#include "wled.h"

/*
 * UDP sync notifier / Realtime / Hyperion / TPM2.NET
 */

#define WLEDPACKETSIZE (40+(MAX_NUM_SEGMENTS*3))
#define UDP_IN_MAXSIZE 1472
#define PRESUMED_NETWORK_DELAY 3 //how many ms could it take on avg to reach the receiver? This will be added to transmitted times

void notify(byte callMode, bool followUp)
{
  if (!udpConnected) return;
  if (!syncGroups) return;
  switch (callMode)
  {
    case CALL_MODE_INIT:          return;
    case CALL_MODE_DIRECT_CHANGE: if (!notifyDirect) return; break;
    case CALL_MODE_BUTTON:        if (!notifyButton) return; break;
    case CALL_MODE_NIGHTLIGHT:    if (!notifyDirect) return; break;
    case CALL_MODE_HUE:           if (!notifyHue)    return; break;
    case CALL_MODE_PRESET_CYCLE:  if (!notifyDirect) return; break;
    case CALL_MODE_BLYNK:         if (!notifyDirect) return; break;
    case CALL_MODE_ALEXA:         if (!notifyAlexa)  return; break;
    default: return;
  }
  byte udpOut[WLEDPACKETSIZE];
	WS2812FX::Segment& mainseg = strip.getSegment(strip.getMainSegmentId());
  udpOut[0] = 0; //0: wled notifier protocol 1: WARLS protocol
  udpOut[1] = callMode;
  udpOut[2] = bri;
  udpOut[3] = col[0];
  udpOut[4] = col[1];
  udpOut[5] = col[2];
  udpOut[6] = nightlightActive;
  udpOut[7] = nightlightDelayMins;
  udpOut[8] = effectCurrent;
  udpOut[9] = effectSpeed;
  udpOut[10] = col[3];
  //compatibilityVersionByte: 
  //0: old 1: supports white 2: supports secondary color
  //3: supports FX intensity, 24 byte packet 4: supports transitionDelay 5: sup palette
  //6: supports timebase syncing, 29 byte packet 7: supports tertiary color 8: supports sys time sync, 36 byte packet
  //9: supports sync groups, 37 byte packet 10: supports CCT, 39 byte packet 11: per segment options, variable packet length (40+MAX_NUM_SEGMENTS*3)
  udpOut[11] = 11; 
  udpOut[12] = colSec[0];
  udpOut[13] = colSec[1];
  udpOut[14] = colSec[2];
  udpOut[15] = colSec[3];
  udpOut[16] = effectIntensity;
  udpOut[17] = (transitionDelay >> 0) & 0xFF;
  udpOut[18] = (transitionDelay >> 8) & 0xFF;
  udpOut[19] = effectPalette;
  uint32_t colTer = mainseg.colors[2];
  udpOut[20] = (colTer >> 16) & 0xFF;
  udpOut[21] = (colTer >>  8) & 0xFF;
  udpOut[22] = (colTer >>  0) & 0xFF;
  udpOut[23] = (colTer >> 24) & 0xFF;
  
  udpOut[24] = followUp;
  uint32_t t = millis() + strip.timebase;
  udpOut[25] = (t >> 24) & 0xFF;
  udpOut[26] = (t >> 16) & 0xFF;
  udpOut[27] = (t >>  8) & 0xFF;
  udpOut[28] = (t >>  0) & 0xFF;

  //sync system time
  udpOut[29] = toki.getTimeSource();
  Toki::Time tm = toki.getTime();
  uint32_t unix = tm.sec;
  udpOut[30] = (unix >> 24) & 0xFF;
  udpOut[31] = (unix >> 16) & 0xFF;
  udpOut[32] = (unix >>  8) & 0xFF;
  udpOut[33] = (unix >>  0) & 0xFF;
  uint16_t ms = tm.ms;
  udpOut[34] = (ms >> 8) & 0xFF;
  udpOut[35] = (ms >> 0) & 0xFF;

