;;; reftex-cite.el --- creating citations with RefTeX  -*- lexical-binding: t; -*-

;; Copyright (C) 1997-2023 Free Software Foundation, Inc.

;; Author: Carsten Dominik <dominik@science.uva.nl>
;; Maintainer: auctex-devel@gnu.org

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;;; Code:

(eval-when-compile (require 'cl-lib))

(require 'reftex)

;;; Variables and constants
(defvar reftex-cite-regexp-hist nil
  "The history list of regular expressions used for citations.")

(defconst reftex-citation-prompt
  "Select: [n]ext [p]revious [r]estrict [ ]full_entry [q]uit RET [?]Help+more"
  "Prompt and help string for citation selection.")

(defconst reftex-citation-help
  " n / p      Go to next/previous entry (Cursor motion works as well).
 g / r      Start over with new regexp / Refine with additional regexp.
 SPC        Show full database entry in other window.
 f          Toggle follow mode: Other window will follow with full db entry.
 .          Show insertion point.
 q          Quit without inserting \\cite macro into buffer.
 TAB        Enter citation key with completion.
 RET        Accept current entry (also on mouse-2) and create \\cite macro.
 m / u      Mark/Unmark the entry.
 e / E      Create BibTeX file with all (marked/unmarked) entries
 a / A      Put all (marked) entries into one/many \\cite commands.")

;;; Find bibtex files
(defmacro reftex-with-special-syntax-for-bib (&rest body)
  `(let ((saved-syntax (syntax-table)))
     (unwind-protect
         (progn
           (set-syntax-table reftex-syntax-table-for-bib)
           ,@body)
       (set-syntax-table saved-syntax))))

;;;###autoload
(defun reftex-default-bibliography ()
  "Return the expanded value of variable `reftex-default-bibliography'.
The expanded value is cached."
  (unless (eq (get 'reftex-default-bibliography :reftex-raw)
              reftex-default-bibliography)
    (put 'reftex-default-bibliography :reftex-expanded
         (reftex-locate-bibliography-files
          default-directory reftex-default-bibliography))
    (put 'reftex-default-bibliography :reftex-raw
         reftex-default-bibliography))
  (get 'reftex-default-bibliography :reftex-expanded))

;;;###autoload
(defun reftex-bib-or-thebib ()
  "Test if BibTeX or \\begin{thebibliography} should be used for the citation.
Find the bof of the current file."
  (let* ((docstruct (symbol-value reftex-docstruct-symbol))
         (rest (or (member (list 'bof (buffer-file-name)) docstruct)
                   docstruct))
         (bib (assq 'bib rest))
         (thebib (assq 'thebib rest))
         (bibmem (memq bib rest))
         (thebibmem (memq thebib rest)))
    (when (not (or thebib bib))
      (setq bib (assq 'bib docstruct)
            thebib (assq 'thebib docstruct)
            bibmem (memq bib docstruct)
            thebibmem (memq thebib docstruct)))
    (if (> (length bibmem) (length thebibmem))
        (if bib 'bib nil)
      (if thebib 'thebib nil))))

;;;###autoload
(defun reftex-get-bibfile-list ()
  "Return list of bibfiles for current document.
When using the chapterbib or bibunits package you should either
use the same database files everywhere, or separate parts using
different databases into different files (included into the master file).
Then this function will return the applicable database files."

  ;; Ensure access to scanning info
  (reftex-access-scan-info)
  (or
   ;; Try inside this file (and its includes)
   (cdr (reftex-last-assoc-before-elt
         'bib (list 'eof (buffer-file-name))
         (member (list 'bof (buffer-file-name))
                 (symbol-value reftex-docstruct-symbol))))
   ;; Try after the beginning of this file
   (cdr (assq 'bib (member (list 'bof (buffer-file-name))
                           (symbol-value reftex-docstruct-symbol))))
   ;; Anywhere in the entire document
   (cdr (assq 'bib (symbol-value reftex-docstruct-symbol)))
   (error "\\bibliography statement missing or .bib files not found")))

;;; Find a certain reference in any of the BibTeX files.
;;;###autoload
(defun reftex-pop-to-bibtex-entry (key file-list &optional mark-to-kill
                                       highlight item return)
  "Find BibTeX KEY in any file in FILE-LIST in another window.
If MARK-TO-KILL is non-nil, mark new buffer to kill.
If HIGHLIGHT is non-nil, highlight the match.
If ITEM in non-nil, search for bibitem instead of database entry.
If RETURN is non-nil, just return the entry and restore point."
  (let* ((re
          (if item
              (concat "\\\\bibitem[ \t]*\\(\\[[^]]*\\]\\)?[ \t]*{"
		      (regexp-quote key) "}")
            (concat "@\\(?:\\w\\|\\s_\\)+[ \t\n\r]*[{(][ \t\n\r]*"
		    (regexp-quote key) "[, \t\r\n}]")))
         (buffer-conf (current-buffer))
         file buf pos oldpos)

    (catch 'exit
      (while file-list
        (setq file (car file-list)
              file-list (cdr file-list))
        (unless (setq buf (reftex-get-file-buffer-force file mark-to-kill))
          (error "No such file %s" file))
        (set-buffer buf)
	(setq oldpos (point))
        (widen)
        (goto-char (point-min))
        (if (not (re-search-forward re nil t))
	    (goto-char oldpos) ;; restore previous position of point
          (goto-char (match-beginning 0))
          (setq pos (point))
          (when return
            ;; Just return the relevant entry
            (if item (goto-char (match-end 0)))
            (setq return (buffer-substring
                          (point) (reftex-end-of-bib-entry item)))
	    (goto-char oldpos) ;; restore point.
            (set-buffer buffer-conf)
            (throw 'exit return))
          (switch-to-buffer-other-window buf)
          (goto-char pos)
          (recenter 0)
          (if highlight
              (reftex-highlight 0 (match-beginning 0) (match-end 0)))
          (throw 'exit (selected-window))))
      (set-buffer buffer-conf)
      (if item
          (error "No \\bibitem with citation key %s" key)
        (error "No BibTeX entry with citation key %s" key)))))

