A Ruby script that checks a Gmail inbox for new mail and shares info about how it was classified

inboxcheck.rb

# inboxcheck.rb monitors a Gmail account for new mails and returns
# info (as JSON) about the first new mail from a specified address
#
# This is used to see if our newsletter testing mails arrive at
# Gmail and then if they go into spam, promotions or the normal inbox.
#
# To use or work on this script for yourself, follow steps 1 and 2 at
# https://developers.google.com/gmail/api/quickstart/ruby to get set
# up with the Google API stuff. Make sure client_secret.json ends up
# in the same directory as this script, then you're good to go.
#
# GmailV1 Ruby API docs I found useful:
# http://www.rubydoc.info/github/google/google-api-ruby-client/Google/Apis/GmailV1
#
# P.S. I know the structure and style of this script is hideous,
# but it works for now =)
#
# Peter Cooper (January 12, 2017)
# WTFPL License, except for 'authorize' method which is Apache 2
# licensed by Google (as it's based on their sample code!)

require 'google/apis/gmail_v1'
require 'googleauth'
require 'googleauth/stores/file_token_store'
require 'fileutils'
require 'json'

MAX_TIME_TO_RUN = 600
SLEEP_TIME = 18
MAX_AGE_OF_EMAIL = 0
FROM_EMAIL = ARGV.first || ''  # No email specified? Check for any address

SERVICE = Google::Apis::GmailV1::GmailService.new
SERVICE.client_options.application_name = 'InboxChecker'

def authorize
  credentials_path = File.join(Dir.home, '.credentials','gmail-api.yaml')

  FileUtils.mkdir_p(File.dirname(credentials_path))

  client_id = Google::Auth::ClientId.from_file(__dir__ + "/client_secret.json")
  token_store = Google::Auth::Stores::FileTokenStore.new(file: credentials_path)
  authorizer = Google::Auth::UserAuthorizer.new(client_id, Google::Apis::GmailV1::AUTH_GMAIL_READONLY, token_store)
  user_id = 'default'
  credentials = authorizer.get_credentials(user_id)
  if credentials.nil?
    url = authorizer.get_authorization_url(base_url: 'urn:ietf:wg:oauth:2.0:oob')
    puts "Open the following URL in the browser and enter the resulting code after authorization:"
    puts url
    code = gets
    credentials = authorizer.get_and_store_credentials_from_code(user_id: user_id, code: code, base_url: 'urn:ietf:wg:oauth:2.0:oob')
  end
  credentials
end

def get_emails
  emails = []
  user_id = 'me'
  messages = SERVICE.list_user_messages(user_id, include_spam_trash: true, max_results: 8).messages

  messages.each do |msg|
    id = msg.id
    message = SERVICE.get_user_message(user_id, id, format: 'metadata')
    headers = Hash[message.payload.headers.map { |h| [h.name, h.value] }]

    date = Time.at(message.internal_date.to_i / 1000)
    labels = message.label_ids
    snippet = message.snippet
    from = headers["From"]
    subject = headers["Subject"]

    status = :unknown
    status = :personal if message.label_ids.include?('CATEGORY_PERSONAL')
    status = :social if message.label_ids.include?('CATEGORY_SOCIAL')
    status = :updates if message.label_ids.include?('CATEGORY_UPDATES')
    status = :forums if message.label_ids.include?('CATEGORY_FORUMS')
    status = :promotions if message.label_ids.include?('CATEGORY_PROMOTIONS')
    status = :spam if message.label_ids.include?('SPAM')

    email = { age: (Time.now - date).to_i / 60, from: from, subject: subject, status: status, snippet: snippet }

    emails << email
  end

  emails
end

# --- main program starts here

SERVICE.authorization = authorize

result = nil
start_time = Time.now.to_i

while Time.now.to_i - start_time < MAX_TIME_TO_RUN
  STDERR.puts "Fetching email."
  emails = get_emails

  # Is there a mail < 1 minute old from the address we want?
  break if result = emails.detect { |e| e[:age] <= MAX_AGE_OF_EMAIL && e[:from].include?(FROM_EMAIL) }

  STDERR.puts "No email found. Waiting #{SLEEP_TIME} seconds."
  sleep SLEEP_TIME
end

puts result ? result.to_json : "{}"