  //sync groups
  udpOut[36] = syncGroups;
	
	//Might be changed to Kelvin in the future, receiver code should handle that case
	//0: byte 38 contains 0-255 value, 255: no valid CCT, 1-254: Kelvin value MSB
	udpOut[37] = strip.hasCCTBus() ? 0 : 255; //check this is 0 for the next value to be significant
	udpOut[38] = mainseg.cct;

	udpOut[39] = strip.getMaxSegments();
  for (uint8_t i = 0; i < strip.getMaxSegments(); i++) {
    WS2812FX::Segment &selseg = strip.getSegment(i);
    udpOut[40+i*3] = selseg.options & 0x0F; //only take into account mirrored, selected, on, reversed
    udpOut[41+i*3] = selseg.spacing;
    udpOut[42+i*3] = selseg.grouping;
  }

  IPAddress broadcastIp;
  broadcastIp = ~uint32_t(Network.subnetMask()) | uint32_t(Network.gatewayIP());

  notifierUdp.beginPacket(broadcastIp, udpPort);
  notifierUdp.write(udpOut, WLEDPACKETSIZE);
  notifierUdp.endPacket();
  notificationSentCallMode = callMode;
  notificationSentTime = millis();
  notificationTwoRequired = (followUp)? false:notifyTwice;
}

void realtimeLock(uint32_t timeoutMs, byte md)
{
  if (!realtimeMode && !realtimeOverride){
    uint16_t totalLen = strip.getLengthTotal();
    for (uint16_t i = 0; i < totalLen; i++)
    {
      strip.setPixelColor(i,0,0,0,0);
    }
  }

  realtimeTimeout = millis() + timeoutMs;
  if (timeoutMs == 255001 || timeoutMs == 65000) realtimeTimeout = UINT32_MAX;
  // if strip is off (bri==0) and not already in RTM
  if (bri == 0 && !realtimeMode) {
    strip.setBrightness(scaledBri(briLast));
  }
  realtimeMode = md;

  if (arlsForceMaxBri && !realtimeOverride) strip.setBrightness(scaledBri(255));
  if (md == REALTIME_MODE_GENERIC) strip.show();
}


#define TMP2NET_OUT_PORT 65442

void sendTPM2Ack() {
  notifierUdp.beginPacket(notifierUdp.remoteIP(), TMP2NET_OUT_PORT);
  uint8_t response_ack = 0xac;
  notifierUdp.write(&response_ack, 1);
  notifierUdp.endPacket();
}


void handleNotifications()
{
  IPAddress localIP;

  //send second notification if enabled
  if(udpConnected && notificationTwoRequired && millis()-notificationSentTime > 250){
    notify(notificationSentCallMode,true);
  }
  
  if (e131NewData && millis() - strip.getLastShow() > 15)
  {
    e131NewData = false;
    strip.show();
  }

  //unlock strip when realtime UDP times out
  if (realtimeMode && millis() > realtimeTimeout)
  {
    if (realtimeOverride == REALTIME_OVERRIDE_ONCE) realtimeOverride = REALTIME_OVERRIDE_NONE;
    strip.setBrightness(scaledBri(bri));
    realtimeMode = REALTIME_MODE_INACTIVE;
    realtimeIP[0] = 0;
  }

  //receive UDP notifications
  if (!udpConnected) return;
    
  bool isSupp = false;
  uint16_t packetSize = notifierUdp.parsePacket();
  if (!packetSize && udp2Connected) {
    packetSize = notifier2Udp.parsePacket();
    isSupp = true;
  }