;;;###autoload
(defun reftex-end-of-bib-entry (item)
  (save-excursion
    (condition-case nil
        (if item
            (progn (end-of-line)
                   (re-search-forward
                    "\\\\bibitem\\|\\\\end{thebibliography}")
                   (1- (match-beginning 0)))
          (progn (forward-list 1) (point)))
      (error (min (point-max) (+ 300 (point)))))))

(defun reftex--query-search-regexps (default)
  "Query for regexps for searching entries using DEFAULT as default.
Return a list of regular expressions."
  (split-string
   (completing-read
    (concat
     "Regex { && Regex...}: "
     "[" default "]: ")
    ;; Ensure default is always in the completion list.
    (let ((def (when default (list default)))
          (coll (if reftex-mode
                    (if (fboundp 'LaTeX-bibitem-list)
                        (LaTeX-bibitem-list)
                      (cdr (assoc 'bibview-cache
                                  (symbol-value reftex-docstruct-symbol))))
                  nil)))
      (if (and def (member def coll))
          coll
        (cons def coll)))
    nil nil nil 'reftex-cite-regexp-hist)
   "[ \t]*&&[ \t]*"))

;;; Parse bibtex buffers
(defun reftex-extract-bib-entries (buffers)
  "Extract bib entries which match regexps from BUFFERS.
BUFFERS is a list of buffers or file names.
Return list with entries."
  (let* (re-list first-re rest-re
                 (buffer-list (if (listp buffers) buffers (list buffers)))
                 found-list entry buffer1 buffer alist
                 key-point start-point end-point default)

    ;; Read a regexp, completing on known citation keys.
    (setq default (regexp-quote (reftex-get-bibkey-default)))
    (setq re-list (reftex--query-search-regexps default))

    (if (or (null re-list ) (equal re-list '("")))
        (setq re-list (list default)))

    (setq first-re (car re-list)    ; We'll use the first re to find things,
          rest-re  (cdr re-list))   ; the others to narrow down.
    (if (string-match "\\`[ \t]*\\'" (or first-re ""))
        (user-error "Empty regular expression"))
    (if (string-match first-re "")
        (user-error "Regular expression matches the empty string"))

    (save-excursion
      (save-window-excursion

        ;; Walk through all bibtex files
        (while buffer-list
          (setq buffer (car buffer-list)
                buffer-list (cdr buffer-list))
          (if (and (bufferp buffer)
                   (buffer-live-p buffer))
              (setq buffer1 buffer)
            (setq buffer1 (reftex-get-file-buffer-force
                           buffer (not reftex-keep-temporary-buffers))))
          (if (not buffer1)
              (message "No such BibTeX file %s (ignored)" buffer)
            (message "Scanning bibliography database %s" buffer1)
	    (unless (verify-visited-file-modtime buffer1)
              (when (y-or-n-p
                     (format "File %s changed on disk.  Reread from disk? "
                             (file-name-nondirectory
                              (buffer-file-name buffer1))))
                (with-current-buffer buffer1 (revert-buffer t t)))))

          (set-buffer buffer1)
          (reftex-with-special-syntax-for-bib
           (save-excursion
             (goto-char (point-min))
             (while (re-search-forward first-re nil t)
               (catch 'search-again
                 (setq key-point (point))
                 (unless (re-search-backward "\\(\\`\\|[\n\r]\\)[ \t]*\
@\\(\\(?:\\w\\|\\s_\\)+\\)[ \t\n\r]*[{(]" nil t)
                   (throw 'search-again nil))
                 (setq start-point (point))
                 (goto-char (match-end 0))
                 (condition-case nil
                     (up-list 1)
                   (error (goto-char key-point)
                          (throw 'search-again nil)))
                 (setq end-point (point))

                 ;; Ignore @string, @comment and @c entries or things
                 ;; outside entries
                 (when (or (string= (downcase (match-string 2)) "string")
                           (string= (downcase (match-string 2)) "comment")
                           (string= (downcase (match-string 2)) "c")
                           (< (point) key-point)) ; this means match not in {}
                   (goto-char key-point)
                   (throw 'search-again nil))

                 ;; Well, we have got a match
                 ;;(setq entry (concat
                 ;;             (buffer-substring start-point (point)) "\n"))
                 (setq entry (buffer-substring start-point (point)))

                 ;; Check if other regexp match as well
                 (setq re-list rest-re)
                 (while re-list
                   (unless (string-match (car re-list) entry)
                     ;; nope - move on
                     (throw 'search-again nil))
                   (pop re-list))

                 (setq alist (reftex-parse-bibtex-entry
                              nil start-point end-point))
                 (push (cons "&entry" entry) alist)

                 ;; check for crossref entries
                 (if (assoc "crossref" alist)
                     (setq alist
                           (append
                            alist (reftex-get-crossref-alist alist))))

                 ;; format the entry
                 (push (cons "&formatted" (reftex-format-bib-entry alist))
                       alist)

                 ;; make key the first element
                 (push (reftex-get-bib-field "&key" alist) alist)

                 ;; add it to the list
                 (push alist found-list)))))
          (reftex-kill-temporary-buffers))))
    (setq found-list (nreverse found-list))

    ;; Sorting
    (cond
     ((eq 'author reftex-sort-bibtex-matches)
      (sort found-list #'reftex-bib-sort-author))
     ((eq 'year   reftex-sort-bibtex-matches)
      (sort found-list #'reftex-bib-sort-year))
     ((eq 'reverse-year reftex-sort-bibtex-matches)
      (sort found-list #'reftex-bib-sort-year-reverse))
     (t found-list))))

(defun reftex-bib-sort-author (e1 e2)
  "Compare bib entries E1 and E2 by author.
The name of the first different author/editor is used."
  (let ((al1 (reftex-get-bib-names "author" e1))
        (al2 (reftex-get-bib-names "author" e2)))
    (while (and al1 al2 (string= (car al1) (car al2)))
      (pop al1)
      (pop al2))
    (if (and (stringp (car al1))
             (stringp (car al2)))
        (string< (car al1) (car al2))
      (not (stringp (car al1))))))

(defun reftex-bib-sort-year (e1 e2)
  "Compare bib entries E1 and E2 by year in ascending order."
  (< (string-to-number (or (cdr (assoc "year" e1)) "0"))
     (string-to-number (or (cdr (assoc "year" e2)) "0"))))

