class Bundler::Graph

def viz(output_file, show_gem_versions = false, show_dependency_requirements = false)
  require 'graphviz'
  populate
  graph_viz = GraphViz::new('Gemfile', {:concentrate => true, :dpi => 65 } )
  graph_viz.edge[:fontname] = graph_viz.node[:fontname] = 'Arial, Helvetica, SansSerif'
  graph_viz.edge[:fontsize] = 12
  viz_nodes = {}
  # populate all of the nodes
  nodes.each do |name, node|
    label = name.dup
    label << "\n#{node.version}" if show_gem_versions
    options = { :label => label }
    options.merge!( USER_OPTIONS ) if node.is_user
    viz_nodes[name] = graph_viz.add_node( name, options )
  end
  group_nodes = {}
  @groups.each do |name, dependencies|
    group_nodes[name] = graph_viz.add_node(name.to_s, { :shape => 'folder', :fontsize => 16 }.merge(USER_OPTIONS))
    dependencies.each do |dependency|
      options = { :weight => 2 }
      if show_dependency_requirements && (dependency.requirement.to_s != ">= 0")
        options[:label] = dependency.requirement.to_s
      end
      graph_viz.add_edge( group_nodes[name], viz_nodes[dependency.name], options )
    end
  end
  @groups.keys.select { |group| group != :default }.each do |group|
    graph_viz.add_edge( group_nodes[group], group_nodes[:default], { :weight => 2 } )
  end
  viz_nodes.each do |name, node|
    nodes[name].dependencies.each do |dependency|
      options = { }
      if nodes[dependency.name].is_user
        options[:constraint] = false
      end
      if show_dependency_requirements && (dependency.requirement.to_s != ">= 0")
        options[:label] = dependency.requirement.to_s
      end
      graph_viz.add_edge( node, viz_nodes[dependency.name], options )
    end
  end
  graph_viz.output( :png => output_file )
end