#!/bin/bash
shopt -s nocasematch

INPUTFILE="${1:-NOFILE}"
OUTPUTFILE="${2:-out.png}"
RES_SIZE="${3:-48x48}"

if [ "${INPUTFILE}" = "NOFILE" ]; then echo "No input file!" && exit 1; fi

TEMPFILE1=$(mktemp)
TEMPFILE2=$(mktemp)

wrestool --extract --type=group_icon "${INPUTFILE}" 2>/dev/null >$TEMPFILE1 || (echo "Fail to extract!" && exit 1)
if [ -s ${TEMPFILE1} ]; then
	read OFFSET INDEX < <(
		icotool --list ${TEMPFILE1} | awk '{
			ci=int(substr($2,index($2,"=") + 1));
			cw=int(substr($3,index($3,"=") + 1));
			cb=int(substr($5,index($5,"=") + 1));
				if ((cw > w && cw <= 256) || (cw == w && cb > b)) {
				b = cb;
				w = cw;
				i = ci;
			}
		}
		END {
			print 16 + (256 - w) / 2, i;
		}'
	)

	if [ "${INDEX}" = '' ]; then
		INDEX=1
		OFFSET=20
	fi

	icotool --extract --index=${INDEX} ${TEMPFILE1} -o ${TEMPFILE2}
	ICON=${TEMPFILE2}
	mogrify -resize ${RES_SIZE} ${ICON}
fi
cp ${ICON} ${OUTPUTFILE}

rm $TEMPFILE1* ${TEMPFILE2} ${TEMPTHUMB}