;;; gamegrid.el --- library for implementing grid-based games on Emacs  -*- lexical-binding:t -*-

;; Copyright (C) 1997-1998, 2001-2021 Free Software Foundation, Inc.

;; Author: Glynn Clements <glynn@sensei.co.uk>
;; Old-Version: 1.02
;; Created: 1997-08-13
;; Keywords: games

;; 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:

;; ;;;;;;;;;;;;; buffer-local variables ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defvar-local gamegrid-use-glyphs t
  "Non-nil means use glyphs when available.")

(defvar-local gamegrid-use-color t
  "Non-nil means use color when available.")

(defvar-local gamegrid-font "-*-courier-medium-r-*-*-*-140-100-75-*-*-iso8859-*"
  "Name of the font used in X mode.")

(defvar-local gamegrid-face nil
  "Indicates the face to use as a default.")

(defvar-local gamegrid-display-options nil)

(defvar-local gamegrid-buffer-width 0)
(defvar-local gamegrid-buffer-height 0)
(defvar-local gamegrid-blank 0)

(defvar-local gamegrid-timer nil)

(defvar-local gamegrid-display-mode nil)

(defvar-local gamegrid-display-table nil)

(defvar-local gamegrid-face-table nil)

(defvar-local gamegrid-buffer-start 1)

(defvar-local gamegrid-score-file-length 50
  "Number of high scores to keep.")

(defvar gamegrid-user-score-file-directory
  (locate-user-emacs-file "games/")
  "A directory for game scores which can't be shared.
If Emacs was built without support for shared game scores, then this
directory will be used.")


;; ;;;;;;;;;;;;; global variables ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defvar gamegrid-grid-x-face nil)
(defvar gamegrid-mono-x-face nil)
(defvar gamegrid-mono-tty-face nil)

(defvar gamegrid-glyph-height-mm 7.0
  "Desired glyph height in mm.")

;; ;;;;;;;;;;;;; glyph generation ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun gamegrid-calculate-glyph-size ()
  "Calculate appropriate glyph size in pixels based on display resolution.
Return a multiple of 8 no less than 16."
  (if (and (display-pixel-height) (display-mm-height))
      (let* ((y-pitch (/ (display-pixel-height) (float (display-mm-height))))
             (pixels (* y-pitch gamegrid-glyph-height-mm))
             (rounded (* (floor (/ (+ pixels 4) 8)) 8)))
        (max 16 rounded))
    16))

;; Example of glyph in XPM format:
;;
;; /* XPM */
;; static char *noname[] = {
;; /* width height ncolors chars_per_pixel */
;; \"16 16 3 1\",
;; /* colors */
;; \"+ s col1\",
;; \". s col2\",
;; \"- s col3\",
;; /* pixels */
;; \"---------------+\",
;; \"--------------++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"--............++\",
;; \"-+++++++++++++++\",
;; \"++++++++++++++++\"
;; };

(defun gamegrid-xpm ()
  "Generate the XPM format image used for each square."
  (let* ((glyph-pixel-count (gamegrid-calculate-glyph-size))
         (border-pixel-count (/ glyph-pixel-count 8))
         (center-pixel-count (- glyph-pixel-count (* border-pixel-count 2))))
    (with-temp-buffer
      (insert (format "\
/* XPM */
static char *noname[] = {
/* width height ncolors chars_per_pixel */
\"%s %s 3 1\",
/* colors */
\"+ s col1\",
\". s col2\",
\"- s col3\",
/* pixels */
" glyph-pixel-count glyph-pixel-count))

      (dotimes (row border-pixel-count)
        (let ((edge-pixel-count (+ row 1)))
          (insert "\"")
          (dotimes (_ (- glyph-pixel-count edge-pixel-count)) (insert "-"))
          (dotimes (_ edge-pixel-count) (insert "+"))
          (insert "\",\n")))

