#!/bin/zsh

if [[ -z "$MUSIC" ]]; then
	MUSIC=/home/music
fi

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

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

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

while [[ "${1#--}" != "$1" && "$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 ! [[ "$size" =~ '^([0-9]*(x[0-9]+)?)$' ]]; 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