif  // USE_EMULATION
    WiFi.disconnect();        // Solve possible Wifi hangs
    _wificonfigflag = type;
    _wifiConfigCounter = WIFI_CONFIG_SEC;   // Allow up to WIFI_CONFIG_SECS seconds for phone to provide ssid/pswd
    _wificounter = _wifiConfigCounter +5;
    blinks = 1999;
    if (_wificonfigflag == WIFI_RESTART) {
      restartflag = 2;
    }
    else if (_wificonfigflag == WIFI_SMARTCONFIG) {
      addLog_P(LOG_LEVEL_INFO, PSTR("Smartconfig: Active for 1 minute"));
      WiFi.beginSmartConfig();
    }
    else if (_wificonfigflag == WIFI_WPSCONFIG) {
      if (WIFI_beginWPSConfig()) {
        addLog_P(LOG_LEVEL_INFO, PSTR("WPSconfig: Active for 1 minute"));
      } else {
        addLog_P(LOG_LEVEL_INFO, PSTR("WPSconfig: Failed to start"));
        _wifiConfigCounter = 3;
      }
    }
#ifdef USE_WEBSERVER
    else if (_wificonfigflag == WIFI_MANAGER) {
      addLog_P(LOG_LEVEL_INFO, PSTR("Wifimanager: Active for 1 minute"));
      beginWifiManager();
    }
#endif  // USE_WEBSERVER
  }
}

void WIFI_begin(uint8_t flag)
{
  const char PhyMode[] = " BGN";
  char log[LOGSZ];

#ifdef USE_EMULATION
  UDP_Disconnect();
#endif  // USE_EMULATION
  if (!strncmp(ESP.getSdkVersion(),"1.5.3",5)) {
    addLog_P(LOG_LEVEL_DEBUG, "Wifi: Patch issue 2186");
    WiFi.mode(WIFI_OFF);    // See https://github.com/esp8266/Arduino/issues/2186
  }
  WiFi.disconnect();
  WiFi.mode(WIFI_STA);      // Disable AP mode
//  if (sysCfg.sleep) wifi_set_sleep_type(LIGHT_SLEEP_T);  // Allow light sleep during idle times
  if (sysCfg.sleep) WiFi.setSleepMode(WIFI_LIGHT_SLEEP);  // Allow light sleep during idle times
//  WiFi.setSleepMode(WIFI_LIGHT_SLEEP);  // Allow light sleep during idle times
//  if (WiFi.getPhyMode() != WIFI_PHY_MODE_11N) WiFi.setPhyMode(WIFI_PHY_MODE_11N);
  if (!WiFi.getAutoConnect()) WiFi.setAutoConnect(true);
//  WiFi.setAutoReconnect(true);
  switch (flag) {
  case 0:  // AP1
  case 1:  // AP2
    sysCfg.sta_active = flag;
    break;
  case 2:  // Toggle
    sysCfg.sta_active ^= 1;
  }        // 3: Current AP
  if (strlen(sysCfg.sta_ssid[1]) == 0) sysCfg.sta_active = 0;
  if (sysCfg.ip_address[0]) 
    WiFi.config(sysCfg.ip_address[0], sysCfg.ip_address[1], sysCfg.ip_address[2], sysCfg.ip_address[3]);  // Set static IP
  WiFi.hostname(Hostname);
  WiFi.begin(sysCfg.sta_ssid[sysCfg.sta_active], sysCfg.sta_pwd[sysCfg.sta_active]);
  snprintf_P(log, sizeof(log), PSTR("Wifi: Connecting to AP%d %s in mode 11%c as %s..."),
    sysCfg.sta_active +1, sysCfg.sta_ssid[sysCfg.sta_active], PhyMode[WiFi.getPhyMode() & 0x3], Hostname);
  addLog(LOG_LEVEL_INFO, log);
}

