#!/bin/sh

######################################################################
#
# roll
#
# SYNOPSIS
#
#     roll [-h] [-v,--verbose] [--version] {FILENAME}
#
# DESCRIPTION
#
#     This script rolls a set of file names through a numeric sequence.
#     The purpose is to allow a rolling backup of things like
#     backups and log files. The given FILENAME will be renamed with
#     an integer before the extension. All files in the same directory
#     will a similar filename pattern will have their integer sequence
#     incremented.
#         service.log --> service.1.log
#         service.1.log --> service.2.log
#         service.2.log --> service.3.log
#
#     Note that this script is not atomic. If you terminate the script while
#     it is running then you may end up with inconsistent and missing files.
#
# EXAMPLE
#
#     roll /var/log/service.log
#
# EXIT STATUS
#
#     This exits with status 0 on success or non-zero on error.
#
# AUTHOR
#
#     Noah Spurrier <noah@noah.org>
#
# LICENSE
#
#     This license is OSI and FSF approved as GPL-compatible.
#     This license identical to the ISC License and is registered with and
#     approved by the Open Source Initiative. For more information vist:
#         http://opensource.org/licenses/isc-license.txt
#
#     Copyright (c) 2012, Noah Spurrier
#
#     Permission to use, copy, modify, and/or distribute this software for any
#     purpose with or without fee is hereby granted, provided that the above
#     copyright notice and this permission notice appear in all copies.
#
#     THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
#     WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
#     MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
#     ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
#     WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
#     ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
#     OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
# VERSION
#
#     Version 1
#
######################################################################

canonical () {
	# This returns the canonical path to the argument.
	# The argument must exist as either a dir or file.
	# This works in a pure POSIX environment.

	if [ -d "${1}" ]; then
		# `cd` requires execute permission on the dir.
		if [ ! -x "${1}" ]; then
			canon=""
			return 1
		fi
		oldwd=$(pwd)
		cd ${1}
		canon=$(pwd)
		# Check special case of `pwd` on root directory.
		if [ -n "${canon#/*}" ]; then
			canon=${canon}/
		fi
		cd "${oldwd}"
	else
		# At this point we know it isn't a dir.
		# But if it looks like a dir then error.
		if [ -z "${1##*/}" ]; then
			canon=""
			return 1
		fi
		# It looks like a path to a file.
		# Test the if the path before the file is a dir.
		dirname=$(dirname "$1")
		if [ -d "${dirname}" ]; then
			# `cd` requires execute permission on the dir.
			if [ ! -x "${dirname}" ]; then
				canon=""
				return 1
			fi
			oldwd=$(pwd)
			cd "${dirname}"
			canon=$(pwd)
			# Check special case of `pwd` on root directory.
			if [ -z "${canon#/*}" ]; then
				canon=/$(basename "$1")
			else
				canon=${canon}/$(basename "$1")
			fi
			cd "${oldwd}"
		else
			# It isn't anything so error.
			canon=""
			return 1
		fi
	fi
	echo "${canon}"
	return 0
}

######################################################################
# Debug
######################################################################

# This makes the debug output of `set +x` (set -o xtrace) easier to read.
# DO NOT export this. It will crash POSIX shell subshells and scripts.
[ -n "$BASH" ] && PS4='+${BASH_SOURCE}:${LINENO}:${FUNCNAME[0]}: '
# set -o trace xtrace
# Do not allow use of unset variables.
#set -o nounset
# Exit script if it does not catch an error from any command it runs.
# For example, this will exit the script:
#     false
# This will not exit the script
#     if false; then echo "This will never be printed."; fi
#set -o errexit

#####################################################################
# Color
#####################################################################

# Don't use color if there is no terminal on stdout.
if type tput >/dev/null 2>/dev/null && tty <&1 >/dev/null 2>&1; then
	COLOR_RED="$(tput setaf 1)"
	COLOR_GRN="$(tput setaf 2)"
	COLOR_BLU="$(tput setaf 4)"
	COLOR_YEL="$(tput setaf 3)"
	COLOR_OFF="$(tput sgr0)"
else
	COLOR_RED=""
	COLOR_GRN=""
	COLOR_BLU=""
	COLOR_YEL=""
	COLOR_OFF=""
fi