      (let ((middle (format "\"%s%s%s\",\n"
                            (make-string border-pixel-count ?-)
                            (make-string center-pixel-count ?.)
                            (make-string border-pixel-count ?+))))
        (dotimes (_ center-pixel-count) (insert middle)))

      (dotimes (row border-pixel-count)
        (let ((edge-pixel-count (- border-pixel-count row 1)))
          (insert "\"")
          (dotimes (_ edge-pixel-count) (insert "-"))
          (dotimes (_ (- glyph-pixel-count edge-pixel-count)) (insert "+"))
          (insert "\"")
          (if (/= row (1- border-pixel-count))
              (insert ",\n")
            (insert "\n};\n"))))
      (buffer-string))))

;; Example of glyph in XBM format:
;;
;; /* gamegrid XBM */
;; #define gamegrid_width 16
;; #define gamegrid_height 16
;; static unsigned char gamegrid_bits[] = {
;;    0xff, 0xff, 0xff, 0x7f, 0xff, 0x3f, 0xaf, 0x0a, 0x57, 0x15, 0xaf, 0x0a,
;;    0x57, 0x15, 0xaf, 0x0a, 0x57, 0x15, 0xaf, 0x0a, 0x57, 0x15, 0xaf, 0x0a,
;;    0x57, 0x15, 0x07, 0x00, 0x03, 0x00, 0x01, 0x00 };

(defun gamegrid-xbm ()
  "Generate XBM format image used for each square."
  (let* ((glyph-pixel-count (gamegrid-calculate-glyph-size))
         (border-pixel-count (1- (/ glyph-pixel-count 4)))
         (center-pixel-count (- glyph-pixel-count (* 2 border-pixel-count))))
    (with-temp-buffer
      (insert (format "\
/* gamegrid XBM */
#define gamegrid_width %s
#define gamegrid_height %s
static unsigned char gamegrid_bits[] = {
" glyph-pixel-count glyph-pixel-count))
      (dotimes (row border-pixel-count)
        (gamegrid-insert-xbm-bits
         (concat (make-string (- glyph-pixel-count row) ?1)
                 (make-string row ?0)))
        (insert ", \n"))

      (let* ((left-border (make-string border-pixel-count ?1))
             (right-border (make-string border-pixel-count ?0))
             (even-line (apply 'concat
                               (append (list left-border)
                                       (make-list (/ center-pixel-count 2) "10")
                                       (list right-border))))
             (odd-line (apply 'concat
                              (append (list left-border)
                                      (make-list (/ center-pixel-count 2) "01")
                                      (list right-border)))))
        (dotimes (row center-pixel-count)
          (gamegrid-insert-xbm-bits (if (eq (logand row 1) 1) odd-line even-line))
          (insert ", \n")))

      (dotimes (row border-pixel-count)
        (let ((edge-pixel-count (- border-pixel-count row)))
          (gamegrid-insert-xbm-bits
           (concat (make-string edge-pixel-count ?1)
                   (make-string (- glyph-pixel-count edge-pixel-count) ?0))))
        (if (/= row (1- border-pixel-count))
            (insert ", \n")
          (insert " };\n")))
      (buffer-string))))

(defun gamegrid-insert-xbm-bits (str)
  "Convert binary to hex and insert in current buffer.
STR should be a string composed of 1s and 0s and be a multiple of
8 in length.  Divide it into 8 bit bytes, reverse the order of
each, convert them to hex and insert them in comma separated C
format."
  (let ((byte-count (/ (length str) 8)))
    (dotimes (i byte-count)
      (let* ((byte (reverse (substring str (* i 8) (+ (* i 8) 8))))
             (value (string-to-number byte 2)))
        (insert (format "0x%02x" value))
        (unless (= i (1- byte-count))
          (insert ", "))))))

;; ;;;;;;;;;;;;;;;; miscellaneous functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defsubst gamegrid-event-x (event)
  (car (posn-col-row (event-end event))))

(defsubst gamegrid-event-y (event)
  (cdr (posn-col-row (event-end event))))

;; ;;;;;;;;;;;;; display functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun gamegrid-color (color shade)
  (let* ((v (floor (* shade 255)))
	 (r (* v (aref color 0)))
	 (g (* v (aref color 1)))
	 (b (* v (aref color 2))))
    (format "#%02x%02x%02x" r g b)))

(defun gamegrid-set-font (face)
  (if gamegrid-font
      (condition-case nil
	  (set-face-font face gamegrid-font)
	(error nil))))

(defun gamegrid-setup-face (face color)
  (set-face-foreground face color)
  (set-face-background face color)
  (gamegrid-set-font face)
  (set-face-background-pixmap face nil))

(defun gamegrid-make-mono-tty-face ()
  (let ((face (make-face 'gamegrid-mono-tty-face)))
    (set-face-inverse-video face t)
    face))

(defun gamegrid-make-color-tty-face (color)
  (let* ((color-str (if (symbolp color) (symbol-value color) color))
	 (name (intern (format "gamegrid-color-tty-face-%s" color-str)))
	 (face (make-face name)))
    (gamegrid-setup-face face color-str)
    face))

(defun gamegrid-make-grid-x-face ()
  (let ((face (make-face 'gamegrid-x-border-face)))
    (gamegrid-set-font face)
    face))

(defun gamegrid-make-mono-x-face ()
  (let ((face (make-face 'gamegrid-mono-x-face))
	(color (face-foreground 'default)))
    (if (null color)
	(setq color
	      (cdr-safe (assq 'foreground-color (frame-parameters)))))
    (gamegrid-setup-face face color)
    face))

(defun gamegrid-make-color-x-face (color)
  (let* ((hex (gamegrid-color color 1.0))
	 (name (intern (format "gamegrid-color-x-face-%s" hex)))
	 (face (make-face name)))
    (gamegrid-setup-face face hex)
    face))

(defun gamegrid-make-face (data-spec-list color-spec-list)
  (let ((data (gamegrid-match-spec-list data-spec-list))
	(color (gamegrid-match-spec-list color-spec-list)))
    (pcase data
      ('color-x
       (gamegrid-make-color-x-face color))
      ('grid-x
       (unless gamegrid-grid-x-face
	 (setq gamegrid-grid-x-face (gamegrid-make-grid-x-face)))
       gamegrid-grid-x-face)
      ('mono-x
       (unless gamegrid-mono-x-face
	 (setq gamegrid-mono-x-face (gamegrid-make-mono-x-face)))
       gamegrid-mono-x-face)
      ('color-tty
       (gamegrid-make-color-tty-face color))
      ('mono-tty
       (unless gamegrid-mono-tty-face
	 (setq gamegrid-mono-tty-face (gamegrid-make-mono-tty-face)))
       gamegrid-mono-tty-face))))

(defun gamegrid-colorize-glyph (color)
  (find-image `((:type xpm :data ,(gamegrid-xpm)
		       :ascent center
		       :color-symbols
		       (("col1" . ,(gamegrid-color color 0.6))
			("col2" . ,(gamegrid-color color 0.8))
			("col3" . ,(gamegrid-color color 1.0))))
		(:type xbm :data ,(gamegrid-xbm)
		       :ascent center
		       :foreground ,(gamegrid-color color 1.0)
		       :background ,(gamegrid-color color 0.5)))))

(defun gamegrid-match-spec (spec)
  (let ((locale (car spec))
	(value (cadr spec)))
    (and (or (eq locale t)
	     (and (listp locale)
		  (memq gamegrid-display-mode locale))
	     (and (symbolp locale)
		  (eq gamegrid-display-mode locale)))
	 value)))

(defun gamegrid-match-spec-list (spec-list)
  (and spec-list
       (or (gamegrid-match-spec (car spec-list))
	   (gamegrid-match-spec-list (cdr spec-list)))))

(defun gamegrid-make-glyph (data-spec-list color-spec-list)
  (let ((data (gamegrid-match-spec-list data-spec-list))
	(color (gamegrid-match-spec-list color-spec-list)))
    (cond ((characterp data)
	   (vector data))
	  ((eq data 'colorize)
	   (gamegrid-colorize-glyph color))
	  ((listp data)
	   (find-image data)) ;untested!
	  ((vectorp data)
	   (gamegrid-make-image-from-vector data)))))

(defun gamegrid-make-image-from-vector (vect)
  "Convert an XEmacs style \"glyph\" to an image-spec."
  (let ((l (list 'image :type)))
    (dotimes (n (length vect))
      (setf l (nconc l (list (aref vect n)))))
    (nconc l (list :ascent 'center))))

(defun gamegrid-display-type ()
  (cond ((and gamegrid-use-glyphs
	      (display-images-p))
	 'glyph)
	((and gamegrid-use-color
	      (display-graphic-p)
	      (display-color-p))
	 'color-x)
	((display-graphic-p)
	 'mono-x)
	((and gamegrid-use-color
	      (display-color-p))
	 'color-tty)
	((display-multi-font-p) ;???
	 'mono-tty)
	(t
	   'emacs-tty)))

(declare-function image-size "image.c" (spec &optional pixels frame))

(defun gamegrid-setup-default-font ()
  (setq gamegrid-face
	(copy-face 'default
		   (intern (concat "gamegrid-face-" (buffer-name)))))
  (when (eq gamegrid-display-mode 'glyph)
    (let ((max-height nil))
      (dotimes (c 256)
        (let ((glyph (aref gamegrid-display-table c)))
          (when (and (listp glyph) (eq (car  glyph) 'image))
            (let ((height (cdr (image-size glyph))))
              (if (or (null max-height)
                      (< max-height height))
                  (setq max-height height))))))
      (when (and max-height (< max-height 1))
	(let ((default-font-height (face-attribute 'default :height))
	      (resy (/ (display-pixel-height) (/ (display-mm-height) 25.4)))
	      point-size pixel-size)
	  (setq point-size (/ (* (float default-font-height) max-height) 10)
		pixel-size (floor (* resy (/ point-size 72.27)))
		point-size (* (/ pixel-size resy) 72.27))
	  (face-spec-set gamegrid-face
			 `((t :height ,(floor (* point-size 10))))))))))

(defun gamegrid-initialize-display ()
  (setq gamegrid-display-mode (gamegrid-display-type))
  (setq gamegrid-display-table (make-display-table))
  (setq gamegrid-face-table (make-vector 256 nil))
  (dotimes (c 256)
    (let* ((spec (aref gamegrid-display-options c))
	   (glyph (gamegrid-make-glyph (car spec) (nth 2 spec)))
	   (face (gamegrid-make-face (cadr spec) (nth 2 spec))))
      (aset gamegrid-face-table c face)
      (aset gamegrid-display-table c glyph)))
  (gamegrid-setup-default-font)
  (setq buffer-display-table gamegrid-display-table)
  (setq cursor-type nil))


(defun gamegrid-set-face (c)
  (if (eq gamegrid-display-mode 'glyph)
      (add-text-properties (1- (point)) (point)
			   (list 'display (list (aref gamegrid-display-table c))))
    (put-text-property (1- (point))
		       (point)
		       'face
		       (aref gamegrid-face-table c))))

(defun gamegrid-cell-offset (x y)
  (+ gamegrid-buffer-start
     (* (1+ gamegrid-buffer-width) y)
     x))

;; ;;;;;;;;;;;;;;;; grid functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun gamegrid-get-cell (x y)
  (char-after (gamegrid-cell-offset x y)))

(defun gamegrid-set-cell (x y c)
  (save-excursion
    (let ((buffer-read-only nil))
      (goto-char (gamegrid-cell-offset x y))
      (delete-char 1)
      (insert-char c 1)
      (gamegrid-set-face c))))

(defun gamegrid-init-buffer (width height blank)
  (setq gamegrid-buffer-width width
	gamegrid-buffer-height height)
  (let ((line (concat
	       (make-string width blank)
	       "\n"))
	(buffer-read-only nil))
    (erase-buffer)
    (setq gamegrid-buffer-start (point))
    (dotimes (_ height)
      (insert line))
    ;; Adjust the height of the default face to the height of the
    ;; images. Unlike XEmacs, Emacs doesn't allow making the default
    ;; face buffer-local; so we do this with an overlay.
    (when (eq gamegrid-display-mode 'glyph)
      (overlay-put (make-overlay (point-min) (point-max))
		   'face gamegrid-face))
    (goto-char (point-min))))

(defun gamegrid-init (options)
  (setq buffer-read-only t
	truncate-lines t
	line-spacing 0
	gamegrid-display-options options)
  (buffer-disable-undo (current-buffer))
  (gamegrid-initialize-display))

;; ;;;;;;;;;;;;;;;; timer functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun gamegrid-start-timer (period func)
  (setq gamegrid-timer
	(run-with-timer period period func (current-buffer))))

(defun gamegrid-set-timer (delay)
  (if gamegrid-timer
      (timer-set-time gamegrid-timer
		      (list (aref gamegrid-timer 1)
			    (aref gamegrid-timer 2)
			    (aref gamegrid-timer 3))
		      delay)))

(defun gamegrid-kill-timer ()
  (if gamegrid-timer
      (cancel-timer gamegrid-timer))
  (setq gamegrid-timer nil))

;; ;;;;;;;;;;;;;;; high score functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun gamegrid-add-score (file score &optional reverse)
  "Add the current score to the high score file.

If REVERSE is non-nil, treat lower scores as better than higher
scores. This is useful for games where lower scores are better.

On POSIX systems there may be a shared game directory for all users in
which the scorefiles are kept.  On such systems Emacs doesn't create
the score file FILE in this directory, if it doesn't already exist.
In this case Emacs searches for FILE in the directory specified by
`gamegrid-user-score-file-directory' and creates it there, if
necessary.

To add the score file for a game to the system wide shared game
directory, create the file with the shell command \"touch\" in this
directory and make sure that it is owned by the correct user and
group.  You probably need special user privileges to do this.

On non-POSIX systems Emacs searches for FILE in the directory
specified by the variable `temporary-file-directory'.  If necessary,
FILE is created there."
  (pcase system-type
    ((or 'ms-dos 'windows-nt)
     (gamegrid-add-score-insecure file score reverse))
    (_
     (gamegrid-add-score-with-update-game-score file score reverse))))


;; On POSIX systems there are four cases to distinguish:

;;     1. FILE is an absolute filename or "update-game-score" does not exist.
;;	  Then FILE should be a file in a temporary file directory.  This is how
;;        `gamegrid-add-score' was supposed to be used in the past and
;;        is covered here for backward-compatibility.
;;
;;     2. The helper program "update-game-score" is setgid or setuid
;;        and the file FILE does already exist in a system wide shared
;;        game directory.  This should be the normal case on POSIX
;;        systems, if the game was installed system wide.  Use
;;        "update-game-score" to add the score to the file in the
;;        shared game directory.
;;
;;     3. "update-game-score" is setgid/setuid, but the file FILE does
;;        *not* exist in the system wide shared game directory.  Use
;;        `gamegrid-add-score-insecure' to create--if necessary--and
;;        update FILE.  This is for the case that a user has installed
;;        a game on her own.
;;
;;     4. "update-game-score" is not setgid/setuid.  Use it to
;;        create/update FILE in the user's home directory.  There is
;;        presumably no shared game directory.

