/**
 * The MIT License (MIT)
 * Copyright (c) 2015 by Fabrice Weinberg
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "NTPClient.h"

NTPClient::NTPClient(UDP& udp) {
  this->_udp            = &udp;
}

NTPClient::NTPClient(UDP& udp, long timeOffset) {
  this->_udp            = &udp;
  this->_timeOffset     = timeOffset;
}

NTPClient::NTPClient(UDP& udp, const char* poolServerName) {
  this->_udp            = &udp;
  this->_poolServerName = poolServerName;
}

NTPClient::NTPClient(UDP& udp, IPAddress poolServerIP) {
  this->_udp            = &udp;
  this->_poolServerIP   = poolServerIP;
  this->_poolServerName = NULL;
}

NTPClient::NTPClient(UDP& udp, const char* poolServerName, long timeOffset) {
  this->_udp            = &udp;
  this->_timeOffset     = timeOffset;
  this->_poolServerName = poolServerName;
}

NTPClient::NTPClient(UDP& udp, IPAddress poolServerIP, long timeOffset){
  this->_udp            = &udp;
  this->_timeOffset     = timeOffset;
  this->_poolServerIP   = poolServerIP;
  this->_poolServerName = NULL;
}

NTPClient::NTPClient(UDP& udp, const char* poolServerName, long timeOffset, unsigned long updateInterval) {
  this->_udp            = &udp;
  this->_timeOffset     = timeOffset;
  this->_poolServerName = poolServerName;
  this->_updateInterval = updateInterval;
}

NTPClient::NTPClient(UDP& udp, IPAddress poolServerIP, long timeOffset, unsigned long updateInterval) {
  this->_udp            = &udp;
  this->_timeOffset     = timeOffset;
  this->_poolServerIP   = poolServerIP;
  this->_poolServerName = NULL;
  this->_updateInterval = updateInterval;
}

void NTPClient::begin() {
  this->begin(NTP_DEFAULT_LOCAL_PORT);
}

void NTPClient::begin(unsigned int port) {
  this->_port = port;

  this->_udp->begin(this->_port);

  this->_udpSetup = true;
}

// Perform some validity checks on the packet
//  https://datatracker.ietf.org/doc/html/rfc4330#section-4
// Check length before calling
static bool isValid(byte const *ntpPacket)
{
  unsigned long highWord = word(ntpPacket[16], ntpPacket[17]);
  unsigned long lowWord  = word(ntpPacket[18], ntpPacket[19]);
  unsigned long refTimeInt  = highWord << 16 | lowWord;
  highWord = word(ntpPacket[20], ntpPacket[21]);
  lowWord  = word(ntpPacket[22], ntpPacket[23]);
  unsigned long refTimeFrac = highWord << 16 | lowWord;

  byte leapIndicator = ((ntpPacket[0] & 0b11000000) >> 6);
  byte version       = ((ntpPacket[0] & 0b00111000) >> 3);
  byte mode          = ( ntpPacket[0] & 0b00000111      );
  byte stratum       =   ntpPacket[1];

  return
  (
    (leapIndicator !=  3) && // LI != UNSYNC
    (version       >=  4) &&
    ((mode == 4) || (mode == 5)) && // Mode == server or broadcast
    (stratum       >=  1) &&
    (stratum       <= 15) &&
    ((refTimeInt !=  0) || (refTimeFrac != 0))
  );
}

bool NTPClient::forceUpdate() {
  #ifdef DEBUG_NTPClient
    Serial.println("Update from NTP Server");
  #endif

  // flush any existing packets
  while(this->_udp->parsePacket() != 0)
    this->_udp->flush();

  this->sendNTPPacket();

