LotaryContract.js

console.log('> LotaryContract: Init: v 0.32')

const _ = require('lodash');

// Define new contract
var contract = {};

// Reset/Init the contract
contract.reset = function() {
  contract.balance = 0;
  contract.players = [];
  contract.threshold = 3;		
}

// Get random winner and send him a TX with the collective reward
contract.executeLotary = function() {
  var w = contract.getWinner();
  var reward = contract.balance * 100000000;
  console.log('> observer:executeLotary: Got a winner and sending his reward: ', w, reward);
  app.serverWallet.sendTx('reward', w.address, Math.floor(reward)).then(()=> {
    contract.reset();
  }).fail((err)=>{
    console.log('> observer:executeLotary: Failed to send the reward. Will retry once.', err);
    app.serverWallet.sendTx('reward', w.address, Math.floor(reward));
  })
}

// Helper: Get a random winner
contract.getWinner = function(){
  var winnerIndex = Math.floor(Math.random() * (contract.players.length));
  return { address: contract.players[winnerIndex], index: winnerIndex };
}

// Event that is triggered on TX that was sent to our contract
app.observer.onDetectPayment = function(data) {
  var d = {};

  // Get the relevant input for our contract
  var input = _.filter(data.payload.transaction.inputs, (v)=> {
    return !_.includes(v.addresses, addr);
  })

  // If input was not found, or empty, ignore event
  if (input == null || input.length == 0 || input[0].addresses[0] == addr) {
    console.log('> observer:onDetectPayment: Detected outgoing transaction, ignoring');
    return;
  }

  // Grab the originator address
  d.from = input[0].addresses; 
  var output = _.filter(data.payload.transaction.outputs, (v)=> {
    return _.includes(v.addresses, addr);
  })
  // Grab the amount
  d.amount = output[0].value_int / 100000000; 

  // Aggregate the amount into total contract balance
  contract.balance = d.amount + (contract.balance || 0);
  // Collect the new participant
  if (contract.players == null) contract.players = [];
  contract.players.push(d.from[0]);

  // Check if reached the max players / threshold, if so, execute the lotary
  if (contract.players.length >= contract.threshold) {
    console.log('> observer:onDetectPayment: reached threshold! rolling the dice');
    contract.executeLotary();
  }
}

// Set the contract to be used in the app
app.contract = contract;

// Assign the contract address
contract.address = app.contractAddress;

// Init the contract
app.contract.reset();