(defun reftex-bib-sort-year-reverse (e1 e2)
  "Compare bib entries E1 and E2 by year in descending order."
  (> (string-to-number (or (cdr (assoc "year" e1)) "0"))
     (string-to-number (or (cdr (assoc "year" e2)) "0"))))

(defun reftex-get-crossref-alist (entry)
  "Return the alist from a crossref ENTRY."
  (let ((crkey (cdr (assoc "crossref" entry)))
        start)
    (save-excursion
      (save-restriction
        (widen)
        (if (re-search-forward
             (concat "@\\w+[{(][ \t\n\r]*" (regexp-quote crkey)
                     "[ \t\n\r]*,") nil t)
            (progn
              (setq start (match-beginning 0))
              (condition-case nil
                  (up-list 1)
                (error nil))
              (reftex-parse-bibtex-entry nil start (point)))
          nil)))))

;; Parse the bibliography environment
(defun reftex-extract-bib-entries-from-thebibliography (files)
  "Extract bib-entries from the \\begin{thebibliography} environment.
Parsing is not as good as for the BibTeX database stuff.
The environment should be located in FILES."
  (let* (start end buf entries re re-list file default)
    (unless files
      (error "Need file name to find thebibliography environment"))
    (while (setq file (pop files))
      (setq buf (reftex-get-file-buffer-force
                 file (not reftex-keep-temporary-buffers)))
      (unless buf
        (error "No such file %s" file))
      (message "Scanning thebibliography environment in %s" file)

      (with-current-buffer buf
	(save-excursion
	  (save-restriction
	    (widen)
	    (goto-char (point-min))
	    (while (re-search-forward
		    "\\(\\`\\|[\n\r]\\)[ \t]*\\\\begin{thebibliography}" nil t)
	      (beginning-of-line 2)
	      (setq start (point))
	      (if (re-search-forward
		   "\\(\\`\\|[\n\r]\\)[ \t]*\\\\end{thebibliography}" nil t)
		  (progn
		    (beginning-of-line 1)
		    (setq end (point))))
	      (when (and start end)
		(setq entries
		      (append entries
			      (mapcar #'reftex-parse-bibitem
				      (delete ""
					      (split-string
					       (buffer-substring-no-properties
						start end)
					       "[ \t\n\r]*\\\\bibitem[ \t]*\
\\(\\[[^]]*]\\)*[ \t]*"))))))
	      (goto-char end))))))
    (unless entries
      (error "No bibitems found"))

    ;; Read a regexp, completing on known citation keys.
    (setq default (regexp-quote (reftex-get-bibkey-default)))
    (setq re-list (reftex--query-search-regexps default))

    (if (or (null re-list ) (equal re-list '("")))
        (setq re-list (list default)))

    (if (string-match "\\`[ \t]*\\'" (car re-list))
        (error "Empty regular expression"))

    (while (and (setq re (pop re-list)) entries)
      (setq entries
            (delq nil (mapcar
                       (lambda (x)
                         (if (string-match re (cdr (assoc "&entry" x)))
                             x nil))
                       entries))))
    (setq entries
          (mapcar
            (lambda (x)
              (push (cons "&formatted" (reftex-format-bibitem x)) x)
              (push (reftex-get-bib-field "&key" x) x)
              x)
           entries))

    entries))

(defun reftex-get-bibkey-default ()
  "Return the word before the cursor.
If the cursor is in a citation macro, return the word before the macro."
  (let* ((macro (reftex-what-macro 1)))
    (save-excursion
      (if (and macro (string-match "cite" (car macro)))
          (goto-char (cdr macro)))
      (skip-chars-backward "^a-zA-Z0-9")
      (reftex-this-word))))

;;; Parse and format individual entries
(defun reftex-get-bib-names (field entry)
  "Return a list with the author or editor names in ENTRY.
If FIELD is empty try \"editor\" field."
  (let ((names (reftex-get-bib-field field entry)))
    (if (equal "" names)
        (setq names (reftex-get-bib-field "editor" entry)))
    (while (string-match "\\band\\b[ \t]*" names)
      (setq names (replace-match "\n" nil t names)))
    (while (string-match "[-.a-zA-Z]+\\.[ \t]*\\|,.*\\|[{}]+" names)
      (setq names (replace-match "" nil t names)))
    (while (string-match "^[ \t]+\\|[ \t]+$" names)
      (setq names (replace-match "" nil t names)))
    (while (string-match "[ \t][ \t]+" names)
      (setq names (replace-match " " nil t names)))
    (split-string names "\n")))

;;;###autoload
(defun reftex-parse-bibtex-entry (entry &optional from to raw)
  "Parse BibTeX ENTRY.
If ENTRY is nil then parse the entry in current buffer between FROM and TO.
If RAW is non-nil, keep double quotes/curly braces delimiting fields."
  (let (alist key start field)
    (save-excursion
      (save-restriction
        (if entry
            (progn
              (set-buffer (get-buffer-create " *RefTeX-scratch*"))
              (fundamental-mode)
              (set-syntax-table reftex-syntax-table-for-bib)
              (erase-buffer)
              (insert entry))
          (widen)
          (if (and from to) (narrow-to-region from to)))
        (goto-char (point-min))

        (if (re-search-forward "@\\(\\(?:\\w\\|\\s_\\)+\\)[ \t\n\r]*\
[{(][ \t\n\r]*\\([^ \t\n\r,]+\\)" nil t)
            (setq alist
                  (list
                   (cons "&type" (downcase (reftex-match-string 1)))
                   (cons "&key"  (reftex-match-string 2)))))
        (while (re-search-forward "\\(\\(?:\\w\\|-\\)+\\)[ \t\n\r]*=[ \t\n\r]*"
				  nil t)
          (setq key (downcase (reftex-match-string 1)))
          (cond
           ((= (following-char) ?{)
            (cond
             (raw
              (setq start (point))
              (forward-char 1))
             (t
              (forward-char 1)
              (setq start (point))
              (condition-case nil
                  (up-list 1)
                (error nil)))))
           ((= (following-char) ?\")
            (cond
             (raw
              (setq start (point))
              (forward-char 1))
             (t
              (forward-char 1)
              (setq start (point))))
            (while (and (search-forward "\"" nil t)
                        (= ?\\ (char-after (- (point) 2))))))
           (t
            (setq start (point))
            (re-search-forward "[ \t]*[\n\r,}]" nil 1)))
          ;; extract field value, ignore trailing comma if in RAW mode
          (let ((stop (if (and raw (not (= (char-after (1- (point))) ?,)))
                        (point)
                        (1- (point))) ))
            (setq field (buffer-substring-no-properties start stop)))
          ;; remove extra whitespace
          (while (string-match "[\n\t\r]\\|[ \t][ \t]+" field)
            (setq field (replace-match " " nil t field)))
          (push (cons key field) alist))))
    alist))

