#!/bin/sh
#
# logd: rotate logfiles

PROG="$0"

error() {
	echo 1>&2 "ERROR: $1"
	exit 127
}

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

usage() {
	error "Usage: $PROG LIMIT{k|s} FILE CYCLES"
}

rotate() {
	local FILE="$1"
	local COUNT="$2"

	for ITEM in $(seq $COUNT \-1 0); do
		CURFILE="${FILE}.${ITEM}"
		NEXTFILE="${FILE}.$((${ITEM}+1))"
		if [ "${ITEM}" = "${COUNT}" ]; then
			rm "${CURFILE}" 2>/dev/null
		else
			mv "${CURFILE}" "${NEXTFILE}" 2>/dev/null
		fi
	done

	mv "${FILE}" "${FILE}.0" && touch "${FILE}"
	echo rotated
}

chksize() {
	local FILE="$1"

	du -k "${FILE}" | cut -f 1
}

THRS="$1"
FILE="$2"
CYCL="$3"

case "$THRS" in
	*k)
		TYPE=size
		LIMIT="${THRS%[ks]}"
		;;
	*s) 
		TYPE=time
		LIMIT="${THRS%[ks]}"
		COUNTER="${LIMIT}"
		;;
	\?)
		usage
		;;
esac

test "${LIMIT:=-1}"	-gt 0		|| usage
test "${CYCL:=-1}"	-gt 0		|| usage
test			-f ${FILE}	|| usage

while :; do
	if [ "${TYPE}" = "size" ]; then
		if [ "$(chksize "${FILE}")" -gt "${LIMIT}" ]; then
			rotate "${FILE}" "${CYCL}"
		fi
	else
		if [ "${COUNTER}" -eq 0 ]; then
			rotate "${FILE}" "${CYCL}"
			COUNTER="${LIMIT}"
		fi
		COUNTER="$((${COUNTER}-1))"
	fi
	sleep 1
done