Ruby Osascript runner

osascript.rb

# @example Simple
#   Osascript.new(<<~SCPT.freeze).()
#     activate application "Finder"
#   SCPT
#
# @example JSC with args
#   # The script takes 2 arguments: directory path & image path
#   # to set a folder icon to the given directory.
#   script = Osascript.new(<<-JS.freeze, lang: 'JavaScript')
#     ObjC.import("Cocoa");
#     function run(input) {
#       var target_path = input[0].toString();
#       var source_image = $.NSImage.alloc.initWithContentsOfFile(input[1].toString());
#       var result = $.NSWorkspace.sharedWorkspace.setIconForFileOptions(source_image, target_path, 0);
#       return target_path;
#     }
#   JS
#   script.(target_dir, folder_icon)
class Osascript
  attr_accessor :script

  def initialize(script = nil, lang: "AppleScript")
    @script = block_given? ? yield : script
    @lang = lang
  end

  def call(*other)
    handle_errors do
      cmd = ["/usr/bin/env", "osascript", *params(*other)]

      IO.popen cmd, "r+", 2 => %i(child out) do |io|
        io.write script
        io.close_write
        io.readlines
      end
    end
  end

  def params(*args)
    ["-l", @lang].tap { |e| e.concat(args.unshift(?-)) unless args.empty? }
  end

  ERROR_PATTERN = /(?<=execution error: )(.+?)(?=$)/
  USER_CANCELLED_PATTERN = /user canceled/i
  NL = "\n"

  private

  def handle_errors
    yield().each_with_object([]) do |line, buf|
      line.match(ERROR_PATTERN) { |m| raise error_for(m[0]), m[0], caller(4) }
      buf << line.strip
    end.join(NL)
  end

  def error_for(msg)
    USER_CANCELLED_PATTERN.test?(msg) ? UserCanceled : ExecutionError
  end

  class ExecutionError < RuntimeError
    CAPTURE_MSG_AND_CODE = /(.+?) \((-?\d+?)\)$/

    attr_reader :code

    def initialize(msg)
      msg.match(CAPTURE_MSG_AND_CODE) { |m| msg, @code, * = m.captures }
      super(msg)
    end
  end

  UserCanceled = Class.new(ExecutionError)
end