(defun reftex-get-bib-field (fieldname entry &optional format)
  "Extract the field FIELDNAME from ENTRY.
If FORMAT is non-nil `format' entry accordingly."
  (let ((cell (assoc fieldname entry)))
    (if cell
        (if format
            (format format (cdr cell))
          (cdr cell))
      "")))

(defun reftex-format-bib-entry (entry)
  "Format a BibTeX ENTRY so that it is nice to look at."
  (let*
      ((auth-list (reftex-get-bib-names "author" entry))
       (authors (mapconcat #'identity auth-list ", "))
       (year      (reftex-get-bib-field "year" entry))
       (title     (reftex-get-bib-field "title" entry))
       (type      (reftex-get-bib-field "&type" entry))
       (key       (reftex-get-bib-field "&key"  entry))
       (extra
        (cond
         ((equal type "article")
          (concat (let ((jt (reftex-get-bib-field "journal" entry)))
                    ;; biblatex prefers the alternative journaltitle
                    ;; field, so check if that exists in case journal
                    ;; is empty.
                    (if (zerop (length jt))
                        (reftex-get-bib-field "journaltitle" entry)
                      jt))
                  " "
                  (reftex-get-bib-field "volume" entry) ", "
                  (reftex-get-bib-field "pages" entry)))
         ((equal type "book")
          (concat "book (" (reftex-get-bib-field "publisher" entry) ")"))
         ((equal type "phdthesis")
          (concat "PhD: " (reftex-get-bib-field "school" entry)))
         ((equal type "mastersthesis")
          (concat "Master: " (reftex-get-bib-field "school" entry)))
         ((equal type "inbook")
          (concat "Chap: " (reftex-get-bib-field "chapter" entry)
                  ", pp. " (reftex-get-bib-field "pages"   entry)))
         ((or (equal type "conference")
              (equal type "incollection")
              (equal type "inproceedings"))
          (reftex-get-bib-field "booktitle" entry "in: %s"))
         (t ""))))
    (setq authors (reftex-truncate authors 30 t t))
    (when (reftex-use-fonts)
      (put-text-property 0 (length key)     'face reftex-label-face
                         key)
      (put-text-property 0 (length authors) 'face reftex-bib-author-face
                         authors)
      (put-text-property 0 (length year)    'face reftex-bib-year-face
                         year)
      (put-text-property 0 (length title)   'face reftex-bib-title-face
                         title)
      (put-text-property 0 (length extra)   'face reftex-bib-extra-face
                         extra))
    (concat key "\n     " authors " " year " " extra "\n     " title "\n\n")))

(defun reftex-parse-bibitem (item)
  "Parse a \\bibitem entry in ITEM."
  (let ((key "") (text ""))
    (when (string-match "\\`{\\([^}]+\\)}\\([^\000]*\\)" item)
      (setq key (match-string 1 item)
            text (match-string 2 item)))
    ;; Clean up the text a little bit
    (while (string-match "[\n\r\t]\\|[ \t][ \t]+" text)
      (setq text (replace-match " " nil t text)))
    (if (string-match "\\`[ \t]+" text)
        (setq text (replace-match "" nil t text)))
    (list
     (cons "&key" key)
     (cons "&text" text)
     (cons "&entry" (concat key " " text)))))

(defun reftex-format-bibitem (item)
  "Format a \\bibitem entry in ITEM so that it is (relatively) nice to look at."
  (let ((text (reftex-get-bib-field "&text" item))
        (key  (reftex-get-bib-field "&key" item))
        (lines nil))

    ;; Wrap the text into several lines.
    (while (and (> (length text) 70)
                (string-match " " (substring text 60)))
        (push (substring text 0 (+ 60 (match-beginning 0))) lines)
        (setq text (substring text (+ 61 (match-beginning 0)))))
    (push text lines)
    (setq text (mapconcat #'identity (nreverse lines) "\n     "))

    (when (reftex-use-fonts)
      (put-text-property 0 (length text) 'face reftex-bib-author-face text))
    (concat key "\n     " text "\n\n")))

;;; Make a citation

;; NB this is a global autoload - see reftex.el.
;;;###autoload
(defun reftex-citation (&optional no-insert format-key)
  "Make a citation using BibTeX database files.
After prompting for a regular expression, scans the buffers with
bibtex entries (taken from the \\bibliography command) and offers the
matching entries for selection.  The selected entry is formatted according
to `reftex-cite-format' and inserted into the buffer.

If NO-INSERT is non-nil, nothing is inserted, only the selected key returned.

FORMAT-KEY can be used to pre-select a citation format.

When called with a \\[universal-argument] prefix, prompt for optional arguments in
cite macros.  When called with a numeric prefix, make that many
citations.  When called with point inside the braces of a `\\cite'
command, it will add another key, ignoring the value of
`reftex-cite-format'.

The regular expression uses an expanded syntax: && is interpreted as `and'.
Thus, `aaaa&&bbb' matches entries which contain both `aaaa' and `bbb'.
While entering the regexp, completion on known citation keys is possible.
`=' is a good regular expression to match all entries in all files."
  (interactive)

  ;; check for recursive edit
  (reftex-check-recursive-edit)

  ;; This function may also be called outside reftex-mode.
  ;; Thus look for the scanning info only if in reftex-mode.

