+;;; Global constants
+;;
+
+(defconst elopher-version "1.0.0"
+ "Current version of elopher.")
+
+(defconst elopher-margin-width 6
+ "Width of left-hand margin used when rendering indicies.")
+
+(defconst elopher-start-index
+ (string-join
+ (list "i\tfake\tfake\t1"
+ "i--------------------------------------------\tfake\tfake\t1"
+ "i Elopher Gopher Client \tfake\tfake\t1"
+ (format "i version %s\tfake\tfake\t1" elopher-version)
+ "i--------------------------------------------\tfake\tfake\t1"
+ "i\tfake\tfake\t1"
+ "iBasic usage:\tfake\tfake\t1"
+ "i - tab/shift-tab: next/prev directory entry\tfake\tfake\t1"
+ "i - RET/mouse-1: open directory entry\tfake\tfake\t1"
+ "i - u: return to parent directory entry\tfake\tfake\t1"
+ "i - g: go to a particular site\tfake\tfake\t1"
+ "i - r: reload current page\tfake\tfake\t1"
+ "i\tfake\tfake\t1"
+ "iPlaces to start exploring Gopherspace:\tfake\tfake\t1"
+ "1Floodgap Systems Gopher Server\t\tgopher.floodgap.com\t70"
+ "1Super-Dimensional Fortress\t\tsdf.org\t70"
+ "i\tfake\tfake\t1"
+ "iTest entries:\tfake\tfake\t1"
+ "pXKCD comic image\t/fun/xkcd/comics/2130/2137/text_entry.png\tgopher.floodgap.com\t70"
+ "1Test server\t\tlocalhost\t70"
+ ".")
+ "\r\n"))
+
+
+;;; Customization group
+;;
+
+(defgroup elopher nil
+ "A simple gopher client."
+ :group 'applications)
+
+(defcustom elopher-index-face '(foreground-color . "cyan")
+ "Face used for index records.")
+(defcustom elopher-text-face '(foreground-color . "white")
+ "Face used for text records.")
+(defcustom elopher-info-face '(foreground-color . "gray")
+ "Face used for info records.")
+(defcustom elopher-image-face '(foreground-color . "green")
+ "Face used for image records.")
+(defcustom elopher-search-face '(foreground-color . "orange")
+ "Face used for image records.")
+(defcustom elopher-unknown-face '(foreground-color . "red")
+ "Face used for unknown record types.")
+
+;;; Model
+;;
+
+;; Address
+
+(defun elopher-make-address (selector host port)
+ (list selector host port))
+
+(defun elopher-address-selector (address)
+ (car address))
+
+(defun elopher-address-host (address)
+ (cadr address))
+
+(defun elopher-address-port (address)
+ (caddr address))
+
+;; Node
+
+(defun elopher-make-node (parent address getter &optional content pos)
+ (list parent address getter content pos))
+
+(defun elopher-node-parent (node)
+ (elt node 0))
+
+(defun elopher-node-address (node)
+ (elt node 1))
+
+(defun elopher-node-getter (node)
+ (elt node 2))
+
+(defun elopher-node-content (node)
+ (elt node 3))
+
+(defun elopher-node-pos (node)
+ (elt node 4))
+
+(defun elopher-set-node-content (node content)
+ (setcar (nthcdr 3 node) content))
+
+(defun elopher-set-node-pos (node pos)
+ (setcar (nthcdr 4 node) pos))
+
+(defun elopher-save-pos ()
+ (when elopher-current-node
+ (elopher-set-node-pos elopher-current-node (point))))
+
+(defun elopher-restore-pos ()
+ (let ((pos (elopher-node-pos elopher-current-node)))
+ (if pos
+ (goto-char pos)
+ (goto-char (point-min)))))
+
+;; Node graph traversal
+
+(defvar elopher-current-node)
+
+(defun elopher-visit-node (node)
+ (elopher-save-pos)
+ (elopher-prepare-buffer)
+ (setq elopher-current-node node)
+ (funcall (elopher-node-getter node)))
+
+(defun elopher-visit-parent-node ()
+ (let ((parent-node (elopher-node-parent elopher-current-node)))
+ (when parent-node
+ (elopher-visit-node parent-node))))
+
+(defun elopher-reload-current-node ()
+ (elopher-set-node-content elopher-current-node nil)
+ (elopher-visit-node elopher-current-node))
+
+
+;;; Buffer preparation
+;;
+
+(defun elopher-prepare-buffer ()
+ (switch-to-buffer "*elopher*")
+ (elopher-mode)
+ (let ((inhibit-read-only t))
+ (erase-buffer)))
+
+
+;;; Index rendering
+;;
+
+(defun elopher-insert-index (string)
+ "Inserts the index corresponding to STRING into the current buffer."
