# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", github: "rails/rails", branch: "main"
  gem "benchmark-ips"
end

require "active_support"
require "active_support/core_ext/module/attribute_accessors_per_thread"
require "minitest/autorun"

# Your patch goes here.
class Module
  def thread_mattr_reader_default(*syms, instance_reader: true, instance_accessor: true, default: nil)
    syms.each do |sym|
      raise NameError.new("invalid attribute name: #{sym}") unless /^[_A-Za-z]\w*$/.match?(sym)
      class_eval(<<-EOS, __FILE__, __LINE__ + 1)
        def self.#{sym}
          if Thread.current["attr_defined_" + name + "_#{sym}"].nil?
            Thread.current["attr_defined_" + name + "_#{sym}"] = true
            Thread.current["attr_" + name + "_#{sym}"] = #{default.inspect}
          end
          Thread.current["attr_" + name + "_#{sym}"]
        end
      EOS

      if instance_reader && instance_accessor
        class_eval(<<-EOS, __FILE__, __LINE__ + 1)
          def #{sym}
            self.class.#{sym}
          end
        EOS
      end
    end
  end

  def thread_mattr_writer_default(*syms, instance_writer: true, instance_accessor: true, default: nil) # :nodoc:
    syms.each do |sym|
      raise NameError.new("invalid attribute name: #{sym}") unless /^[_A-Za-z]\w*$/.match?(sym)

      # The following generated method concatenates `name` because we want it
      # to work with inheritance via polymorphism.
      class_eval(<<-EOS, __FILE__, __LINE__ + 1)
        def self.#{sym}=(obj)
          if Thread.current["attr_defined_" + name + "_#{sym}"].nil?
            Thread.current["attr_defined_" + name + "_#{sym}"] = true
          end
          Thread.current["attr_" + name + "_#{sym}"] = obj
        end
      EOS

      if instance_writer && instance_accessor
        class_eval(<<-EOS, __FILE__, __LINE__ + 1)
          def #{sym}=(obj)
            self.class.#{sym} = obj
          end
        EOS
      end

      public_send("#{sym}=", default) unless default.nil?
    end
  end

  def thread_mattr_accessor_default(*syms, instance_reader: true, instance_writer: true, instance_accessor: true, default: nil)
    thread_mattr_reader_default(*syms, instance_reader: instance_reader, instance_accessor: instance_accessor, default: default)
    thread_mattr_writer_default(*syms, instance_writer: instance_writer, instance_accessor: instance_accessor)
  end
end

module A
  thread_mattr_accessor_default :attribute_with_default, default: 42
  thread_mattr_accessor :attribute, default: 42
end

Benchmark.ips do |x|
  x.report("original")      { A.attribute }
  x.report("patched_default") { A.attribute_with_default }
  x.compare!
end

class BugTest < Minitest::Test
  def test_stuff
    assert(A.attribute_with_default == 42)
    Thread.new do
      assert(A.attribute_with_default == 42)
    end.join
    A.attribute_with_default = nil
    assert(A.attribute_with_default.nil?)
  end
end

Thread.current[:var] = 1
Thread.current.key?(:var) # => true 
Thread.current[:var] = nil
Thread.current.key?(:var) # => false 

    NIL_OBJECT = Object.new

    # ...

      class_eval(<<-EOS, __FILE__, __LINE__ + 1)
        def self.#{sym}
          key = "attr_" + name + "_#{sym}"
          obj = Thread.current[key]
          
          if obj.nil?
            obj = #{default.inspect}
            Thread.current[key] = obj.nil? ? NIL_OBJECT : obj
          end

          NIL_OBJECT == obj ? nil : obj
        end
      EOS

    # ...

      class_eval(<<-EOS, __FILE__, __LINE__ + 1)
        def self.#{sym}=(obj)
          Thread.current["attr_" + name + "_#{sym}"] = obj.nil? ? NIL_OBJECT : obj
        end
      EOS

    # ...