elopher.el

   1 ;;; elopher.el --- gopher client
   2
   3 ;;; Commentary:
   4
   5 ;; Simple gopher client in elisp.
   6
   7 ;;; Code:
   8
   9 ;;; Global constants
  10 ;;
  11
  12 (defconst elopher-version "1.0.0"
  13   "Current version of elopher.")
  14
  15 (defconst elopher-margin-width 6
  16   "Width of left-hand margin used when rendering indicies.")
  17
  18 (defconst elopher-start-page
  19   (string-join
  20    (list "i\tfake\tfake\t1"
  21          "i--------------------------------------------\tfake\tfake\t1"
  22          "i          Elopher Gopher Client             \tfake\tfake\t1"
  23          (format "i              version %s\tfake\tfake\t1" elopher-version)
  24          "i--------------------------------------------\tfake\tfake\t1"
  25          "i\tfake\tfake\t1"
  26          "iBasic usage:\tfake\tfake\t1"
  27          "i - tab/shift-tab: next/prev directory entry\tfake\tfake\t1"
  28          "i - RET/mouse-1: open directory entry\tfake\tfake\t1"
  29          "i - u: return to parent directory entry\tfake\tfake\t1"
  30          "i - g: go to a particular site\tfake\tfake\t1"
  31          "i - r: reload current page\tfake\tfake\t1"
  32          "i\tfake\tfake\t1"
  33          "iPlaces to start exploring Gopherspace:\tfake\tfake\t1"
  34          "1Floodgap Systems Gopher Server\t\tgopher.floodgap.com\t70"
  35          "1Super-Dimensional Fortress\t\tsdf.org\t70"
  36          "i\tfake\tfake\t1"
  37          "iTest entries:\tfake\tfake\t1"
  38          "pXKCD comic image\t/fun/xkcd/comics/2130/2137/text_entry.png\tgopher.floodgap.com\t70"
  39          "1Test server\t\tlocalhost\t70"
  40          ".")
  41    "\r\n"))
  42
  43
  44 ;;; Customization group
  45 ;;
  46
  47 (defgroup elopher nil
  48   "A simple gopher client."
  49   :group 'applications)
  50
  51 (defcustom elopher-index-face '(foreground-color . "cyan")
  52   "Face used for index records.")
  53 (defcustom elopher-text-face '(foreground-color . "white")
  54   "Face used for text records.")
  55 (defcustom elopher-info-face '(foreground-color . "gray")
  56   "Face used for info records.")
  57 (defcustom elopher-image-face '(foreground-color . "green")
  58   "Face used for image records.")
  59 (defcustom elopher-unknown-face '(foreground-color . "red")
  60   "Face used for unknown record types.")
  61
  62 ;;; Model
  63 ;;
  64
  65 ;; Address
  66
  67 (defun elopher-make-address (selector host port)
  68   (list selector host port))
  69
  70 (defun elopher-address-selector (address)
  71   (car address))
  72
  73 (defun elopher-address-host (address)
  74   (cadr address))
  75
  76 (defun elopher-address-port (address)
  77   (caddr address))
  78
  79 ;; Node
  80
  81 (defun elopher-make-node (parent address getter &optional content pos)
  82   (list parent address getter content pos))
  83
  84 (defun elopher-node-parent (node)
  85   (elt node 0))
  86
  87 (defun elopher-node-address (node)
  88   (elt node 1))
  89
  90 (defun elopher-node-getter (node)
  91   (elt node 2))
  92
  93 (defun elopher-node-content (node)
  94   (elt node 3))
  95
  96 (defun elopher-node-pos (node)
  97   (elt node 4))
  98
  99 (defun elopher-set-node-content (node content)
 100   (setcar (nthcdr 3 node) content))
 101
 102 (defun elopher-set-node-pos (node pos)
 103   (setcar (nthcdr 4 node) pos))
 104
 105 (defun elopher-save-pos ()
 106   (when elopher-current-node
 107     (elopher-set-node-pos elopher-current-node (point))))
 108
 109 (defun elopher-restore-pos ()
 110   (let ((pos (elopher-node-pos elopher-current-node)))
 111     (if pos
