# frozen_string_literal: true

module RuboCop # :nodoc:
  module Cop # :nodoc:
    module Packaging # :nodoc:
      # This cop flags the usage of `git ls-files` in gemspec
      # and suggests to use a plain Ruby alternative, like `Dir`,
      # `Dir.glob`, or `Rake::FileList` instead.
      #
      # @example
      #
      #   # bad
      #   Gem::Specification.new do |spec|
      #     spec.files = `git ls-files`.split("\n")
      #   end
      #
      #   # good
      #   Gem::Specification.new do |spec|
      #     spec.files = Dir["lib/**/*", "LICENSE", "README.md"]
      #   end
      #
      #   # bad
      #   Gem::Specification.new do |spec|
      #     spec.files = Dir.chdir(File.expand_path(__dir__)) do
      #       `git ls-files -z`.split("\\x0").reject { |f| f.match(%r{^(test|spec|features)/}) }
      #     end
      #   end
      #
      #   # good
      #   require "rake/file_list"
      #
      #   Gem::Specification.new do |spec|
      #     spec.files = Rake::FileList["**/*"].exclude(*File.read(".gitignore").split)
      #   end
      #
      #   # bad
      #   Gem::Specification.new do |spec|
      #     spec.files        = `git ls-files -- lib/`.split("\n")
      #     spec.executables  = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
      #   end
      #
      #   # good
      #   Gem::Specification.new do |spec|
      #     spec.files        = Dir.glob("lib/**/*")
      #     spec.executables  = Dir.glob("bin/*").map{ |f| File.basename(f) }
      #   end
      #
      class GemspecGit < Base
        # This is the message that will be displayed when RuboCop finds an
        # offense of using `git ls-files`.
        MSG = "Avoid using git to produce lists of files. " \
              "Downstreams often need to build your package in an environment " \
              "that does not have git (on purpose). " \
              "Use some pure Ruby alternative, like `Dir` or `Dir.glob`."

        def_node_search :xstr, <<~PATTERN
          (block
            (send
              (const
                (const {cbase nil?} :Gem) :Specification) :new)
            (args
              (arg _)) `$(xstr (str #starts_with_git?)))
        PATTERN

        # Extended from the Cop class.
        # More about the `#investigate` method can be found here:
        # https://github.com/rubocop-hq/rubocop/blob/59543c8e2b66bff249de131fa9105f3eb11e9edb/lib/rubocop/cop/cop.rb#L13-L25
        #
        # Processing of the AST happens here.
        def on_new_investigation
          return if processed_source.blank?

          xstr(processed_source.ast).each do |node|
            add_offense(
              node.loc.expression,
              message: MSG
            )
          end
        end

        # This method is called from inside `#def_node_search`.
        # It is used to find strings which start with "git".
        def starts_with_git?(str)
          str.start_with?("git")
        end
      end
    end
  end
end
