require "net/imap"
class FetchEmails
  include Interactor

  OUTLOOK_IMAP_HOST = 'outlook.office365.com'
  OUTLOOK_IMAP_PORT = 993
  SENT_FOLDER_NAME = 'Sent Items'
  INBOX_FOLDER_NAME = 'INBOX'
  DRAFTS_FOLDER_NAME = 'Drafts'

  def call
    establish_imap_connection(
      host: OUTLOOK_IMAP_HOST,
      port: OUTLOOK_IMAP_PORT,
      username: context.email,
      password: context.password
    ) do |imap|
      context.messages=get_messages(
        imap: imap,
        folder: INBOX_FOLDER_NAME,
        after_datetime: context.query_from
      )
    end
  end

  def establish_imap_connection(host:, port:, username:, password:)
    connection = Net::IMAP.new(OUTLOOK_IMAP_HOST, OUTLOOK_IMAP_PORT, ssl: true)
    connection.login(username, password)
    return connection unless block_given?
    begin
      yield connection
    ensure
      connection&.disconnect
    end
  end

  # imap_query: is an array following IMAP query format such as ["SINCE", "11-Jan-2021"]
  def get_messages(imap:, folder: INBOX_FOLDER_NAME, after_datetime: nil, imap_query: nil)
    raise ::NotImplementedError, 'Still to be implemented fetching of all messages' unless imap_query || after_datetime

    query = if imap_query
              imap_query
            elsif after_datetime
              # The IMAP SINCE filter does not accept a time component to be able to skip
              # the fetching will iterate over the emails but will not include the ones that
              # have a date on the envelope that is in the past respect to after_datetime
              # therefore ignoring these.
              ['SINCE', after_datetime.strftime('%d-%b-%Y')]
            end

    messages = []
    
    imap.examine(folder)
    imap.search(query).each do |message_id|
      res = imap.fetch(message_id, %w(RFC822 ENVELOPE UID))[0]
      envelope = res.attr['ENVELOPE']
      next if after_datetime && envelope.date.to_time.to_i < after_datetime.to_i

      rfc = res.attr['RFC822']
      uid = res.attr['UID']
      mail = Mail::Message.new(rfc)
      message = OpenStruct.new(
        date: envelope.date.to_time.utc.iso8601,
        thread: mail.references,
        from: "#{envelope.from&.dig(0)&.name} <#{envelope.from&.dig(0)&.mailbox}@#{envelope.from&.dig(0)&.host}>",
        subject: envelope.subject,
        mail_object: mail,
        uid: uid,
      )
      messages << message
    end

    messages
  end
end