 112         (goto-char (elopher-node-pos elopher-current-node))
 113       (goto-char (point-min)))))
 114
 115 ;; Node graph traversal
 116
 117 (defvar elopher-start-node (elopher-make-node nil nil #'elopher-get-index-node))
 118 (defvar elopher-current-node)
 119
 120 (defun elopher-visit-node (node)
 121   (elopher-save-pos)
 122   (elopher-prepare-buffer)
 123   (setq elopher-current-node node)
 124   (funcall (elopher-node-getter node)))
 125
 126 (defun elopher-visit-parent-node ()
 127   (let ((parent-node (elopher-node-parent elopher-current-node)))
 128     (when parent-node
 129       (setq elopher-current-node parent-node)
 130       (elopher-visit-node elopher-current-node))))
 131
 132 (defun elopher-reload-current-node ()
 133   (elopher-set-node-content elopher-current-node nil)
 134   (elopher-visit-node elopher-current-node))
 135
 136
 137 ;;; Buffer preparation
 138 ;;
 139
 140 (defun elopher-prepare-buffer ()
 141   (switch-to-buffer "*elopher*")
 142   (elopher-mode)
 143   (let ((inhibit-read-only t))
 144     (erase-buffer)))
 145
 146
 147 ;;; Index rendering
 148 ;;
 149
 150 (defun elopher-insert-index (string)
 151   "Inserts the index corresponding to STRING into the current buffer."
 152   (dolist (line (split-string string "\r\n"))
 153     (unless (string-empty-p line)
 154       (elopher-insert-index-record line))))
 155
 156 (defun elopher-insert-margin (&optional type-name)
 157   (if type-name
 158       (progn
 159         (insert (format (concat "%" (number-to-string (- elopher-margin-width 1)) "s")
 160                         (concat
 161                          (propertize "[" 'face '(foreground-color . "blue"))
 162                          (propertize type-name 'face '(foreground-color . "white"))
 163                          (propertize "]" 'face '(foreground-color . "blue")))))
 164         (insert " "))
 165     (insert (make-string elopher-margin-width ?\s))))
 166
 167 (defun elopher-insert-index-record (line)
 168   "Inserts the index record corresponding to LINE into the current buffer."
 169   (let* ((type (elt line 0))
 170          (fields (split-string (substring line 1) "\t"))
 171          (display-string (elt fields 0))
 172          (address (elopher-make-address (elt fields 1) (elt fields 2) (elt fields 3))))
 173     (pcase type
 174       (?i (elopher-insert-margin)
 175           (insert (propertize display-string
 176                               'face elopher-info-face)))
 177       (?0 (elopher-insert-margin "T")
 178           (insert-text-button display-string
 179                               'face elopher-text-face
 180                               'elopher-node (elopher-make-node elopher-current-node
 181                                                                address
 182                                                                #'elopher-get-text-node)
 183                               'action #'elopher-click-link
 184                               'follow-link t))
 185       (?1 (elopher-insert-margin "/")
 186           (insert-text-button display-string
 187                               'face elopher-index-face
 188                               'elopher-node (elopher-make-node elopher-current-node
 189                                                                address
 190                                                                #'elopher-get-index-node)
 191                               'action #'elopher-click-link
 192                               'follow-link t))
 193       (?.) ; Occurs at end of index, can safely ignore.
 194       (tp (elopher-insert-margin (concat (char-to-string tp) "?"))