  //hyperion / raw RGB
  if (!packetSize && udpRgbConnected) {
    packetSize = rgbUdp.parsePacket();
    if (packetSize) {
      if (!receiveDirect) return;
      if (packetSize > UDP_IN_MAXSIZE || packetSize < 3) return;
      realtimeIP = rgbUdp.remoteIP();
      DEBUG_PRINTLN(rgbUdp.remoteIP());
      uint8_t lbuf[packetSize];
      rgbUdp.read(lbuf, packetSize);
      realtimeLock(realtimeTimeoutMs, REALTIME_MODE_HYPERION);
      if (realtimeOverride) return;
      uint16_t id = 0;
      uint16_t totalLen = strip.getLengthTotal();
      for (uint16_t i = 0; i < packetSize -2; i += 3)
      {
        setRealtimePixel(id, lbuf[i], lbuf[i+1], lbuf[i+2], 0);
        id++; if (id >= totalLen) break;
      }
      strip.show();
      return;
    } 
  }

  if (!(receiveNotifications || receiveDirect)) return;
  
  localIP = Network.localIP();
  //notifier and UDP realtime
  if (!packetSize || packetSize > UDP_IN_MAXSIZE) return;
  if (!isSupp && notifierUdp.remoteIP() == localIP) return; //don't process broadcasts we send ourselves

  uint8_t udpIn[packetSize +1];
  uint16_t len;
  if (isSupp) len = notifier2Udp.read(udpIn, packetSize);
  else        len =  notifierUdp.read(udpIn, packetSize);

  // WLED nodes info notifications
  if (isSupp && udpIn[0] == 255 && udpIn[1] == 1 && len >= 40) {
    if (!nodeListEnabled || notifier2Udp.remoteIP() == localIP) return;

    uint8_t unit = udpIn[39];
    NodesMap::iterator it = Nodes.find(unit);
    if (it == Nodes.end() && Nodes.size() < WLED_MAX_NODES) { // Create a new element when not present
      Nodes[unit].age = 0;
      it = Nodes.find(unit);
    }

    if (it != Nodes.end()) {
      for (byte x = 0; x < 4; x++) {
        it->second.ip[x] = udpIn[x + 2];
      }
      it->second.age = 0; // reset 'age counter'
      char tmpNodeName[33] = { 0 };
      memcpy(&tmpNodeName[0], reinterpret_cast<byte *>(&udpIn[6]), 32);
      tmpNodeName[32]     = 0;
      it->second.nodeName = tmpNodeName;
      it->second.nodeName.trim();
      it->second.nodeType = udpIn[38];
      uint32_t build = 0;
      if (len >= 44)
        for (byte i=0; i<sizeof(uint32_t); i++)
          build |= udpIn[40+i]<<(8*i);
      it->second.build = build;
    }
    return;
  }

  //wled notifier, ignore if realtime packets active
  if (udpIn[0] == 0 && !realtimeMode && receiveNotifications)
  {
    //ignore notification if received within a second after sending a notification ourselves
    if (millis() - notificationSentTime < 1000) return;
    if (udpIn[1] > 199) return; //do not receive custom versions

    //compatibilityVersionByte: 
    byte version = udpIn[11];

    // if we are not part of any sync group ignore message
    if (version < 9 || version > 199) {
      // legacy senders are treated as if sending in sync group 1 only
      if (!(receiveGroups & 0x01)) return;
    } else if (!(receiveGroups & udpIn[36])) return;
    
    bool someSel = (receiveNotificationBrightness || receiveNotificationColor || receiveNotificationEffects);
    //apply colors from notification
    if (receiveNotificationColor || !someSel)
    {
      col[0] = udpIn[3];
      col[1] = udpIn[4];
      col[2] = udpIn[5];
      if (version > 0) //sending module's white val is intended
      {
        col[3] = udpIn[10];
        if (version > 1)
        {
          colSec[0] = udpIn[12];
          colSec[1] = udpIn[13];
          colSec[2] = udpIn[14];
          colSec[3] = udpIn[15];
        }
        if (version > 6)
        {
          strip.setColor(2, udpIn[20], udpIn[21], udpIn[22], udpIn[23]); //tertiary color
        }
				if (version > 9 && version < 200 && udpIn[37] < 255) { //valid CCT/Kelvin value
					uint8_t cct = udpIn[38];
					if (udpIn[37] > 0) { //Kelvin
						cct = (((udpIn[37] << 8) + udpIn[38]) - 1900) >> 5; 
					}
					uint8_t segid = strip.getMainSegmentId();
					strip.getSegment(segid).setCCT(cct, segid);
				}
      }
    }

