module Rostra
  module BaseHelper

    # Method used to render to user names (e.g. where it says: "John Does says:"). You can,
    # for example, use this method to turn "John Doe" into a link to his profile page.
    #
    def link_to_profile(user)
      link_to user.rostra_user_name, main_app.user_path(user)
    end

    # Used to populate both the <tt>title</tt> and <tt>h1</tt> elements for each page.
    #
    def page_title_helper
      case "#{controller_name}##{action_name}"
      when "questions#show" then @question.title
      when "questions#index" then
        if params[:tag_search].present?
          "Recent Questions for tag #{params[:tag_search]}"
        else
          "Recent Questions"
        end
      when "questions#new" then "Post a new question"
      when "questions#edit" then "Editing question"
      when "answers#edit" then "Editing answer"
      else "Recent Questions"
      end
    end

    # Creates a list of tags linking to the index showing only questions with that tag
    #
    def tag_list(question)
      tags = question.tags.map { |tag| link_to tag, questions_path(:tag_search => "#{tag}")}.join
      content_tag :div, "Tags: #{tags}".html_safe, class: 'tags'
    end

    # Finds the url to the user's avatar following this logic:
    #
    #   1. Calls <tt>avatar</tt> on the user object
    #   2. Uses the users email address to look for a gravatar
    #   3. Renders <tt>app/assets/images/rostra/anonymous_avatar.png</tt>
    #
    def rostra_user_avatar(user)
      if user.respond_to?(:avatar)
        url = user.avatar
      else
        default_url = "#{main_app.root_url}assets/rostra/anonymous_avatar.png"
        gravatar_id = Digest::MD5.hexdigest(user.rostra_user_email.downcase)
        url = "http://gravatar.com/avatar/#{gravatar_id}.png?s=48&d=#{CGI.escape(default_url)}"
      end
      image_tag(url, class: 'avatar')
    end

    # Method to build links for ajax-y voting arrows.
    #
    def link_to_vote(direction, resource)
      if user_signed_in? && ( (direction == :up && rostra_user.voted_for?(resource)) || (direction == :down && rostra_user.voted_against?(resource)) )
        selected = 'selected'
      else
        selected = ''
      end

      link_to "Vote #{direction.capitalize}", vote_path(resource, direction), method: :put, remote: true, class: "vote #{direction} #{selected}"
    end

    # Returns a rostra object's base class name. For example, <tt>@question</tt> is an instance of
    # Rostra::Question and so:
    #
    #   class_name(@question)  # => 'question'
    #
    def class_name(resource)
      resource.class.name.split('::').last.downcase
    end

    private

    def vote_path(resource, direction)
      return '#' if !user_signed_in? || can?(:manage, resource)

      if resource.is_a?(Rostra::Question)
        vote_question_path(resource, vote_direction: direction)
      else
        vote_question_answer_path(resource.question, resource, vote_direction: direction)
      end
    end

  end
end