  (when reftex-mode
    (reftex-access-scan-info nil))

  ;; Call reftex-do-citation, but protected
  (unwind-protect
      (reftex-do-citation current-prefix-arg no-insert format-key)
    (reftex-kill-temporary-buffers)))

(defun reftex-do-citation (&optional arg no-insert format-key)
  "This really does the work of `reftex-citation'."
  (let* ((format (reftex-figure-out-cite-format arg no-insert format-key))
         (docstruct-symbol reftex-docstruct-symbol)
         (selected-entries (reftex-offer-bib-menu))
         (insert-entries selected-entries)
         entry string cite-view)

    (unless selected-entries (error "Quit"))

    (if (stringp selected-entries)
        ;; Nonexistent entry
        (setq insert-entries (list (list selected-entries
                                         (cons "&key" selected-entries)))
	      selected-entries nil)
      ;; It makes sense to compute the cite-view strings.
      (setq cite-view t))

    (when (eq (car selected-entries) 'concat)
      ;; All keys go into a single command - we need to trick a little
      ;; FIXME: Unfortunately, this means that commenting does not work right.
      (pop selected-entries)
      (let ((concat-keys (mapconcat #'car selected-entries
				    reftex-cite-key-separator)))
        (setq insert-entries
              (list (list concat-keys (cons "&key" concat-keys))))))

    (unless no-insert

      ;; We shall insert this into the buffer...
      (message "Formatting...")

      (while (setq entry (pop insert-entries))
        ;; Format the citation and insert it
        (setq string (if reftex-format-cite-function
                         (funcall reftex-format-cite-function
                                  (reftex-get-bib-field "&key" entry)
                                  format)
                       (reftex-format-citation entry format)))
        (when (or (eq reftex-cite-prompt-optional-args t)
                  (and reftex-cite-prompt-optional-args
                       (equal arg '(4))))
          (let ((start 0) (nth 0) value)
            (while (setq start (string-match "\\[\\]" string start))
              (setq value (save-match-data
			    (read-string (format "Optional argument %d: "
						 (setq nth (1+ nth))))))
              (setq string (replace-match (concat "[" value "]") t t string))
              (setq start (1+ start)))))
        ;; Should we cleanup empty optional arguments?
        ;; if the first is empty, it can be removed.  If the second is empty,
        ;; it has to go.  If there is only a single arg and empty, it can go
        ;; as well.
        (when reftex-cite-cleanup-optional-args
          (cond
           ((string-match "\\([a-zA-Z0-9]\\)\\[\\]{" string)
            (setq string (replace-match "\\1{" nil nil string)))
           ((string-match "\\[\\]\\(\\[[a-zA-Z0-9., ]+\\]\\)" string)
            (setq string (replace-match "\\1" nil nil string)))
           ((string-match "\\[\\]\\[\\]" string)
            (setq string (replace-match "" t t string)))))
        (insert string))

      ;; Reposition cursor?
      (when (string-search "?" string)
        (search-backward "?")
        (delete-char 1))

      ;; Tell AUCTeX
      (when (and reftex-mode
                 (fboundp 'LaTeX-add-bibitems)
                 reftex-plug-into-AUCTeX)
        (apply #'LaTeX-add-bibitems (mapcar #'car selected-entries)))

      ;; Produce the cite-view strings
      (when (and reftex-mode reftex-cache-cite-echo cite-view)
        (mapc (lambda (entry)
                (reftex-make-cite-echo-string entry docstruct-symbol))
              selected-entries))

      (message ""))

    (set-marker reftex-select-return-marker nil)
    (reftex-kill-buffer "*RefTeX Select*")

    ;; Check if the prefix arg was numeric, and call recursively
    (when (integerp arg)
      (if (> arg 1)
          (progn
            (skip-chars-backward "}")
            (cl-decf arg)
            (reftex-do-citation arg))
        (forward-char 1)))

    ;; Return the citation key
    (mapcar #'car selected-entries)))

(defun reftex-figure-out-cite-format (arg &optional no-insert format-key)
  "Check if there is already a cite command at point and change cite format
in order to only add another reference in the same cite command."
  (let ((macro (car (reftex-what-macro 1)))
        (cite-format-value (reftex-get-cite-format))
        key format)
    (cond
     (no-insert
      ;; Format does not really matter because nothing will be inserted.
      (setq format "%l"))

     ((and (stringp macro)
           ;; Match also commands from biblatex ending with `s'
           ;; (\parencites) or `*' (\parencite*) and `texts?'
           ;; (\footcitetext and \footcitetexts).
           (string-match "\\`\\\\cite\\|cite\\([s*]\\|texts?\\)?\\'" macro))
      ;; We are already inside a cite macro
      (if (or (not arg) (not (listp arg)))
          (setq format
                (concat
                 (if (member (preceding-char) '(?\{ ?,))
		     ""
		   reftex-cite-key-separator)
                 "%l"
                 (if (member (following-char) '(?\} ?,))
		     ""
		   reftex-cite-key-separator)))
        (setq format "%l")))
     (t
      ;; Figure out the correct format
      (setq format
            (if (and (symbolp cite-format-value)
                     (assq cite-format-value reftex-cite-format-builtin))
                (nth 2 (assq cite-format-value reftex-cite-format-builtin))
              cite-format-value))
      (when (listp format)
        (setq key
              (or format-key
                  (reftex-select-with-char
                   "" (concat "SELECT A CITATION FORMAT\n\n"
                              (mapconcat
                               (lambda (x)
                                 (format "[%c] %s  %s" (car x)
                                         (if (> (car x) 31) " " "")
                                         (cdr x)))
                               format "\n")))))
        (if (assq key format)
            (setq format (cdr (assq key format)))
          (error "No citation format associated with key `%c'" key)))))
    format))

;;;###autoload
(defun reftex-citep ()
  "Call `reftex-citation' with a format selector `?p'."
  (interactive)
  (reftex-citation nil ?p))

;;;###autoload
(defun reftex-citet ()
  "Call `reftex-citation' with a format selector `?t'."
  (interactive)
  (reftex-citation nil ?t))

(defvar reftex-select-bib-mode-map)
(defvar reftex--found-list)
(defun reftex-offer-bib-menu ()
  "Offer bib menu and return list of selected items."
  (let ((bibtype (reftex-bib-or-thebib))
        reftex--found-list rtn key data selected-entries)
    (while
        (not
         (catch 'done
           ;; Scan bibtex files
           (setq reftex--found-list
              (cond
               ((eq bibtype 'bib)
;              ((assq 'bib (symbol-value reftex-docstruct-symbol))
                ;; using BibTeX database files.
                (reftex-extract-bib-entries (reftex-get-bibfile-list)))
               ((eq bibtype 'thebib)
;              ((assq 'thebib (symbol-value reftex-docstruct-symbol))
                ;; using thebibliography environment.
                (reftex-extract-bib-entries-from-thebibliography
                 (reftex-uniquify
                  (mapcar #'cdr
                          (reftex-all-assq
                           'thebib (symbol-value reftex-docstruct-symbol))))))
               (reftex-default-bibliography
                (message "Using default bibliography")
                (reftex-extract-bib-entries (reftex-default-bibliography)))
               (t (error "No valid bibliography in this document, and no default available"))))