void WIFI_check_ip()
{
  if ((WiFi.status() == WL_CONNECTED) && (static_cast<uint32_t>(WiFi.localIP()) != 0)) {
    _wificounter = WIFI_CHECK_SEC;
    _wifiretry = WIFI_RETRY_SEC;
    addLog_P((_wifistatus != WL_CONNECTED) ? LOG_LEVEL_INFO : LOG_LEVEL_DEBUG_MORE, PSTR("Wifi: Connected"));
    if (_wifistatus != WL_CONNECTED) {
//      addLog_P(LOG_LEVEL_INFO, PSTR("Wifi: Set IP addresses"));
      sysCfg.ip_address[1] = (uint32_t)WiFi.gatewayIP();
      sysCfg.ip_address[2] = (uint32_t)WiFi.subnetMask();
      sysCfg.ip_address[3] = (uint32_t)WiFi.dnsIP();
    }
    _wifistatus = WL_CONNECTED;
  } else {
    _wifistatus = WiFi.status();
    switch (_wifistatus) {
      case WL_CONNECTED:
        addLog_P(LOG_LEVEL_INFO, PSTR("Wifi: Connect failed as no IP address received"));
        _wifistatus = 0;
        _wifiretry = WIFI_RETRY_SEC;
        break;
      case WL_NO_SSID_AVAIL:
        addLog_P(LOG_LEVEL_INFO, PSTR("Wifi: Connect failed as AP cannot be reached"));
        if (_wifiretry > (WIFI_RETRY_SEC / 2)) _wifiretry = WIFI_RETRY_SEC / 2;
        else if (_wifiretry) _wifiretry = 0;
        break;
      case WL_CONNECT_FAILED:
        addLog_P(LOG_LEVEL_INFO, PSTR("Wifi: Connect failed with AP incorrect password"));
        if (_wifiretry > (WIFI_RETRY_SEC / 2)) _wifiretry = WIFI_RETRY_SEC / 2;
        else if (_wifiretry) _wifiretry = 0;
        break;
      default:  // WL_IDLE_STATUS and WL_DISCONNECTED
        if (!_wifiretry || (_wifiretry == (WIFI_RETRY_SEC / 2))) {
          addLog_P(LOG_LEVEL_INFO, PSTR("Wifi: Connect failed with AP timeout"));
        } else {
          addLog_P(LOG_LEVEL_DEBUG, PSTR("Wifi: Attempting connection..."));
        }
    }
    if (_wifiretry) {
      if (_wifiretry == WIFI_RETRY_SEC) WIFI_begin(3);        // Select default SSID
      if (_wifiretry == (WIFI_RETRY_SEC / 2)) WIFI_begin(2);  // Select alternate SSID
      _wificounter = 1;
      _wifiretry--;
    } else {
      WIFI_config(sysCfg.sta_config);
      _wificounter = 1;
      _wifiretry = WIFI_RETRY_SEC;
    }
  }
}

void WIFI_Check(uint8_t param)
{
  char log[LOGSZ];

  _wificounter--;
  switch (param) {
  case WIFI_SMARTCONFIG:
  case WIFI_MANAGER:
  case WIFI_WPSCONFIG:
    WIFI_config(param);
    break;
  default:
    if (_wifiConfigCounter) {
      _wifiConfigCounter--;
      _wificounter = _wifiConfigCounter +5;
      if (_wifiConfigCounter) {
        if ((_wificonfigflag == WIFI_SMARTCONFIG) && WiFi.smartConfigDone()) _wifiConfigCounter = 0;
        if ((_wificonfigflag == WIFI_WPSCONFIG) && WIFI_WPSConfigDone()) _wifiConfigCounter = 0;
        if (!_wifiConfigCounter) {
          if (strlen(WiFi.SSID().c_str())) strlcpy(sysCfg.sta_ssid[0], WiFi.SSID().c_str(), sizeof(sysCfg.sta_ssid[0]));
          if (strlen(WiFi.psk().c_str())) strlcpy(sysCfg.sta_pwd[0], WiFi.psk().c_str(), sizeof(sysCfg.sta_pwd[0]));
          sysCfg.sta_active = 0;
          snprintf_P(log, sizeof(log), PSTR("Wificonfig: SSID1 %s and Password1 %s"), sysCfg.sta_ssid[0], sysCfg.sta_pwd[0]);
          addLog(LOG_LEVEL_INFO, log);
        }
      }
      if (!_wifiConfigCounter) {
        if (_wificonfigflag == WIFI_SMARTCONFIG) WiFi.stopSmartConfig();
        restartflag = 2;
      }
    } else {
      if (_wificounter <= 0) {
        addLog_P(LOG_LEVEL_DEBUG_MORE, PSTR("Wifi: Checking connection..."));
        _wificounter = WIFI_CHECK_SEC;
        WIFI_check_ip();
      }
      if ((WiFi.status() == WL_CONNECTED) && (static_cast<uint32_t>(WiFi.localIP()) != 0) && !_wificonfigflag) {
#ifdef USE_DISCOVERY
        if (!mDNSbegun) {
          mDNSbegun = MDNS.begin(Hostname);
          snprintf_P(log, sizeof(log), PSTR("mDNS: %s"), (mDNSbegun)?"Initialized":"Failed");
          addLog(LOG_LEVEL_INFO, log);
        }
#endif  // USE_DISCOVERY
#ifdef USE_WEBSERVER
        if (sysCfg.webserver) {
          startWebserver(sysCfg.webserver, WiFi.localIP());
#ifdef USE_DISCOVERY
#ifdef WEBSERVER_ADVERTISE
          MDNS.addService("http", "tcp", 80);
#endif  // WEBSERVER_ADVERTISE          
#endif  // USE_DISCOVERY
        } else {
          stopWebserver();
        }
#ifdef USE_EMULATION
        if (sysCfg.emulation) UDP_Connect();
#endif  // USE_EMULATION
#endif  // USE_WEBSERVER
      } else {
#ifdef USE_EMULATION
        UDP_Disconnect();
#endif  // USE_EMULATION
        mDNSbegun = false;
      }
    }
  }
}