+ (dolist (line (split-string string "\r\n"))
+ (unless (string-empty-p line)
+ (elopher-insert-index-record line))))
+
+(defun elopher-insert-margin (&optional type-name)
+ "Insert index margin, optionally containing the TYPE-NAME, into the current buffer."
+ (if type-name
+ (progn
+ (insert (format (concat "%" (number-to-string (- elopher-margin-width 1)) "s")
+ (concat
+ (propertize "[" 'face '(foreground-color . "blue"))
+ (propertize type-name 'face '(foreground-color . "white"))
+ (propertize "]" 'face '(foreground-color . "blue")))))
+ (insert " "))
+ (insert (make-string elopher-margin-width ?\s))))
+
+(defun elopher-insert-index-record (line)
+ "Inserts the index record corresponding to LINE into the current buffer."
+ (let* ((type (elt line 0))
+ (fields (split-string (substring line 1) "\t"))
+ (display-string (elt fields 0))
+ (address (elopher-make-address (elt fields 1) (elt fields 2) (elt fields 3)))
+ (help-string (format "mouse-1, RET: open %s on %s port %s"
+ (elopher-address-selector address)
+ (elopher-address-host address)
+ (elopher-address-port address))))
+ (pcase type
+ (?i (elopher-insert-margin)
+ (insert (propertize display-string
+ 'face elopher-info-face)))
+ (?0 (elopher-insert-margin "T")
+ (insert-text-button display-string
+ 'face elopher-text-face
+ 'elopher-node (elopher-make-node elopher-current-node
+ address
+ #'elopher-get-text-node)
+ 'action #'elopher-click-link
+ 'follow-link t
+ 'help-echo help-string))
+ (?1 (elopher-insert-margin "/")
+ (insert-text-button display-string
+ 'face elopher-index-face
+ 'elopher-node (elopher-make-node elopher-current-node
+ address
+ #'elopher-get-index-node)
+ 'action #'elopher-click-link
+ 'follow-link t
+ 'help-echo help-string))
+ ((or ?g ?p ?I) (elopher-insert-margin "im")
+ (insert-text-button display-string
+ 'face elopher-image-face
+ 'elopher-node (elopher-make-node elopher-current-node
+ address
+ #'elopher-get-image-node)
+ 'action #'elopher-click-link
+ 'follow-link t
+ 'help-echo help-string))
+ (?7 (elopher-insert-margin "?")
+ (insert-text-button display-string
+ 'face elopher-search-face
+ 'elopher-node (elopher-make-node elopher-current-node
+ address
+ #'elopher-get-search-node)
+ 'action #'elopher-click-link
+ 'follow-link t
+ 'help-echo help-string))
+ (?.) ; Occurs at end of index, can safely ignore.
+ (tp (elopher-insert-margin (concat (char-to-string tp) "?"))
+ (insert (propertize display-string
+ 'face elopher-unknown-face))))
+ (insert "\n")))
+
+
+;;; Selector retrieval (all kinds)
+;;
+
+(defvar elopher-selector-string)
+
+(defun elopher-get-selector (address after &optional binary)
+ "Retrieve selector specified by ADDRESS and store it in the
+string elopher-selector-string, then execute AFTER as the
+sentinal function."
+ (setq elopher-selector-string "")
+ (let ((p (get-process "elopher-process")))
+ (if p (delete-process p)))