class AbstractUrlGenerator

  def initialize(controller)
    raise 'Controller cannot be nil' if controller.nil?
    @controller = controller
  end

  # Create a link for the given page (or file) name and link text based
  # on the render mode in options and whether the page (file) exists
  # in the web.
  def make_link(name, web, text = nil, options = {})
    text = CGI.escapeHTML(text || WikiWords.separate(name))
    mode = (options[:mode] || :show).to_sym
    link_type = (options[:link_type] || :show).to_sym

    if (link_type == :show)
      known_page = web.has_page?(name)
    else
      known_page = web.has_file?(name)
    end
    
    case link_type
    when :show
      page_link(mode, name, text, web.address, known_page)
    when :file
      file_link(mode, name, text, web.address, known_page)
    when :pic
      pic_link(mode, name, text, web.address, known_page)
    else
      raise "Unknown link type: #{link_type}"
    end
  end
  
end

class UrlGenerator < AbstractUrlGenerator

  private

  def file_link(mode, name, text, web_address, known_file)
    case mode
    when :export
      if known_file
        %{<a class="existingWikiWord" href="#{CGI.escape(name)}.html">#{text}</a>}
      else 
        %{<span class="newWikiWord">#{text}</span>}
      end
    when :publish
      if known_file 
        href = @controller.url_for :controller => 'file', :web => web_address, :action => 'file', 
            :id => name
        %{<a class="existingWikiWord" href="#{href}">#{text}</a>}
      else 
        %{<span class="newWikiWord">#{text}</span>}
      end
    else 
      href = @controller.url_for :controller => 'file', :web => web_address, :action => 'file', 
          :id => name
      if known_file
        %{<a class="existingWikiWord" href="#{href}">#{text}</a>}
      else 
        %{<span class="newWikiWord">#{text}<a href="#{href}">?</a></span>}
      end
    end
  end

  def page_link(mode, name, text, web_address, known_page)
    case mode
    when :export
      if known_page 
        %{<a class="existingWikiWord" href="#{CGI.escape(name)}.html">#{text}</a>}
      else 
        %{<span class="newWikiWord">#{text}</span>} 
      end
    when :publish
      if known_page
        href = @controller.url_for :controller => 'wiki', :web => web_address, :action => 'published', 
            :id => name
        %{<a class="existingWikiWord" href="#{href}">#{text}</a>}
      else 
        %{<span class="newWikiWord">#{text}</span>} 
      end
    else 
      if known_page
        href = @controller.url_for :controller => 'wiki', :web => web_address, :action => 'show', 
            :id => name
        %{<a class="existingWikiWord" href="#{href}">#{text}</a>}
      else 
        href = @controller.url_for :controller => 'wiki', :web => web_address, :action => 'new', 
            :id => name
        %{<span class="newWikiWord">#{text}<a href="#{href}">?</a></span>}
      end
    end
  end

  def pic_link(mode, name, text, web_address, known_pic)
    case mode
    when :export
      if known_pic 
        %{<img alt="#{text}" src="#{CGI.escape(name)}" />}
      else 
        %{<img alt="#{text}" src="no image" />}
      end
    when :publish
      if known_pic 
        %{<img alt="#{text}" src="#{CGI.escape(name)}" />}
      else 
        %{<span class="newWikiWord">#{text}</span>} 
      end
    else 
      href = @controller.url_for :controller => 'file', :web => web_address, :action => 'file', 
          :id => name
      if known_pic 
        %{<img alt="#{text}" src="#{href}" />}
      else 
        %{<span class="newWikiWord">#{text}<a href="#{href}">?</a></span>} 
      end
    end
  end

end