module Redmine::MenuManager::MenuHelper
  # Returns the current menu item name
  def current_menu_item
    @controller.current_menu_item
  end
  
  # Renders the application main menu
  def render_main_menu(project)
    render_menu((project && !project.new_record?) ? :project_menu : :application_menu, project)
  end
  
  def display_main_menu?(project)
    menu_name = project && !project.new_record? ? :project_menu : :application_menu
    Redmine::MenuManager.items(menu_name).size > 1 # 1 element is the root
  end

  def render_menu(menu, project=nil)
    links = []
    menu_items_for(menu, project) do |node|
      links << render_menu_node(node, project)
    end
    links.empty? ? nil : content_tag('ul', links.join("\n"))
  end

  def render_menu_node(node, project=nil)
    if node.hasChildren? || !node.child_menus.nil?
      return render_menu_node_with_children(node, project)
    else
      caption, url, selected = extract_node_details(node, project)
      return content_tag('li',
                           render_single_menu_node(node, caption, url, selected))
    end
  end

  def render_menu_node_with_children(node, project=nil)
    caption, url, selected = extract_node_details(node, project)

    html = [].tap do |html|
      html << '<li>'
      # Parent
      html << render_single_menu_node(node, caption, url, selected)

      # Standard children
      standard_children_list = "".tap do |child_html|
        node.children.each do |child|
          child_html << render_menu_node(child, project)
        end
      end

      html << content_tag(:ul, standard_children_list, :class => 'menu-children') unless standard_children_list.empty?

      # Unattached children
      unattached_children_list = render_unattached_children_menu(node, project)
      html << content_tag(:ul, unattached_children_list, :class => 'menu-children unattached') unless unattached_children_list.blank?

      html << '</li>'
    end
    return html.join("\n")
  end

  # Returns a list of unattached children menu items
  def render_unattached_children_menu(node, project)
    return nil unless node.child_menus

    "".tap do |child_html|
      unattached_children = node.child_menus.call(project)
      # Tree nodes support #each so we need to do object detection
      if unattached_children.is_a? Array
        unattached_children.each do |child|
          child_html << content_tag(:li, render_unattached_menu_item(child, project)) 
        end
      else
        raise Redmine::MenuManager::MenuError, ":child_menus must be an array of MenuItems"
      end
    end
  end

  def render_single_menu_node(item, caption, url, selected)
    link_to(h(caption), url, item.html_options(:selected => selected))
  end

  def render_unattached_menu_item(menu_item, project)
    raise Redmine::MenuManager::MenuError, ":child_menus must be an array of MenuItems" unless menu_item.is_a? Redmine::MenuManager::MenuItem

    if User.current.allowed_to?(menu_item.url, project)
      link_to(h(menu_item.caption),
              menu_item.url,
              menu_item.html_options)
    end
  end
  
  def menu_items_for(menu, project=nil)
    items = []
    Redmine::MenuManager.items(menu).root.children.each do |node|
      if allowed_node?(node, User.current, project)
        if block_given?
          yield node
        else
          items << node  # TODO: not used?
        end
      end
    end
    return block_given? ? nil : items
  end

  def extract_node_details(node, project=nil)
    item = node
    url = case item.url
    when Hash
      project.nil? ? item.url : {item.param => project}.merge(item.url)
    when Symbol
      send(item.url)
    else
      item.url
    end
    caption = item.caption(project)
    return [caption, url, (current_menu_item == item.name)]
  end

  # Checks if a user is allowed to access the menu item by:
  #
  # * Checking the conditions of the item
  # * Checking the url target (project only)
  def allowed_node?(node, user, project)
    if node.condition && !node.condition.call(project)
      # Condition that doesn't pass
      return false
    end

    if project
      return user && user.allowed_to?(node.url, project)
    else
      # outside a project, all menu items allowed
      return true
    end
  end
end