module Bundler
  class RubygemsIntegration
    def initialize
      # Work around a RubyGems bug
      configuration
    end

    def loaded_specs(name)
      Gem.loaded_specs[name]
    end

    def mark_loaded(spec)
      Gem.loaded_specs[spec.name] = spec
    end

    def path(obj)
      obj.to_s
    end

    def platforms
      Gem.platforms
    end

    def configuration
      Gem.configuration
    end

    def ruby_engine
      Gem.ruby_engine
    end

    def read_binary(path)
      Gem.read_binary(path)
    end

    def inflate(obj)
      Gem.inflate(obj)
    end

    def sources=(val)
      Gem.sources = val
    end

    def sources
      Gem.sources
    end

    def gem_dir
      Gem.dir.to_s
    end

    def gem_bindir
      Gem.bindir
    end

    def user_home
      Gem.user_home
    end

    def gem_path
      # Make sure that Gem.path is an array of Strings, not some
      # internal Rubygems object
      Gem.path.map { |x| x.to_s }
    end

    def marshal_spec_dir
      Gem::MARSHAL_SPEC_DIR
    end

    def clear_paths
      Gem.clear_paths
    end

    def bin_path(gem, bin, ver)
      Gem.bin_path(gem, bin, ver)
    end

    def ui=(obj)
      Gem::DefaultUserInteraction.ui = obj
    end

    def fetch_specs(all, pre, &blk)
      Gem::SpecFetcher.new.list(all, pre).each(&blk)
    end

    def with_build_args(args)
      old_args = Gem::Command.build_args
      begin
        Gem::Command.build_args = args
        yield
      ensure
        Gem::Command.build_args = old_args
      end
    end

    def spec_from_gem(path)
      Gem::Format.from_file_by_path(path).spec
    end

    def download_gem(spec, uri, path)
      Gem::RemoteFetcher.fetcher.download(spec, uri, path)
    end

    def reverse_rubygems_kernel_mixin
      # Disable rubygems' gem activation system
      ::Kernel.class_eval do
        if private_method_defined?(:gem_original_require)
          alias rubygems_require require
          alias require gem_original_require
        end

        undef gem
      end
    end

    def replace_gem(specs)
      executables = specs.map { |s| s.executables }.flatten

      ::Kernel.send(:define_method, :gem) do |dep, *reqs|
        if executables.include? File.basename(caller.first.split(':').first)
          return
        end
        opts = reqs.last.is_a?(Hash) ? reqs.pop : {}

        unless dep.respond_to?(:name) && dep.respond_to?(:requirement)
          dep = Gem::Dependency.new(dep, reqs)
        end

        spec = specs.find  { |s| s.name == dep.name }

        if spec.nil?

          e = Gem::LoadError.new "#{dep.name} is not part of the bundle. Add it to Gemfile."
          e.name = dep.name
          if e.respond_to?(:requirement=)
            e.requirement = dep.requirement
          else
            e.version_requirement = dep.requirement
          end
          raise e
        elsif dep !~ spec
          e = Gem::LoadError.new "can't activate #{dep}, already activated #{spec.full_name}. " \
                                 "Make sure all dependencies are added to Gemfile."
          e.name = dep.name
          if e.respond_to?(:requirement=)
            e.requirement = dep.requirement
          else
            e.version_requirement = dep.requirement
          end
          raise e
        end

        true
      end
    end

    def stub_source_index137(specs)
      # Rubygems versions lower than 1.7 use SourceIndex#from_gems_in
      source_index_class = (class << Gem::SourceIndex ; self ; end)
      source_index_class.send(:remove_method, :from_gems_in)
      source_index_class.send(:define_method, :from_gems_in) do |*args|
        source_index = Gem::SourceIndex.new
        source_index.spec_dirs = *args
        source_index.add_specs(*specs)
        source_index
      end
    end

    def stub_source_index170(specs)
      Gem::SourceIndex.send(:define_method, :initialize) do |*args|
        @gems = {}
        self.spec_dirs = *args
        add_specs(*specs)
      end
    end

    # Used to make bin stubs that are not created by bundler work
    # under bundler. The new Gem.bin_path only considers gems in
    # +specs+
    def replace_bin_path(specs)
      gem_class = (class << Gem ; self ; end)
      gem_class.send(:remove_method, :bin_path)
      gem_class.send(:define_method, :bin_path) do |name, *args|
        exec_name, *reqs = args

        if exec_name == 'bundle'
          return ENV['BUNDLE_BIN_PATH']
        end

        spec = nil

        if exec_name
          spec = specs.find { |s| s.executables.include?(exec_name) }
          spec or raise Gem::Exception, "can't find executable #{exec_name}"
        else
          spec = specs.find  { |s| s.name == name }
          exec_name = spec.default_executable or raise Gem::Exception, "no default executable for #{spec.full_name}"
        end

        gem_bin = File.join(spec.full_gem_path, spec.bindir, exec_name)
        gem_from_path_bin = File.join(File.dirname(spec.loaded_from), spec.bindir, exec_name)
        File.exist?(gem_bin) ? gem_bin : gem_from_path_bin
      end
    end

    # Because Bundler has a static view of what specs are available,
    # we don't #reflesh, so stub it out.
    def replace_refresh
      gem_class = (class << Gem ; self ; end)
      gem_class.send(:remove_method, :refresh)
      gem_class.send(:define_method, :refresh) { }
    end

    # Replace or hook into Rubygems to provide a bundlerized view
    # of the world.
    def replace_entrypoints(specs)
      reverse_rubygems_kernel_mixin

      replace_gem(specs)

      stub_rubygems(specs)

      replace_bin_path(specs)
      replace_refresh

      Gem.clear_paths
    end

    class Modern < RubygemsIntegration
      def stub_rubygems(specs)
        Gem::Specification.all = specs

        Gem.post_reset {
          Gem::Specification.all = specs
        }

        stub_source_index170(specs)
      end

      def all_specs
        Gem::Specification.to_a
      end

      def find_name(name)
        Gem::Specification.find_all_by_name name
      end

    end

    class Legacy < RubygemsIntegration
      def stub_rubygems(specs)
        stub_source_index137(specs)
      end

      def all_specs
        Gem.source_index.all_gems.values
      end

      def find_name(name)
        Gem.source_index.find_name(name)
      end
    end

    class Transitional < Legacy
      def stub_rubygems(specs)
        stub_source_index170(specs)
      end
    end

  end

  if Gem::Version.new(Gem::VERSION) >= Gem::Version.new('1.7.0')
    if Gem::Specification.respond_to? :all=
      @rubygems = RubygemsIntegration::Modern.new
    else
      @rubygems = RubygemsIntegration::Transitional.new
    end
  else
    @rubygems = RubygemsIntegration::Legacy.new
  end

  class << self
    attr_reader :rubygems
  end
end