From 48051ad829dbfba2c58c19eb67f2622fbd2357a6 Mon Sep 17 00:00:00 2001
From: Thien-Thi Nguyen <ttn@gnuvola.org>
Date: Tue, 18 Jan 2022 05:04:35 -0500
Subject: Add Emacs Lisp command ‘TDM-recursive-help’
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* manpages/TDM.el (TDM-recursive-help): New command.
---
 manpages/TDM.el | 50 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 48 insertions(+), 2 deletions(-)

diff --git a/manpages/TDM.el b/manpages/TDM.el
index b4fabc7a..a58fb1c8 100644
--- a/manpages/TDM.el
+++ b/manpages/TDM.el
@@ -1,6 +1,6 @@
 ;;; TDM.el --- editing Taler docs.git/manpages/*   -*- lexical-binding: t -*-
 
-;; Copyright (C) 2021 Taler Systems SA
+;; Copyright (C) 2021, 2022 Taler Systems SA
 ;;
 ;; This file is part of GNU TALER.
 ;;
@@ -22,7 +22,10 @@
 
 ;;; Commentary:
 
-;; This library currently provides one command: ‘TDM-convert-options’.
+;; This library currently provides two commands: ‘TDM-convert-options’
+;; and ‘TDM-recursive-help’.
+;;
+;; * ‘TDM-convert-options’
 ;; The intended workflow is simple:
 ;;  - Create a new file from template.
 ;;  - Do the <FOO> substitutions / deletions as necessary.
@@ -49,6 +52,15 @@
 ;; There are a couple TODO items, which point to situations that
 ;; have not yet arisen in practice, but that might theoretically
 ;; bother us in the future.
+;;
+;; * ‘TDM-recursive-help’
+;; This command is intended for libeufin programs, specifically
+;; libeufin-sandbox, libeufin-nexus, and libeufin-cli.  However,
+;; it should work with any Java program that uses clikt, or any
+;; Python program that uses click, for its command-line handling.
+;;
+;; You can obtain the --help output (recursively) in a buffer
+;; and write it to a file for further analysis / processing.
 
 ;;; Code:
 
@@ -121,6 +133,40 @@ Prefix arg KEEP-ORIG means don't delete them."
       (save-excursion
         (delete-region p q)))))
 
+(defun TDM-recursive-help (command)
+  "Call COMMAND --help and recurse on its subcommands.
+Subcommands are identified by \"Commands:\" in column 0
+in the output.
+
+Collect the output in a new buffer *COMMAND --help*,
+with one page per --help output."
+  (interactive "sCommand: ")
+  (let ((out (get-buffer-create (format "*%s --help*" command))))
+    (with-current-buffer out
+      (erase-buffer))
+    (cl-labels
+        ;; visit command
+        ((v (c) (with-temp-buffer
+                  (apply #'call-process (car c) nil t nil
+                         (append (cdr c) (list "--help")))
+                  (goto-char (point-min))
+                  (when (re-search-forward "^Commands:\n" nil t)
+                    (while (looking-at "[ ][ ]\\(\\S +\\)")
+                      (let ((sub (match-string 1)))
+                        (v (append c (list sub))))
+                      (forward-line 1)
+                      (while (looking-at "[ ][ ][ ]")
+                        (forward-line 1))))
+                  (let ((s (buffer-string)))
+                    (message "c: %s" c)
+                    (with-current-buffer out
+                      (goto-char (point-min))
+                      (insert "\f\n")
+                      (insert "$ " (substring (format "%s" c) 1 -1) "\n")
+                      (insert s "\n"))))))
+      (v (list command)))
+    (switch-to-buffer out)))
+
 (provide 'TDM)
 
 ;;; TDM.el ends here
-- 
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