From 04851aceb8b4668aece48a5fc2ae42929bc5a617 Mon Sep 17 00:00:00 2001
From: Kyle Brennan <kylos101@gmail.com>
Date: Sun, 7 Nov 2021 16:30:18 +0000
Subject: [PATCH] Fixes #852 optionally add last newline

Signed-off-by: Kyle Brennan <kylos101@gmail.com>
---
 commands/new_function.go | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/commands/new_function.go b/commands/new_function.go
index 61cfcd1c..b631e09b 100644
--- a/commands/new_function.go
+++ b/commands/new_function.go
@@ -152,6 +152,11 @@ Download templates:
 		}
 
 		fileName = appendFile
+
+		newLineErr := addLastNewline("./" + fileName)
+		if newLineErr != nil {
+			return newLineErr
+		}
 		outputMsg = fmt.Sprintf("Stack file updated: %s\n", fileName)
 
 	} else {
@@ -346,3 +351,33 @@ Cannot have duplicate function names in same yaml file`, functionName, appendFil
 
 	return nil
 }
+
+func addLastNewline(fileName string) error {
+	// open a file as read write
+	file, err := os.OpenFile(fileName, os.O_RDWR, 0600)
+	defer file.Close()
+	if err != nil {
+		return fmt.Errorf("could not open '%s' to check for new lines %s", fileName, err)
+	}
+
+	// read the last byte of the file (excludes EOF)
+	buffer := make([]byte, 1)
+	fileStats, _ := file.Stat()
+	bytesRead, err := file.ReadAt(buffer, fileStats.Size()-1)
+
+	// handle I/O errors
+	if err != nil {
+		return fmt.Errorf("could not read the last byte of '%s' %s", fileName, err)
+	} else if bytesRead != 1 {
+		return fmt.Errorf("read unexpected # of bytes in '%s'", fileName)
+	}
+
+	hasTrailingNewline := string(buffer) == "\n"
+	if !hasTrailingNewline {
+		// add 2 trailing newlines
+		// this is consistent with append behavior when last byte is already \n
+		file.Seek(0, 2)
+		file.Write([]byte("\n\n"))
+	}
+	return nil
+}