#####################################################################
# Exit cleanup
#####################################################################

exit_with_message() {
	local EXIT_CODE="${1:-0}"
	local EXIT_MESSAGE="${2:-''}"

	# Exit with error will print to stderr and highlight in red.
	if [ "${EXIT_CODE}" != "0" ]; then
		exec 1>&2
		echo
                echo "Usage: $0 [-h | --help] FILE"
                echo "  -h --help         : Shows this help."
                echo "  FILE              : The filename to be rotated. Must exist."
                echo "All files names that fit the pattern, FILE.[0-9] will have their"
                echo "integer incremented. The base file, FILE, will be renamed to FILE.1."
                echo "If the files have an extension then integer will before placed"
                echo "before the extension. So 'server.log' would be rolled as"
                echo "server.1.log, server.2.log, server.3.log, etc."
		echo
		echo $COLOR_RED
	fi
	echo "${EXIT_MESSAGE}"
	echo ${COLOR_OFF}
	exit ${EXIT_CODE}
}

#####################################################################
# Global traps and aliases
#####################################################################

# Must set 'die' as an alias in order for LINENO to make sense.
#shopt -s expand_aliases
#alias die='echo -n "${COLOR_YEL}${0} at line ${LINENO}:${COLOR_OFF} "; exit_with_message'
####
####trap "die 1 'Received SIGHUP'" SIGHUP
####trap "die 1 'Received SIGINT'" SIGINT
####trap "die 1 'Received SIGTERM'" SIGTERM

#####################################################################
# MAIN
#####################################################################

while [ $# != 0 ]; do
	if [ "-h" = "${1}" ]; then
		exit_with_message 1 "Help"
		# Should not get here
		exit 2
	elif [ "--help" = "${1}" ]; then
		exit_with_message 1 "Help"
		# Should not get here
		exit 2
	else
		FILENAME=${1}
		shift
	fi
done

#
# Cleanup the filename and extract the extension.
#
FILENAME_CANONICAL=$(canonical "${FILENAME}")
if [ -z ${FILENAME##*/} ]; then
	FILENAME_CANONICAL=${FILENAME_CANONICAL}/
fi
DIRNAME=${FILENAME_CANONICAL%/*}
FILENAME=${FILENAME_CANONICAL#${DIRNAME}/}
FILENAME_WITHOUT_EXT=${FILENAME%%.*}
FILE_EXT=${FILENAME#*.}
if [ ${FILE_EXT} = ${FILENAME} ]; then
	FILE_EXT=""
else
	FILE_EXT=.${FILE_EXT}
fi

#
# Check that the destination file and directory exists.
#
if [ ! -w ${DIRNAME} ]; then
	msg="ERROR: no write permission on directory.\n"
	msg=${msg}"Write permission must be granted on ${DIRNAME} to rename files."
	exit_with_message 1 ${msg}
fi
if [ ! -f ${FILENAME_CANONICAL} ]; then
	msg="ERROR: file does not exist\n"
	msg=${msg}"The following file must exist: ${FILENAME_CANONICAL}."
	exit_with_message 1 "${msg}"
fi

#
# Loop through the file names and increment their index numbers.
#
RUNNING=1
index=1
filename_curr=${DIRNAME}/${FILENAME_WITHOUT_EXT}${FILE_EXT}
mv ${filename_curr} ${filename_curr}.old
filename_next=${DIRNAME}/${FILENAME_WITHOUT_EXT}.${index}${FILE_EXT}
while [ ${RUNNING} -eq 1 ] ; do
	if [ -f ${filename_next} ]; then
		mv ${filename_next} ${filename_next}.old
	else
		RUNNING=0
	fi
	if [ -f ${filename_curr}.old ]; then
		mv ${filename_curr}.old ${filename_next}
	fi
	filename_curr=${DIRNAME}/${FILENAME_WITHOUT_EXT}.${index}${FILE_EXT}
	index=$((index+1))
	filename_next=${DIRNAME}/${FILENAME_WITHOUT_EXT}.${index}${FILE_EXT}
done

#####################################################################
# END
#########1#########2#########3#########4#########5#########6#########7
# vim:set sr et ts=4 sw=4 ft=sh: // See Vim, :help 'modeline'