add_trailing_newlines

#!/usr/bin/env bash
#
# @license Apache-2.0
#
# Copyright (c) 2024 The Stdlib Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Script to add trailing newlines to files if they don't already have one.
#
# Usage: add_trailing_newlines file1 [file2 file3 ...]
#
# Arguments:
#
#   file1       File path.
#   file2       File path.
#   file3       File path.

# Ensure that the exit status of pipelines is non-zero in the event that at least one of the commands in a pipeline fails:
set -o pipefail


# VARIABLES #

# List of file extensions to process:
extensions=("js" "mjs" "cjs" "json" "ts" "py" "jl" "R" "c" "h" "cpp" "hpp" "f" "sh" "awk" "html" "xml" "css" "md" "yml" "gyp" "gypi" "bib" "tex" "mk")


# FUNCTIONS #

# Convert Windows CRLF to Unix LF line endings.
convert_line_endings() {
	if [[ "$OSTYPE" == "darwin"* ]]; then
		# macOS requires an empty string argument with -i to edit in-place without backup...
		sed -i '' 's/\r$//' "$1"
	else
		# Linux and other Unix-like systems...
		sed -i 's/\r$//' "$1"
	fi
}

# Prints a success message.
print_success() {
	echo 'Success!' >&2
}

# Main execution sequence.
main() {
	# Assuming all arguments are passed as one string and split by spaces:
	IFS=' ' read -r -a files <<< "$*"

	for file in "${files[@]}"; do
		echo "Processing file: $file"
		if [[ ! -f "$file" ]]; then
			echo "File not found: $file"
			continue
		fi

		# Convert line endings from CRLF to LF:
		convert_line_endings "$file"

		extension="${file##*.}"
		filename=$(basename "$file")

		local match_found=false
		if [[ "$filename" == "Makefile" ]]; then
			match_found=true
		elif [[ "$file" == *.* ]]; then
			for ext in "${extensions[@]}"; do
				if [[ "$ext" == "$extension" ]]; then
					match_found=true
					break
				fi
			done
		fi
		if [[ "$match_found" == true ]]; then
			if [[ "$(tail -c1 "$file"; echo x)" != $'\nx' ]]; then
				echo "Adding newline to: $file"
				echo >> "$file"
			fi
		else
			echo "Skipping file (unsupported extension): $file"
		fi
	done

	print_success
	exit 0
}

# Call main with all command-line arguments:
main "$@"