#!/bin/zsh

music=/stuff/music
thumbs="$HOME/.fvwm/.thumbs"

if [ ! -d "$thumbs" ]; then
	mkdir "$thumbs" || exit 1
fi

size="x128"
printimg=""
ismusic=""

while [ "${1#--}" != "$1" -a "$1" != "-" ]; do
	if [ "$1" = "--small" ]; then
		size="56"
	elif [ "$1" = "--size" ]; then
		size="$2"
		shift
	elif [ "$1" = "--music" ]; then
		ismusic="yes"
	elif [ "$1" = "--image" ]; then
		printimg="yes"
	else
		echo "unrecognised option: $1" 1>&2
		exit 1
	fi
	shift
done
[ "$1" = "-" ] && shift

if ! expr match "$size" '^\([0-9]*\(x[0-9]\+\)\?\)$' >/dev/null 2>&1; then
	echo "invalid size specification: $size" 1>&2
	exit 1
fi

if [ -z "$1" ]; then
	echo "usage: thumbnail.zsh [--small|--size <spec>] [--image] [--music] path" 1>&2
	exit 1
fi

if [ -n "$ismusic" ]; then
	imgpath="$music/`dirname "${1#$music}"`/cover.jpg"
	[ ! -f "$imgpath" ] && imgpath="${imgpath%jpg}png"
else
	imgpath="$1"
fi

[ ! -f "$imgpath" ] && exit 0

image="$(readlink -f -- "$imgpath")"
[ ! -f "$image" ] && exit 0

thumb="$thumbs/`echo -n $image | md5sum - | cut -d ' ' -f 1`_$size.png"
if [ -f "$thumb" ]; then
	mtime_s="`stat -c %Y -- "$image"`"
	mtime_t="`stat -c %Y -- "$thumb"`"
	if [ "$mtime_s" -gt "$mtime_t" ]; then
		convert -scale "$size" "$image" "$thumb"
	fi
else
	convert -scale "$size" "$image" "$thumb"
fi

echo "$thumb"
[ -n "$printimg" ] && echo "$image"
exit 0