create graph api client to handle requests

lib/microsoft_graph.rb

@@ -0,0 +1,83 @@
+require 'httparty'
+
+class MicrosoftGraph
+  BASE_URL = 'https://graph.microsoft.com/v1.0'.freeze
+  BETA_BASE_URL = 'https://graph.microsoft.com/beta'.freeze
+  # Documentation says that "common" can be used (instead of tenantID) to refresh access token
+  REFRESH_TOKEN_URL = 'https://login.microsoftonline.com/common/oauth2/v2.0/token'.freeze
+
+  def initialize(current_user, client_id, client_secret, scopes)
+    @current_user = current_user
+    @uid = current_user.microsoft_user_id
+    @token = current_user.microsoft_access_token
+    @refresh_token = current_user.microsoft_refresh_token
+    @expires_at = current_user.microsoft_token_expires_at
+
+    @client_id = client_id
+    @client_secret = client_secret
+    @scopes = scopes
+  end
+
+  def request(resource)
+    return false unless @token
+
+    response = HTTParty.get(
+      "#{BASE_URL}/#{resource}",
+      headers: {
+        Authorization: "Bearer #{@token}"
+      }
+    )
+
+    if response.code != 200
+      p '[Microsoft Graph API Error]'
+      p response.inspect
+      false
+    else
+      JSON.parse(response.body)
+    end
+  end
+
+  def create_teams_meeting(start_date_time, end_date_time, subject)
+    # check if token expired and obtain new access_token using refresh token
+
+    response = HTTParty.post(
+      "#{BETA_BASE_URL}/me/onlineMeetings",
+      body: {
+        startDateTime: start_date_time,
+        endDateTime: end_date_time,
+        subject: subject,
+        participants: {
+          organizer: {
+            identity: {
+              user: {
+                id: @uid
+              }
+            }
+          }
+        }
+      },
+      headers: {
+        Authorization: "Bearer #{@token}"
+      }
+    )
+
+    if response.code != 201
+      p '[Microsoft Graph API Error] Failed to create online meeting'
+      p response.inspect
+    else
+      JSON.parse(response.body)
+    end
+  end
+
+  def refresh_token
+    response = HTTParty.post(REFRESH_TOKEN_URL,
+                             body: {
+                               client_id: @client_id,
+                               client_secret: @client_secret,
+                               refresh_token: @refresh_token,
+                               grant_type: 'refresh_token',
+                               scope: @scopes
+                             })
+
+  end
+end