class Gem::DependencyInstaller

def consider_local?
  @domain == :both || @domain == :local
end

def consider_remote?
  @domain == :both || @domain == :remote
end

def in_background(what) # :nodoc:
  fork_happened = false
  if @build_docs_in_background && Process.respond_to?(:fork)
    begin
      Process.fork do
        yield
      end
      fork_happened = true
      say "#{what} in a background process."
    rescue NotImplementedError
    end
  end
  yield unless fork_happened
end

def initialize(options = {})
  @only_install_dir = !options[:install_dir].nil?
  @install_dir = options[:install_dir] || Gem.dir
  @build_root = options[:build_root]
  options = DEFAULT_OPTIONS.merge options
  @bin_dir             = options[:bin_dir]
  @dev_shallow         = options[:dev_shallow]
  @development         = options[:development]
  @document            = options[:document]
  @domain              = options[:domain]
  @env_shebang         = options[:env_shebang]
  @force               = options[:force]
  @format_executable   = options[:format_executable]
  @ignore_dependencies = options[:ignore_dependencies]
  @prerelease          = options[:prerelease]
  @security_policy     = options[:security_policy]
  @user_install        = options[:user_install]
  @wrappers            = options[:wrappers]
  @build_args          = options[:build_args]
  @build_jobs          = options[:build_jobs]
  @build_docs_in_background = options[:build_docs_in_background]
  @dir_mode = options[:dir_mode]
  @data_mode = options[:data_mode]
  @prog_mode = options[:prog_mode]
  # Indicates that we should not try to update any deps unless
  # we absolutely must.
  @minimal_deps = options[:minimal_deps]
  @available      = nil
  @installed_gems = []
  @toplevel_specs = nil
  @cache_dir = options[:cache_dir] || @install_dir
  @errors = []
end

def install(dep_or_name, version = Gem::Requirement.default)
  request_set = resolve_dependencies dep_or_name, version
  @installed_gems = []
  options = {
    bin_dir: @bin_dir,
    build_args: @build_args,
    build_jobs: @build_jobs,
    document: @document,
    env_shebang: @env_shebang,
    force: @force,
    format_executable: @format_executable,
    ignore_dependencies: @ignore_dependencies,
    prerelease: @prerelease,
    security_policy: @security_policy,
    user_install: @user_install,
    wrappers: @wrappers,
    build_root: @build_root,
    dir_mode: @dir_mode,
    data_mode: @data_mode,
    prog_mode: @prog_mode,
  }
  options[:install_dir] = @install_dir if @only_install_dir
  request_set.install options do |_, installer|
    @installed_gems << installer.spec if installer
  end
  @installed_gems.sort!
  # Since this is currently only called for docs, we can be lazy and just say
  # it's documentation. Ideally the hook adder could decide whether to be in
  # the background or not, and what to call it.
  in_background "Installing documentation" do
    Gem.done_installing_hooks.each do |hook|
      hook.call self, @installed_gems
    end
  end unless Gem.done_installing_hooks.empty?
  @installed_gems
end

def install_development_deps # :nodoc:
  if @development && @dev_shallow
    :shallow
  elsif @development
    :all
  else
    :none
  end
end

def resolve_dependencies(dep_or_name, version) # :nodoc:
  request_set = Gem::RequestSet.new
  request_set.development         = @development
  request_set.development_shallow = @dev_shallow
  request_set.soft_missing = @force
  request_set.prerelease = @prerelease
  installer_set = Gem::Resolver::InstallerSet.new @domain
  installer_set.ignore_installed = (@minimal_deps == false) || @only_install_dir
  installer_set.force = @force
  if consider_local?
    if dep_or_name =~ /\.gem$/ && File.file?(dep_or_name)
      src = Gem::Source::SpecificFile.new dep_or_name
      installer_set.add_local dep_or_name, src.spec, src
      version = src.spec.version if version == Gem::Requirement.default
    elsif dep_or_name =~ /\.gem$/ # rubocop:disable Performance/RegexpMatch
      Dir[dep_or_name].each do |name|
        src = Gem::Source::SpecificFile.new name
        installer_set.add_local dep_or_name, src.spec, src
      rescue Gem::Package::FormatError
      end
      # else This is a dependency. InstallerSet handles this case
    end
  end
  dependency =
    if spec = installer_set.local?(dep_or_name)
      installer_set.remote = nil if spec.dependencies.none?
      Gem::Dependency.new spec.name, version
    elsif String === dep_or_name
      Gem::Dependency.new dep_or_name, version
    else
      dep_or_name
    end
  dependency.prerelease = @prerelease
  request_set.import [dependency]
  installer_set.add_always_install dependency
  request_set.always_install = installer_set.always_install
  request_set.remote = installer_set.consider_remote?
  if @ignore_dependencies
    installer_set.ignore_dependencies = true
    request_set.ignore_dependencies   = true
    request_set.soft_missing          = true
  end
  request_set.resolve installer_set
  @errors.concat request_set.errors
  request_set
end