# encoding: utf-8

module Mail
  # The IMAP retriever allows to get the last, first or all emails from a POP3 server.
  # Each email retrieved (RFC2822) is given as an instance of +Message+.
  #
  # While being retrieved, emails can be yielded if a block is given.
  #
  # === Example of retrieving Emails from GMail:
  #
  #   Mail.defaults do
  #     retriever_method :imap, { :address             => "imap.googlemail.com",
  #                               :port                => 993,
  #                               :user_name           => '<username>',
  #                               :password            => '<password>',
  #                               :enable_ssl          => true }
  #   end
  #
  #   Mail.all    #=> Returns an array of all emails
  #   Mail.first  #=> Returns the first unread email
  #   Mail.last   #=> Returns the first unread email
  #
  # You can also pass options into Mail.find to locate an email in your imap mailbox
  # with the following options:
  #
  #   mailbox: name of the mailbox used for email retrieval. The default is 'INBOX'.
  #   what:    last or first emails. The default is :first.
  #   order:   order of emails returned. Possible values are :asc or :desc. Default value is :asc.
  #   count:   number of emails to retrieve. The default value is 10. A value of 1 returns an
  #            instance of Message, not an array of Message instances.
  #
  #   Mail.find(:what => :first, :count => 10, :order => :asc)
  #   #=> Returns the first 10 emails in ascending order
  #
  class IMAP
    require 'net/imap'
    
    def initialize(values)
      self.settings = { :address              => "localhost",
                        :port                 => 110,
                        :user_name            => nil,
                        :password             => nil,
                        :authentication       => nil,
                        :enable_ssl           => false }.merge!(values)
    end

    attr_accessor :settings

    # Get the oldest received email(s)
    #
    # Possible options:
    #   mailbox: mailbox to retrieve the oldest received email(s) from. The default is 'INBOX'.
    #   count:   number of emails to retrieve. The default value is 1.
    #   order:   order of emails returned. Possible values are :asc or :desc. Default value is :asc.
    #   keys:    keywords for the imap SEARCH command. Can be either a string holding the entire 
    #            search string or a single-dimension array of search keywords and arguments.
    #
    def first(options={}, &block)
      options ||= {}
      options[:what] = :first
      options[:count] ||= 1
      find(options, &block)
    end

    # Get the most recent received email(s)
    #
    # Possible options:
    #   mailbox: mailbox to retrieve the most recent received email(s) from. The default is 'INBOX'.
    #   count:   number of emails to retrieve. The default value is 1.
    #   order:   order of emails returned. Possible values are :asc or :desc. Default value is :asc.
    #   keys:    keywords for the imap SEARCH command. Can be either a string holding the entire 
    #            search string or a single-dimension array of search keywords and arguments.
    #
    def last(options={}, &block)
      options ||= {}
      options[:what] = :last
      options[:count] ||= 1
      find(options, &block)
    end

    # Get all emails.
    #
    # Possible options:
    #   mailbox: mailbox to retrieve all email(s) from. The default is 'INBOX'.
    #   count:   number of emails to retrieve. The default value is 1.
    #   order:   order of emails returned. Possible values are :asc or :desc. Default value is :asc.
    #   keys:    keywords for the imap SEARCH command. Can be either a string holding the entire 
    #            search string or a single-dimension array of search keywords and arguments.
    #
    def all(options={}, &block)
      options ||= {}
      options[:count] = :all
      options[:keys]  = 'ALL'
      find(options, &block)
    end
    
    # Find emails in a POP3 mailbox. Without any options, the 10 last received emails are returned.
    #
    # Possible options:
    #   mailbox: mailbox to search the email(s) in. The default is 'INBOX'.
    #   what:    last or first emails. The default is :first.
    #   order:   order of emails returned. Possible values are :asc or :desc. Default value is :asc.
    #   count:   number of emails to retrieve. The default value is 10. A value of 1 returns an
    #            instance of Message, not an array of Message instances.
    #
    def find(options={}, &block)
      options = validate_options(options)

      start do |imap|
        imap.select(options[:mailbox])

        message_ids = imap.uid_search(options[:keys])
        message_ids.reverse! if options[:what].to_sym == :last
        message_ids = message_ids.first(options[:count]) if options[:count].is_a?(Integer)
        message_ids.reverse! if (options[:what].to_sym == :last && options[:order].to_sym == :asc) ||
                                (options[:what].to_sym != :last && options[:order].to_sym == :desc)

        if block_given?
          message_ids.each do |message_id|
            fetchdata = imap.uid_fetch(message_id, ['RFC822'])[0]

            yield Mail.new(fetchdata.attr['RFC822'])
          end
        else
          emails = []
          message_ids.each do |message_id|
            fetchdata = imap.uid_fetch(message_id, ['RFC822'])[0]

            emails << Mail.new(fetchdata.attr['RFC822'])
          end
          emails.size == 1 && options[:count] == 1 ? emails.first : emails
        end
      end
    end

    # Delete all emails from a IMAP mailbox
    def delete_all(mailbox='INBOX')
      mailbox ||= 'INBOX'

      start do |imap|
        imap.select(mailbox)
        imap.uid_search(['ALL']).each do |message_id|
          imap.uid_store(message_id, "+FLAGS", [Net::IMAP::DELETED])
        end
        imap.expunge
      end
    end

    # Returns the connection object of the retrievable (IMAP or POP3)
    def connection(&block)
      raise ArgumentError.new('Mail::Retrievable#connection takes a block') unless block_given?

      start do |imap|
        yield imap
      end
    end

    private

      # Set default options
      def validate_options(options)
        options ||= {}
        options[:mailbox] ||= 'INBOX'
        options[:count]   ||= 10
        options[:order]   ||= :asc
        options[:what]    ||= :first
        options[:keys]    ||= 'ALL'
        options
      end

      # Start an IMAP session and ensures that it will be closed in any case.
      def start(config=Mail::Configuration.instance, &block)
        raise ArgumentError.new("Mail::Retrievable#imap_start takes a block") unless block_given?

        imap = Net::IMAP.new(settings[:address], settings[:port], settings[:enable_ssl], nil, false)
        imap.login(settings[:user_name], settings[:password])

        yield imap
      ensure
        if defined?(imap) && imap && !imap.disconnected?
          imap.disconnect
        end
      end

  end
end