int WIFI_State()
{
  int state;

  if ((WiFi.status() == WL_CONNECTED) && (static_cast<uint32_t>(WiFi.localIP()) != 0)) state = WIFI_RESTART;
  if (_wificonfigflag) state = _wificonfigflag;
  return state;
}

void WIFI_Connect()
{
  WiFi.persistent(false);   // Solve possible wifi init errors
  _wifistatus = 0;
  _wifiretry = WIFI_RETRY_SEC;
  _wificounter = 1;
}

#ifdef USE_DISCOVERY
/*********************************************************************************************\
 * mDNS
\*********************************************************************************************/

#ifdef MQTT_HOST_DISCOVERY
boolean mdns_discoverMQTTServer()
{
  char log[LOGSZ], ip_str[20];
  int n;

  if (!mDNSbegun) return false;

  n = MDNS.queryService("mqtt", "tcp");  // Search for mqtt service

  snprintf_P(log, sizeof(log), PSTR("mDNS: Query done with %d mqtt services found"), n);
  addLog(LOG_LEVEL_INFO, log);

  if (n > 0) {
    // Note: current strategy is to get the first MQTT service (even when many are found)
    IPtoCharArray(MDNS.IP(0), ip_str, 20);
    
    snprintf_P(log, sizeof(log), PSTR("mDNS: Service found on %s ip %s port %d"),
      MDNS.hostname(0).c_str(), ip_str, MDNS.port(0));
    addLog(LOG_LEVEL_INFO, log);

    strlcpy(sysCfg.mqtt_host, ip_str, sizeof(sysCfg.mqtt_host));
    sysCfg.mqtt_port = MDNS.port(0);
  }

  return n > 0;
}
#endif  // MQTT_HOST_DISCOVERY

void IPtoCharArray(IPAddress address, char *ip_str, size_t size)
{
    String str = String(address[0]);
    str += ".";
    str += String(address[1]);
    str += ".";
    str += String(address[2]);
    str += ".";
    str += String(address[3]);
    str.toCharArray(ip_str, size);
}
#endif  // USE_DISCOVERY

/*********************************************************************************************\
 * Basic I2C routines
\*********************************************************************************************/

#ifdef USE_I2C
#define I2C_RETRY_COUNTER 3

int32_t i2c_read(uint8_t addr, uint8_t reg, uint8_t size)
{
  byte x = 0;
  int32_t data = 0;

  do {
    Wire.beginTransmission(addr);             // start transmission to device
    Wire.write(reg);                          // sends register address to read from
    if (Wire.endTransmission(false) == 0) {   // Try to become I2C Master, send data and collect bytes, keep master status for next request...
      Wire.requestFrom((int)addr, (int)size); // send data n-bytes read
      if (Wire.available() == size)
        for(byte i = 0; i < size; i++) {
          data <<= 8;
          data |= Wire.read();                // receive DATA
        }
    }
    x++;
  } while (Wire.endTransmission(true) != 0 && x <= I2C_RETRY_COUNTER); // end transmission
  return data;
}

uint8_t i2c_read8(uint8_t addr, uint8_t reg)
{
  return i2c_read(addr, reg, 1);
}

uint16_t i2c_read16(uint8_t addr, uint8_t reg)
{
  return i2c_read(addr, reg, 2);
}

