#!/bin/sh

# Copy the N versions of a file for log or backup rotation
# Stephane Bortzmeyer <stephane@bortzmeyer.org>
USAGE="Usage: $0 [-n number-of-copies] [-v] [-c] filename ..."

TEMP=$(getopt -o "n:vch" -- "$@")
if [ $? != 0 ]; then
    echo $USAGE >&2 
    exit 1
fi

set -e

# Yes, some people prefer:
#       ncopies=${COPY_N_FILES:-"5"}
if [ -z "$COPY_N_FILES" ]; then
    ncopies=5
else
    ncopies=$COPY_N_FILES
fi
if [ -z "$MODE_NEW_FILE" ]; then
    mode=0600
else
    mode=$MODE_NEW_FILE
fi
verbose=0
create=0
eval set -- "$TEMP"

while true ; do
        case "$1" in
                -n) ncopies=$2; shift 2;;
                -v) verbose=1; shift;;
                -c) create=1; shift;;
	        -h) echo $USAGE >&2; exit 0;;
                --) shift ; break ;;
                *) echo "Internal error!" >&2 ; exit 1 ;;
        esac
done

if ! which seq > /dev/null; then
    echo "Cannot find command \"seq\" in PATH" >&2
    exit 1
fi

if [ -z "$@" ]; then
    echo $USAGE >&2
    exit 1
fi

for filename in "$@"; do
    # Yes, we could drop seq and use shell arithmetic but I like the
    # power of seq
    for i in $(seq $((ncopies-2)) -1 0); do
	previous=$((i+1))
	if [ -e "$filename.$i" ]; then
	    if [ $verbose = 1 ]; then
		echo "Moving $filename.$i to $filename.$previous..."
	    fi
	    mv -f "$filename.$i" "$filename.$previous"
	fi
    done
    if [ -e "$filename" ]; then
	if [ $verbose = 1 ]; then
	    echo "Copying $filename to $filename.$i..."
	fi
	cp -pf "$filename" "$filename.$i"
    elif [ $create = 1 ]; then
	    if [ $verbose = 1 ]; then
		echo "Creating $filename with mode $mode..."
	    fi
            touch "$filename"
	    chmod $mode "$filename"
    else
	    echo "Warning: $filename does not exist" >&2
    fi
done