refactor: write line-wrapped code files into temp files

We shouldn't modify student submissions, instead we use the
temp file when rendering them to PDF. Cleanup will be performed
after rendering is complete.

app/helpers/file_helper.rb

@@ -530,21 +530,16 @@ def task_submission_identifier_path_with_timestamp(type, task, timestamp)
     "#{task_submission_identifier_path(type, task)}/#{timestamp.to_s}"
   end
 
-  def text_line_length_limit(path, width: 200)
-    tempfile = Tempfile.new('processed-source')
+  def line_wrap(path, width: 200)
+    dir = File.dirname(path)
+    basename = File.basename(path)
+    output = File.join(dir, "WRAPPED-#{basename}")
     begin
-      # run fold (from coreutils) on the source file, write the output to the temporary file
-      fold_cmd = "fold --width #{width} #{path.shellescape} > #{tempfile.path}"
+      fold_cmd = "fold --width #{width} #{path.shellescape} > #{output}"
       logger.debug "Running fold on #{path} to limit line width to #{width}"
       system_try_within 5, "Failed running fold on #{path} to limit line width to #{width}", fold_cmd
-      # copy the output file to the input file path
-      FileUtils.cp tempfile.path, path
     rescue => e
       logger.error "Failed to run fold on #{path} to limit line width to #{width}. Rescued with error:\n\t#{e.message}"
-    ensure
-      # ensure the temporary file is closed and deleted immediately
-      tempfile.close
-      tempfile.unlink
     end
   end
   # Export functions as module functions
@@ -590,5 +585,5 @@ def text_line_length_limit(path, width: 200)
   module_function :task_submission_identifier_path_with_timestamp
   module_function :known_extension?
   module_function :pages_in_pdf
-  module_function :text_line_length_limit
+  module_function :line_wrap
 end

app/models/task.rb

@@ -993,15 +993,36 @@ def init(task, is_retry)
     end
 
     def make_pdf
-      logger.debug "Running QPDF on all documents before rendering to repair any potential broken files."
+      logger.debug "Rendering PDF for a task, preprocessing attachments."
       @files.each do |f|
         if f[:type] == "document"
+          logger.debug "Running QPDF on #{f[:path]} before rendering to repair any potential broken files."
           FileHelper.qpdf(f[:path])
         elsif f[:type] == "code"
-          FileHelper.text_line_length_limit(f[:path])
+          extension = File.extname(f[:path])[1..-1]
+          case extension
+          when "ipynb"
+            logger.debug "File #{f[:path]} is a Jupyter Notebook, not performing line wrapping."
+          else
+            logger.debug "Performing line wrapping on #{f[:path]} before rendering to break up long lines."
+            FileHelper.line_wrap(f[:path])
+          end
         end
       end
+      logger.debug "Preprocessing complete, rendering file."
       render_to_string(template: '/task/task_pdf', layout: true)
+    ensure
+      logger.debug "Cleaning up line-wrapped temporary files after rendering."
+      @files.each do |f|
+        next unless f[:type] == "code"
+        name = File.basename(f[:path])
+        dir = File.dirname(f[:path])
+        tempfile_path = File.join(dir, "WRAPPED-" + name)
+        if File.exist? tempfile_path
+          File.unlink(tempfile_path)
+          logger.debug "Deleted #{tempfile_path}"
+        end
+      end
     end
   end