print Asciidoctor PDF version in CLI output

- trap -V and --version flags and -v flag when used alone
- prepending Asciidoctor PDF version to version output

1 files changed, 15 insertions, 2 deletions

diff --git a/bin/asciidoctor-pdf b/bin/asciidoctor-pdf
index a10876c4..083860bc 100755
--- a/bin/asciidoctor-pdf
+++ b/bin/asciidoctor-pdf
@@ -4,9 +4,22 @@ require_relative '../lib/asciidoctor-pdf'
 require 'asciidoctor/cli'
 
 options = Asciidoctor::Cli::Options.new backend: 'pdf', header_footer: true
+
+# FIXME provide an API in Asciidoctor for sub-components to print version information
+unless ARGV != ['-v'] && (ARGV & ['-V', '--version']).empty?
+  $stdout.write %(Asciidoctor PDF #{Asciidoctor::Pdf::VERSION} using )
+  # NOTE the print_version method was added in Asciidoctor 1.5.2
+  if options.respond_to? :print_version
+    options.print_version
+  else
+    puts %(Asciidoctor #{::Asciidoctor::VERSION} [http://asciidoctor.org])
+  end
+  exit 0
+end
+
 # FIXME This is a really bizarre API. Please make me simpler.
-result = options.parse! ARGV
-if Integer === result
+case (result = options.parse! ARGV)
+when Integer
   exit result
 else
   invoker = Asciidoctor::Cli::Invoker.new options