    bool timebaseUpdated = false;
    //apply effects from notification
    if (version < 200 && (receiveNotificationEffects || !someSel))
    {
      if (currentPlaylist>=0) unloadPlaylist();
      if (version>10) {
        if (receiveSegmentOptions) {
          // will not sync start & stop
          uint8_t srcSegs = udpIn[39];
          if (srcSegs > strip.getMaxSegments()) srcSegs = strip.getMaxSegments();
          for (uint8_t i = 0; i < srcSegs; i++) {
            WS2812FX::Segment& selseg = strip.getSegment(i);
            for (uint8_t j = 0; j<4; j++) selseg.setOption(j, (udpIn[40+i*3] >> j) & 0x01); //only take into account mirrored, selected, on, reversed
            strip.setSegment(i, selseg.start, selseg.stop, udpIn[42+i*3], udpIn[41+i*3], selseg.offset); // will also properly reset segments
          }
        }
      }
      if (udpIn[8] < strip.getModeCount()) effectCurrent = udpIn[8];
      effectSpeed   = udpIn[9];
      if (version > 2) effectIntensity = udpIn[16];
      if (version > 4 && udpIn[19] < strip.getPaletteCount()) effectPalette = udpIn[19];
      if (version > 5)
      {
        uint32_t t = (udpIn[25] << 24) | (udpIn[26] << 16) | (udpIn[27] << 8) | (udpIn[28]);
        t += PRESUMED_NETWORK_DELAY; //adjust trivially for network delay
        t -= millis();
        strip.timebase = t;
        timebaseUpdated = true;
      }
    }

    //adjust system time, but only if sender is more accurate than self
    if (version > 7 && version < 200)
    {
      Toki::Time tm;
      tm.sec = (udpIn[30] << 24) | (udpIn[31] << 16) | (udpIn[32] << 8) | (udpIn[33]);
      tm.ms = (udpIn[34] << 8) | (udpIn[35]);
      if (udpIn[29] > toki.getTimeSource()) { //if sender's time source is more accurate
        toki.adjust(tm, PRESUMED_NETWORK_DELAY); //adjust trivially for network delay
        uint8_t ts = TOKI_TS_UDP;
        if (udpIn[29] > 99) ts = TOKI_TS_UDP_NTP;
        else if (udpIn[29] >= TOKI_TS_SEC) ts = TOKI_TS_UDP_SEC;
        toki.setTime(tm, ts);
      } else if (timebaseUpdated && toki.getTimeSource() > 99) { //if we both have good times, get a more accurate timebase
        Toki::Time myTime = toki.getTime();
        uint32_t diff = toki.msDifference(tm, myTime);
        strip.timebase -= PRESUMED_NETWORK_DELAY; //no need to presume, use difference between NTP times at send and receive points
        if (toki.isLater(tm, myTime)) {
          strip.timebase += diff;
        } else {
          strip.timebase -= diff;
        }
      }
    }
    
    if (version > 3)
    {
      transitionDelayTemp = ((udpIn[17] << 0) & 0xFF) + ((udpIn[18] << 8) & 0xFF00);
    }

    nightlightActive = udpIn[6];
    if (nightlightActive) nightlightDelayMins = udpIn[7];
    
    if (receiveNotificationBrightness || !someSel) bri = udpIn[2];
    colorUpdated(CALL_MODE_NOTIFICATION);
    return;
  }

  if (!receiveDirect) return;
  