 195           (insert (propertize display-string
 196                               'face elopher-unknown-face))))
 197     (insert "\n")))
 198
 199
 200 ;;; Selector retrieval (all kinds)
 201 ;;
 202
 203 (defvar elopher-selector-string)
 204
 205 (defun elopher-get-selector (address after)
 206   (setq elopher-selector-string "")
 207   (let ((p (get-process "elopher-process")))
 208     (if p (delete-process p)))
 209   (make-network-process
 210    :name "elopher-process"
 211    :host (elopher-address-host address)
 212    :service (elopher-address-port address)
 213    :filter (lambda (proc string)
 214              (setq elopher-selector-string (concat elopher-selector-string string)))
 215    :sentinel after)
 216   (process-send-string "elopher-process"
 217                        (concat (elopher-address-selector address) "\n")))
 218
 219 ;; Index retrieval
 220
 221 (defun elopher-get-index-node ()
 222   (let ((content (elopher-node-content elopher-current-node))
 223         (address (elopher-node-address elopher-current-node)))
 224     (if content
 225         (let ((inhibit-read-only t))
 226           (insert content))
 227         (elopher-restore-pos)
 228       (if address
 229           (elopher-get-selector address
 230                                 (lambda (proc event)
 231                                   (let ((inhibit-read-only t))
 232                                     (elopher-insert-index elopher-selector-string))
 233                                   (elopher-restore-pos)
 234                                   (elopher-set-node-content elopher-current-node
 235                                                             (buffer-string))))
 236         (progn
 237           (let ((inhibit-read-only t))
 238             (elopher-insert-index elopher-start-page))
 239           (elopher-restore-pos)
 240           (elopher-set-node-content elopher-current-node
 241                                     (buffer-string)))))))
 242
 243 ;; Text retrieval
 244
 245 (defun elopher-strip-CRs (string)
 246   (replace-regexp-in-string "\r" "" string))
 247
 248 (defun elopher-get-text-node ()
 249   (let ((content (elopher-node-content elopher-current-node))
 250         (address (elopher-node-address elopher-current-node)))
 251     (if content
 252         (let ((inhibit-read-only t))
 253           (save-excursion
 254             (insert content)))
 255       (elopher-get-selector address
 256                             (lambda (proc event)
 257                               (let ((inhibit-read-only t))
 258                                 (erase-buffer)
 259                                 (save-excursion
 260                                   (insert
 261                                    (elopher-strip-CRs elopher-selector-string))))
 262                               (elopher-set-node-content elopher-current-node
 263                                                         (buffer-string)))))))
 264
 265 ;;; Navigation methods
 266 ;;
 267
 268 (defun elopher-next-link ()
 269   (interactive)
 270   (forward-button 1))
 271
 272 (defun elopher-prev-link ()
 273   (interactive)
 274   (backward-button 1))
 275
 276 (defun elopher-click-link (button)
 277   (let ((node (button-get button 'elopher-node)))
 278     (elopher-visit-node node)))
 279
 280 (defun elopher-follow-closest-link ()
 281   (interactive)
 282   (push-button))
 283
 284 (defun elopher-go ()
 285   "Go to a particular gopher site."
 286   (interactive)
 287   (let* ((selector "")
 288          (hostname (read-from-minibuffer "Gopher host: "))
 289          (port 70)
 290          (address (list selector hostname port)))
 291     (elopher-visit-node
 292      (elopher-make-node elopher-current-node
 293                         address
 294                         #'elopher-get-index-node))))
 295
 296 (defun  elopher-reload ()
 297   "Reload current site."
 298   (interactive)
 299   (elopher-reload-current-node))
 300
 301 (defun elopher-back ()
 302   "Go to previous site."
 303   (interactive)
 304   (elopher-visit-parent-node))
 305
 306 ;;; Main start procedure
 307 ;;
 308 (defun elopher ()
 309   "Start elopher with default landing page."
 310   (interactive)
 311   (setq elopher-current-node nil)
 312   (elopher-visit-node elopher-start-node))
 313
 314
 315 ;;; Mode and keymap
 316 ;;
 317
 318 (defvar elopher-mode-map
 319   (let ((map (make-sparse-keymap)))
 320     (define-key map (kbd "<tab>") 'elopher-next-link)
 321     (define-key map (kbd "<S-tab>") 'elopher-prev-link)
 322     (define-key map (kbd "u") 'elopher-back)
 323     (define-key map (kbd "g") 'elopher-go)
 324     (define-key map (kbd "r") 'elopher-reload)
 325     (when (require 'evil nil t)
 326       (evil-define-key 'normal map
 327         (kbd "C-]") 'elopher-follow-closest-link
 328         (kbd "C-t") 'elopher-back
 329         (kbd "u") 'elopher-back
 330         (kbd "g") 'elopher-go
 331         (kbd "r") 'elopher-reload))
 332     map)
 333   "Keymap for gopher client.")
 334
 335 (define-derived-mode elopher-mode special-mode "elopher"
 336   "Major mode for elopher, an elisp gopher client.")
 337
 338
 339 ;;; elopher.el ends here