Migrating to stack-based history.
[elpher.git] / elpher.el
index a17c403..95c3057 100644 (file)
--- a/elpher.el
+++ b/elpher.el
@@ -4,9 +4,9 @@
 
 ;; Author: Tim Vaughan <tgvaughan@gmail.com>
 ;; Created: 11 April 2019
-;; Version: 2.3.6
+;; Version: 2.4.4
 ;; Keywords: comm gopher
-;; Homepage: https://github.com/tgvaughan/elpher
+;; Homepage: http://thelambdalab.xyz/elpher
 ;; Package-Requires: ((emacs "26"))
 
 ;; This file is not part of GNU Emacs.
@@ -37,7 +37,7 @@
 ;; - direct visualisation of image files,
 ;; - a simple bookmark management system,
 ;; - connections using TLS encryption,
-;; - basic support for the fledgling Gemini protocol.
+;; - support for the fledgling Gemini protocol.
 
 ;; To launch Elpher, simply use 'M-x elpher'.  This will open a start
 ;; page containing information on key bindings and suggested starting
@@ -46,7 +46,8 @@
 ;; Full instructions can be found in the Elpher info manual.
 
 ;; Elpher is under active development.  Any suggestions for
-;; improvements are welcome!
+;; improvements are welcome, and can be made on the official
+;; project page, gopher://thelambdalab.xyz/1/projects/elpher/.
 
 ;;; Code:
 
@@ -66,7 +67,7 @@
 ;;; Global constants
 ;;
 
-(defconst elpher-version "2.3.6"
+(defconst elpher-version "2.4.4"
   "Current version of elpher.")
 
 (defconst elpher-margin-width 6
@@ -307,36 +308,8 @@ If no address is defined, returns 0.  (This is for compatibility with the URL li
       ""
     (substring (url-filename address) 2)))
 
-;; Node
+;; Page
 
-(defun elpher-make-node (display-string address &optional parent)
-  "Create a node in the page hierarchy.
-
-DISPLAY-STRING records the display string used for the page.
-
-ADDRESS specifies the address object of the page.
-
-The optional PARENT specifies the parent node in the hierarchy.
-This is set every time the node is visited, so while it forms
-an important part of the node data there is no need to set it
-initially."
-  (list display-string address parent))
-
-(defun elpher-node-display-string (node)
-  "Retrieve the display string of NODE."
-  (elt node 0))
-
-(defun elpher-node-address (node)
-  "Retrieve the ADDRESS object of NODE."
-  (elt node 1))
-
-(defun elpher-node-parent (node)
-  "Retrieve the parent node of NODE."
-  (elt node 2))
-
-(defun elpher-set-node-parent (node parent)
-  "Set the parent node of NODE to be PARENT."
-  (setcar (cdr (cdr node)) parent))
 
 ;; Cache
 
@@ -359,24 +332,31 @@ initially."
   "Set the cursor position cache for ADDRESS to POS."
   (puthash address pos elpher-pos-cache))
 
-;; Node graph traversal
+;; Page
+
+(defun elpher-make-page (address display-string)
+  (list address display-string))
+
+(defun elpher-page-address (page)
+  (elt page 0))
 
-(defvar elpher-current-node nil)
+(defun elpher-page-display-string (page)
+  (elt page 1))
 
-(defun elpher-visit-node (node &optional renderer preserve-parent)
-  "Visit NODE using its own renderer or RENDERER, if non-nil.
-Additionally, set the parent of NODE to `elpher-current-node',
-unless PRESERVE-PARENT is non-nil."
+
+(defvar elpher-current-page nil)
+(defvar elpher-history nil)
+
+(defun elpher-visit-page (page &optional renderer no-history)
+  "Visit PAGE using its own renderer or RENDERER, if non-nil.
+Additionally, push PAGE onto the stack of previously-visited pages,
+unless NO-HISTORY is non-nil."
   (elpher-save-pos)
   (elpher-process-cleanup)
-  (unless preserve-parent
-    (if (and (elpher-node-parent elpher-current-node)
-             (equal (elpher-node-address elpher-current-node)
-                    (elpher-node-address node)))
-        (elpher-set-node-parent node (elpher-node-parent elpher-current-node))
-      (elpher-set-node-parent node elpher-current-node)))
-  (setq elpher-current-node node)
-  (let* ((address (elpher-node-address node))
+  (unless no-history
+    (push page elpher-history))
+  (setq elpher-current-page page)
+  (let* ((address (elpher-page-address node))
          (type (elpher-address-type address))
          (type-record (cdr (assoc type elpher-type-map))))
     (if type-record
@@ -384,7 +364,7 @@ unless PRESERVE-PARENT is non-nil."
                  (if renderer
                      renderer
                    (cadr type-record)))
-      (elpher-visit-parent-node)
+      (elpher-visit-previous-page)
       (pcase type
         (`(gopher ,type-char)
          (error "Unsupported gopher selector type '%c' for '%s'"
@@ -393,13 +373,13 @@ unless PRESERVE-PARENT is non-nil."
          (error "Unsupported address type '%S' for '%s'"
                 other (elpher-address-to-url address)))))))
 
