#!/usr/bin/env bash

bgroot="$XDG_DATA_HOME/wayland"
bgdesk="$bgroot/desktop"
bglock="$bgroot/lockscreen"
walldir="$HOME/pix/wall"

die()
{
	command -v notify-send > /dev/null &&
		notify-send "  cwall" "$1"

	printf "\033[31;1merr: %b\033[0m\n" "$1" 1>&2
	exit "${2:-1}"
}

usage()
{
	echo 'Usage: cwall [wallpaper.img|directory]'
}

mimetype()
{
	file --brief --dereference --mime-type "$1"
}

randimg()
{
	# usage: randbg dir
	: "${1:?}"
	maxattempts=10
	attempt=0

	img=
	while :; do
		img="$(find "$1" \
			-iname "*.avif" \
			-o -iname "*.heic" \
			-o -iname "*.heif" \
			-o -iname "*.jpeg" \
			-o -iname "*.jpg" \
			-o -iname "*.jxl" \
			-o -iname "*.png" \
			-o -iname "*.webp" | shuf -n1)"

		[ -z "$img" ] &&
			return 1

		# make sure the file is an actual image
		case "$(mimetype "$img")" in
		"image/"*)
			echo "$img"
			break
			;;
		*)
			attempt=$((attempt + 1))
			[ "$attempt" -gt "$maxattempts" ] &&
				return 1
		esac
	done
}

updatewall()
{
	: "${1:?}"

	rm -f "$bgdesk" "$bglock"
	cp  "$1" "$bgdesk"
	swaymsg "output * background '${bgdesk}' fill"
	ffmpeg -loglevel quiet -i "$bgdesk" -vf "boxblur=50" -f mjpeg "$bglock"
}

########
# MAIN #
########

if [ "$#" -eq 0 ]; then
	input="$walldir"
elif [ "$1" = "-h" ]; then
	usage && exit 0
else
	input="$1"
fi

if [ ! -r "$input" ]; then
	die "can't read $input"
fi
if [ ! -d "$bgroot" ]; then
	mkdir -p "$bgroot"
fi

case "$(mimetype "$input")" in
"image/"*)
	updatewall "$input"
	;;
"inode/directory")
	if ! img=$(randimg "$input"); then
		die "no image file in $input"
	fi

	updatewall "$img"
	;;
*)
	die "invalid input $input"
	;;
esac