#!/bin/bash

if [ "$1" == "" ]; then

echo
echo "reverse 1.0 is a lumalab.net bash script to reverse a file sequence."
echo "This script is using sed."
echo "Usage as xfce custom action command: reverse.sh %n"
echo
echo "Shell usage: reverse.sh <name>.<ext>"
echo
echo "Example: reverse.sh image0122.png"
echo
echo "         This example will reverse a file sequence in the current directory"
echo "         with the name image and the extension png"
echo "         based on the starting number 0000"
echo
echo "This script has the intension to be useful but comes without any warranty."
echo "Feel free to modify it for your own purpose."
echo

else

IN_NOEXT=`echo "$1" | cut -d'.' -f 1` # remove extension
IN_NAME=`echo "$IN_NOEXT" | sed 's/[0-9]*//g'` #remove all digits
IN_EXT=`echo "$1" | cut -d'.' -f 2-` # get selected extension

# Count sequence files
COUNTER=0
for FILENAME in $IN_NAME*.$IN_EXT; do
   let COUNTER++
done

# Create temp files to prevent overwriting
for FILENAME in $IN_NAME*.$IN_EXT; do
   mv "$FILENAME" temp_$IN_NAME$(printf %04d $COUNTER).$IN_EXT  
   let COUNTER--
done

# Replace temp with the original file name
COUNTER=0
for FILENAME in temp_$IN_NAME*.$IN_EXT; do
   mv "$FILENAME" $IN_NAME$(printf %04d $COUNTER).$IN_EXT  
   let COUNTER++  
done

fi