  //TPM2.NET
  if (udpIn[0] == 0x9c)
  {
    //WARNING: this code assumes that the final TMP2.NET payload is evenly distributed if using multiple packets (ie. frame size is constant)
    //if the number of LEDs in your installation doesn't allow that, please include padding bytes at the end of the last packet
    byte tpmType = udpIn[1];
    if (tpmType == 0xaa) { //TPM2.NET polling, expect answer
      sendTPM2Ack(); return;
    }
    if (tpmType != 0xda) return; //return if notTPM2.NET data

    realtimeIP = (isSupp) ? notifier2Udp.remoteIP() : notifierUdp.remoteIP();
    realtimeLock(realtimeTimeoutMs, REALTIME_MODE_TPM2NET);
    if (realtimeOverride) return;

    tpmPacketCount++; //increment the packet count
    if (tpmPacketCount == 1) tpmPayloadFrameSize = (udpIn[2] << 8) + udpIn[3]; //save frame size for the whole payload if this is the first packet
    byte packetNum = udpIn[4]; //starts with 1!
    byte numPackets = udpIn[5];

    uint16_t id = (tpmPayloadFrameSize/3)*(packetNum-1); //start LED
    uint16_t totalLen = strip.getLengthTotal();
    for (uint16_t i = 6; i < tpmPayloadFrameSize + 4; i += 3)
    {
      if (id < totalLen)
      {
        setRealtimePixel(id, udpIn[i], udpIn[i+1], udpIn[i+2], 0);
        id++;
      }
      else break;
    }
    if (tpmPacketCount == numPackets) //reset packet count and show if all packets were received
    {
      tpmPacketCount = 0;
      strip.show();
    }
    return;
  }

  //UDP realtime: 1 warls 2 drgb 3 drgbw
  if (udpIn[0] > 0 && udpIn[0] < 5)
  {
    realtimeIP = (isSupp) ? notifier2Udp.remoteIP() : notifierUdp.remoteIP();
    DEBUG_PRINTLN(realtimeIP);
    if (packetSize < 2) return;

    if (udpIn[1] == 0)
    {
      realtimeTimeout = 0;
      return;
    } else {
      realtimeLock(udpIn[1]*1000 +1, REALTIME_MODE_UDP);
    }
    if (realtimeOverride) return;

    uint16_t totalLen = strip.getLengthTotal();
    if (udpIn[0] == 1) //warls
    {
      for (uint16_t i = 2; i < packetSize -3; i += 4)
      {
        setRealtimePixel(udpIn[i], udpIn[i+1], udpIn[i+2], udpIn[i+3], 0);
      }
    } else if (udpIn[0] == 2) //drgb
    {
      uint16_t id = 0;
      for (uint16_t i = 2; i < packetSize -2; i += 3)
      {
        setRealtimePixel(id, udpIn[i], udpIn[i+1], udpIn[i+2], 0);

        id++; if (id >= totalLen) break;
      }
    } else if (udpIn[0] == 3) //drgbw
    {
      uint16_t id = 0;
      for (uint16_t i = 2; i < packetSize -3; i += 4)
      {
        setRealtimePixel(id, udpIn[i], udpIn[i+1], udpIn[i+2], udpIn[i+3]);
        
        id++; if (id >= totalLen) break;
      }
    } else if (udpIn[0] == 4) //dnrgb
    {
      uint16_t id = ((udpIn[3] << 0) & 0xFF) + ((udpIn[2] << 8) & 0xFF00);
      for (uint16_t i = 4; i < packetSize -2; i += 3)
      {
        if (id >= totalLen) break;
        setRealtimePixel(id, udpIn[i], udpIn[i+1], udpIn[i+2], 0);
        id++;
      }
    } else if (udpIn[0] == 5) //dnrgbw
    {
      uint16_t id = ((udpIn[3] << 0) & 0xFF) + ((udpIn[2] << 8) & 0xFF00);
      for (uint16_t i = 4; i < packetSize -2; i += 4)
      {
        if (id >= totalLen) break;
        setRealtimePixel(id, udpIn[i], udpIn[i+1], udpIn[i+2], udpIn[i+3]);
        id++;
      }
    }
    strip.show();
    return;
  }