           (unless reftex--found-list
             (error "Sorry, no matches found"))

          ;; Remember where we came from
          (setq reftex-call-back-to-this-buffer (current-buffer))
          (set-marker reftex-select-return-marker (point))

          ;; Offer selection
          (save-window-excursion
            (delete-other-windows)
            (reftex-kill-buffer "*RefTeX Select*")
            (switch-to-buffer-other-window "*RefTeX Select*")
            (unless (derived-mode-p 'reftex-select-bib-mode)
              (reftex-select-bib-mode))
            (let ((inhibit-read-only t))
              (erase-buffer)
              (reftex-insert-bib-matches reftex--found-list))
            (setq buffer-read-only t)
            (if (= 0 (buffer-size))
                (error "No matches found"))
            (setq truncate-lines t)
            (goto-char 1)
            (while t
              (setq rtn
                    (reftex-select-item
                     reftex-citation-prompt
                     reftex-citation-help
                     reftex-select-bib-mode-map
                     nil
                     'reftex-bibtex-selection-callback nil))
              (setq key (car rtn)
                    data (nth 1 rtn))
              (unless key (throw 'done t))
              (cond
               ((eq key ?g)
                ;; Start over
                (throw 'done nil))
               ((eq key ?r)
                ;; Restrict with new regular expression
                (setq reftex--found-list
                      (reftex-restrict-bib-matches reftex--found-list))
                (let ((buffer-read-only nil))
                  (erase-buffer)
                  (reftex-insert-bib-matches reftex--found-list))
                (goto-char 1))
               ((eq key ?A)
                ;; Take all (marked)
                (setq selected-entries
                      (if reftex-select-marked
                          (mapcar #'car (nreverse reftex-select-marked))
                        reftex--found-list))
                (throw 'done t))
               ((eq key ?a)
                ;; Take all (marked), and push the symbol 'concat
                (setq selected-entries
                      (cons 'concat
                            (if reftex-select-marked
                                (mapcar #'car (nreverse reftex-select-marked))
                              reftex--found-list)))
                (throw 'done t))
               ((eq key ?e)
                ;; Take all (marked), and push the symbol 'concat
                (reftex-extract-bib-file reftex--found-list
                                         reftex-select-marked)
                (setq selected-entries "BibTeX database file created")
                (throw 'done t))
               ((eq key ?E)
                ;; Take all (marked), and push the symbol 'concat
                (reftex-extract-bib-file reftex--found-list reftex-select-marked
                                         'complement)
                (setq selected-entries "BibTeX database file created")
                (throw 'done t))
               ((or (eq key ?\C-m)
                    (eq key 'return))
                ;; Take selected
                (setq selected-entries
                      (if reftex-select-marked
                          (cons 'concat
                                (mapcar #'car (nreverse reftex-select-marked)))
                        (if data (list data) nil)))
                (throw 'done t))
               ((stringp key)
                ;; Got this one with completion
                (setq selected-entries key)
                (throw 'done t))
               (t
                (ding))))))))
    selected-entries))

(defun reftex-restrict-bib-matches (found-list)
  "Limit FOUND-LIST with more regular expressions."
  (let ((re-list (split-string (read-string
                                "RegExp [ && RegExp...]: "
                                nil 'reftex-cite-regexp-hist)
                               "[ \t]*&&[ \t]*"))
        (found-list-r found-list)
        re)
    (while (setq re (pop re-list))
      (setq found-list-r
            (delq nil
                  (mapcar
                   (lambda (x)
                     (if (string-match
                          re (cdr (assoc "&entry" x)))
                         x
                       nil))
                   found-list-r))))
    (if found-list-r
        found-list-r
      (ding)
      found-list)))

(defun reftex-extract-bib-file (all &optional marked complement)
  "Limit FOUND-LIST with more regular expressions."
  (let ((file (read-file-name "File to create: ")))
    (find-file-other-window file)
    (if (> (buffer-size) 0)
        (unless (yes-or-no-p
                 (format "Overwrite non-empty file %s? " file))
          (error "Abort")))
    (erase-buffer)
    (setq all (delq nil
                    (mapcar
                     (lambda (x)
                       (if marked
                           (if (or (and (assoc x marked) (not complement))
                                   (and (not (assoc x marked)) complement))
                               (cdr (assoc "&entry" x))
                             nil)
                         (cdr (assoc "&entry" x))))
                     all)))
    (insert (mapconcat #'identity all "\n\n"))
    (save-buffer)
    (goto-char (point-min))))

(defun reftex-insert-bib-matches (list)
  "Insert the bib matches and number them correctly."
  (let ((mouse-face
         (if (memq reftex-highlight-selection '(mouse both))
             reftex-mouse-selected-face
           nil))
        tmp len)
    (mapc
     (lambda (x)
       (setq tmp (cdr (assoc "&formatted" x))
             len (length tmp))
       (put-text-property 0 len :data x tmp)
       (put-text-property 0 (1- len) 'mouse-face mouse-face tmp)
       (insert tmp))
     list))
  (run-hooks 'reftex-display-copied-context-hook))

(defun reftex-format-names (namelist n)
  (let (last (len (length namelist)))
    (if (= n 0) (setq n len))
    (cond
     ((< len 1) "")
     ((= 1 len) (car namelist))
     ((> len n) (concat (car namelist) (nth 2 reftex-cite-punctuation)))
     (t
      (setq n (min len n)
            last (nth (1- n) namelist))
      (setcdr (nthcdr (- n 2) namelist) nil)
      (concat
       (mapconcat #'identity namelist (nth 0 reftex-cite-punctuation))
       (nth 1 reftex-cite-punctuation)
       last)))))

