class Gem::RequestSet

def gem name, *reqs
  if dep = @dependency_names[name] then
    dep.requirement.concat reqs
  else
    dep = Gem::Dependency.new name, *reqs
    @dependency_names[name] = dep
    @dependencies << dep
  end
end

def import deps
  @dependencies.concat deps
end

def initialize *deps
  @dependencies = deps
  @always_install      = []
  @conservative        = false
  @dependency_names    = {}
  @development         = false
  @development_shallow = false
  @errors              = []
  @git_set             = nil
  @ignore_dependencies = false
  @install_dir         = Gem.dir
  @prerelease          = false
  @remote              = true
  @requests            = []
  @sets                = []
  @soft_missing        = false
  @sorted              = nil
  @specs               = nil
  @vendor_set          = nil
  @source_set          = nil
  yield self if block_given?
end

def install options, &block # :yields: request, installer
  if dir = options[:install_dir]
    requests = install_into dir, false, options, &block
    return requests
  end
  @prerelease = options[:prerelease]
  requests = []
  sorted_requests.each do |req|
    if req.installed? then
      req.spec.spec.build_extensions
      if @always_install.none? { |spec| spec == req.spec.spec } then
        yield req, nil if block_given?
        next
      end
    end
    spec = req.spec.install options do |installer|
      yield req, installer if block_given?
    end
    requests << spec
  end
  return requests if options[:gemdeps]
  specs = requests.map do |request|
    case request
    when Gem::Resolver::ActivationRequest then
      request.spec.spec
    else
      request
    end
  end
  require 'rubygems/dependency_installer'
  inst = Gem::DependencyInstaller.new options
  inst.installed_gems.replace specs
  Gem.done_installing_hooks.each do |hook|
    hook.call inst, specs
  end unless Gem.done_installing_hooks.empty?
  requests
end

def install_from_gemdeps options, &block
  gemdeps = options[:gemdeps]
  @install_dir = options[:install_dir] || Gem.dir
  @prerelease  = options[:prerelease]
  @remote      = options[:domain] != :local
  @conservative = true if options[:conservative]
  gem_deps_api = load_gemdeps gemdeps, options[:without_groups], true
  resolve
  if options[:explain]
    puts "Gems to install:"
    sorted_requests.each do |spec|
      puts "  #{spec.full_name}"
    end
    if Gem.configuration.really_verbose
      @resolver.stats.display
    end
  else
    installed = install options, &block
    if options.fetch :lock, true then
      lockfile =
        Gem::RequestSet::Lockfile.build self, gemdeps, gem_deps_api.dependencies
      lockfile.write
    end
    installed
  end
end

def install_into dir, force = true, options = {}
  gem_home, ENV['GEM_HOME'] = ENV['GEM_HOME'], dir
  existing = force ? [] : specs_in(dir)
  existing.delete_if { |s| @always_install.include? s }
  dir = File.expand_path dir
  installed = []
  options[:development] = false
  options[:install_dir] = dir
  options[:only_install_dir] = true
  @prerelease = options[:prerelease]
  sorted_requests.each do |request|
    spec = request.spec
    if existing.find { |s| s.full_name == spec.full_name } then
      yield request, nil if block_given?
      next
    end
    spec.install options do |installer|
      yield request, installer if block_given?
    end
    installed << request
  end
  installed
ensure
  ENV['GEM_HOME'] = gem_home
end

def load_gemdeps path, without_groups = [], installing = false
  @git_set    = Gem::Resolver::GitSet.new
  @vendor_set = Gem::Resolver::VendorSet.new
  @source_set = Gem::Resolver::SourceSet.new
  @git_set.root_dir = @install_dir
  lock_file = "#{File.expand_path(path)}.lock".dup.untaint
  begin
    tokenizer = Gem::RequestSet::Lockfile::Tokenizer.from_file lock_file
    parser = tokenizer.make_parser self, []
    parser.parse
  rescue Errno::ENOENT
  end
  gf = Gem::RequestSet::GemDependencyAPI.new self, path
  gf.installing = installing
  gf.without_groups = without_groups if without_groups
  gf.load
end

def pretty_print q # :nodoc:
  q.group 2, '[RequestSet:', ']' do
    q.breakable
    if @remote then
      q.text 'remote'
      q.breakable
    end
    if @prerelease then
      q.text 'prerelease'
      q.breakable
    end
    if @development_shallow then
      q.text 'shallow development'
      q.breakable
    elsif @development then
      q.text 'development'
      q.breakable
    end
    if @soft_missing then
      q.text 'soft missing'
    end
    q.group 2, '[dependencies:', ']' do
      q.breakable
      @dependencies.map do |dep|
        q.text dep.to_s
        q.breakable
      end
    end
    q.breakable
    q.text 'sets:'
    q.breakable
    q.pp @sets.map { |set| set.class }
  end
end

def resolve set = Gem::Resolver::BestSet.new
  @sets << set
  @sets << @git_set
  @sets << @vendor_set
  @sets << @source_set
  set = Gem::Resolver.compose_sets(*@sets)
  set.remote = @remote
  set.prerelease = @prerelease
  resolver = Gem::Resolver.new @dependencies, set
  resolver.development         = @development
  resolver.development_shallow = @development_shallow
  resolver.ignore_dependencies = @ignore_dependencies
  resolver.soft_missing        = @soft_missing
  if @conservative
    installed_gems = {}
    Gem::Specification.find_all do |spec|
      (installed_gems[spec.name] ||= []) << spec
    end
    resolver.skip_gems = installed_gems
  end
  @resolver = resolver
  @requests = resolver.resolve
  @errors = set.errors
  @requests
end

def resolve_current
  resolve Gem::Resolver::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 # :nodoc:
  node.spec.dependencies.each do |dep|
    next if dep.type == :development and not @development
    match = @requests.find { |r|
      dep.match? r.spec.name, r.spec.version, @prerelease
    }
    unless match then
      next if dep.type == :development and @development_shallow
      next if @soft_missing
      raise Gem::DependencyError,
            "Unresolved dependency found during sorting - #{dep} (requested by #{node.spec.full_name})"
    end
    yield match
  end
end

def tsort_each_node &block # :nodoc:
  @requests.each(&block)
end