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; Footnote behavior customization
; + left-align footnote text to first character of first paragraph,
;   not to left margin.
; + Instructions:
;   + toggle the feature using 'mode-map-prexic q' (usually 'C-c ! q')
;   + whenever you run `auto-fill' (M-q), it will act
;   + if you set visual-line-mode, it acts automatically
(require 'footnote)

(setq Footnote-align-to-fn-text t
      body-auto-fill-prefix nil)

(defun Footnote-calc-fn-alignment-column()
  (+ footnote-body-tag-spacing
    (length
       (concat footnote-start-tag  footnote-end-tag
         (Footnote-index-to-string
            (caar (last footnote-text-marker-alist)))))))

(defun Footnote-align-to-fn()
  (when Footnote-align-to-fn-text
    (setq body-auto-fill-prefix fill-prefix
          fill-prefix (make-string (Footnote-calc-fn-alignment-column) 32))))

(defun Footnote-align-to-body()
  (when (not Footnote-align-to-fn-text)
    (setq fill-prefix body-auto-fill-prefix)))

(defun Footnote-toggle-alignment()
  (interactive)
  (setq Footnote-align-to-fn-text (not Footnote-align-to-fn-text))
  (when footnote-text-marker-alist
    (if (>= (point) (cdr (first footnote-text-marker-alist)))
      (if Footnote-align-to-fn-text
        (Footnote-align-to-fn)
       (Footnote-align-to-body))))
  (if Footnote-align-to-fn-text
    (message "Footnotes will left-align to footnote text")
   (message "Footnotes will left-align to body text")))

(define-key footnote-mode-map
  (kbd "q") 'Footnote-toggle-alignment)

(defadvice Footnote-add-footnote (after update-auto-fill-prefix activate)
  (interactive)
  (Footnote-align-to-fn))

(defadvice Footnote-back-to-message (after restore-auto-fill-prefix
                                     activate)
  (interactive)
  (setq fill-prefix body-auto-fill-prefix))

(defadvice Footnote-add-footnote (around abort-when-in-fn-area activate)
  (interactive)
  (if (or
        (not footnote-text-marker-alist)
        (< (point) (cdr (first footnote-text-marker-alist))))
    ad-do-it
   (message "Add footnotes only while in text body")))
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