added syntax highlighting

en

@@ -10,7 +10,14 @@
 argv0="$0"
 
 if test -z "$1"; then
-	printf "Usage: %s file...\n" "$argv0"
+	printf "Usage: %s file...\n" "$argv0" 1>&2
+	exit 1
+fi
+
+if ! command -v mktemp >/dev/null 2>&1
+then
+	printf "%s: mktemp(1): Missing dependency." "$argv0"
+	exit 1
 fi
 
 help="Commands:\n\
@@ -30,7 +37,18 @@ To learn more about a command verb, type \`h verb'.
 
 while test -n "$1"; do
 	content="$(cat "$1")"
-	cat "$1"
+	file="$(printf "%s\n" "$1" | tr -d '/')"
+
+	# use bat for syntax highlighting if it’s available, but remove the frills
+	if command -v bat >/dev/null
+	then
+		# there has to be a temp file for writing the highlighted text to
+		syntax_h() {
+			temp_highlight="$(mktemp -t "XXXXX$file")"
+			printf "%s\n" "$1" >"$temp_highlight"
+			bat -pp --color always "$temp_highlight"
+		}
+	fi
 
 	while true; do
 		printf ">> "
@@ -45,44 +63,25 @@ while test -n "$1"; do
 				clear
 				;;
 			"d")
-				printf "%s: d: Command not implemented.\n" "$argv0"
+				printf "%s: d: Command not implemented.\n" "$argv0" 1>&2
 				;;
 			"e")
 				eval "$args"
 				;;
 			"h")
 				if test -z "$args"; then
-					printf "$help\n"
+					printf "%s: %s\n" "$argv0" "$help"
 				else
-					printf "%s: Command-specific help not implemented.\n" "$argv0"
+					printf "%s: Command-specific help not implemented.\n" "$argv0" 1>&2
 					continue
-					case $args in
-						"c")
-							;;
-						"d")
-							;;
-						"e")
-							;;
-						"h")
-							;;
-						"i")
-							;;
-						"p")
-							;;
-						"q")
-							;;
-						"r")
-							;;
-						"w")
-							;;
-					esac
 				fi
 				;;
 			"i")
-				printf "%s: i: Command not implemented.\n" "$argv0"
+				printf "%s: i: Command not implemented.\n" "$argv0" 1>&2
 				;;
 			"p")
-				printf "%s\n" "$content"
+				out="$(syntax_h "$content" || printf "%s\n" "$content")"
+				printf "%s" "$out" | nl -ba
 				;;
 			"q")
 				if test -n "$(printf "%s\n" "$content" | diff "$1" -)"
@@ -90,7 +89,7 @@ while test -n "$1"; do
 					printf "%s: %s: Unsaved changes in the buffer. Quit anyway? [y/N] " \
 						"$argv0" \
 						"$1"
-					read quit
+					read -r quit
 					if [ "$quit" = "y" ]; then
 						break
 					else