cask-pr-local-check: improve with optparse (#82084)

developer/bin/cask-pr-local-check

@@ -1,12 +1,32 @@
 #!/usr/bin/env ruby
 
-require 'open-uri'
 require 'json'
+require 'open-uri'
+require 'optparse'
 require 'tmpdir'
 
+# Options
+ARGV.push('--help') if ARGV.empty?
+
+OptionParser.new do |opt|
+  opt.banner = <<~BANNER
+    Run `brew cask` `audi` and `style` checks locally, from a pull request URL.
+    Useful when online CI is broken.
+
+    Usage:
+      #{File.basename($PROGRAM_NAME)} <pr url>
+
+    Options:
+  BANNER
+
+  opt.on('-h', '--help', 'Show this help.') do
+    puts opt
+    exit 0
+  end
+end.parse!
+
 pr_url = ARGV[0]
 
-abort 'You need to give the script exactly one argument, the URL to a pull request from an official Homebrew Cask tap' if pr_url.nil?
 abort 'URL is not from an official Homebrew Cask tap' if pr_url !~ %r{^https://github.com/Homebrew/homebrew-cask.*}
 
 pr_api = pr_url.sub(%r{^https://github.com/([^/]+)/([^/]+)/pull/([^/]+).*}, 'https://api.github.com/repos/\1/\2/pulls/\3/files')