A ruby script to get a message by Message-Id via IMAP from Gmail

get-message-by-id-via-imap-from-gmail.rb

# # get-message-by-id-via-imap-from-gmail.rb
#
# ## Usage
#
# 1. Put the decryption key in a file
#
# ```console
# $ bundle install sekrets
# $ echo $your_decryption_key > .sekrets.key
# ```
#
# 2. Edit your settings file
#
# ```console
# $ sekrets edit settings.yml.enc
# ```
#
# ```settings.yml.enc
# imap:
#   host: imap.gmail.com
#   port: 993
#   usessl: true　
#   auth:
#     user: <%= your_user_name %>
#     password: <%= your_app_password %>
# ```
#
# 3. Run nyancat.rb
#
# ```console
# $ ruby get-message-by-id-via-imap-from-gmail.rb $message_id
# ```

require 'bundler/inline'

gemfile do
  source 'https://rubygems.org'
  gem 'mail'
  gem 'colorize'
  gem 'activesupport'
  gem 'sekrets'
  gem 'pry'
end

require 'net/imap'
require 'nkf'
require 'active_support/core_ext'

class NyanCat

  def initialize(settings_file_path:, message_id:)
    @settings_file_path = settings_file_path
    @message_id = message_id
  end

  def run
    if @message_id.blank?
      STDERR.puts("error: :message_id cannot be blank")
      return
    end
    @imap = Net::IMAP.new(
      settings.dig(:imap, :host),
      settings.dig(:imap, :port),
      settings.dig(:imap, :usessl)
    )
    STDERR.puts @imap.login(
      settings.dig(:imap, :auth, :user),
      settings.dig(:imap, :auth, :password),
    ).raw_data.strip.green
    STDERR.puts @imap.examine(
      Net::IMAP.encode_utf7('[Gmail]/すべてのメール')
    ).raw_data.strip.green
    uids = @imap.uid_search(['HEADER', 'MESSAGE-ID', @message_id])
    @imap.uid_fetch(uids, 'BODY.PEEK[]').each do |data|
     if data.attr.has_key?('UID') && data.attr.has_key?('BODY[]')
       mail = Mail.new(data.attr['BODY[]'])
       puts_mail(STDOUT, mail)
     else
       STDERR.puts("error: #{data}")
     end
    end
    STDERR.puts @imap.logout(
    ).raw_data.strip.green
    @imap.disconnect
  end

  private

    def settings
      @settings ||= Sekrets
        .settings_for(@settings_file_path)
        .deep_symbolize_keys
    end

    def puts_mail(stream, mail)
      stream.puts '```'
      stream.puts "Date: #{mail.date}"
      stream.puts "From: #{mail.from_addrs.join(', ')}"
      stream.puts "To: #{mail.to_addrs.join(', ')}"
      stream.puts "Cc: #{mail.cc_addrs.join(', ')}"
      stream.puts "Bcc: #{mail.bcc_addrs.join(', ')}"
      stream.puts "Message-Id: <#{mail.message_id}>"
      stream.puts "Subject: #{mail.subject}"
      stream.puts
      if mail.multipart?
        if mail.text_part
          body = mail.text_part.decoded
          stream.puts body
        elsif mail.html_part
          body = mail.html_part.decoded
          stream.puts body
        end
      else
        body = mail.body.to_s
        stream.puts body
      end
      stream.puts '```'
    end
end

NyanCat.new(
  settings_file_path: './settings.yml.enc',
  message_id: ARGV.first
).run