Parse command-line options

lib/imbecile/cli.rb

@@ -1,10 +1,41 @@
 module Imbecile
   module CLI
 
+    USAGE = <<EOF
+Usage: #{$0} [options] <input-file>
+Options:
+  --version   Show program version and exit
+  -h, --help  Show this usage and exit
+EOF
+
     class << self
 
       def run(args)
-        p args
+        input_file = nil
+        args.each do |arg|
+          case arg
+          when "--version"
+            puts "imbecile v#{VERSION}"
+            return 0
+          when "-h", "--help"
+            puts USAGE
+            return 0
+          when /^-/
+            $stderr.puts "Error: unknown option #{arg}"
+            return 1
+          else
+            if input_file
+              $stderr.puts "Error: only one input file supported"
+              return 1
+            else
+              input_file = arg
+            end
+          end
+        end
+        if input_file.nil?
+          $stderr.puts "Error: must specify input file"
+          return 1
+        end
       end
 
     end