Add org-hugo-suppress-lastmod-period

https://github.com/kaushalmodi/ox-hugo/pull/197

doc/ox-hugo-manual.org

@@ -985,6 +985,32 @@ Examples of RFC3339-compatible values for this variable:
 
 Do =C-h v org-hugo-date-format= for more information (within Emacs,
 once the =ox-hugo= package is loaded).
+
+***** =org-hugo-suppress-lastmod-period=
+ - Default value :: =0.0=
+
+A suppressing period not to write the =lastmod= item in the front matter.
+
+This variable is used to control the duration of the suppressing
+period. If the value is 86400.0, the =lastmod= item will not be added to
+the front matter within 24 hours from the initial exporting.
+
+=lastmod= would be exported when you initially change the Org TODO
+state to =DONE= by saving the file automatically with the following
+conditions. Some users may not prefer this behavior.
+
+| Variable                         | Value |
+|----------------------------------+-------|
+| org-hugo-auto-set-lastmod        | t     |
+| org-hugo-auto-export-on-save     | t     |
+| org-log-done                     | time  |
+
+In such case, you can suppress =lastmod= in the front matter if you set
+=org-hugo-suppress-lastmod-period= to =60.0= or other appropriate value.
+
+Note that to enable this feature, set =org-hugo-auto-set-lastmod= or
+=EXPORT_HUGO_AUTO_SET_LASTMOD= to non-nil.
+
 **** File-based Exports
 :PROPERTIES:
 :CUSTOM_ID: dates-file-based-exports

ox-hugo.el

@@ -533,6 +533,19 @@ it is if `org-hugo-prefer-hyphen-in-tags' is nil."
   :type 'boolean
   :safe #'booleanp)
 
+(defcustom org-hugo-suppress-lastmod-period 0.0
+  "A suppressing period not to write the lastmod item in the front matter.
+The default value is 0.0, which means that the lastmod item will be
+added to front matter even if the entry is modified within just 0.1[s]
+after the initial creation of the entry.
+This variable is used to control the duration of the suppressing period.
+If the value is 86400.0, the lastmod item will not be added to the front
+matter within 24 hours from the initial exporting.
+Note that to enable this feature, set `org-hugo-auto-set-lastmod' or
+`EXPORT_HUGO_AUTO_SET_LASTMOD' to non-nil."
+  :group 'org-export-hugo
+  :type 'float)
+
 (defcustom org-hugo-export-with-toc nil
   "When non-nil, Markdown format TOC will be inserted.
 
@@ -1436,6 +1449,52 @@ INFO is a plist used as a communication channel."
                   (setf (car found-key-cell) key-repl))))))))
     data))
 
+;;;; Helper function to use `time-subtract'
+(defun org-hugo--date-to-time (date &optional ignoretz)
+  "Return a valid time that can be passed to `time-subtract'.
+If IGNORETZ is non-nil, the timezone is removed from DATE."
+  (let ((ignoretz (or ignoretz nil))
+        (key (car date))
+        (value (cdr date))
+        (tz (format-time-string "%:z" (current-time))))
+    (cond ((eq (length value) 10) ;; "2000-01-01"
+           (setq value (concat value "T00:00:00" (unless ignoretz tz ))))
+          ((eq (length value) 19) ;; "2000-01-01T00:00:00"
+           (setq value (concat value (unless ignoretz tz))))
+          ((and (eq (length value) 25) ;; "2000-01-01T00:00:00+09:00"
+                ignoretz)
+           (setq value (substring value 0 19))))
+    ;; (message "[ox-hugo auto-lastmod] output %s:\t%s" key value)
+    (let ((time (safe-date-to-time value)))
+      (if (equal '(0 0) time)
+          (user-error "Invalid %s value: \"%s\"" key (cdr date))
+        time))))
+
+;;;; Amend lastmod
+(defun org-hugo--amend-lastmod (data info)
+  "Return updated DATA.
+The lastmode value in DATA could be nil on the basis of
+`org-hugo-suppress-lastmod-period'.
+INFO is a plist used as a communication channel."
+  (when (and (or (org-hugo--plist-get-true-p info :hugo-auto-set-lastmod)
+                 org-hugo-auto-set-lastmod)
+             (not (plist-get info :lastmod)))
+    (let ((date (assoc 'date data))
+          (lastmod (assoc 'lastmod data)))
+      ;; (message "[ox-hugo auto-lastmod] input date=%s, lastmod=%s"
+      ;;          (cdr date) (cdr lastmod))
+      ;; (message (concat "[ox-hugo auto-lastmod] val"
+      ;;                  (format " org-hugo-suppress-lastmod-period=%s"
+      ;;                          org-hugo-suppress-lastmod-period)))
+      (when (and (cdr date)
+                 (cdr lastmod)
+                 (>= org-hugo-suppress-lastmod-period
+                     (float-time (time-subtract
+                                  (org-hugo--date-to-time lastmod)
+                                  (org-hugo--date-to-time date)))))
+        (setf (cdr lastmod) nil))))
+  data)
+
 ;;;; TODO keywords
 (defun org-hugo--todo (todo info)
   "Format TODO keywords into HTML.
@@ -3044,6 +3103,7 @@ INFO is a plist used as a communication channel."
     ;; (message "[fm categories DBG] %S" categories)
     ;; (message "[fm keywords DBG] %S" keywords)
     (setq data (org-hugo--replace-keys-maybe data info))
+    (setq data (org-hugo--amend-lastmod data info))
     (setq ret (org-hugo--gen-front-matter data fm-format))
     (if (and (string= "toml" fm-format)
              (org-hugo--pandoc-citations-enabled-p info))

