#! /bin/bash -u 
# Last edited on 2009-04-08 03:57:45 by stolfilocal

usage="$0 [ -suffix {SUFFIX} ] < FILES.dir > ICONS.dir"

# Reads a list of file names from standard input. If each {FILENAME}
# read is an icon-like name, outputs {FILENAME} itself. Otherwise,
# looks for an icon-like version of {FILENAME}, in the same directory;
# if such exists, outputs the name of that icon file. Otherwise
# outputs {FILENAME}{SUFFIX}.png (where the {SUFFIX} defaults to
# "-icon")
#
# An `icon-like name' must have one of the following extensions
#   .png .PNG .jpg .JPG .jpeg .JPEG
# possibly with ".gz" or ".Z" appedned; and its name minus extension
# must end in one of "-icon" "_icon" "-thumb" "_thumb" "-i" "_i".

cmd=${0##*/}

function error()
{ 
  echo "${cmd}: $1" >&2; 
  echo "usage: ${usage}" >&2; 
  echo "(unknown)";
  exit 1;
}

suffix="-icon"
while [ $# -gt 0 ]; do
  case "$1" in
    -suffix ) 
      if [ $# -lt 2 ]; then error "missing suffix"; fi
      suffix="$2"; shift; shift ;;
    -* )
      error "unrecognized option $1" ;;
    * ) break;;
  esac;
done

if [ $# != 0 ]; then
  error "excess parameters «$*»";
fi

while read -r fname; do

  # Get extension and root name:

  uname="${fname}"
  case "${uname}" in
    *.gz | *.Z ) uname="${uname%.*}" ;;
  esac;
  case "${uname}" in
    *.png | *.PNG | *.jpg | *.JPG | *.jpeg | *.JPEG ) 
      uname="${uname%.*}"
      case ${uname} in
        *_icon | *-icon | *-thumb | *_thumb | *-i | *_i )
          # image is already an icon in right format
          echo "${fname}"; continue;;
      esac
      ;;
    *.* )
      uname="${uname%.*}"
      case ${uname} in
        *_icon | *_thumb | *_i ) uname="${uname%_*}" ;;
        *-icon | *-thumb | *-i ) uname="${uname%-*}" ;;
      esac
      ;;
    *)
      ;;
  esac

  # Check if icon already exists:
  # Note the "." to avoid empty list troubles (bash 'e uma boshta)

  icons=( $(shopt -s nullglob; echo . ${uname}{-,_}{icon,thumb,i}.{png,PNG,jpg,JPG,jpeg,JPEG,gif,GIF}{,.gz,.Z}* ) )

  if [ ${#icons[@]} -gt 1 ]; then
    echo "${icons[1]}"; continue;
  else
    echo "${uname}${suffix}.png"; continue;
  fi;
done