int16_t i2c_readS16(uint8_t addr, uint8_t reg)
{
  return (int16_t)i2c_read(addr, reg, 2);
}

uint16_t i2c_read16_LE(uint8_t addr, uint8_t reg)
{
  uint16_t temp = i2c_read(addr, reg, 2);
  return (temp >> 8) | (temp << 8);
}

int16_t i2c_readS16_LE(uint8_t addr, uint8_t reg)
{
  return (int16_t)i2c_read16_LE(addr, reg);
}

int32_t i2c_read24(uint8_t addr, uint8_t reg)
{
  return i2c_read(addr, reg, 3);
}

void i2c_write8(uint8_t addr, uint8_t reg, uint8_t val)
{
  byte x = I2C_RETRY_COUNTER;

  do {
    Wire.beginTransmission((uint8_t)addr);  // start transmission to device
    Wire.write(reg);                         // sends register address to read from
    Wire.write(val);                         // write data
    x--;
  } while (Wire.endTransmission(true) != 0 && x != 0); // end transmission
}

void i2c_scan(char *devs, unsigned int devs_len)
{
  byte error, address, any = 0;
  char tstr[10];

  snprintf_P(devs, devs_len, PSTR("{\"I2Cscan\":\"Device(s) found at"));
  for (address = 1; address <= 127; address++) {
    Wire.beginTransmission(address);
    error = Wire.endTransmission();
    if (error == 0) {
      snprintf_P(tstr, sizeof(tstr), PSTR(" 0x%2x"), address);
      strncat(devs, tstr, devs_len);
      any = 1;
    }
    else if (error == 4) snprintf_P(devs, devs_len, PSTR("{\"I2Cscan\":\"Unknown error at 0x%2x\"}"), address);
  }
  if (any) {
    strncat(devs, "\"}", devs_len);
  } else {
    snprintf_P(devs, devs_len, PSTR("{\"I2Cscan\":\"No devices found\"}"));
  }
}
#endif  // USE_I2C

/*********************************************************************************************\
 * Real Time Clock
 *
 * Sources: Time by Michael Margolis and Paul Stoffregen (https://github.com/PaulStoffregen/Time)
 *          Timezone by Jack Christensen (https://github.com/JChristensen/Timezone)
\*********************************************************************************************/

extern "C" {
#include "sntp.h"
}

#define SECS_PER_MIN  ((uint32_t)(60UL))
#define SECS_PER_HOUR ((uint32_t)(3600UL))
#define SECS_PER_DAY  ((uint32_t)(SECS_PER_HOUR * 24UL))
#define LEAP_YEAR(Y)  (((1970+Y)>0) && !((1970+Y)%4) && (((1970+Y)%100) || !((1970+Y)%400)))

Ticker tickerRTC;

static const uint8_t monthDays[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; // API starts months from 1, this array starts from 0
static const char monthNames[] = "JanFebMarAprMayJunJulAugSepOctNovDec";

uint32_t utctime = 0, loctime = 0, dsttime = 0, stdtime = 0, ntptime = 0, midnight = 1451602800;

String getBuildDateTime()
{
  // "2017-03-07T11:08:02"
  char bdt[21];
  char *str, *p, *smonth;
  char mdate[] = __DATE__;  // "Mar  7 2017"
  int month, day, year;
  
//  sscanf(mdate, "%s %d %d", bdt, &day, &year);  // Not implemented in 2.3.0 and probably too many code
  byte i = 0;
  for (str = strtok_r(mdate, " ", &p); str && i < 3; str = strtok_r(NULL, " ", &p)) {
    switch (i++) {
    case 0:  // Month
      smonth = str;
      break;
    case 1:  // Day
      day = atoi(str);
      break;
    case 2:  // Year
      year = atoi(str);
    }
  }
  month = (strstr(monthNames, smonth) -monthNames) /3 +1;
  snprintf_P(bdt, sizeof(bdt), PSTR("%d-%02d-%02dT%s"), year, month, day, __TIME__);
  return String(bdt);
}

String getDateTime()
{
  // "2017-03-07T11:08:02"
  char dt[21];
  
  snprintf_P(dt, sizeof(dt), PSTR("%04d-%02d-%02dT%02d:%02d:%02d"),
    rtcTime.Year, rtcTime.Month, rtcTime.Day, rtcTime.Hour, rtcTime.Minute, rtcTime.Second);
  return String(dt);
}

void breakTime(uint32_t timeInput, TIME_T &tm)
{
// break the given timeInput into time components
// this is a more compact version of the C library localtime function
// note that year is offset from 1970 !!!

