#!/bin/sh

#set -e

basedir="/etc"
targetdir="$(mktemp -td localtweaks.XXXXXX)"
includefile="/etc/local/localtweaks.include"
excludefile="/etc/local/localtweaks.exclude"
extensions=".orig .old"

for ext in $extensions; do
	extfiles="$(find $basedir -name "*$ext")"
	for extfile in $extfiles; do
		xextfile="${extfile%$ext}"
		files="$files ${xextfile#$basedir}"
	done
done

includes=""
if [ -d "$(dirname "$includefile")" ] && [ -r "$includefile" ]; then
	includes="$(cat "$includefile")"
	for include in $includes; do
		files="$files ${include#$basedir}"
	done
fi

excludes=""
if [ -d "$(dirname "$excludefile")" ] && [ -r "$excludefile" ]; then
	xexcludes="$(cat "$excludefile")"
	for exclude in $xexcludes; do
		excludes="$excludes ${exclude#$basedir}"
	done
fi

# process all files once each
for file in $(for x in $files; do echo $x; done | uniq | sort); do

	# file were chosen based on backups - it may not exist itelf
	[ -s "$basedir/$file" ] || continue

	for exclude in $excludes; do
		[ "$file" = "$exclude" ] && continue 2
	done

	ext=""
	for xext in $extensions; do
		if [ -e $basedir/$file$xext ]; then
			ext="$xext"
			continue
		fi
	done

	newdir="$targetdir/$basedir/$(dirname "$file")"
	mkdir -p "$newdir"
	cp -af "$basedir/$file" "$newdir"

	# Only diff against existing and non-empty files.
	if [ -n "$ext" ] && [ -s "$basedir/$file$ext" ]; then
		diff -ruN "$basedir/$file$ext" "$basedir/$file" > "$targetdir/$basedir/$file.diff"
		chown --reference="$basedir/$file" "$targetdir/$basedir/$file.diff"
		chmod --reference="$basedir/$file" "$targetdir/$basedir/$file.diff"
		chmod a-x "$targetdir/$basedir/$file.diff"
	fi
done