(defun reftex-format-citation (entry format)
  "Format a citation from the info in the BibTeX ENTRY according to FORMAT."
  (unless (stringp format) (setq format "\\cite{%l}"))

  (if (and reftex-comment-citations
           (string-match "%l" reftex-cite-comment-format))
      (error "reftex-cite-comment-format contains invalid %%l"))

  (while (string-match
          "\\(\\`\\|[^%]\\)\\(\\(%\\([0-9]*\\)\\([a-zA-Z]\\)\\)[.,;: ]*\\)"
          format)
    (let ((n (string-to-number (match-string 4 format)))
          (l (string-to-char (match-string 5 format)))
          rpl b e)
      (save-match-data
        (setq rpl
              (cond
               ((= l ?l) (concat
                          (reftex-get-bib-field "&key" entry)
                          (if reftex-comment-citations
                              reftex-cite-comment-format
                            "")))
               ((= l ?a) (reftex-format-names
                          (reftex-get-bib-names "author" entry)
                          (or n 2)))
               ((= l ?A) (car (reftex-get-bib-names "author" entry)))
               ((= l ?b) (reftex-get-bib-field "booktitle" entry "in: %s"))
               ((= l ?B) (reftex-abbreviate-title
                          (reftex-get-bib-field "booktitle" entry "in: %s")))
               ((= l ?c) (reftex-get-bib-field "chapter" entry))
               ((= l ?d) (reftex-get-bib-field "edition" entry))
               ((= l ?e) (reftex-format-names
                          (reftex-get-bib-names "editor" entry)
                          (or n 2)))
               ((= l ?E) (car (reftex-get-bib-names "editor" entry)))
               ((= l ?h) (reftex-get-bib-field "howpublished" entry))
               ((= l ?i) (reftex-get-bib-field "institution" entry))
               ((= l ?j) (reftex-get-bib-field "journal" entry))
               ((= l ?k) (reftex-get-bib-field "key" entry))
               ((= l ?m) (reftex-get-bib-field "month" entry))
               ((= l ?n) (reftex-get-bib-field "number" entry))
	       ((= l ?N) (reftex-get-bib-field "note" entry))
               ((= l ?o) (reftex-get-bib-field "organization" entry))
               ((= l ?p) (reftex-get-bib-field "pages" entry))
               ((= l ?P) (car (split-string
                               (reftex-get-bib-field "pages" entry)
                               "[- .]+")))
               ((= l ?s) (reftex-get-bib-field "school" entry))
               ((= l ?u) (reftex-get-bib-field "publisher" entry))
	       ((= l ?U) (reftex-get-bib-field "url" entry))
               ((= l ?r) (reftex-get-bib-field "address" entry))
               ((= l ?t) (reftex-get-bib-field "title" entry))
               ((= l ?T) (reftex-abbreviate-title
                          (reftex-get-bib-field "title" entry)))
               ((= l ?v) (reftex-get-bib-field "volume" entry))
               ((= l ?y) (reftex-get-bib-field "year" entry)))))

      (if (string= rpl "")
          (setq b (match-beginning 2) e (match-end 2))
        (setq b (match-beginning 3) e (match-end 3)))
      (setq format (concat (substring format 0 b) rpl (substring format e)))))
  (while (string-match "%%" format)
    (setq format (replace-match "%" t t format)))
  (while (string-match "[ ,.;:]*%<" format)
    (setq format (replace-match "" t t format)))
  format)

;;;###autoload
(defun reftex-make-cite-echo-string (entry docstruct-symbol)
  "Format a bibtex ENTRY for the echo area and cache the result."
  (let* ((key (reftex-get-bib-field "&key" entry))
         (string
          (let* ((reftex-cite-punctuation '(" " " & " " etal.")))
            (reftex-format-citation entry reftex-cite-view-format)))
         (cache (assq 'bibview-cache (symbol-value docstruct-symbol)))
         (cache-entry (assoc key (cdr cache))))
    (unless cache
      ;; This docstruct has no cache - make one.
      (set docstruct-symbol (cons (cons 'bibview-cache nil)
                                  (symbol-value docstruct-symbol))))
    (when reftex-cache-cite-echo
      (setq key (copy-sequence key))
      (set-text-properties 0 (length key) nil key)
      (set-text-properties 0 (length string) nil string)
      (if cache-entry
          (unless (string= (cdr cache-entry) string)
            (setcdr cache-entry string)
            (put reftex-docstruct-symbol 'modified t))
        (push (cons key string) (cdr cache))
        (put reftex-docstruct-symbol 'modified t)))
    string))

(defun reftex-bibtex-selection-callback (data _ignore no-revisit)
  "Callback function to be called from the BibTeX selection, in
order to display context.  This function is relatively slow and not
recommended for follow mode.  It works OK for individual lookups."
  (let ((win (selected-window))
        (key (reftex-get-bib-field "&key" data))
        bibfile-list item bibtype)

    (catch 'exit
      (with-current-buffer reftex-call-back-to-this-buffer
        (setq bibtype (reftex-bib-or-thebib))
        (cond
         ((eq bibtype 'bib)
          ;; ((assq 'bib (symbol-value reftex-docstruct-symbol))
          (setq bibfile-list (reftex-get-bibfile-list)))
         ((eq bibtype 'thebib)
          ;; ((assq 'thebib (symbol-value reftex-docstruct-symbol))
          (setq bibfile-list
                (reftex-uniquify
                 (mapcar #'cdr
                         (reftex-all-assq
                          'thebib (symbol-value reftex-docstruct-symbol))))
                item t))
         (reftex-default-bibliography
          (setq bibfile-list (reftex-default-bibliography)))
         (t (ding) (throw 'exit nil))))

      (when no-revisit
        (setq bibfile-list (reftex-visited-files bibfile-list)))

      (condition-case nil
          (reftex-pop-to-bibtex-entry
           key bibfile-list (not reftex-keep-temporary-buffers) t item)
        (error (ding))))

    (select-window win)))

