const API_KEY = "af462d6b6a9814ebd17fcc53e7316afb";

function readFromAddress(address, success, failure) {
  function toByteArray(hex) {
    return hex.match(/.{1,2}/g).map(function(h) { return parseInt(h, 16) });
  }
  function toHexString(bytes) {
    return bytes.map(function(b) { return b.toString(16) }).join('');
  }

  function parseResponse(responseText) {
    var response = JSON.parse(responseText).filter(function(transaction) {
      return transaction.receiver_addresses.contains(address);
    }).map(function(transaction) {
      var payload = toByteArray(transaction.hex);
      var version = (payload[0] >> 5);
      var command = (payload[0] & ((1 << 5) - 1));
      var data = payload.slice(1);
      if (command & parseInt('10000', 2)) {
        var counter = parseInt(toHexString(data.slice(0, 4)), 16);
        var string = data.slice(4);
        return {counter: counter, command: command, payload: string};
      } else {
        return null;
      }
    }).filter(function(transaction) {
      return transaction != null
    }).sort(function(a, b) {
      return a.counter - b.counter;
    });

    var output = [], buffer = [];
    for (var i = 0; i < reseponse.length; i++) {
      if (response.command & 1) {
        buffer = [];
      }
      buffer = buffer.concat(response.payload);
      if (response.command & 2) {
        output.push(new Uint8Array(buffer));
      }
    }
    return output;
  }

  var promise = null;
  if (typeof success == 'undefined') {
    // Try to load a promise
    if (typeof Promise != 'undefined') {  // ECMAScript 6 Promises
      promise = new Promise();
    } else if (typeof jQuery != 'undefined') {  // jQuery
      promise = jQuery.Deferred();
    } else if (typeof $q != 'undefined') {  // AngularJS and Q
      promise = $q.defer();
    } else {
      console.warn("No promise engine detected and no success callback received. Ignoring call...");
      return;
    }
  }
  var xmlHttp = new XMLHttpRequest();
  xmlHttp.onreadystatechange = function() {
    if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {
      if (promise != null) {
        promise.resolve(parseResponse(xmlHttp.responseText));
      } else if (success) {
        success(parseResponse(xmlHttp.responseText));
      }
    } else {
      if (promise != null) {
        promise.reject("Received HTTP status: " + xmlHttp.status + ", " + xmlHttp.responseText);
      } else if (failure) {
        failure("Received HTTP status: " + xmlHttp.status + ", " + xmlHttp.responseText);
      }
    }
  };
  xmlHttp.open("GET", "https://api.chain.com/v2/bitcoin/addresses/" + address + "/op-returns?api-key=" + API_KEY);
  xmlHttp.send(null);
}

function main() {
  if (process.argv.length < 2) {
    console.error("Usage: reader.js <receiving address>");
  } else {
    console.log(readFromAddress(process.argv[1]));
  }
}

if (typeof window == 'undefined' && require.main === module) {  // Node.js
  main();
}