Feat: Support for Microsoft Oauth in Email Channel (#6227)

- Adds the backend APIs required for Microsoft Email Channels

Co-authored-by: Pranav Raj S <pranav@chatwoot.com>
Co-authored-by: Sojan <sojan@pepalo.com>

app/jobs/inboxes/fetch_imap_emails_job.rb

@@ -6,9 +6,7 @@ class Inboxes::FetchImapEmailsJob < ApplicationJob
   def perform(channel)
     return unless should_fetch_email?(channel)
 
-    fetch_mail_for_channel(channel)
-    # clearing old failures like timeouts since the mail is now successfully processed
-    channel.reauthorized!
+    process_email_for_channel(channel)
   rescue *ExceptionList::IMAP_EXCEPTIONS
     channel.authorization_error!
   rescue EOFError => e
@@ -23,6 +21,17 @@ class Inboxes::FetchImapEmailsJob < ApplicationJob
     channel.imap_enabled? && !channel.reauthorization_required?
   end
 
+  def process_email_for_channel(channel)
+    # fetching email for microsoft provider
+    if channel.microsoft?
+      fetch_mail_for_ms_provider(channel)
+    else
+      fetch_mail_for_channel(channel)
+    end
+    # clearing old failures like timeouts since the mail is now successfully processed
+    channel.reauthorized!
+  end
+
   def fetch_mail_for_channel(channel)
     # TODO: rather than setting this as default method for all mail objects, lets if can do new mail object
     # using Mail.retriever_method.new(params)
@@ -41,9 +50,51 @@ class Inboxes::FetchImapEmailsJob < ApplicationJob
     end
   end
 
+  def fetch_mail_for_ms_provider(channel)
+    return if channel.provider_config['access_token'].blank?
+
+    access_token = valid_access_token channel
+
+    return unless access_token
+
+    imap = imap_authenticate(channel, access_token)
+
+    process_mails(imap, channel)
+  end
+
+  def process_mails(imap, channel)
+    imap.search(['BEFORE', tomorrow, 'SINCE', yesterday]).each do |message_id|
+      inbound_mail = Mail.read_from_string imap.fetch(message_id, 'RFC822')[0].attr['RFC822']
+
+      next if channel.inbox.messages.find_by(source_id: inbound_mail.message_id).present?
+
+      process_mail(inbound_mail, channel)
+    end
+  end
+
+  def imap_authenticate(channel, access_token)
+    imap = Net::IMAP.new(channel.imap_address, channel.imap_port, true)
+    imap.authenticate('XOAUTH2', channel.imap_login, access_token)
+    imap.select('INBOX')
+    imap
+  end
+
+  def yesterday
+    (Time.zone.today - 1).strftime('%d-%b-%Y')
+  end
+
+  def tomorrow
+    (Time.zone.today + 1).strftime('%d-%b-%Y')
+  end
+
   def process_mail(inbound_mail, channel)
     Imap::ImapMailbox.new.process(inbound_mail, channel)
   rescue StandardError => e
     ChatwootExceptionTracker.new(e, account: channel.account).capture_exception
   end
+
+  # Making sure the access token is valid for microsoft provider
+  def valid_access_token(channel)
+    Microsoft::RefreshOauthTokenService.new(channel: channel).access_token
+  end
 end