  uint8_t year, month, monthLength;
  uint32_t time;
  unsigned long days;

  time = timeInput;
  tm.Second = time % 60;
  time /= 60;                // now it is minutes
  tm.Minute = time % 60;
  time /= 60;                // now it is hours
  tm.Hour = time % 24;
  time /= 24;                // now it is days
  tm.Wday = ((time + 4) % 7) + 1;  // Sunday is day 1

  year = 0;
  days = 0;
  while((unsigned)(days += (LEAP_YEAR(year) ? 366 : 365)) <= time) {
    year++;
  }
  tm.Year = year;            // year is offset from 1970

  days -= LEAP_YEAR(year) ? 366 : 365;
  time -= days;              // now it is days in this year, starting at 0
  tm.DayOfYear = time;

  days = 0;
  month = 0;
  monthLength = 0;
  for (month = 0; month < 12; month++) {
    if (month == 1) { // february
      if (LEAP_YEAR(year)) {
        monthLength = 29;
      } else {
        monthLength = 28;
      }
    } else {
      monthLength = monthDays[month];
    }

    if (time >= monthLength) {
      time -= monthLength;
    } else {
      break;
    }
  }
  strlcpy(tm.MonthName, monthNames + (month *3), 4);
  tm.Month = month + 1;      // jan is month 1
  tm.Day = time + 1;         // day of month
  tm.Valid = (timeInput > 1451602800);  // 2016-01-01
}

uint32_t makeTime(TIME_T &tm)
{
// assemble time elements into time_t
// note year argument is offset from 1970

  int i;
  uint32_t seconds;

  // seconds from 1970 till 1 jan 00:00:00 of the given year
  seconds = tm.Year * (SECS_PER_DAY * 365);
  for (i = 0; i < tm.Year; i++) {
    if (LEAP_YEAR(i)) {
      seconds +=  SECS_PER_DAY;   // add extra days for leap years
    }
  }

  // add days for this year, months start from 1
  for (i = 1; i < tm.Month; i++) {
    if ((i == 2) && LEAP_YEAR(tm.Year)) {
      seconds += SECS_PER_DAY * 29;
    } else {
      seconds += SECS_PER_DAY * monthDays[i-1];  // monthDay array starts from 0
    }
  }
  seconds+= (tm.Day - 1) * SECS_PER_DAY;
  seconds+= tm.Hour * SECS_PER_HOUR;
  seconds+= tm.Minute * SECS_PER_MIN;
  seconds+= tm.Second;
  return seconds;
}

uint32_t toTime_t(TimeChangeRule r, int yr)
{
    TIME_T tm;
    uint32_t t;
    uint8_t m, w;            // temp copies of r.month and r.week

    m = r.month;
    w = r.week;
    if (w == 0) {            // Last week = 0
        if (++m > 12) {      // for "Last", go to the next month
            m = 1;
            yr++;
        }
        w = 1;               // and treat as first week of next month, subtract 7 days later
    }

    tm.Hour = r.hour;
    tm.Minute = 0;
    tm.Second = 0;
    tm.Day = 1;
    tm.Month = m;
    tm.Year = yr - 1970;
    t = makeTime(tm);        // First day of the month, or first day of next month for "Last" rules
    breakTime(t, tm);
    t += (7 * (w - 1) + (r.dow - tm.Wday + 7) % 7) * SECS_PER_DAY;
    if (r.week == 0) t -= 7 * SECS_PER_DAY;    //back up a week if this is a "Last" rule
    return t;
}

String rtc_time(int type)
{
  char stime[25];   // Skip newline

  uint32_t time = utctime;
  if (type == 1) time = loctime;
  if (type == 2) time = dsttime;
  if (type == 3) time = stdtime;
  snprintf_P(stime, sizeof(stime), PSTR("%s"), sntp_get_real_time(time));
  return String(stime);
}

uint32_t rtc_loctime()
{
  return loctime;
}

uint32_t rtc_midnight()
{
  return midnight;
}

void rtc_second()
{
  char log[LOGSZ];
  byte ntpsync;
  uint32_t stdoffset, dstoffset;
  TIME_T tmpTime;

