From 7f3910390b1b7720fe54307bec0656ec9e21e21c Mon Sep 17 00:00:00 2001
From: Matthias Kruk <m@m10k.eu>
Date: Sat, 9 Jul 2022 11:50:06 +0900
Subject: [PATCH] toolbox.sh: Make command-not-found errors more helpful

Command-not-found errors often occur because the user forgot to
include a module. In such cases, it would be helpful if the default
error message included suggestions for modules to include.

This commit adds a `command_not_found_handle()` function that
overrides bash's default behavior: aside of the usual error message,
this function will print all module names that the missing function
may be part of (as determined by its name) to stderr.
---
 toolbox.sh | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/toolbox.sh b/toolbox.sh
index f690b01..b267299 100644
--- a/toolbox.sh
+++ b/toolbox.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 
 # toolbox.sh - Framework for modular bash scripts
-# Copyright (C) 2021 Matthias Kruk
+# Copyright (C) 2021-2022 Matthias Kruk
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -36,6 +36,7 @@ __toolbox_init() {
 	readonly -f have
 	readonly -f _try_include
 	readonly -f include
+	readonly -f command_not_found_handle
 
 	return 0
 }
@@ -108,6 +109,40 @@ include() {
 	return 0
 }
 
+command_not_found_handle() {
+	local command="$1"
+	# local args=("${@:2}") # not used
+
+	local searchpath
+	declare -A candidates
+
+	# Display the same message that bash usually would
+	echo "bash: $command: command not found" 1>&2
+
+	for searchpath in "${__TOOLBOX_MODULEPATH[@]}"; do
+		local module
+
+		while read -r module; do
+			local module_name
+			local prefix
+
+			module_name="${module#"$searchpath"/}"
+			module_name="${module_name%.sh}"
+			prefix="${module_name//\//_}"
+
+			if [[ "$command" == "$prefix"* ]]; then
+				candidates["$module_name"]="$module"
+			fi
+		done < <(find -L "$searchpath" -type f -iname "*.sh")
+	done
+
+	if (( ${#candidates[@]} > 0 )); then
+		echo "Did you forget to include a module? Possible candidates are: ${!candidates[*]}" 1>&2
+	fi
+
+	return 127
+}
+
 {
 	if ! compgen -v | grep "^__TOOLBOX_INCLUDED$" &> /dev/null; then
 		if ! __toolbox_init; then
-- 
2.47.3