class AliasBehavior < Behavior::Base
  
  register "Alias"
  
  description %{
    Causes a page to be an alias to another page.  The source is given in the
    "source" page part as a slug path (not the URL).

    However, the page will search it's own children before searching it's
    source's children.  This is to allow pages to override portions of it's
    destination (CSS files, for example).
  }

  def find_page_by_url(url, live = true, clean = true)
    url = clean_url(url) if clean

    # Find source
    source = @page.part 'source'
    source = find_page_by_path source.content.strip
    return super unless source

    if page_url == url && (not live or @page.published?)
      return source
    else
      # Find my children
      @page.children.each do |child|
        if (url =~ Regexp.compile('^' + Regexp.quote(child.url))) and (not child.virtual?)
          found = child.behavior.find_page_by_url(url, live, clean)
          return found if found
        end
      end

      # Modify URL to source's URL
      url.sub!(Regexp.compile('^' + Regexp.quote(page_url)), source.url)

      # Find source's children
      source.children.each do |child|
        if (url =~ Regexp.compile('^' + Regexp.quote(child.url))) and (not child.virtual?)
          found = child.behavior.find_page_by_url(url, live, clean)
          return found if found
        end
      end

      # I couldn't find anything.
      return nil
    end
  end

  private
    def find_page_by_path(path)
      return nil unless path # No path, abort!

      path.gsub! %r{//+}, '/' # Remove dup /s
      path.gsub! %{[^/]+/..}, '' # remote path/..

      return nil if path == '' # No path, abort!

      # Catch root case
      if path.sub! %r{^/}, ''
        page = Page.find_by_parent_id nil
      else
        # Begin relative to parent if possible
        page = @page.parent
        page = @page unless page
      end

      path.split('/').each do |slug|
        case slug
        when '..'
          page = page.parent
        when '.'
          next
        else
          page = page.children.find_by_slug slug
        end

        break if page.nil? # We ran out of pages somewhere
      end

      page
    end
end