  ntpsync = 0;
  if (rtcTime.Year < 2016) {
    if (WiFi.status() == WL_CONNECTED) {
      ntpsync = 1;  // Initial NTP sync
    }
  } else {
    if ((rtcTime.Minute == 1) && (rtcTime.Second == 1)) {
      ntpsync = 1;  // Hourly NTP sync at xx:01:01
    }
  }
  if (ntpsync) {
    ntptime = sntp_get_current_timestamp();
    if (ntptime) {
      utctime = ntptime;
      breakTime(utctime, tmpTime);
      rtcTime.Year = tmpTime.Year + 1970;
      dsttime = toTime_t(myDST, rtcTime.Year);
      stdtime = toTime_t(mySTD, rtcTime.Year);
      snprintf_P(log, sizeof(log), PSTR("RTC: (UTC) %s"), rtc_time(0).c_str());
      addLog(LOG_LEVEL_DEBUG, log);
      snprintf_P(log, sizeof(log), PSTR("RTC: (DST) %s"), rtc_time(2).c_str());
      addLog(LOG_LEVEL_DEBUG, log);
      snprintf_P(log, sizeof(log), PSTR("RTC: (STD) %s"), rtc_time(3).c_str());
      addLog(LOG_LEVEL_DEBUG, log);
    }
  }
  utctime++;
  loctime = utctime;
  if (loctime > 1451602800) {  // 2016-01-01
    if (sysCfg.timezone == 99) {
      dstoffset = myDST.offset * SECS_PER_MIN;
      stdoffset = mySTD.offset * SECS_PER_MIN;
      if ((utctime >= (dsttime - stdoffset)) && (utctime < (stdtime - dstoffset))) {
        loctime += dstoffset;  // Daylight Saving Time
      } else {
        loctime += stdoffset;  // Standard Time
      }
    } else {
      loctime += sysCfg.timezone * SECS_PER_HOUR;
    }
  }
  breakTime(loctime, rtcTime);
  if (!rtcTime.Hour && !rtcTime.Minute && !rtcTime.Second && rtcTime.Valid) {
    midnight = loctime;
  }
  rtcTime.Year += 1970;
}

void rtc_init()
{
  sntp_setservername(0, sysCfg.ntp_server[0]);
  sntp_setservername(1, sysCfg.ntp_server[1]);
  sntp_setservername(2, sysCfg.ntp_server[2]);
  sntp_stop();
  sntp_set_timezone(0);      // UTC time
  sntp_init();
  utctime = 0;
  breakTime(utctime, rtcTime);
  tickerRTC.attach(1, rtc_second);
}

/*********************************************************************************************\
 * Syslog
\*********************************************************************************************/

void syslog(const char *message)
{
  char str[TOPSZ + MESSZ];

  if (portUDP.beginPacket(sysCfg.syslog_host, sysCfg.syslog_port)) {
    snprintf_P(str, sizeof(str), PSTR("%s ESP-%s"), Hostname, message);
    portUDP.write(str);
    portUDP.endPacket();
  } else {
    syslog_level = 0;
    syslog_timer = SYSLOG_TIMER;
    snprintf_P(str, sizeof(str), PSTR("SYSL: Syslog Host not found so logging disabled for %d seconds. Consider syslog 0"), SYSLOG_TIMER);
    addLog(LOG_LEVEL_INFO, str);
  }
}

void addLog(byte loglevel, const char *line)
{
  char mxtime[9];

  snprintf_P(mxtime, sizeof(mxtime), PSTR("%02d:%02d:%02d"), rtcTime.Hour, rtcTime.Minute, rtcTime.Second);

  if (loglevel <= seriallog_level) Serial.printf("%s %s\n", mxtime, line);
#ifdef USE_WEBSERVER
  if (sysCfg.webserver && (loglevel <= sysCfg.weblog_level)) {
    Log[logidx] = String(mxtime) + " " + String(line);
    logidx++;
    if (logidx > MAX_LOG_LINES -1) logidx = 0;
  }
#endif  // USE_WEBSERVER
//  if (sysCfg.emulation) return;  // Disable syslog (UDP) when emulation using UDP is selected
  if ((WiFi.status() == WL_CONNECTED) && (loglevel <= syslog_level)) syslog(line);
}

void addLog_P(byte loglevel, const char *formatP)
{
  char mess[LOGSZ];  // was MESSZ

  snprintf_P(mess, sizeof(mess), formatP);
  addLog(loglevel, mess);
}

/*********************************************************************************************\
 *
\*********************************************************************************************/