  // API over UDP
  udpIn[packetSize] = '\0';

  if (udpIn[0] >= 'A' && udpIn[0] <= 'Z') { //HTTP API
    String apireq = "win&";
    apireq += (char*)udpIn;
    handleSet(nullptr, apireq);
  } else if (udpIn[0] == '{') { //JSON API
    DynamicJsonDocument jsonBuffer(2048);
    DeserializationError error = deserializeJson(jsonBuffer, udpIn);
    JsonObject root = jsonBuffer.as<JsonObject>();
    if (!error && !root.isNull()) deserializeState(root);
  }
}


void setRealtimePixel(uint16_t i, byte r, byte g, byte b, byte w)
{
  uint16_t pix = i + arlsOffset;
  if (pix < strip.getLengthTotal())
  {
    if (!arlsDisableGammaCorrection && strip.gammaCorrectCol)
    {
      strip.setPixelColor(pix, strip.gamma8(r), strip.gamma8(g), strip.gamma8(b), strip.gamma8(w));
    } else {
      strip.setPixelColor(pix, r, g, b, w);
    }
  }
}

/*********************************************************************************************\
   Refresh aging for remote units, drop if too old...
\*********************************************************************************************/
void refreshNodeList()
{
  for (NodesMap::iterator it = Nodes.begin(); it != Nodes.end();) {
    bool mustRemove = true;

    if (it->second.ip[0] != 0) {
      if (it->second.age < 10) {
        it->second.age++;
        mustRemove = false;
        ++it;
      }
    }

    if (mustRemove) {
      it = Nodes.erase(it);
    }
  }
}

/*********************************************************************************************\
   Broadcast system info to other nodes. (to update node lists)
\*********************************************************************************************/
void sendSysInfoUDP()
{
  if (!udp2Connected) return;

  IPAddress ip = Network.localIP();
  if (!ip || ip == IPAddress(255,255,255,255)) ip = IPAddress(4,3,2,1);

  // TODO: make a nice struct of it and clean up
  //  0: 1 byte 'binary token 255'
  //  1: 1 byte id '1'
  //  2: 4 byte ip
  //  6: 32 char name
  // 38: 1 byte node type id
  // 39: 1 byte node id
  // 40: 4 byte version ID
  // 44 bytes total

  // send my info to the world...
  uint8_t data[44] = {0};
  data[0] = 255;
  data[1] = 1;
  
  for (byte x = 0; x < 4; x++) {
    data[x + 2] = ip[x];
  }
  memcpy((byte *)data + 6, serverDescription, 32);
  #ifdef ESP8266
  data[38] = NODE_TYPE_ID_ESP8266;
  #elif defined(ARDUINO_ARCH_ESP32)
  data[38] = NODE_TYPE_ID_ESP32;
  #else
  data[38] = NODE_TYPE_ID_UNDEFINED;
  #endif
  data[39] = ip[3]; // unit ID == last IP number

  uint32_t build = VERSION;
  for (byte i=0; i<sizeof(uint32_t); i++)
    data[40+i] = (build>>(8*i)) & 0xFF;

  IPAddress broadcastIP(255, 255, 255, 255);
  notifier2Udp.beginPacket(broadcastIP, udpPort2);
  notifier2Udp.write(data, sizeof(data));
  notifier2Udp.endPacket();
}


/*********************************************************************************************\
 * Art-Net, DDP, E131 output - work in progress
\*********************************************************************************************/

#define DDP_HEADER_LEN 10
#define DDP_SYNCPACKET_LEN 10

#define DDP_FLAGS1_VER 0xc0  // version mask
#define DDP_FLAGS1_VER1 0x40 // version=1
#define DDP_FLAGS1_PUSH 0x01
#define DDP_FLAGS1_QUERY 0x02
#define DDP_FLAGS1_REPLY 0x04
#define DDP_FLAGS1_STORAGE 0x08
#define DDP_FLAGS1_TIME 0x10

