#!/usr/bin/env bash
# SPDX-FileCopyrightText: 2022 Robin Vobruba <hoijui.quaero@gmail.com>
# SPDX-License-Identifier: AGPL-3.0-or-later
#
# See the output of "$0 -h" for details.

# Exit immediately on each error and unset variable;
# see: https://vaneyckt.io/posts/safer_bash_scripts_with_set_euxo_pipefail/
set -Eeuo pipefail
#set -Eeu

APP_NAME="Listing to File-System converter"

# parameters
output_dir="$(pwd)"

function print_help() {

	script_name="$(basename "$0")"
	echo -e ""
	echo -e "$APP_NAME - Given a file listing, creates the actual file-system representation of it."
	echo -e "The input file-listing format has to follow these rules:"
	echo -e "* one file/dir per line"
	echo -e "* full paths, relative to the output-dir"
	echo -e "* each line indicating a dir needs to end with a '/'"
	echo -e "* empty lines and lines starting with '#' or ';', are ignored"
	echo -e "* any other line indicates a file"
	echo -e ""
	echo -e "Usage:"
	echo -e "\t$script_name [OPTION...]"
	echo -e "Options:"
	echo -e "\t-o, --output-dir"
	echo -e "\t\tAdditionally prints a tree view of the created dir structure"
	echo -e "\t-h, --help"
	echo -e "\t\tPrint this usage help and exit"
	echo -e ""
}

# Process command line arguments
while [[ $# -gt 0 ]]
do
	arg="$1"
	shift # $2 -> $1, $3 -> $2, ...

	case "$arg" in
		-o|--output-dir)
			output_dir="$1"
			shift
			;;
		-h|--help)
			print_help
			exit 0
			;;
		-*) # unknown switch
			>&2 echo "ERROR: Unknown switch '$arg'"
			exit 1
			;;
		*) # non-switch
			POSITIONAL+=("$arg") # save it in an array for later
			;;
	esac
done
set -- "${POSITIONAL[@]}" # restore positional parameters

if ! [ -d "$output_dir" ] || [ -n "$(/usr/bin/ls -A "$output_dir")" ]
then
	>&2 echo "The output dir is not an existing, empty dir: '$output_dir'"
	exit 1
fi

while IFS= read -r line
do
	if [ -z "$line" ] || [[ $line =~ ^[#\;].* ]]
	then
		continue
	fi
	if [[ $line =~ (^\|/)\.\.(/\|$) ]]
	then
		>&2 echo "Invalid sequence '..' found in: '$line'"
		exit 1
	fi
	if [[ $line =~ ^/ ]]
	then
		>&2 echo "Please use relative listing paths; found: '$line'"
		exit 1
	fi
	if [[ $line =~ .*/$ ]]
	then
		mkdir -p "$output_dir/$line"
	else
		parent_dir="$(dirname "$line")"
		mkdir -p "$output_dir/$parent_dir"
		touch "$output_dir/$line"
	fi
done