cli.rb in handbrake-0.2.0

- old
+ new

@@ -57,15 +57,92 @@
 
     ##
     # Performs a conversion. This method immediately begins the
     # transcoding process; set all other options first.
     #
+    # @param [String] filename the desired name for the final output
+    #   file
+    # @param [Hash] options additional options to control the behavior
+    #   of the output process
+    # @option options [Boolean,:ignore] :overwrite (true) determines
+    #   the behavior if the desired output file already exists. If
+    #   `true`, the file is replaced. If `false`, an exception is
+    #   thrown. If `:ignore`, the file is skipped; i.e., HandBrakeCLI
+    #   is not invoked.
+    # @option options [Boolean] :atomic (false) provides a
+    #   pseudo-atomic mode for transcoded output. If true, the
+    #   transcode will go into a temporary file and only be copied to
+    #   the specified filename if it completes. The temporary filename
+    #   is the target filename with `.handbraking` inserted before the
+    #   extension. Any `:overwrite` checking will be applied to the
+    #   target filename both before and after the transcode happens
+    #   (the temporary file will always be overwritten). This option
+    #   is intended to aid in writing automatically resumable batch
+    #   scripts.
+    #
     # @return [void]
-    def output(filename)
-      run('--output', filename)
+    def output(filename, options={})
+      overwrite = options.delete :overwrite
+      case overwrite
+      when true, nil
+        # no special behavior
+      when false
+        raise FileExistsError, filename if File.exist?(filename)
+      when :ignore
+        if File.exist?(filename)
+          trace "Ignoring transcode to #{filename.inspect} because it already exists"
+          return
+        end
+      else
+        raise "Unsupported value for :overwrite: #{overwrite.inspect}"
+      end
+
+      atomic = options.delete :atomic
+      interim_filename =
+        if atomic
+          partial_filename(filename)
+        else
+          filename
+        end
+
+      unless options.empty?
+        raise "Unknown options for output: #{options.keys.inspect}"
+      end
+
+      run('--output', interim_filename)
+
+      if filename != interim_filename
+        replace =
+          if File.exist?(filename)
+            trace "#{filename.inspect} showed up during transcode"
+            case overwrite
+            when false
+              raise FileExistsError, filename
+            when :ignore
+              trace "- will leave #{filename.inspect} as is; copy #{interim_filename.inspect} manually if you want to replace it"
+              false
+            else
+              trace '- will replace with new transcode'
+              true
+            end
+          else
+            true
+          end
+        FileUtils.mv interim_filename, filename if replace
+      end
     end
 
+    def partial_filename(name)
+      if File.basename(name).index '.'
+        dot_at = name.rindex '.'
+        name.dup.insert dot_at, '.handbraking'
+      else
+        name + '.handbraking'
+      end
+    end
+    private :partial_filename
+
     ##
     # Performs a title scan. Unlike HandBrakeCLI, if you do not
     # specify a title, this method will return information for all
     # titles. (HandBrakeCLI defaults to only returning information for
     # title 1.)
@@ -132,9 +209,13 @@
             $stderr.puts result.output
           end
           raise "HandBrakeCLI execution failed (#{result.status.inspect})"
         end
       end
+    end
+
+    def trace(msg)
+      $stderr.puts msg if trace?
     end
 
     ##
     # Copies this CLI instance and appends another command line switch
     # plus optional arguments.