-(defun elpher-visit-parent-node ()
+(defun elpher-visit-previous-page ()
   "Visit the parent of the current node."
-  (let ((parent-node (elpher-node-parent elpher-current-node)))
-    (when parent-node
-      (elpher-visit-node parent-node nil t))))
+  (let ((previous-page (pop elpher-history)))
+    (when previous-page
+      (elpher-visit-node previous-page nil t))))
       
-(defun elpher-reload-current-node ()
+(defun elpher-reload-current-page ()
   "Reload the current node, discarding any existing cached content."
   (elpher-cache-content (elpher-node-address elpher-current-node) nil)
   (elpher-visit-node elpher-current-node))
@@ -482,6 +462,9 @@ ERROR can be either an error object or a string."
 ;;; Gopher selector retrieval
 ;;
 
+(defvar elpher-network-timer nil
+  "Timer used for network connections.")
+
 (defun elpher-process-cleanup ()
   "Immediately shut down any extant elpher process and timers."
   (let ((p (get-process "elpher-process")))
@@ -492,8 +475,6 @@ ERROR can be either an error object or a string."
 (defvar elpher-use-tls nil
   "If non-nil, use TLS to communicate with gopher servers.")
 
-(defvar elpher-network-timer)
-
 (defun elpher-get-selector (address renderer &optional force-ipv4)
   "Retrieve selector specified by ADDRESS, then render it using RENDERER.
 If FORCE-IPV4 is non-nil, explicitly look up and use IPv4 address corresponding
@@ -503,64 +484,66 @@ to ADDRESS."
         (when (not elpher-use-tls)
           (setq elpher-use-tls t)
           (message "Engaging TLS gopher mode."))
-      (elpher-network-error "Cannot retrieve TLS gopher selector: GnuTLS not available")))
+      (error "Cannot retrieve TLS gopher selector: GnuTLS not available")))
   (unless (< (elpher-address-port address) 65536)
-    (elpher-network-error "Cannot retrieve gopher selector: port number > 65536"))
-  (let* ((kill-buffer-query-functions nil)
-         (port (elpher-address-port address))
-         (host (elpher-address-host address))
-         (selector-string "")
-         (proc (open-network-stream "elpher-process"
-                                    nil
-                                    (if force-ipv4 (dns-query host) host)
-                                    (if (> port 0) port 70)
-                                    :type (if elpher-use-tls 'tls 'plain)
-                                    :nowait t))
-         (timer (run-at-time elpher-connection-timeout
-                             nil
-                             (lambda ()
-                               (pcase (process-status proc)
-                                 ('failed
-                                  (if (and (not (equal (elpher-address-protocol address)
-                                                       "gophers"))
-                                           elpher-use-tls
-                                           (or elpher-auto-disengage-TLS
-                                               (yes-or-no-p "Could not establish encrypted connection.  Disable TLS mode?")))
-                                      (progn
-                                        (message "Disabling TLS mode.")
-                                        (setq elpher-use-tls nil)
-                                        (elpher-get-selector address renderer))
-                                    (elpher-network-error "Could not establish encrypted connection.")))
-                                 ('connect
-                                  (elpher-process-cleanup)
-                                  (unless force-ipv4
-                                    (message "Connection timed out. Retrying with IPv4 address.")
-                                    (elpher-get-selector address renderer t))))))))
-    (setq elpher-network-timer timer)
-    (set-process-coding-system proc 'binary)
-    (set-process-filter proc
-                        (lambda (_proc string)
-                          (cancel-timer timer)
-                          (setq selector-string
-                                (concat selector-string string))))
-    (set-process-sentinel proc
-                          (lambda (_proc event)
-                            (condition-case the-error
-                                (cond
-                                 ((string-prefix-p "deleted" event))
-                                 ((string-prefix-p "open" event)
-                                  (let ((inhibit-eol-conversion t))
-                                    (process-send-string
-                                     proc
-                                     (concat (elpher-gopher-address-selector address)
-                                             "\r\n"))))
-                                 (t
-                                  (cancel-timer timer)
-                                  (funcall renderer selector-string)
-                                  (elpher-restore-pos)))
-                              (error
-                               (elpher-network-error address
-                                                     (error-message-string the-error))))))))
+    (error "Cannot retrieve gopher selector: port number > 65536"))
+  (condition-case nil
+      (let* ((kill-buffer-query-functions nil)
+             (port (elpher-address-port address))
+             (host (elpher-address-host address))
+             (selector-string "")
+             (proc (open-network-stream "elpher-process"
+                                        nil
+                                        (if force-ipv4 (dns-query host) host)
+                                        (if (> port 0) port 70)
+                                        :type (if elpher-use-tls 'tls 'plain)
+                                        :nowait t))
+             (timer (run-at-time elpher-connection-timeout
+                                 nil
+                                 (lambda ()
+                                   (pcase (process-status proc)
+                                     ('failed
+                                      (if (and (not (equal (elpher-address-protocol address)
+                                                           "gophers"))
+                                               elpher-use-tls
+                                               (or elpher-auto-disengage-TLS
+                                                   (yes-or-no-p "Could not establish encrypted connection.  Disable TLS mode?")))
+                                          (progn
+                                            (message "Disabling TLS mode.")
+                                            (setq elpher-use-tls nil)
+                                            (elpher-get-selector address renderer))
+                                        (elpher-network-error address "Could not establish encrypted connection")))
+                                     ('connect
+                                      (elpher-process-cleanup)
+                                      (unless force-ipv4
+                                        (message "Connection timed out. Retrying with IPv4 address.")
+                                        (elpher-get-selector address renderer t))))))))
+        (setq elpher-network-timer timer)
+        (set-process-coding-system proc 'binary)
+        (set-process-filter proc
+                            (lambda (_proc string)
+                              (cancel-timer timer)
+                              (setq selector-string
+                                    (concat selector-string string))))
+        (set-process-sentinel proc
+                              (lambda (_proc event)
+                                (condition-case the-error
+                                    (cond
+                                     ((string-prefix-p "deleted" event))
+                                     ((string-prefix-p "open" event)
+                                      (let ((inhibit-eol-conversion t))
+                                        (process-send-string
+                                         proc
+                                         (concat (elpher-gopher-address-selector address)
+                                                 "\r\n"))))
+                                     (t
+                                      (cancel-timer timer)
+                                      (funcall renderer selector-string)
+                                      (elpher-restore-pos)))
+                                  (error
+                                   (elpher-network-error address the-error))))))
+    (error
+     (error "Error initiating connection to server"))))
 
 (defun elpher-get-gopher-node (renderer)
   "Getter function for gopher nodes.
@@ -574,7 +557,10 @@ once they are retrieved from the gopher server."
          (elpher-restore-pos))
       (elpher-with-clean-buffer
        (insert "LOADING... (use 'u' to cancel)"))
-      (elpher-get-selector address renderer))))
+      (condition-case the-error
+          (elpher-get-selector address renderer)
+        (error
+         (elpher-network-error address the-error))))))
 
 ;; Index rendering
 
@@ -665,7 +651,7 @@ If ADDRESS is not supplied or nil the record is rendered as an
 ;; Text rendering
 
 (defconst elpher-url-regex
-  "\\([a-zA-Z]+\\)://\\([a-zA-Z0-9.\-]*[a-zA-Z0-9\-]\\|\[[a-zA-Z0-9:]+\]\\)\\(:[0-9]+\\)?\\(/\\([0-9a-zA-Z\-_~?/@|:.]*[0-9a-zA-Z\-_~?/@|]\\)?\\)?"
+  "\\([a-zA-Z]+\\)://\\([a-zA-Z0-9.\-]*[a-zA-Z0-9\-]\\|\[[a-zA-Z0-9:]+\]\\)\\(:[0-9]+\\)?\\(/\\([0-9a-zA-Z\-_~?/@|:.%#]*[0-9a-zA-Z\-_~?/@|#]\\)?\\)?"
   "Regexp used to locate and buttniofy URLs in text files loaded by elpher.")
 
 (defun elpher-buttonify-urls (string)
@@ -797,9 +783,8 @@ to ADDRESS."
       (error "Cannot establish gemini connection: GnuTLS not available")
     (unless (< (elpher-address-port address) 65536)
       (error "Cannot establish gemini connection: port number > 65536"))
-    (condition-case the-error
+    (condition-case nil
         (let* ((kill-buffer-query-functions nil)
-               (network-security-level 'medium)
                (port (elpher-address-port address))
                (host (elpher-address-host address))
                (response-string "")
@@ -840,19 +825,19 @@ to ADDRESS."
                                         (message "Connection failed. Retrying with IPv4.")
                                         (cancel-timer timer)
                                         (elpher-get-gemini-response address renderer t))
-                                       (t 
+                                       (t
                                         (funcall #'elpher-process-gemini-response
                                                  response-string
                                                  renderer)
                                         (elpher-restore-pos)))
-                                    (error the-error
+                                    (error
                                            (elpher-network-error address the-error))))))
       (error
        (error "Error initiating connection to server")))))
 
 (defun elpher-parse-gemini-response (response)
-  "Parse the RESPONSE string and return a list of components
-The list is of the form (code meta body). A response of nil implies
+  "Parse the RESPONSE string and return a list of components.
+The list is of the form (code meta body).  A response of nil implies
 that the response was malformed."
   (let ((header-end-idx (string-match "\r\n" response)))
     (if header-end-idx
@@ -987,7 +972,9 @@ For instance, the filename /a/b/../c/./d will reduce to /a/c/d"
   (let ((address (url-generic-parse-url url)))
     (unless (and (url-type address) (not (url-fullness address))) ;avoid mangling mailto: urls
       (setf (url-fullness address) t)
-      (unless (url-host address) ;if there is an explicit host, filenames are absolute
+      (if (url-host address) ;if there is an explicit host, filenames are absolute
+          (if (string-empty-p (url-filename address))
+              (setf (url-filename address) "/")) ;ensure empty filename is marked as absolute
         (setf (url-host address) (url-host (elpher-node-address elpher-current-node)))
         (unless (string-prefix-p "/" (url-filename address)) ;deal with relative links
           (setf (url-filename address)
@@ -1099,6 +1086,13 @@ For instance, the filename /a/b/../c/./d will reduce to /a/c/d"
    (insert "\n"
            "This page contains your bookmarked sites (also visit with B):\n")
    (elpher-insert-index-record "Your Bookmarks" 'bookmarks)
+   (insert "\n"
+           "For Elpher release news or to leave feedback, visit:\n")
+   (elpher-insert-index-record "The Elpher Project Page"
+                               (elpher-make-gopher-address ?1
+                                                           "/projects/elpher/"
+                                                           "thelambdalab.xyz"
+                                                           70))
    (insert "\n"
            "** Refer to the ")
    (let ((help-string "RET,mouse-1: Open Elpher info manual (if available)"))
@@ -1112,7 +1106,7 @@ For instance, the filename /a/b/../c/./d will reduce to /a/c/d"
    (insert " for the full documentation. **\n")
    (insert (propertize
             (concat "  (This should be available if you have installed Elpher using\n"
-                    "   MELPA. Otherwise you will have to install the manual yourself.)")
+                    "   MELPA. Otherwise you will have to install the manual yourself.)\n")
             'face 'shadow))
    (elpher-restore-pos)))
 
@@ -1132,12 +1126,23 @@ For instance, the filename /a/b/../c/./d will reduce to /a/c/d"
                  (address (elpher-address-from-url (elpher-bookmark-url bookmark))))
              (elpher-insert-index-record display-string address)))
        (insert "No bookmarks found.\n")))
-   (insert "\n-----------------------\n\n"
+   (insert "\n-----------------------\n"
+           "\n"
            "- u: return to previous page\n"
            "- x: delete selected bookmark\n"
-           "- a: rename selected bookmark\n\n"
-           "Bookmarks are stored in the file "
-           (locate-user-emacs-file "elpher-bookmarks"))
+           "- a: rename selected bookmark\n"
+           "\n"
+           "Bookmarks are stored in the file ")
+   (let ((filename (locate-user-emacs-file "elpher-bookmarks"))
+         (help-string "RET,mouse-1: Open bookmarks file in new buffer for editing."))
+     (insert-text-button filename
+                         'face 'link
+                         'action (lambda (_)
+                                   (interactive)
+                                   (find-file filename))
+                         'follow-link t
+                         'help-echo help-string))
+   (insert "\n")
    (elpher-restore-pos)))