class Gem::RequestSet

def gem(name, *reqs)
  @dependencies << Gem::Dependency.new(name, reqs)
end

def import(deps)
  @dependencies += deps
end

def initialize(*deps)
  @dependencies = deps
  yield self if block_given?
end

def install(options, &b)
  if dir = options[:install_dir]
    return install_into(dir, false, &b)
  end
  cache_dir = options[:cache_dir] || Gem.dir
  specs = []
  sorted_requests.each do |req|
    if req.installed?
      b.call req, nil if b
      next
    end
    path = req.download cache_dir
    inst = Gem::Installer.new path, options
    b.call req, inst if b
    specs << inst.install
  end
  specs
end

def install_into(dir, force=true, &b)
  existing = force ? [] : specs_in(dir)
  dir = File.expand_path dir
  installed = []
  sorted_requests.each do |req|
    if existing.find { |s| s.full_name == req.spec.full_name }
      b.call req, nil if b
      next
    end
    path = req.download(dir)
    inst = Gem::Installer.new path, :install_dir => dir,
                                    :only_install_dir => true
    b.call req, inst if b
    inst.install
    installed << req
  end
  installed
end

def load_gemdeps(path)
  gf = GemDepedencyAPI.new(self, path)
  gf.load
end

def resolve(set=nil)
  r = Gem::DependencyResolver.new(@dependencies, set)
  @requests = r.resolve
end

def resolve_current
  resolve DependencyResolver::CurrentSet.new
end

def sorted_requests
  @sorted ||= strongly_connected_components.flatten
end

def specs
  @specs ||= @requests.map { |r| r.full_spec }
end

def specs_in(dir)
  Dir["#{dir}/specifications/*.gemspec"].map do |g|
    Gem::Specification.load g
  end
end

def tsort_each_child(node)
  node.spec.dependencies.each do |dep|
    next if dep.type == :development
    match = @requests.find { |r| dep.match? r.spec.name, r.spec.version }
    if match
      begin
        yield match
      rescue TSort::Cyclic
      end
    else
      raise Gem::DependencyError, "Unresolved depedency found during sorting - #{dep}"
    end
  end
end

def tsort_each_node(&block)
  @requests.each(&block)
end