#!/bin/sh

# This script simply takes a rrd file and doubles the rows of all its RRA
#
# Result in tmp.rrd
#
# Make backups before any important use !

RESULT_FILENAME="result.rrd"

set -e

if [ ! -f "$1" ]; then
	echo "ERROR: no file specified." >&2
	exit 1
fi

SRC="$1"
DST="$( dirname "$SRC" )/$RESULT_FILENAME"
# rrdtool seems to always create in current directory
RRD_SPECIAL_FILE="resize.rrd"

if [ -f "$RRD_SPECIAL_FILE" ] || [ -f "$DST" ]; then
	echo "ERROR: files with names '$RRD_SPECIAL_FILE' or '$DST' already exist. Trouble ?" >&2
	exit 1
fi

# Initial copy
cp -ai "$SRC" "$DST"

# Only use the SRC for enumeration : all the work after that is done on DST
rrdtool info "$SRC" | grep rows | while read LINE; do
	RRANUM="$( echo "$LINE" | sed 's/.*\[\([0-9]\+\)\].rows.*/\1/' )"
	ROWS="$( echo "$LINE" | sed 's/.* = //' )"
	if [ -z "$RRANUM" ] || [ -z "$ROWS" ]; then
		echo "Trouble at the mill." >&2
		exit 2
	fi

	rrdtool resize "$DST" $RRANUM GROW $ROWS && mv "$RRD_SPECIAL_FILE" "$DST"
done

# I often forget this one...
chmod "--reference=$SRC" "$DST"
chown "--reference=$SRC" "$DST"