plugin_manager.rb

require File.join( RAILS_ROOT, "lib", "ansuz", "plugin_settings.rb" )
module Ansuz
  class PluginManager
    include Ansuz::PluginSettings
    attr_accessor :plugins, :plugin_nav, :admin_plugin_nav, :admin_menu, :admin_menu_top_level_entries, :page_types, :admin_dashboard_boxes, :at_a_glance_entries
    ADMIN_MENU_TOP_LEVEL_ENTRIES = ["Create", "Manage", "Ansuz"]

    def initialize
      @plugins = []
      @plugin_nav = []
      @admin_plugin_nav = []
      @admin_menu = {}
      @admin_menu_top_level_entries = ADMIN_MENU_TOP_LEVEL_ENTRIES.clone
      @admin_dashboard_boxes = []
      @page_types = []
      @at_a_glance_entries = []
      setup_admin_menu
    end

    # A plugin can call register_plugin(ClassName) to add itself to the plugins array
    def register_plugin klass
      self.plugins << klass
      settings_name = klass.to_s.tableize.gsub(/\//,'_').to_sym
      create_settings( settings_name )
    end

    # A plugin can call register_plugin_nav(title, link) to add itself to the
    # user-facing navigation menu
    def register_plugin_nav title, link
      self.plugin_nav << [title, link]
    end

    # A plugin can register a box to be shown in the admin dashboard
    # The partial is expected to contain everything necessary to
    # render the box.
    def register_admin_dashboard_box title, partial_path
      @admin_dashboard_boxes << [title, partial_path]
    end

    # At-a-Glance is a way to see what's going on in your website in one
    # box on the admin dashboard.  This method may be used to register a new
    # statistic.  You should call it with:
    #     register_at_a_glance_statistic "Posts" do
    #       Post.count
    #     end
    def register_at_a_glance_statistic title, options={}, &block
      @at_a_glance_entries << [title, options[:url], block]
    end

    # Plugins may have external gem depdencies, such as ansuz_content_section (RedCloth/BlueCloth)
    # The arguments are the same as the gem examples in config/environment.rb
    def add_gem_dependency(name, options = {})
      Rails.configuration.gem(name, options)
    end

    # A plugin can call register_admin_plugin_nav(title, link) to add itself to the
    # admin-facing navigation menu
    def register_admin_plugin_nav title, link
      self.admin_plugin_nav << [title, link]
      # We're going to register plugins that use the old naming convention just underneath 
      # the Add-Ons dropdown.  They can use the register_admin_menu_entry method if they want finer-grained control.
      register_admin_menu_entry "Add-ons", title, link
    end

    def register_admin_menu_entry top_level_menu_name, text, link, options={}
      raise "There was an attempt to add a link to the admin menu with a non-existent top level menu entry as parent." unless admin_menu_top_level_entries.include?(top_level_menu_name)
      self.admin_menu[top_level_menu_name] << [text, link, options]
    end

    def add_top_level_menu_entry name
      @admin_menu_top_level_entries << name unless @admin_menu_top_level_entries.include?(name)
      @admin_menu[name] = []
    end

    # The admin menu is just a hash with an array for sub menus for now.
    def setup_admin_menu
      ADMIN_MENU_TOP_LEVEL_ENTRIES.each do |menu_entry|
        add_top_level_menu_entry menu_entry
      end
    end

    def register_page_type name, modules=[]
      @page_types << [name, modules]
    end

    protected
    def create_settings(name)
      begin
        # This method gets run before the rake ansuz:install task. Naturally, things break if the database doesn't exist.
        ActiveRecord::Base.connection
        return false if SiteSetting.count == 0 # Stupid, mean hack. There's some test that clears site settings and breaks things.
        site_setting = SiteSetting.first
        unless( site_setting.nil? && site_setting.first.settings[name])
          site_setting.settings[name] = {}  
          site_setting.save
        end
      rescue
      end
    end
  end
end