Update vim plugin manager script to proper standard

.scripts/vimplugin.sh

@@ -1,5 +1,8 @@
 #!/bin/sh
 
+# Vim plugin manager
+# Depends: git
+
 #----
 BASE="$XDG_CONFIG_HOME/vim/pack"
 #----
@@ -10,34 +13,59 @@ OPT="$DIR/opt"
 
 help() {
 	B=$(tput bold)
+	U=$(tput smul)
 	N=$(tput sgr0)
 
 	cat << EOF
 ${B}NAME${N}
-	vimplugin - vim plugin manager
+	vimplugin.sh - vim plugin manager
 
 ${B}SYNOPSIS${N}
-	./vimplugin.sh <command> [<arg1> <arg2>]
+	${B}vimplugin.sh${N} [${U}OPTION${N}] [${U}COMMAND${N}] [<${U}ARG${N}>...]
+
+${B}OPTIONS${N}
+	${B}-h${N}	Display usage message and exit.
 
 ${B}COMMANDS${N}
 	${B}init${N}
 		Creates all the required directories/files.
 
-	${B}install <url> ["start"/"opt"]${N}
-		Install a new plugin, <url> need to be a valid GitHub URL,
-		start/opt to install the plugin in the start/opt directory
-		(default: start).
+	${B}install${N} ${U}URL${N} <${U}LOCATION${N}>
+		Install a new plugin from a valid GitHub ${U}URL${N}.
+		Store this plugin in <${U}LOCATION${N}> (start/opt), default to start.
+
+	${B}list${N} <${U}NUMBER${N}>
+		Print all the installed plugins.
+		If <${U}NUMBER${N}> is provided, print only the plugin in that position.
 
-	${B}list <number>${N}
-		Prints all the installed plugins,
-		<number> prints just the plugin in that position.
 	${B}remove${N}
-		Remove plugin, script will prompt a selection menu.
+		Remove plugin, pick from selection menu.
+
 	${B}update${N}
-		Installs/updates all plugins from the config file.
+		Install/update all plugins stored in the config file.
 EOF
 }
 
+# Exit if no option is provided
+[ "$#" -eq 0 ] && help && exit 1
+
+SCRIPT="$(basename "$0")"
+
+# Option handling
+while getopts ':h?' opt; do
+	case $opt in
+		h)
+			help
+			exit 0
+			;;
+		\?)
+			echo "$SCRIPT: invalid option '$OPTARG'"
+			echo "Try '$SCRIPT -h' for more information."
+			exit 1
+			;;
+	esac
+done
+
 init() {
 	sudo mkdir -p "$START"
 	sudo mkdir -p "$OPT"
@@ -49,30 +77,11 @@ init() {
 	fi
 }
 
-list() {
-	if [ -z "$1" ]; then
-		echo "Listing all installed plugins.."
-	fi
-
-	PLUGIN="$(find "$DIR" -mindepth 2 -maxdepth 2 \
-		| sort | awk -F '/' '{ print $(NF-1)"/"$NF }')"
-	NUM=0
-	for p in $PLUGIN; do
-		NUM=$(( NUM + 1 ))
-
-		if [ -z "$1" ]; then
-			echo "$NUM) $p"
-		elif [ "$NUM" = "$1" ]; then
-			echo "$p"
-		fi
-	done
-}
-
 install() {
 	# Check if correct git URL
 	if [ -z "$(echo "$1" | sed -nr \
 		's/^https:\/\/github\.com\/(.*\/.*).git$/\1/p')" ]; then
-		echo "script: url invalid: $1"
+		echo "$SCRIPT: url invalid: $1"
 	else
 		# cd to correct directory if called from the CLI
 		if [ -z "$2" ]; then
@@ -110,26 +119,28 @@ install() {
 	fi
 }
 
-update() {
-	echo "Updating.."
+list() {
+	if [ -z "$1" ]; then
+		echo "Listing all installed plugins.."
+	fi
 
-	init
+	PLUGIN="$(find "$DIR" -mindepth 2 -maxdepth 2 \
+		| sort | awk -F '/' '{ print $(NF-1)"/"$NF }')"
+	NUM=0
+	for p in $PLUGIN; do
+		NUM=$((NUM + 1))
 
-	cd "$START" || exit
-	while read -r l; do
-		if [ "$l" = "start:"  ]; then
-			cd "$START" || exit
-		elif [ "$l" = "opt:"  ]; then
-			cd "$OPT" || exit
-		else
-			install "$l" "script"
+		if [ -z "$1" ]; then
+			echo "$NUM) $p"
+		elif [ "$NUM" = "$1" ]; then
+			echo "$p"
 		fi
-	done < "$LIST"
+	done
 }
 
 remove() {
 	list
-	echo -n "Enter the number to remove: "
+	printf "Enter the number to remove: "
 	read -r OPTION
 
 	if [ -z "$(echo "$OPTION" | sed -nr 's/^([0-9]+)$/\1/p')" ]; then
@@ -139,13 +150,37 @@ remove() {
 		if [ -n "$TO_REMOVE" ]; then
 			sudo rm -rf "$DIR/$TO_REMOVE"
 			sudo sed -i '/'"$(basename "$TO_REMOVE")"'\.git/d' "$LIST"
+			echo "Removed plugin: $TO_REMOVE"
 		fi
 	fi
 }
 
-if type "$1" 2> /dev/null | grep -q "function"; then
-	"$@"
+update() {
+	echo "Updating.."
+
+	init
+
+	cd "$START" || exit
+	while read -r l; do
+		if [ "$l" = "start:"  ]; then
+			cd "$START" || exit
+		elif [ "$l" = "opt:"  ]; then
+			cd "$OPT" || exit
 		else
-	help
+			install "$l" "script"
 		fi
+	done < "$LIST"
+}
 
+# Command handling
+shift $((OPTIND - 1))
+case "$1" in
+	init | install | list | remove | update)
+		"$1" "$2" "$3"
+		;;
+	*)
+		echo "$SCRIPT: invalid command '$1'"
+		echo "Try '$SCRIPT -h' for more information."
+		exit 1
+		;;
+esac