Added Kramdown::Man::CLI (closes #17).

bin/kramdown-man

@@ -3,24 +3,5 @@
 lib_dir = File.expand_path('../lib',__dir__)
 $LOAD_PATH.unshift(lib_dir) unless $LOAD_PATH.include?(lib_dir)
 
-require 'kramdown'
-require 'kramdown/man'
-
-case ARGV[0]
-when '-V', '--version'
-  puts "kramdown-man #{Kramdown::Man::VERSION}"
-  exit
-when '-h', '--help'
-  if $stdout.tty?
-    man_page = File.join(__dir__,'..','man','kramdown-man.1')
-
-    system('man',man_page)
-  else
-    puts "usage: #{File.basename($0)} <INPUT.md >OUTPUT"
-  end
-
-  exit
-end
-
-doc = Kramdown::Document.new(ARGF.read)
-puts doc.to_man
+require 'kramdown/man/cli'
+exit Kramdown::Man::CLI.run(ARGV)

lib/kramdown/man/cli.rb

@@ -0,0 +1,202 @@
+require 'kramdown'
+require 'kramdown/man'
+
+require 'optparse'
+
+module Kramdown
+  module Man
+    #
+    # Represents the `kramdown-man` command's logic.
+    #
+    # @api private
+    #
+    # @since 1.0.0
+    #
+    class CLI
+
+      # The program name.
+      PROGRAM_NAME = "kramdown-man"
+
+      # The URL to report bugs to.
+      BUG_REPORT_URL = "https://github.com/postmodern/kramdown-man/issues/new"
+
+      # The path to the man/ directory.
+      MAN_PAGE = File.join(__dir__,'..','..','..','man','kramdown-man.1')
+
+      # The command's option parser.
+      #
+      # @return [OptionParser]
+      attr_reader :option_parser
+
+      # The optional output file to write to.
+      #
+      # @return [String, nil]
+      attr_reader :output
+
+      #
+      # Initializes the command.
+      #
+      def initialize
+        @option_parser = option_parser
+
+        @output = nil
+      end
+
+      #
+      # Initializes and runs the command.
+      #
+      # @param [Array<String>] argv
+      #   Command-line arguments.
+      #
+      # @return [Integer]
+      #   The exit status of the command.
+      #
+      def self.run(argv)
+        new().run(argv)
+      rescue Interrupt
+        # https://tldp.org/LDP/abs/html/exitcodes.html
+        return 130
+      rescue Errno::EPIPE
+        # STDOUT pipe broken
+        return 0
+      end
+
+      #
+      # Runs the command.
+      #
+      # @param [Array<String>] argv
+      #   Command-line arguments.
+      #
+      # @return [Integer]
+      #   The return status code.
+      #
+      def run(argv=ARGV)
+        argv = begin
+                 @option_parser.parse(argv)
+               rescue OptionParser::ParseError => error
+                 print_error(error.message)
+                 return -1
+               end
+
+        markdown = case argv.length
+                   when 1
+                     path = argv[0]
+
+                     unless File.file?(path)
+                       print_error "no such file or directory: #{path}"
+                       return -1
+                     end
+
+                     File.read(path)
+                   when 0
+                     print_error "a MARKDOWN_FILE argument is required"
+                     return -1
+                   else
+                     print_error "too many arguments given"
+                     return -1
+                   end
+
+        doc = Kramdown::Document.new(markdown)
+        man_page = doc.to_man
+
+        if @output
+          File.write(@output,man_page)
+        elsif $stdout.tty?
+          view_man_page(man_page)
+        else
+          puts man_page
+        end
+
+        return 0
+      rescue => error
+        print_backtrace(error)
+        return -1
+      end
+
+      #
+      # Displays the man page using the `man` command.
+      #
+      # @param [String] man_page
+      #   The man page output.
+      #
+      def view_man_page(man_page)
+        io  = IO.popen(%w[man -l -],'w')
+        pid = io.pid
+
+        begin
+          io.puts man_page
+        rescue Errno::EPIPE
+        ensure
+          io.close
+
+          begin
+            Process.waitpid(pid)
+          rescue Errno::EPIPE, Errno::ECHILD
+          end
+        end
+      end
+
+      #
+      # The option parser.
+      #
+      # @return [OptionParser]
+      #
+      def option_parser
+        OptionParser.new do |opts|
+          opts.banner = "usage: #{PROGRAM_NAME} [options] MARKDOWN_FILE"
+
+          opts.on('-o','--output FILE','Write man page output to the file') do |file|
+            @output = file
+          end
+
+          opts.on('-V','--version','Print the version') do
+            puts "#{PROGRAM_NAME} #{VERSION}"
+            exit
+          end
+
+          opts.on('-h','--help','Print the help output') do
+            if $stdout.tty?
+              system('man',MAN_PAGE)
+            else
+              puts opts
+            end
+
+            exit
+          end
+
+          opts.separator ""
+          opts.separator "Examples:"
+          opts.separator "    #{PROGRAM_NAME} -o man/myprogram.1 man/myprogram.1.md"
+          opts.separator "    #{PROGRAM_NAME} man/myprogram.1.md"
+          opts.separator ""
+        end
+      end
+
+      #
+      # Prints an error message to stderr.
+      #
+      # @param [String] error
+      #   The error message.
+      #
+      def print_error(error)
+        $stderr.puts "#{PROGRAM_NAME}: #{error}"
+      end
+
+      #
+      # Prints a backtrace to stderr.
+      #
+      # @param [Exception] exception
+      #   The exception.
+      #
+      def print_backtrace(exception)
+        $stderr.puts "Oops! Looks like you've found a bug!"
+        $stderr.puts "Please report the following text to: #{BUG_REPORT_URL}"
+        $stderr.puts
+        $stderr.puts "```"
+        $stderr.puts "#{exception.full_message}"
+        $stderr.puts "```"
+      end
+
+    end
+  end
+end