#define DDP_ID_DISPLAY 1
#define DDP_ID_CONFIG 250
#define DDP_ID_STATUS 251

// 1440 channels per packet
#define DDP_CHANNELS_PER_PACKET 1440 // 480 leds

//
// Send real time UDP updates to the specified client
//
// type   - protocol type (0=DDP, 1=E1.31, 2=ArtNet)
// client - the IP address to send to
// length - the number of pixels
// buffer - a buffer of at least length*4 bytes long
// isRGBW - true if the buffer contains 4 components per pixel

uint8_t sequenceNumber = 0; // this needs to be shared across all outputs

uint8_t realtimeBroadcast(uint8_t type, IPAddress client, uint16_t length, uint8_t *buffer, uint8_t bri, bool isRGBW)  {
  if (!interfacesInited) return 1;  // network not initialised

  WiFiUDP ddpUdp;

  switch (type) {
    case 0: // DDP
    {
      // calclate the number of UDP packets we need to send
      uint16_t channelCount = length * 3; // 1 channel for every R,G,B value
      uint16_t packetCount = channelCount / DDP_CHANNELS_PER_PACKET;
      if (channelCount % DDP_CHANNELS_PER_PACKET) {
        packetCount++;
      }

      // there are 3 channels per RGB pixel
      uint32_t channel = 0; // TODO: allow specifying the start channel
      // the current position in the buffer 
      uint16_t bufferOffset = 0;

      for (uint16_t currentPacket = 0; currentPacket < packetCount; currentPacket++) {
        if (sequenceNumber > 15) sequenceNumber = 0;

        if (!ddpUdp.beginPacket(client, DDP_DEFAULT_PORT)) {  // port defined in ESPAsyncE131.h
          DEBUG_PRINTLN(F("WiFiUDP.beginPacket returned an error"));
          return 1; // problem
        }

        // the amount of data is AFTER the header in the current packet
        uint16_t packetSize = DDP_CHANNELS_PER_PACKET;

        uint8_t flags = DDP_FLAGS1_VER1;
        if (currentPacket == (packetCount - 1)) {
          // last packet, set the push flag
          // TODO: determine if we want to send an empty push packet to each destination after sending the pixel data
          flags = DDP_FLAGS1_VER1 | DDP_FLAGS1_PUSH;
          if (channelCount % DDP_CHANNELS_PER_PACKET) {
            packetSize = channelCount % DDP_CHANNELS_PER_PACKET;
          }
        }

        // write the header
        /*0*/ddpUdp.write(flags);
        /*1*/ddpUdp.write(sequenceNumber++ & 0x0F); // sequence may be unnecessary unless we are sending twice (as requested in Sync settings)
        /*2*/ddpUdp.write(0);
        /*3*/ddpUdp.write(DDP_ID_DISPLAY);
        // data offset in bytes, 32-bit number, MSB first
        /*4*/ddpUdp.write(0xFF & (channel >> 24));
        /*5*/ddpUdp.write(0xFF & (channel >> 16));
        /*6*/ddpUdp.write(0xFF & (channel >>  8));
        /*7*/ddpUdp.write(0xFF & (channel      ));
        // data length in bytes, 16-bit number, MSB first
        /*8*/ddpUdp.write(0xFF & (packetSize >> 8));
        /*9*/ddpUdp.write(0xFF & (packetSize     ));

        // write the colors, the write write(const uint8_t *buffer, size_t size) 
        // function is just a loop internally too
        for (uint16_t i = 0; i < packetSize; i += 3) {
          ddpUdp.write(scale8(buffer[bufferOffset++], bri)); // R
          ddpUdp.write(scale8(buffer[bufferOffset++], bri)); // G
          ddpUdp.write(scale8(buffer[bufferOffset++], bri)); // B
          if (isRGBW) bufferOffset++;
        }

        if (!ddpUdp.endPacket()) {            
          DEBUG_PRINTLN(F("WiFiUDP.endPacket returned an error"));
          return 1; // problem
        }

        channel += packetSize;
      }
    } break;

    case 1: //E1.31
    {
    } break;

    case 2: //ArtNet
    {
    } break;
  }
  return 0;
}