require 'rbconfig'
require 'pathname'
require 'guard/ui'
require 'guard/notifiers/gntp'
require 'guard/notifiers/growl'
require 'guard/notifiers/growl_notify'
require 'guard/notifiers/libnotify'
require 'guard/notifiers/rb_notifu'

module Guard

  # The notifier handles sending messages to different notifiers. Currently the following
  # libraries are supported:
  #
  # * Ruby GNTP
  # * Growl
  # * GrowlNotify
  # * Libnotify
  # * rb-notifu
  #
  # Please see the documentation of each notifier for more information about the requirements
  # and configuration possibilities.
  #
  # Guard knows four different notification types:
  #
  # * success
  # * pending
  # * failed
  # * notify
  #
  # The notification type selection is based on the image option that is
  # sent to {#notify}. Each image type has its own notification type, and
  # notifications with custom images goes all sent as type `notify`. The
  # `gntp` and `growl_notify` notifiers are able to register these types
  # at Growl and allows customization of each notification type.
  #
  # Guard can be configured to make use of more than one notifier at once, @see Guard::Dsl
  #
  module Notifier
    extend self

    # List of available notifiers.
    NOTIFIERS = {
        :gntp         => ::Guard::Notifier::GNTP,
        :growl        => ::Guard::Notifier::Growl,
        :growl_notify => ::Guard::Notifier::GrowlNotify,
        :libnotify    => ::Guard::Notifier::Libnotify,
        :notifu       => ::Guard::Notifier::Notifu
    }

    # Get the available notifications.
    #
    # @return [Hash] the notifications
    #
    def notifications
      @notifications ||= []
    end

    # Set the available notifications.
    #
    # @param [Array<Hash>] notifications the notifications
    #
    def notifications=(notifications)
      @notifications = notifications
    end

    # Turn notifications on. If no notifications are defined
    # in the `Guardfile` Guard auto detects the first available
    # library.
    #
    def turn_on
      auto_detect_notification if notifications.empty? && (!::Guard.options || ::Guard.options[:notify])

      if notifications.empty?
        ENV['GUARD_NOTIFY'] = 'false'
      else
        notifications.each do |notification|
          ::Guard::UI.info "Guard uses #{ NOTIFIERS[notification[:name]].to_s.split('::').last } to send notifications."
        end

        ENV['GUARD_NOTIFY'] = 'true'
      end
    end

    # Turn notifications off.
    #
    def turn_off
      ENV['GUARD_NOTIFY'] = 'false'
    end

    # Test if the notifications are on.
    #
    # @return [Boolean] whether the notifications are on
    #
    def enabled?
      ENV['GUARD_NOTIFY'] == 'true'
    end

    # Add a notification library to be used.
    #
    # @param [Symbol] name the name of the notifier to use
    # @param [Boolean] silent disable any error message
    # @param [Hash] options the notifier options
    # @return [Boolean] if the notification could be added
    #
    def add_notification(name, options = { }, silent = false)
      return turn_off if name == :off

      if NOTIFIERS.has_key?(name) && NOTIFIERS[name].available?(silent)
        notifications << { :name => name, :options => options }
        true
      else
        false
      end
    end

    # Show a system notification with all configured notifiers.
    #
    # @param [String] message the message to show
    # @option options [Symbol, String] image the image symbol or path to an image
    # @option options [String] title the notification title
    #
    def notify(message, options = { })
      if enabled?
        type  = notification_type(options[:image] || :success)
        image = image_path(options.delete(:image) || :success)
        title = options.delete(:title) || 'Guard'

        notifications.each do |notification|
          begin
            NOTIFIERS[notification[:name]].notify(type, title, message, image, options.merge(notification[:options]))
          rescue Exception => e
            ::Guard::UI.error "Error sending notification with #{ notification[:name] }: #{ e.message }"
          end
        end
      end
    end

    private

    # Auto detect the available notification library. This goes through
    # the list of supported notification gems and picks the first that
    # is available.
    #
    def auto_detect_notification
      available = [:growl_notify, :gntp, :growl, :libnotify, :notifu].any? { |notifier| add_notification(notifier, { }, true) }
      ::Guard::UI.info('Guard could not detect any of the supported notification libraries.') unless available
    end

    # Get the image path for an image symbol for the following
    # known image types:
    #
    # - failed
    # - pending
    # - success
    #
    # If the image is not a known symbol, it will be returned unmodified.
    #
    # @param [Symbol, String] image the image symbol or path to an image
    # @return [String] the image path
    #
    def image_path(image)
      case image
      when :failed
        images_path.join('failed.png').to_s
      when :pending
        images_path.join('pending.png').to_s
      when :success
        images_path.join('success.png').to_s
      else
        image
      end
    end

    # Paths where all Guard images are located
    #
    # @return [Pathname] the path to the images directory
    #
    def images_path
      @images_path ||= Pathname.new(File.dirname(__FILE__)).join('../../images')
    end

    # Get the notification type depending on the
    # image that has been selected for the notification.
    #
    # @param [Symbol, String] image the image symbol or path to an image
    # @return [String] the notification type
    #
    def notification_type(image)
      case image
      when :failed
        'failed'
      when :pending
        'pending'
      when :success
        'success'
      else
        'notify'
      end
    end
  end

end