test/site/content-org/single-posts/suppress-lastmod.org

@@ -0,0 +1,18 @@
+#+title: Single Post with suppressed lastmod
+#+hugo_base_dir: ../../
+#+hugo_section: singles
+#+date: [2118-09-01 Sat 05:08]
+#+macro: doc [[https://ox-hugo.scripter.co/doc/$1][$2]]
+#+hugo_auto_set_lastmod: t
+
+This post will not export =lastmod= because
+=org-hugo-suppress-lastmod-period= is greater than the time
+difference between =[2118-09-01 Sat 05:08]= and the current
+date.
+
+* Local Variables :ARCHIVE:
+# Local Variables:
+# org-hugo-auto-set-lastmod: nil
+# org-hugo-suppress-lastmod-period: 0.0
+# End:
+

test/site/content-org/single-posts/unsuppress-lastmod.org

@@ -0,0 +1,16 @@
+#+title: Single Post with unsuppressed lastmod
+#+hugo_base_dir: ../../
+#+hugo_section: singles
+#+date: [1999-09-01 Sat 05:11]
+#+hugo_auto_set_lastmod: t
+
+This post will export =lastmod= because
+=org-hugo-suppress-lastmod-period= is less than the time difference
+between =[1999-09-01 Sat 05:11]= and the current date.
+
+* Local Variables :ARCHIVE:
+# Local Variables:
+# org-hugo-auto-set-lastmod: nil
+# org-hugo-suppress-lastmod-period: 0.0
+# End:
+

test/site/content-org/suppress-lastmod.org

@@ -0,0 +1,58 @@
+#+hugo_base_dir: ../
+
+* org-hugo-suppress-lastmod-period
+** DONE suppress lastmod with auto-set-lastmod
+   CLOSED: [2118-09-01 Wed 08:35]
+:PROPERTIES:
+:EXPORT_FILE_NAME: suppress-lastmod-in-subtree-with-auto-lastmod
+:EXPORT_HUGO_AUTO_SET_LASTMOD: t
+:END:
+
+This post will never export =lastmod= when you initially change the
+Org TODO state to =DONE= by saving the file because
+=org-hugo-suppress-lastmod-period= is always greater than the time
+difference between =date= and =lastmod= in the following condition.
+
+| Variable                         | Value |
+|----------------------------------+-------|
+| org-hugo-suppress-lastmod-period | 60.0  |
+| org-hugo-auto-set-lastmod        | t     |
+| org-hugo-auto-export-on-save     | t     |
+| org-log-done                     | time  |
+
+For instance, auto generated =date= would be =2018-09-01T08:00:00+00:00=
+and =lastmod= could be =2018-09-01T08:00:59+00:00=. The time
+difference is less than =org-hugo-suppress-lastmod-period= so
+=lastmod= filed will not be exported. But if you change something in
+this post after the initial exporting, the =lastmod= will be exported
+because the time difference will exceed
+=org-hugo-suppress-lastmod-period=.
+
+** DONE unsuppress lastmod
+   CLOSED: [1999-09-01 Sat 02:57]
+:PROPERTIES:
+:EXPORT_FILE_NAME: unsuppress-lastmod-in-subtree
+:EXPORT_HUGO_AUTO_SET_LASTMOD: t
+:END:
+
+This post will export =lastmod= because
+=org-hugo-suppress-lastmod-period= is less than the time difference
+between =[1999-09-01 Sat 02:57]= and the current date.
+
+** DONE ignore suppress lastmod
+   CLOSED: [2018-09-05 Wed 14:19]
+:PROPERTIES:
+:EXPORT_FILE_NAME: ignore-suppress-lastmod-in-subtree
+:EXPORT_HUGO_LASTMOD: 1999-09-05
+:EXPORT_HUGO_AUTO_SET_LASTMOD: nil
+:END:
+
+This post will export =lastmod= because =EXPORT_HUGO_LASTMOD= is
+provided even if =org-hugo-suppress-lastmod-period= is less than the
+time difference between =[2018-09-05 Wed 14:19]= and =1999-09-05=.
+
+* Local Variables :ARCHIVE:
+# Local Variables:
+# org-hugo-auto-set-lastmod: nil
+# org-hugo-suppress-lastmod-period: 0.0
+# End: