;;; cookie1.el --- retrieve random phrases from fortune cookie files

;; Copyright (C) 1993, 2001-2021 Free Software Foundation, Inc.

;; Author: Eric S. Raymond <esr@snark.thyrsus.com>
;; Maintainer: emacs-devel@gnu.org
;; Keywords: games, extensions
;; Created: Mon Mar 22 17:06:26 1993

;; 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:

;; Support for random cookie fetches from phrase files, used for such
;; critical applications as confounding the NSA Trunk Trawler.
;;
;; The two entry points are `cookie' and `cookie-insert'.  The helper
;; function `cookie-shuffle-vector' may be of interest to programmers.
;;
;; The code expects phrase files to be in one of two formats:
;;
;; * ITS-style LINS format (strings terminated by ASCII 0 characters,
;; leading whitespace ignored).
;;
;; * UNIX fortune file format (quotes terminated by %% on a line by itself).
;;
;; Everything up to the first delimiter is treated as a comment.  Other
;; formats could be supported by adding alternates to the regexp
;; `cookie-delimiter'.
;;
;; strfile(1) is the program used to compile the files for fortune(6).
;; In order to achieve total compatibility with strfile(1), cookie files
;; should start with two consecutive delimiters (and no comment).
;;
;; This code derives from Steve Strassmann's 1987 spook.el package, but
;; has been generalized so that it supports multiple simultaneous
;; cookie databases and fortune files.  It is intended to be called
;; from other packages such as spook.el.

;;; Code:

(defgroup cookie nil
  "Random cookies from phrase files."
  :prefix "cookie-"
  :group 'games)

(defcustom cookie-file nil
  "Default phrase file for cookie functions."
  :type '(choice (const nil) file)
  :version "24.4")

(defconst cookie-delimiter "\n%%\n\\|\n%\n\\|\0"
  "Delimiter used to separate cookie file entries.")

(defvar cookie-cache (make-vector 511 0)
  "Cache of cookie files that have already been snarfed.")

(defun cookie-check-file (file)
  "Return either FILE or `cookie-file'.
Signal an error if the result is nil or not readable."
  (or (setq file (or file cookie-file)) (user-error "No phrase file specified"))
  (or (file-readable-p file) (user-error "Cannot read file `%s'" file))
  file)

;;;###autoload
(defun cookie (phrase-file &optional startmsg endmsg)
  "Return a random phrase from PHRASE-FILE.
When the phrase file is read in, display STARTMSG at the beginning
of load, ENDMSG at the end.
Interactively, PHRASE-FILE defaults to `cookie-file', unless that
is nil or a prefix argument is used."
  (interactive (list (if (or current-prefix-arg (not cookie-file))
			 (read-file-name "Cookie file: " nil
					 cookie-file t cookie-file)
		       cookie-file) nil nil))
  (setq phrase-file (cookie-check-file phrase-file))
  (let ((cookie-vector (cookie-snarf phrase-file startmsg endmsg))
	res)
    (cookie-shuffle-vector cookie-vector)
    (setq res (aref cookie-vector 0))
    (if (called-interactively-p 'interactive)
	(message "%s" res)
      res)))

;;;###autoload
(defun cookie-insert (phrase-file &optional count startmsg endmsg)
  "Insert random phrases from PHRASE-FILE; COUNT of them.
When the phrase file is read in, display STARTMSG at the beginning
of load, ENDMSG at the end."
  (setq phrase-file (cookie-check-file phrase-file))
  (let ((cookie-vector (cookie-snarf phrase-file startmsg endmsg)))
    (cookie-shuffle-vector cookie-vector)
    (let ((start (point)))
      (insert ?\n)
      (cookie1 (min (- (length cookie-vector) 1) (or count 1)) cookie-vector)
      (insert ?\n)
      (fill-region-as-paragraph start (point) nil))))

(defun cookie1 (arg cookie-vec)
  "Inserts a cookie phrase ARG times."
  (cond ((zerop arg) t)
	(t (insert (aref cookie-vec arg))
	   (insert " ")
	   (cookie1 (1- arg) cookie-vec))))

;;;###autoload
(defun cookie-snarf (phrase-file &optional startmsg endmsg)
  "Reads in the PHRASE-FILE, returns it as a vector of strings.
Emit STARTMSG and ENDMSG before and after.  Caches the result; second
and subsequent calls on the same file won't go to disk."
  (setq phrase-file (cookie-check-file phrase-file))
  (let ((sym (intern-soft phrase-file cookie-cache)))
    (and sym (not (equal (symbol-function sym)
			 (file-attribute-modification-time
                          (file-attributes phrase-file))))
	 (yes-or-no-p (concat phrase-file
			      " has changed.  Read new contents? "))
	 (setq sym nil))
    (if sym
	(symbol-value sym)
      (setq sym (intern phrase-file cookie-cache))
      (if startmsg (message "%s" startmsg))
      (fset sym (file-attribute-modification-time
                 (file-attributes phrase-file)))
      (let (result)
	(with-temp-buffer
	  (insert-file-contents (expand-file-name phrase-file))
	  (re-search-forward cookie-delimiter)
	  (while (progn (skip-chars-forward " \t\n\r\f") (not (eobp)))
	    (let ((beg (point)))
	      (re-search-forward cookie-delimiter)
	      (setq result (cons (buffer-substring beg (match-beginning 0))
				 result)))))
	(if endmsg (message "%s" endmsg))
	(set sym (apply 'vector result))))))

