termux-wallpaper: rewrite

- allow spaces in the option -f
- fix shellcheck errors

fixes termux/termux-api#298

Author: xalexalex

scripts/termux-wallpaper

@@ -3,69 +3,50 @@
 set -e
 
 SCRIPTNAME=termux-wallpaper
-
 show_usage () {
 	echo "Change wallpaper on your device"
 	echo
-	echo "Usage: $SCRIPTNAME cmd [args]"
+	echo "Usage: $SCRIPTNAME [options]"
 	echo "-h         show this help"
 	echo "-f <file>  set wallpaper from file"
 	echo "-u <url>   set wallpaper from url resource"
 	echo "-l         set wallpaper for lockscreen (Nougat and later)"
 	exit 1
 }
 
-call_api() {
-	/data/data/com.termux/files/usr/libexec/termux-api Wallpaper "$@"
-}
-
-usage_error () {
-	echo "ERROR: $@"
-	show_usage
-}
-
-LOCKSCREEN_FLAG=1
-RESOURCE_FLAG=2
-
-FLAGS=0
-
-set_single () {
-	if [ $((FLAGS & $1)) -ne 0 ]; then
-		usage_error "Option already set"
-	fi
-	FLAGS=$((FLAGS | $1))
-	PARAMS="$PARAMS $2"
-}
-
-set_resource () {
-	if [ $((FLAGS & $RESOURCE_FLAG)) -ne 0 ]; then
-		usage_error "More than one image resource specified!"
-	fi
-	set_single $RESOURCE_FLAG "$1"
-}
-
-set_file () {
-	if [ ! -f $1 ]; then
-		usage_error "'$1' is not a file!"
-	fi
-	set_resource "--es file "$(realpath $1)""
-}
+OPT_LS=""
+OPT_FILE=""
+OPT_URL=""
 
 while getopts :h,:l,f:,u: option
 do
 	case "$option" in
 		h) show_usage ;;
-		l) set_single $LOCKSCREEN_FLAG "--ez lockscreen true" ;;
-		f) set_file $OPTARG ;;
-		u) set_resource "--es url $OPTARG" ;;
+		l) OPT_LS="true" ;;
+		f) path="$(realpath "$OPTARG")"
+			if [[ ! -f "$path" ]]; then
+				echo "$SCRIPTNAME: $path is not a file!"
+				exit 1
+			fi
+			OPT_FILE="$path" ;;
+		u) OPT_URL="$OPTARG" ;;
 		?) echo "$SCRIPTNAME: illegal option -$OPTARG"; exit 1 ;;
 	esac
 done
 
-shift $((OPTIND - 1))
-
-if [ $((FLAGS & RESOURCE_FLAG)) -eq 0 ]; then
-	usage_error "No file or url provided!"
+if [[ -z "$OPT_FILE""$OPT_URL" ]]; then
+	echo "$SCRIPTNAME: you must specify either -f or -u"
+	exit 1
+elif [[ -n "$OPT_FILE" ]] && [[ -n "$OPT_URL" ]]; then
+	echo "$SCRIPTNAME: you must specify either -f or -u, but not both"
+	exit 1
 fi
 
-call_api $PARAMS
+shift $((OPTIND - 1))
+if [ $# != 0 ]; then echo "$SCRIPTNAME: too many arguments"; exit 1; fi
+
+set --
+[ -n "$OPT_LS" ]   && set -- "$@" --ez lockscreen "$OPT_LS"
+[ -n "$OPT_FILE" ] && set -- "$@" --es file "$OPT_FILE"
+[ -n "$OPT_URL" ]  && set -- "$@" --es url "$OPT_URL"
+/data/data/com.termux/files/usr/libexec/termux-api Wallpaper "$@"