#!/bin/bash

# TODO: Support `exclude` option

CONFIG=meta/install.conf.yaml

set -o noglob
# Match all source and target paths of the link segment
links=( $(
	sed -n '/^- link:$/,$ p' "$CONFIG" \
	| grep -Po "(?<=path: ).*|(?<=^    ).*(?=:$)" \
	| sed "s/~/${HOME//\//\\/}/g"
) )
set +o noglob

# Assemble files that would be potentially overwritten by the `link` step
typeset -a to_archive
for (( i = 0; i < ${#links[@]}; i+=2 )); do
	# Source and target of link
	src="${links[$((i+1))]}"
	tar="${links[$i]}"

	# TODO: This assumes that the globbing can only be specified at the end
	if [[ ${src##*\*} ]]; then
		# `glob` set to false; just add the target
		to_archive+=("$tar")
	else
		# `glob` set to true; add globbed path portion in target

		# TODO: this breaks on files with spaces, but quotes must not be used for
		#       the globbing to take effect
		for path in $src; do
			# Keep the dirname as base
			base="${src%%/*}/"
			# Only the matched portion
			file="${path#$base}"

			# Skip `.` and `..` when globbing hidden files through `/.*`
			[[ $file != '.' && $file != '..' ]] || continue

			# Avoid potential double slashes (e.g. `//`)
			to_archive+=("${tar%/}${file:+/$file}")
		done
	fi
done

tmpd="$(mktemp -d)"

for file in "${to_archive[@]}"; do
	[[ ! -e "$file" ]] || mv "$file" "$tmpd"
done

if rmdir "$tmpd" 2>/dev/null; then
	>&2 echo "Nothing to archive"
else
	name="existing-$(date +"%Y%m%d_%H%M%S").tar.gz"
	if tar czvf "$name" "$tmpd"; then
		rm -rf "$tmpd"
		>&2 echo "$name created"
	else
		errc=$?
		>&2 echo "Archive could not be created. See $tmpd."
		exit $errc
	fi
fi