#!/bin/sh
set -e

if [ "$VCS" = git ]; then
	dir=.git
	file=.gitignore
elif [ "$VCS" = hg ]; then
	dir=.hg
	file=.hgignore
elif [ "$VCS" = bzr ]; then
	dir=.bzr
	file=.bzrignore
elif [ "$VCS" = darcs ]; then
	dir=_darcs
	file=.darcsignore
else
	echo "etckeeper: unsupported VCS $VCS" >&2
	exit 1
fi

if [ ! -d "$dir" ]; then
	exit 0
fi

managed_by_etckeeper="managed by etckeeper"

nl() {
	echo >>"$file"
}

comment() {
	comment="$1"
	echo "# $comment" >>"$file"
}

ignore() {
	glob="$1"
	
	case "$VCS" in
		git|bzr)
			echo "$glob" >>"$file"
		;;
		hg)
			# rather than converting the glob to a regexp, just
			# configure hg to use globs
			if [ -z "$hg_syntax_printed" ]; then
				comment "use glob syntax"
				echo "syntax: glob" >>"$file"
				nl
				hg_syntax_printed=1
			fi
			echo "$glob" >>"$file"
		;;
		darcs)
			# darcs doesn't understand globs, so we need to translate
			# them into regexs. Not a complete converter, but suitable
			# for given globs.
			if [ "${glob%\*}" != "$glob" ]; then
				glob="${glob%\*}"
			else
				glob="$glob"'($|/)'
			fi
			if [ "${glob#\*}" != "$glob" ]; then
				glob="${glob#\*}"
			else
				glob='(^|/)'"$glob"
			fi
			glob="$( printf %s $glob | sed -e 's/\./\\./g;s/\*/[^\/]*/g;s/\?/[^\/]/g' )"
			echo "$glob" >>"$file"
	esac
}

writefile () {
	comment "begin section $managed_by_etckeeper (do not edit this section by hand)"
	nl

	if [ "$VCS" = darcs ]; then
		darcs setpref boringfile .darcsignore
	fi

	if [ "$LOWLEVEL_PACKAGE_MANAGER" = dpkg ]; then
		comment "new and old versions of conffiles, stored by dpkg"
		ignore "*.dpkg-*"
		nl
	elif [ "$LOWLEVEL_PACKAGE_MANAGER" = "rpm" ]; then
		comment "new and old versions of conffiles, stored by apt/rpm"
		ignore "*.rpm*"
		nl
	elif [ "$LOWLEVEL_PACKAGE_MANAGER" = "pacman-g2" ]; then
		comment "new and old versions of conffiles, stored by pacman"
		ignore "*.pacnew"
		ignore "*.pacorig"
		ignore "*.pacsave"
		nl
	fi
	
	comment "mount(8) records system state here, no need to store these"
	ignore blkid.tab
	ignore blkid.tab.old
	nl
	
	comment "some other files in /etc that typically do not need to be tracked"
	ignore nologin
	ignore ld.so.cache
	ignore mtab
	ignore .pwd.lock
	ignore network/run
	ignore adjtime
	ignore lvm/cache
	nl
	
	comment "editor temp files"
	ignore "*~"
	ignore ".*.sw?"
	ignore "#*#"
	ignore DEADJOE

	nl
	comment "end section $managed_by_etckeeper"
}

if [ -e "$file" ]; then
	if ! grep -q "$managed_by_etckeeper" "$file"; then
		echo "etckeeper: "$file" does not contain \"$managed_by_etckeeper\" comment; not updating"
		exit 1
	fi
	realfile="$file"
	file=$(tempfile)
	(
		skipping=
		while read line; do
			if echo "$line" | grep -q "$managed_by_etckeeper"; then
				if [ ! "$skipping" ]; then
					skipping=1
				else
					skipping=
					writefile
				fi
			elif [ ! "$skipping" ]; then
				echo "$line" >> "$file"
			fi
		done
		if [ "$skipping" ]; then
			# reached end of file w/o ending block
			writefile
		fi
	) <"$realfile"

	mv -f "$file" "$realfile"
else
	writefile
fi
