PUNEET PANDEY's WEBLOG

# lib/box_api.rb
require 'json'
require "openssl"
require 'securerandom'
require 'jwt'
require 'json'
require 'uri'
require 'net/https'
class BoxApi
  def initialize unique_identifier = nil
    @unique_identifier  = unique_identifier
    @access_token       = Rails.cache.fetch("users/#{@unique_identifier}/box/access_token")
  end
  def get_token
    return @access_token unless @access_token.nil?
    set_auth
    # Make the request
    uri = URI.parse(@authentication_url)
    http = Net::HTTP.start(uri.host, uri.port, use_ssl: true)
    request = Net::HTTP::Post.new(uri.request_uri)
    request.body = @params
    response = http.request(request)
    # Parse the JSON and extract the access token
    @access_token = Rails.cache.fetch("users/#{@unique_identifier}/box/access_token", expires_in: 60.minutes) do
      JSON.parse(response.body)['access_token']
    end
    return @access_token
  end
  def find_or_create_folder_by_folder_name folder_name = @unique_identifier
    root_folder     = find_folder "Client Uploads"
    root_folder     = create_folder "Client Uploads" if !root_folder
    child_folder    = find_folder folder_name, root_folder["id"]
    child_folder    = create_folder folder_name, root_folder["id"] if !child_folder
    return child_folder["id"]
  end
  def find_folder folder_name, parent_folder_id = nil
    base_url = "https://api.box.com/2.0/search?query='#{folder_name}'&type=folder"
    base_url += "&ancestor_folder_ids=#{parent_folder_id}" if parent_folder_id
    uri = URI.parse(base_url)
    request = Net::HTTP::Get.new(uri)
    request["Authorization"] = "Bearer #{@access_token}"
    req_options = {
      use_ssl: uri.scheme == "https",
    }
    response = Net::HTTP.start(uri.hostname, uri.port, req_options) do |http|
      http.request(request)
    end
    response_body = JSON.parse(response.body)
    return false if response_body["total_count"] == 0 && response_body["entries"].empty?
    return response_body["entries"][0]
  end
  def create_folder folder_name, parent_folder_id = nil
    uri = URI.parse("https://api.box.com/2.0/folders")
    request = Net::HTTP::Post.new(uri)
    request.content_type = "application/json"
    request["Authorization"] = "Bearer #{@access_token}"
    params = {}
    params["name"] = folder_name
    params["parent"] = {
      "id" => parent_folder_id ? parent_folder_id : "0"
    }
    request.body = JSON.dump(params)
    req_options = {
      use_ssl: uri.scheme == "https",
    }
    response = Net::HTTP.start(uri.hostname, uri.port, req_options) do |http|
      http.request(request)
    end
    response_body = JSON.parse(response.body)
    return response_body if response.code == "201"
  end
private
  def set_auth
    @config = JSON.parse(
      File.read("#{Rails.root.join}/config/box_config.json")
    )
    @config = Rails.env.production? ? @config["production"] : @config["base"]
    @appAuth = @config['boxAppSettings']['appAuth']
    key = OpenSSL::PKey::RSA.new(
      @appAuth['privateKey'],
      @appAuth['passphrase']
    )
    @authentication_url = 'https://api.box.com/oauth2/token'
    claims = {
      iss: @config['boxAppSettings']['clientID'],
      sub: @config['enterpriseID'],
      box_sub_type: 'enterprise',
      aud: @authentication_url,
      # This is an identifier that helps protect against
      # replay attacks
      jti: SecureRandom.hex(64),
      # We give the assertion a lifetime of 45 seconds
      # before it expires
      exp: Time.now.to_i + 45
    }
    keyId = @appAuth['publicKeyID']
    # Rather than constructing the JWT assertion manually, we are
    # using the pyjwt library.
    # The API support "RS256", "RS384", and "RS512" encryption
    assertion = JWT.encode(claims, key, 'RS512', { kid: keyId })
    # We are using the excellent axios package
    # to simplify the API call
    @params = URI.encode_www_form({
      # This specifies that we are using a JWT assertion
      # to authenticate
      grant_type: 'urn:ietf:params:oauth:grant-type:jwt-bearer',
      # Our JWT assertion
      assertion: assertion,
      # The OAuth 2 client ID and secret
      client_id: @config['boxAppSettings']['clientID'],
      client_secret: @config['boxAppSettings']['clientSecret']
    })
  end
end

# /app/controllers/home_controller.rb
class HomeController < ApplicationController
  def connect_to_box
    api        = BoxApi.new(user.company.name)
    token      = api.get_token
    folder_id  = api.find_or_create_folder_by_folder_name
    respond_to do | wants |
      wants.json do
        render json: {
          success: true,
          access_token: token,
          folder_id: folder_id
        }
      end
    end
  end
end

/app/views/home/files.html.erb
<%= content_for :page_css do %>
  <link rel="stylesheet" href="https://cdn01.boxcdn.net/platform/elements/13.0.0/en-US/explorer.css" />
<% end %>
<%= content_for :page_js do %>
  <!-- polyfill.io only loads the polyfills your browser needs -->
  https://cdn.polyfill.io/v2/polyfill.min.js?features=es6,Intl
  https://cdn01.boxcdn.net/platform/elements/13.0.0/en-US/explorer.js
<% end %>
<div class=<%= "#{controller_name}_#{action_name}" %>>
  <div id="uploader-panel" class="box-light-blue">
    <div class="container">
      <div class="row">
        <div class="col-md-12">
          <div class="text-center result-overlay">
            <%= image_tag 'pageloader.svg' %>
          </div>
          <div class="box-list-container" style="width: 100%; height: 100%; margin: 0; padding: 0; min-width: 320px;"></div>
        </div>
      </div>
    </div>
  </div>
</div>
<script type="text/javascript">
  $(document).ready(function() {
    //connecting to box to fetch required token and folder
    $.ajax({
      url: '/home/connect_to_box',
      type: 'POST',
      dataType: 'json',
      success: function(response) {
        if(response['success'] === true){
          $("div.result-overlay").hide();
          const folderId = response['folder_id'];
          const accessToken = response['access_token'];
          const logoUrl = "<%= asset_path('logo-blue.jpg') %>";
          const contentExplorer = new Box.ContentExplorer();
          // for more options visit: https://developer.box.com/guides/embed/ui-elements/uploader/#options
          contentExplorer.show(folderId, accessToken, {
            container: ".box-list-container",
            canDownload: true,
            canUpload: true,
            canCreateNewFolder: true,
            sortBy: "date",
            sortDirection: "DESC",
            logoUrl: logoUrl,
            onClose: null
          });
          contentExplorer.on('upload', (data) => {
            //notify via slack
            $.ajax({
              url: '/home/upload_notify',
              type: 'POST',
              beforeSend: function(xhr) {xhr.setRequestHeader('X-CSRF-Token', $('meta[name="csrf-token"]').attr('content'))},
              dataType: "json",
              data: {files: JSON.stringify(data)}
            });
          });
          contentExplorer.on('error', (data) => {
            alert(`Error uploading file with name "${data.file.name}". The error was: "${data.error}"`);
          });
        }
      }
    })
  });
</script>