;;; Global BibTeX file
(defun reftex-all-used-citation-keys ()
  "Return a list of all citation keys used in document."
  (reftex-access-scan-info)
  ;; FIXME: multicites macros provided by biblatex
  ;; are not covered in this function.
  (let ((files (reftex-all-document-files))
        (re (concat "\\\\"
                    "\\(?:"
                    ;; biblatex volcite macros take these args:
                    ;; \volcite[prenote]{volume}[pages]{key}
                    ;; so cater for the first 3 args:
                    (regexp-opt '("volcite"  "Volcite"
                                  "pvolcite" "Pvolcite"
                                  "fvolcite" "ftvolcite"
                                  "svolcite" "Svolcite"
                                  "tvolcite" "Tvolcite"
                                  "avolcite" "Avolcite"))
                    "\\(?:\\[[^]]*\\]\\)?"
                    "{[^}]*}"
                    "\\(?:\\[[^]]*\\]\\)?"
                    "\\|"
                    ;; Other cite macros usually go like:
                    ;; \cite[prenote][postnote]{key}
                    ;; so cater for the optional args:
                    "\\(?:bibentry\\|[a-zA-Z]*[Cc]ite[a-zA-Z*]*\\)"
                    "\\(?:\\[[^]]*\\]\\)\\{0,2\\}"
                    "\\)"
                    ;; Now match the key:
                    "{\\([^}]+\\)}"))
        file keys kk k)
    (save-current-buffer
      (while (setq file (pop files))
        (set-buffer (reftex-get-file-buffer-force file 'mark))
        (save-excursion
          (save-restriction
            (widen)
            (goto-char (point-min))
            (while (re-search-forward re nil t)
              ;; Make sure we're not inside a comment:
              (unless (save-match-data
                        (nth 4 (syntax-ppss)))
                (setq kk (match-string-no-properties 1))
                (while (string-match "%.*\n?" kk)
                  (setq kk (replace-match "" t t kk)))
                (setq kk (split-string kk "[, \t\r\n]+"))
                (while (setq k (pop kk))
                  (or (member k keys)
                      (setq keys (cons k keys))))))))))
    (reftex-kill-temporary-buffers)
    keys))

(defun reftex-get-string-refs (alist)
  "Return a list of BibTeX @string references that appear as values in ALIST."
  (reftex-remove-if (lambda (x) (string-match "^\\([\"{]\\|[0-9]+$\\)" x))
		    ;; get list of values, discard keys
		    (mapcar #'cdr
			    ;; remove &key and &type entries
			    (reftex-remove-if (lambda (pair)
						(string-match "^&" (car pair)))
					      alist))))

;;;###autoload
(defun reftex-create-bibtex-file (bibfile)
  "Create a new BibTeX database BIBFILE with all entries referenced in document.
The command prompts for a filename and writes the collected
entries to that file.  Only entries referenced in the current
document with any \\cite-like macros are used.  The sequence in
the new file is the same as it was in the old database.

Entries referenced from other entries must appear after all
referencing entries.

You can define strings to be used as header or footer for the
created files in the variables `reftex-create-bibtex-header' or
`reftex-create-bibtex-footer' respectively."
  (interactive "FNew BibTeX file: ")
  (let ((keys (reftex-all-used-citation-keys))
        (files (reftex-get-bibfile-list))
        key entries beg end entry string-keys string-entries)
    (save-current-buffer
      (dolist (file files)
        (set-buffer (reftex-get-file-buffer-force file 'mark))
        (reftex-with-special-syntax-for-bib
         (save-excursion
           (save-restriction
             (widen)
             (goto-char (point-min))
             (while (re-search-forward "^[ \t]*@\\(?:\\w\\|\\s_\\)+[ \t\n\r]*\
[{(][ \t\n\r]*\\([^ \t\n\r,]+\\)" nil t)
               (setq key (match-string 1)
                     beg (match-beginning 0)
                     end (progn
                           (goto-char (match-beginning 1))
                           (condition-case nil
                               (up-list 1)
                             (error (goto-char (match-end 0))))
                           (point)))
               (when (member key keys)
                 (setq entry (buffer-substring beg end)
                       entries (cons entry entries)
                       keys (delete key keys))

                 ;; check for crossref entries
                 (let* ((attr-list (reftex-parse-bibtex-entry nil beg end))
                        (xref-key (cdr (assoc "crossref" attr-list))))
                   (if xref-key (cl-pushnew xref-key keys)))
                 ;; check for string references
                 (let* ((raw-fields (reftex-parse-bibtex-entry nil beg end t))
                        (string-fields (reftex-get-string-refs raw-fields)))
                   (dolist (skey string-fields)
                     (unless (member skey string-keys)
                       (push skey string-keys)))))))))))
    ;; second pass: grab @string references
    (if string-keys
        (save-current-buffer
          (dolist (file files)
            (set-buffer (reftex-get-file-buffer-force file 'mark))
            (reftex-with-special-syntax-for-bib
             (save-excursion
               (save-restriction
                 (widen)
                 (goto-char (point-min))
                 (while (re-search-forward
                         "^[ \t]*@[Ss][Tt][Rr][Ii][Nn][Gg][ \t]*{[ \t]*\\([^ \t\r\n]+\\)"
                         nil t)
                   (setq key (match-string 1)
                         beg (match-beginning 0)
                         end (progn
                               (goto-char (match-beginning 1))
                               (condition-case nil
                                   (up-list 1)
                                 (error (goto-char (match-end 0))))
                               (point)))
                   (when (member key string-keys)
                     (setq entry (buffer-substring beg end)
                           string-entries (cons entry string-entries)
                           string-keys (delete key string-keys))))))))))
    (find-file-other-window bibfile)
    (if (> (buffer-size) 0)
        (unless (yes-or-no-p
                 (format "Overwrite non-empty file %s? " bibfile))
          (error "Abort")))
    (erase-buffer)
    (if reftex-create-bibtex-header (insert reftex-create-bibtex-header "\n\n"))
    (insert (mapconcat #'identity (reverse string-entries) "\n\n"))
    (if string-entries (insert "\n\n\n"))
    (insert (mapconcat #'identity (reverse entries) "\n\n"))
    (if reftex-create-bibtex-footer (insert "\n\n" reftex-create-bibtex-footer))
    (goto-char (point-min))
    (save-buffer)
    (message "%d entries extracted and copied to new database"
             (length entries))))

(provide 'reftex-cite)
;;; reftex-cite.el ends here

;; Local Variables:
;; generated-autoload-file: "reftex-loaddefs.el"
;; End: