GRN-59: Implemented pagination on the API call (#370)

* Added the env variable and functionality to paginate the call to the bbbapi

* Update user.rb

app/models/concerns/api_concern.rb

@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+
+# BigBlueButton open source conferencing system - http://www.bigbluebutton.org/.
+#
+# Copyright (c) 2018 BigBlueButton Inc. and by respective authors (see below).
+#
+# This program is free software; you can redistribute it and/or modify it under the
+# terms of the GNU Lesser General Public License as published by the Free Software
+# Foundation; either version 3.0 of the License, or (at your option) any later
+# version.
+#
+# BigBlueButton is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+# PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License along
+# with BigBlueButton; if not, see <http://www.gnu.org/licenses/>.
+
+module APIConcern
+  extend ActiveSupport::Concern
+  def bbb_endpoint
+    Rails.configuration.bigbluebutton_endpoint
+  end
+
+  def bbb_secret
+    Rails.configuration.bigbluebutton_secret
+  end
+
+  # Sets a BigBlueButtonApi object for interacting with the API.
+  def bbb
+    @bbb ||= if Rails.configuration.loadbalanced_configuration
+      lb_user = retrieve_loadbalanced_credentials(owner.provider)
+      BigBlueButton::BigBlueButtonApi.new(remove_slash(lb_user["apiURL"]), lb_user["secret"], "0.8")
+    else
+      BigBlueButton::BigBlueButtonApi.new(remove_slash(bbb_endpoint), bbb_secret, "0.8")
+    end
+  end
+
+  # Rereives the loadbalanced BigBlueButton credentials for a user.
+  def retrieve_loadbalanced_credentials(provider)
+    # Include Omniauth accounts under the Greenlight provider.
+    provider = "greenlight" if Rails.configuration.providers.include?(provider.to_sym)
+
+    # Build the URI.
+    uri = encode_bbb_url(
+      Rails.configuration.loadbalancer_endpoint + "getUser",
+      Rails.configuration.loadbalancer_secret,
+      name: provider
+    )
+
+    # Make the request.
+    http = Net::HTTP.new(uri.host, uri.port)
+    http.use_ssl = (uri.scheme == 'https')
+    response = http.get(uri.request_uri)
+
+    unless response.is_a?(Net::HTTPSuccess)
+      raise "Error retrieving provider credentials: #{response.code} #{response.message}"
+    end
+
+    # Parse XML.
+    doc = XmlSimple.xml_in(response.body, 'ForceArray' => false)
+
+    # Return the user credentials if the request succeeded on the loadbalancer.
+    return doc['user'] if doc['returncode'] == RETURNCODE_SUCCESS
+
+    raise "User with provider #{provider} does not exist." if doc['messageKey'] == "noSuchUser"
+    raise "API call #{url} failed with #{doc['messageKey']}."
+  end
+
+  # Builds a request to retrieve credentials from the load balancer.
+  def encode_bbb_url(base_url, secret, params)
+    encoded_params = OAuth::Helper.normalize(params)
+    string = "getUser" + encoded_params + secret
+    checksum = OpenSSL::Digest.digest('sha1', string).unpack("H*").first
+
+    URI.parse("#{base_url}?#{encoded_params}&checksum=#{checksum}")
+  end
+
+  # Removes trailing forward slash from a URL.
+  def remove_slash(s)
+    s.nil? ? nil : s.chomp("/")
+  end
+
+  # Format recordings to match their current use in the app
+  def format_recordings(api_res)
+    api_res[:recordings].each do |r|
+      next if r.key?(:error)
+      # Format playbacks in a more pleasant way.
+      r[:playbacks] = if !r[:playback] || !r[:playback][:format]
+        []
+      elsif r[:playback][:format].is_a?(Array)
+        r[:playback][:format]
+      else
+        [r[:playback][:format]]
+      end
+      r.delete(:playback)
+    end
+
+    api_res[:recordings].sort_by { |rec| rec[:endTime] }.reverse
+  end
+end