  // Wait till data is there or timeout...
  byte timeout = 0;
  int cb = 0;
  do {
    delay ( 10 );
    cb = this->_udp->parsePacket();
    if (timeout > 100) return false; // timeout after 1000 ms
    timeout++;
  } while (cb == 0);

  if ((cb >= NTP_PACKET_SIZE) &&
      (this->_udp->read(this->_packetBuffer, NTP_PACKET_SIZE) == NTP_PACKET_SIZE) &&
      isValid(this->_packetBuffer))
  {
    this->_lastUpdate = millis() - (10 * (timeout + 1)); // Account for delay in reading the time

    unsigned long highWord = word(this->_packetBuffer[40], this->_packetBuffer[41]);
    unsigned long lowWord = word(this->_packetBuffer[42], this->_packetBuffer[43]);
    // combine the four bytes (two words) into a long integer
    // this is NTP time (seconds since Jan 1 1900):
    unsigned long secsSince1900 = highWord << 16 | lowWord;

    this->_currentEpoc = secsSince1900 - SEVENTYYEARS;

    return true;  // return true after successful update
  }
  else
  {
    return false;
  }
}

bool NTPClient::update() {
  if ((millis() - this->_lastUpdate >= this->_updateInterval)     // Update after _updateInterval
    || this->_lastUpdate == 0) {                                // Update if there was no update yet.
    if (!this->_udpSetup || this->_port != NTP_DEFAULT_LOCAL_PORT) this->begin(this->_port); // setup the UDP client if needed
    return this->forceUpdate();
  }
  return false;   // return false if update does not occur
}

unsigned long NTPClient::getEpochTime() const {
  return this->_timeOffset + // User offset
         this->_currentEpoc + // Epoch returned by the NTP server
         ((millis() - this->_lastUpdate) / 1000); // Time since last update
}

int NTPClient::getDay() const {
  return (((this->getEpochTime()  / 86400L) + 4 ) % 7); //0 is Sunday
}
int NTPClient::getHours() const {
  return ((this->getEpochTime()  % 86400L) / 3600);
}
int NTPClient::getMinutes() const {
  return ((this->getEpochTime() % 3600) / 60);
}
int NTPClient::getSeconds() const {
  return (this->getEpochTime() % 60);
}

String NTPClient::getFormattedTime() const {
  unsigned long rawTime = this->getEpochTime();
  unsigned long hours = (rawTime % 86400L) / 3600;
  String hoursStr = hours < 10 ? "0" + String(hours) : String(hours);

  unsigned long minutes = (rawTime % 3600) / 60;
  String minuteStr = minutes < 10 ? "0" + String(minutes) : String(minutes);

  unsigned long seconds = rawTime % 60;
  String secondStr = seconds < 10 ? "0" + String(seconds) : String(seconds);

  return hoursStr + ":" + minuteStr + ":" + secondStr;
}

void NTPClient::end() {
  this->_udp->stop();

  this->_udpSetup = false;
}

void NTPClient::setTimeOffset(int timeOffset) {
  this->_timeOffset     = timeOffset;
}

void NTPClient::setUpdateInterval(unsigned long updateInterval) {
  this->_updateInterval = updateInterval;
}

void NTPClient::setPoolServerName(const char* poolServerName) {
    this->_poolServerName = poolServerName;
}

void NTPClient::sendNTPPacket() {
  // set all bytes in the buffer to 0
  memset(this->_packetBuffer, 0, NTP_PACKET_SIZE);
  // Initialize values needed to form NTP request
  this->_packetBuffer[0] = 0b11100011;   // LI, Version, Mode
  this->_packetBuffer[1] = 0;     // Stratum, or type of clock
  this->_packetBuffer[2] = 6;     // Polling Interval
  this->_packetBuffer[3] = 0xEC;  // Peer Clock Precision
  // 8 bytes of zero for Root Delay & Root Dispersion
  this->_packetBuffer[12]  = 49;
  this->_packetBuffer[13]  = 0x4E;
  this->_packetBuffer[14]  = 49;
  this->_packetBuffer[15]  = 52;

  // all NTP fields have been given values, now
  // you can send a packet requesting a timestamp:
  if  (this->_poolServerName) {
    this->_udp->beginPacket(this->_poolServerName, 123);
  } else {
    this->_udp->beginPacket(this->_poolServerIP, 123);
  }
  this->_udp->write(this->_packetBuffer, NTP_PACKET_SIZE);
  this->_udp->endPacket();
}

void NTPClient::setRandomPort(unsigned int minValue, unsigned int maxValue) {
  randomSeed(analogRead(0));
  this->_port = random(minValue, maxValue);
}