Inject [draft] option to documentclass if draft option is passed

app/coffee/DraftModeManager.coffee

@@ -0,0 +1,21 @@
+fs = require "fs"
+logger = require "logger-sharelatex"
+
+module.exports = DraftModeManager =
+	injectDraftMode: (filename, callback = (error) ->) ->
+		fs.readFile filename, "utf8", (error, content) ->
+			return callback(error) if error?
+			modified_content = DraftModeManager._injectDraftOption content
+			logger.log {
+				content: content.slice(0,1024), # \documentclass is normally v near the top
+				modified_content: modified_content.slice(0,1024),
+				filename
+			}, "injected draft class"
+			fs.writeFile filename, modified_content, callback
+	
+	_injectDraftOption: (content) ->
+		content
+			# With existing options (must be first, otherwise both are applied)
+			.replace(/\\documentclass\[/, "\\documentclass[draft,")
+			# Without existing options
+			.replace(/\\documentclass\{/, "\\documentclass[draft]{")