Steem Blockchain Baby Rocking Cradle - https://steemit.com/steemhacks/@roelandp/rocking-our-baby-daughter-to-sleep-on-the-blockchain-powered-cradle-rocker

baby-rocking.js

var noble = require('noble-mac');

const control_service = "7d8f60dda0684320a05ffcb8c60d86bc";
const battery_service = "180f";

const state_characteristic = "88d3cea890bf40acae8d4ba145d6b009"
const speed_characteristic = "7653f4cc08594387a35789dfd4593a3c";
const mode_characteristic = "d49d811f8acc4bd0b020b64b26d0b038";

const battery_characteristic = "2a19";

var char_state;
var char_speed;
var char_mode;

var peripheral_global;

var dsteem = require('dsteem')

var mode = 2; // available modes: 0 = stop, 1 = snooze, 2 = wave, 3 = swing
var modes = ['stop','snooze','wave','swing'];


function message(msg){
    process.stdout.write('\033c');
    process.stdout.clearLine();
    process.stdout.cursorTo(0);
    process.stdout.write(msg);
}

function setSpeed(speed) {
  var speeddata = new Uint8Array(1);
  speeddata[0] = speed; // mode wave... (0 = stop)

  char_speed.write(new Buffer(speeddata), false, function(char_mode_write_err){
    if(char_mode_write_err) {
      message('char_speed_write_err', char_mode_write_err);
    } else {
      //message('wrote to characteristic and put the thing on speed: ',speed);
    }
  });
}

function setMode(mode) {
  var wavedata = new Uint8Array(1);
  wavedata[0] = mode; // mode wave... (0 = stop)

  char_mode.write(new Buffer(wavedata), false, function(char_mode_write_err){
    if(char_mode_write_err) {
      message('char_mode_write_err', char_mode_write_err);
    } else {
      message('Started Cradle Wave');
    }
  });
}

noble.on('stateChange', function(state) {
  if (state === 'poweredOn') {

    (noble.startScanning(control_service, false, function(err) {
      if(err) {
          message('err',err);
      } else {
        message('started scanning for peripherals');
      }

    }));

    noble.on('discover', function(peripheral) {
      //message(peripheral);

                  if(peripheral.id == "53aaf079d3784934b5deb7b3e143d26d"){

                    //message((peripheral))
                    message('peripheral found!');
                    peripheral_global = peripheral;

                    var serviceUUIDs = [control_service];

                    message('connecting to cradle...');

                    peripheral.connect(function(err){
                      if(err) {
                          message('connect err', err);
                      }

                      message(peripheral.state);
                      //peripheral.disconnect();

                      if(peripheral.state == "connected") {
                        peripheral.discoverServices(serviceUUIDs, function(error, services){
                          if(error) {
                              message('servdiscovery error',error);
                          } else {

                            message(':::::service found ::::');



                            services[0].discoverCharacteristics([state_characteristic,speed_characteristic,mode_characteristic], function(charerr,characteristics){
                              if(charerr) {
                                message('characteristics error',charerr);
                              } else {
                                message(':::::characteristics found, now mapping ::::', characteristics.length);
                                message("\n\n");


                                for(var i = 0; i < characteristics.length; i++) {

                                    if(characteristics[i].uuid == state_characteristic) {
                                      char_state = characteristics[i];
                                    }

                                    if(characteristics[i].uuid == speed_characteristic) {
                                      char_speed = characteristics[i];
                                    }

                                    if(characteristics[i].uuid == mode_characteristic) {
                                      char_mode = characteristics[i];
                                    }
                                }

                                message('mapped characteristics');

                                message('connecting to Steem chain');


                                var currentspeed = 0
                                var currenttxsize = 0
                                var maxtxsize = 0
                                var blockcount = 0;
                                var totaltx = 0;

                                var averagespeed = 2;

                                var client = new dsteem.Client('https://rpc.steemviz.com')
                                stream = client.blockchain.getBlockStream();

                                var waving = false;

                                stream.on('data', function(block) {

                                  if(!waving) {

                                    setMode(mode);
                                    waving = true;
                                  }



                                  //console.log(block);
                                  // analyse tx length
                                  var txsize = block.transactions.length

                                  totaltx += txsize;
                                  blockcount++;

                                  var avgtx = totaltx / blockcount;

                                  // if tx length > maxtxsize = maxtxsize = tx.length;

                                  var modifier = (txsize - avgtx) / avgtx;
                                  var speedmodifier = 4 * modifier;


                                  var cradlespeed = ((averagespeed + speedmodifier))

                                  if(cradlespeed < 0){

                                    cradlespeed = 0;
                                  }

                                  if(cradlespeed > 4){
                                    cradlespeed = 4;
                                  }

                                  var swappedtxt = '';
                                  if(block.witness == "roelandp") {
                                    // swap modes (!)

                                    mode++;
                                    if(mode > 3) {
                                      mode = 1;
                                    }

                                    setMode(mode);

                                    swappedtxt = 'OMG! Block signed by daddy! Swapping rocker mode to '+modes[mode];

                                  }

                                  message(block.block_id + ' signed by '+ block.witness + ' on ' + block.timestamp + '\n\nTransactions in block: + '+ block.transactions.length + 'tx\nAverage transactions: '+ avgtx+'\nModifier:'+ modifier +'\n\nSetting cradle wave speed to: '+ cradlespeed+'\n\n'+swappedtxt);

                                  setSpeed(cradlespeed);

                              })
                              .on('end', function() {
                                  // done
                                  message('END STREAMING BLOCKS');
                              });



                              }
                            });

                          }



                        }); // particular UUID's
                      }

                    });
                  }



    });

}  else {
    message('stop scanning');
    noble.stopScanning();
  }
});