# frozen_string_literal: true

module Bundler
  class Standalone
    def initialize(groups, definition)
      @specs = groups.empty? ? definition.requested_specs : definition.specs_for(groups.map(&:to_sym))
    end

    def generate
      SharedHelpers.filesystem_access(bundler_path) do |p|
        FileUtils.mkdir_p(p)
      end
      File.open File.join(bundler_path, "setup.rb"), "w" do |file|
        file.puts "require 'rbconfig'"
        file.puts "ruby_engine = RUBY_ENGINE"
        file.puts "ruby_version = RbConfig::CONFIG[\"ruby_version\"]"
        file.puts "path = File.expand_path('..', __FILE__)"
        file.puts reverse_rubygems_kernel_mixin
        paths.each do |path|
          file.puts %($:.unshift File.expand_path("\#{path}/#{path}"))
        end
      end
    end

    private

    def paths
      @specs.map do |spec|
        next if spec.name == "bundler"
        Array(spec.require_paths).map do |path|
          gem_path(path, spec).sub(version_dir, '#{ruby_engine}/#{ruby_version}')
          # This is a static string intentionally. It's interpolated at a later time.
        end
      end.flatten
    end

    def version_dir
      "#{Bundler::RubyVersion.system.engine}/#{RbConfig::CONFIG["ruby_version"]}"
    end

    def bundler_path
      Bundler.root.join(Bundler.settings[:path], "bundler")
    end

    def gem_path(path, spec)
      full_path = Pathname.new(path).absolute? ? path : File.join(spec.full_gem_path, path)
      Pathname.new(full_path).relative_path_from(Bundler.root.join(bundler_path)).to_s
    rescue TypeError
      error_message = "#{spec.name} #{spec.version} has an invalid gemspec"
      raise Gem::InvalidSpecificationException.new(error_message)
    end

    def reverse_rubygems_kernel_mixin
      <<~END
      kernel = (class << ::Kernel; self; end)
      [kernel, ::Kernel].each do |k|
        if k.private_method_defined?(:gem_original_require)
          private_require = k.private_method_defined?(:require)
          k.send(:remove_method, :require)
          k.send(:define_method, :require, k.instance_method(:gem_original_require))
          k.send(:private, :require) if private_require
        end
      end
      END
    end
  end
end