C_RED="$(echo -e '\e[31m')"
C_GREEN="$(echo -e '\e[32m')"
C_YELLOW="$(echo -e '\e[33m')"
C_NORMAL="$(echo -e '\e[0m')"

export DEBIAN_FRONTEND=noninteractive
B_APT_UPDATED=

progress ()
{
	echo "${C_GREEN}$1${C_NORMAL}" >&2
}

note ()
{
	echo "${C_YELLOW}$1${C_NORMAL}" >&2
}

warn ()
{
	echo "${C_RED}WARNING: $1${C_NORMAL}" >&2
}

die ()
{
	echo "${C_RED}ERROR: $1${C_NORMAL}" >&2
	exit 1
}

update-pkgs ()
{
	if [ -z "$B_APT_UPDATED" ] ; then
		apt update
		B_APT_UPDATED=1
	fi
}

install-pkgs ()
{
	update-pkgs
	apt install -y --no-install-recommends --no-install-suggests "$@"
}

install-config ()
{
	[ $# = 2 ] || die "Usage: install-config <source> (<target-file> | <target-dir>/)"
	local S=$1
	local T=$2
	if [ ${T%/} != $T ] ; then
		T=$T$(basename $S)
	fi
	local B=$BUILD_CONFIG$T
	mkdir -p $(dirname $B) $(dirname $T)
	if [ -f $T ] ; then
		if [ ! -f $B.orig ] ; then
			echo "Backing up $T to $B.orig"
			cp $T $B.orig
		else
			echo "Backup of $T already present in $B.orig"
		fi
	fi
	if [ -f $S ] ; then
		# Just a new file: overwrite
		echo "Overwriting $T"
		cp $S $T
		cp $S $B.new
	elif [ -f $S.orig -a -f $S.new ] ; then
		# Try 3-way merge
		if cmp --quiet $S.new $T ; then
			warn "Skipping merge of $T: changes already present"
		else
			echo "Merging $T"
			if diff3 -m $S.new $S.orig $T >$B.new ; then
				cp $B.new $T
			else
				die "Merge failed, please review $B.new"
			fi
		fi
	else
		die "Do not know how to install config $T"
	fi
}

sed-config ()
{
	[ $# = 2 ] || die "Usage: sed-config <target> <sed-script>"
	local T=$1
	local SCRIPT=$2
	local B=$BUILD_CONFIG$T
	mkdir -p $(dirname $B)
	[ -f $T ] || die "Want to sed $T, but it is missing"
	if [ ! -f $B.orig ] ; then
		echo "Backing up $T to $B.orig"
		cp $T $B.orig
	else
		echo "Backup of $T already present in $B.orig"
	fi
	sed -ri "$SCRIPT" $T
	cp $T $B.new
}

pipe-config ()
{
	[ $# = 1 ] || die "Usage: <command> | pipe-config <target>"
	local TMP=$(mktemp)
	cat >$TMP
	install-config $TMP $1
	rm $TMP
}

rm-config ()
{
	[ $# = 1 ] || die "Usage: rm-config <target>"
	local T=$1
	local B=$BUILD_CONFIG$T
	if [ -f $T ] ; then
		if [ ! -f $B.orig ] ; then
			echo "Backing up $T to $B.orig"
			cp $T $B.orig
		fi
		echo "Removing $T"
		rm -f $T
	else
		echo "Wanted to remove $T, but it does not exist"
	fi
}

download ()
{
	[ $# = 3 ] || die "Usage: download <URL> <hash-type> <hash>"
	local URL=$1
	local HTYPE=$2
	local HASH=$3
	local DEST=$(basename $URL)
	local CACHE=/root/.cache/download
	if [ -d $CACHE ] ; then
		if [ -f $CACHE/$DEST ] ; then
			echo "Using cached $DEST"
		else
			echo "Downloading $URL with caching"
			curl $URL >$CACHE/$DEST.tmp
			mv $CACHE/$DEST.tmp $CACHE/$DEST
		fi
		ln -s $CACHE/$DEST .
	else
		warn "Cache $CACHE not found: downloading directly"
		echo "Downloading $URL"
		curl $URL >$DEST
	fi
	local H=$(${HTYPE}sum $DEST | cut -d' ' -f1)
	[ $H == $HASH ] || die "Mismatched hash: got $H, want $HASH"
}