require 'hpricot'
require 'open-uri'
require 'builder'
require 'darkext/hash'

module Darkext
  class Darkext::SitemapBuilder
    FORUM_CLASS_DEFAULT = 'forumtitle'
    TOPIC_CLASS_DEFAULT = 'topictitle'
    FORUM_PRIORITY_DEFAULT = 0.8
    TOPIC_PRIORITY_DEFAULT = 0.5
    PAGE_PRIORITY_DEFAULT = 0.1
    FORUM_CHANGE_FREQ_DEFAULT = 'daily'
    TOPIC_CHANGE_FREQ_DEFAULT = 'hourly'
    PAGE_CHANGE_FREQ_DEFAULT = 'monthly'

    def initialize(opts={})
      defaults = {
        :forum => {
          :class => FORUM_CLASS_DEFAULT,
          :priority => FORUM_PRIORITY_DEFAULT,
          :change_freq => FORUM_CHANGE_FREQ_DEFAULT
        },
        :topic => {
          :class => TOPIC_CLASS_DEFAULT,
          :priority => TOPIC_PRIORITY_DEFAULT,
          :change_freq => TOPIC_CHANGE_FREQ_DEFAULT
        },
        :page => {
          :priority => PAGE_PRIORITY_DEFAULT,
          :change_freq => PAGE_CHANGE_FREQ_DEFAULT
        }
      }
      defaults.deep_merge!(opts)

      @options = defaults

      @forums = Array.new
      @topics = Array.new
      @pages = Array.new
    end

    def index(url, target = $stdout)
      @pages << url

      root = Hpricot(open(url))
      (root/"a.#{@options.nested_find(:forum,:class)}").each do |link|
        index_forum(link.attributes['href'].to_s)
      end

      xml = Builder::XmlMarkup.new(:target => $stdout, :indent => 1)
      xml.instruct!
      xml.urlset "xmlns" => "http://www.sitemaps.org/schemas/sitemap/0.9" do
        @pages.each do |page|
          xml.url do
            xml.loc(page)
            xml.changefreq(@options.nested_find(:page,:change_freq))
            xml.priority(@options.nested_find(:page,:priority))
          end
        end
        @forums.each do |forum|
          xml.url do
            xml.loc(forum)
            xml.changefreq(@options.nested_find(:forum,:change_freq))
            xml.priority(@options.nested_find(:forum,:priority))
          end
        end
        @topics.each do |topic|
          xml.url do
            xml.loc(topic)
            xml.changefreq(@options.nested_find(:topic,:change_freq))
            xml.priority(@options.nested_find(:topic,:priority))
          end
        end
      end
    end

    private
    def index_forum(href)
      root = Hpricot(open(href))
      (root/"a.#{@options.nested_find(:forum,:class)}").each do |link|
        index_forum(link.attributes['href'].to_s)
      end
      (root/"a.#{@options.nested_find(:topic,:class)}").each do |link|
        @topics << link.attributes['href'].to_s
      end
      @forums << href
    end
  end
end