(defun cookie-read (prompt phrase-file &optional startmsg endmsg require-match)
  "Prompt with PROMPT and read with completion among cookies in PHRASE-FILE.
STARTMSG and ENDMSG are passed along to `cookie-snarf'.
Argument REQUIRE-MATCH non-nil forces a matching cookie."
  (setq phrase-file (cookie-check-file phrase-file))
  ;; Make sure the cookies are in the cache.
  (or (intern-soft phrase-file cookie-cache)
      (cookie-snarf phrase-file startmsg endmsg))
  (completing-read prompt
		   (let ((sym (intern phrase-file cookie-cache)))
		     ;; We cache the alist form of the cookie in a property.
		     (or (get sym 'completion-alist)
			 (let* ((alist nil)
				(vec (cookie-snarf phrase-file
						   startmsg endmsg))
				(i (length vec)))
			   (while (>= (setq i (1- i)) 0)
			     (setq alist (cons (list (aref vec i)) alist)))
			   (put sym 'completion-alist alist))))
		   nil require-match nil nil))

(define-obsolete-function-alias 'read-cookie 'cookie-read "24.4")

;; Thanks to Ian G Batten <BattenIG@CS.BHAM.AC.UK>
;; [of the University of Birmingham Computer Science Department]
;; for the iterative version of this shuffle.
(defun cookie-shuffle-vector (vector)
  "Randomly permute the elements of VECTOR (all permutations equally likely)."
  (let ((len (length vector))
	j temp)
    (dotimes (i len vector)
      (setq j (+ i (random (- len i)))
	    temp (aref vector i))
      (aset vector i (aref vector j))
      (aset vector j temp))))

(define-obsolete-function-alias 'shuffle-vector 'cookie-shuffle-vector "24.4")


(defun cookie-apropos (regexp phrase-file &optional display)
  "Return a list of all entries matching REGEXP from PHRASE-FILE.
Interactively, uses `read-regexp' to read REGEXP.
Interactively, PHRASE-FILE defaults to `cookie-file', unless that
is nil or a prefix argument is used.
If called interactively, or if DISPLAY is non-nil, display a list of matches."
  (interactive (list (read-regexp "Apropos phrase (regexp): ")
		     (if (or current-prefix-arg (not cookie-file))
			 (read-file-name "Cookie file: " nil
					 cookie-file t cookie-file)
		       cookie-file) t))
  (setq phrase-file (cookie-check-file phrase-file))
  ;; Make sure phrases are loaded.
  (cookie phrase-file)
  (let* ((case-fold-search t)
         (cookie-table-symbol (intern phrase-file cookie-cache))
         (string-table (symbol-value cookie-table-symbol))
         (matches nil))
    (and (dotimes (i (length string-table) matches)
           (and (string-match-p regexp (aref string-table i))
                (setq matches (cons (aref string-table i) matches))))
         (setq matches (sort matches 'string-lessp)))
    (and display
         (if matches
             (let ((l matches))
               (with-output-to-temp-buffer "*Cookie Apropos*"
                 (while l
                   (princ (car l))
                   (setq l (cdr l))
                   (and l (princ "\n\n")))
                 (help-print-return-message)))
           (message "No matches found.")))
    matches))


(declare-function doctor-ret-or-read "doctor" (arg))

(defun cookie-doctor (phrase-file)
  "Feed cookie phrases from PHRASE-FILE to the doctor.
Interactively, PHRASE-FILE defaults to `cookie-file', unless that
is nil or a prefix argument is used."
  (interactive (list (if (or current-prefix-arg (not cookie-file))
			 (read-file-name "Cookie file: " nil
					 cookie-file t cookie-file)
		       cookie-file)))
  (setq phrase-file (cookie-check-file phrase-file))
  (doctor)				; start the psychotherapy
  (message "")
  (switch-to-buffer "*doctor*")
  (sit-for 0)
  (while (not (input-pending-p))
    (insert (cookie phrase-file))
    (sit-for 0)
    (doctor-ret-or-read 1)
    (doctor-ret-or-read 1)))


(provide 'cookie1)

;;; cookie1.el ends here