1 files changed, 51 insertions, 0 deletions
diff --git a/vendor/gems/microsoft_graph_mailer/lib/microsoft_graph_mailer/client.rb b/vendor/gems/microsoft_graph_mailer/lib/microsoft_graph_mailer/client.rb
new file mode 100644
index 00000000000..b779bb28c39
--- /dev/null
+++ b/vendor/gems/microsoft_graph_mailer/lib/microsoft_graph_mailer/client.rb
@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+require "oauth2"
+
+module MicrosoftGraphMailer
+  class Client
+    attr_accessor :user_id, :tenant, :client_id, :client_secret, :azure_ad_endpoint, :graph_endpoint
+
+    def initialize(user_id:, tenant:, client_id:, client_secret:, azure_ad_endpoint:, graph_endpoint:)
+      @user_id = user_id
+      @tenant = tenant
+      @client_id = client_id
+      @client_secret = client_secret
+      @azure_ad_endpoint = azure_ad_endpoint
+      @graph_endpoint = graph_endpoint
+    end
+
+    def send_mail(message_in_mime_format)
+      # https://docs.microsoft.com/en-us/graph/api/user-sendmail
+      token.post(
+        send_mail_url,
+        headers: { "Content-type" => "text/plain" },
+        body: Base64.encode64(message_in_mime_format)
+      )
+    end
+
+    private
+
+    def token
+      # https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-oauth2-client-creds-grant-flow
+      OAuth2::Client.new(
+        client_id,
+        client_secret,
+        site: azure_ad_endpoint,
+        token_url: "/#{tenant}/oauth2/v2.0/token"
+      ).client_credentials.get_token({ scope: scope })
+    end
+
+    def scope
+      "#{graph_endpoint}/.default"
+    end
+
+    def base_url
+      "#{graph_endpoint}/v1.0/users/#{user_id}"
+    end
+
+    def send_mail_url
+      "#{base_url}/sendMail"
+    end
+  end
+end