(defvar gamegrid-shared-game-dir)

(defun gamegrid-add-score-with-update-game-score (file score &optional reverse)
  (let* ((update-game-score-modes
	  (file-modes (expand-file-name "update-game-score" exec-directory)))
	 (gamegrid-shared-game-dir
	  (not (zerop (logand #o6000 (or update-game-score-modes 0))))))
    (cond ((or (not update-game-score-modes) (file-name-absolute-p file))
	   (gamegrid-add-score-insecure file score
                                        gamegrid-user-score-file-directory
                                        reverse))
	  ((and gamegrid-shared-game-dir
		(file-exists-p (expand-file-name file shared-game-score-directory)))
	   ;; Use the setgid (or setuid) "update-game-score" program
	   ;; to update a system-wide score file.
	   (gamegrid-add-score-with-update-game-score-1 file
	    (expand-file-name file shared-game-score-directory) score reverse))
	  ;; Else: Add the score to a score file in the user's home
	  ;; directory.
	  (gamegrid-shared-game-dir
	   ;; If gamegrid-shared-game-dir is non-nil the
	   ;; "update-gamescore" program is setuid, so don't use it.
	   (unless (file-exists-p
		    (directory-file-name gamegrid-user-score-file-directory))
	     (make-directory gamegrid-user-score-file-directory t))
	   (gamegrid-add-score-insecure file score
					gamegrid-user-score-file-directory
                                        reverse))
	  (t
	   (unless (file-exists-p
		    (directory-file-name gamegrid-user-score-file-directory))
	     (make-directory gamegrid-user-score-file-directory t))
	   (let ((f (expand-file-name file
				      gamegrid-user-score-file-directory)))
	     (unless (file-exists-p f)
	       (write-region "" nil f nil 'silent nil 'excl))
	     (gamegrid-add-score-with-update-game-score-1 file f score reverse))))))

(defun gamegrid-add-score-with-update-game-score-1 (file target score &optional reverse)
  (let ((default-directory "/")
	(errbuf (generate-new-buffer " *update-game-score loss*"))
        (marker-string (concat
			(user-full-name)
			" <" user-mail-address ">  "
			(current-time-string))))
    ;; This can be called from a timer, so enable local quits.
    (with-local-quit
      (apply
       'call-process
       `(,(expand-file-name "update-game-score" exec-directory)
         nil ,errbuf nil
         "-m" ,(int-to-string gamegrid-score-file-length)
         "-d" ,(if gamegrid-shared-game-dir
                   (expand-file-name shared-game-score-directory)
                 (file-name-directory target))
         ,@(if reverse '("-r"))
         ,file
         ,(int-to-string score)
         ,marker-string)))
    (if (buffer-modified-p errbuf)
	(progn
	  (display-buffer errbuf)
	  (error "Failed to update game score file"))
      (kill-buffer errbuf))
    (let ((buf (find-buffer-visiting target)))
      (save-excursion
        (if buf
	    (progn
	      (switch-to-buffer buf)
	      (revert-buffer nil t nil)
	      (display-buffer buf))
	  (find-file-read-only target))
        (view-mode)
        (goto-char (point-min))
        (search-forward (concat (int-to-string score)
				" " (user-login-name) " "
				marker-string) nil t)
        (beginning-of-line)))))

(defun gamegrid-add-score-insecure (file score &optional directory reverse)
  (save-excursion
    (setq file (expand-file-name file (or directory
					  temporary-file-directory)))
    (unless (file-exists-p (file-name-directory file))
      (make-directory (file-name-directory file) t))
    (find-file-other-window file)
    (setq buffer-read-only nil)
    (goto-char (point-max))
    (insert (format "%05d\t%s\t%s <%s>\n"
		    score
		    (current-time-string)
		    (user-full-name)
		    user-mail-address))
    (sort-fields 1 (point-min) (point-max))
    (unless reverse
      (reverse-region (point-min) (point-max)))
    (goto-char (point-min))
    (forward-line gamegrid-score-file-length)
    (delete-region (point) (point-max))
    (setq buffer-read-only t)
    (save-buffer)
    (view-mode)))


;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(provide 'gamegrid)

;;; gamegrid.el ends here