;;; sbbs.el --- SchemeBBS client -*- lexical-binding: t -*-
;; Version: 0.1.0
;; Keywords: comm
;; Package-Requires: ((emacs "24.4"))
;; This file is NOT part of Emacs.
;;
;; This file is in the public domain, to the extent possible under law,
;; published under the CC0 1.0 Universal license.
;;
;; For a full copy of the CC0 license see
;; https://creativecommons.org/publicdomain/zero/1.0/legalcode
;;; Commentary:
;;
;; sbbs is a SchemeBBS (https://textboard.org) client in Emacs.
;;
;; Start browsing a board by invoking M-x `sbbs'.
;; Open a board
;;; Code:
(require 'tabulated-list)
(require 'button)
(require 'url)
(require 'hl-line)
(require 'rx)
;; CUSTOMIZABLE DATA
(defgroup sbbs nil
"SchemeBBS client."
:group 'applications
:prefix "sbbs-")
(defcustom sbbs-boards
'(("textboard.org" ("sol" "prog") nil))
"List of SchemeBBS sites and boards."
:type '(repeat (list (string :tag "Board Domain")
(repeat (string :tag "Board Name"))
(boolean :tag "Use TLS?"))))
(defcustom sbbs-jump-to-link t
"Jump to first link after narrowing posts."
:type 'boolean)
(defcustom sbbs-recenter-to-top t
"Move point to top of frame when moving through posts."
:type 'boolean)
(defface sbbs--spoiler-face
'((((background light)) :background "black" :foreground "black")
(((background dark)) :background "white" :foreground "white"))
"Face for spoiler text in threads.")
(defface sbbs--code-face
'((((background light)) :background "gray89")
(((background dark)) :background "gray11"))
"Face for code blocks in threads.")
;; VARIABLES
(defvar-local sbbs--board nil
"Buffer local reference to current board.
See `sbbs-make-board'.")
(defvar-local sbbs--thread-id nil
"Buffer local reference to current thread id.
Used in thread and reply buffers.")
(defvar-local sbbs--limit-stack nil
"Stack of last limit specs.")
;; BOARD OBJECT AND FUNCTIONS
(defun sbbs-make-board (domain name &optional tls)
"Create board object, using DOMAIN, NAME and TLS flag."
(vector domain name tls))
(defsubst sbbs--board-domain (board)
"Get domain part of a BOARD object."
(aref board 0))
(defsubst sbbs--board-name (board)
"Get board name part of a BOARD object."
(aref board 1))
(defsubst sbbs--board-protocol (board)
"Determine protocol to be used for BOARD object."
(if (aref board 2) "https" "http"))
(defun sbbs--board-url (&optional path api-p board)
"Generate URL for BOARD to access PATH.
If API-P is non-nil, prefix path with \"sexp\"."
(let ((board (or board sbbs--board)))
(format "%s://%s/%s%s/%s"
(sbbs--board-protocol board)
(sbbs--board-domain board)
(if api-p "sexp/" "")
(sbbs--board-name board)
(or path ""))))
(defun sbbs--list-boards ()
(let (boards)
(dolist (ent sbbs-boards)
(dolist (board (cadr ent))
(push (sbbs-make-board (car ent) board (caddr ent))
boards)))
boards))
(defun sbbs-read-board ()
"Read in a board using `completing-read'.
The list will be generated using `sbbs-boards', and the result
will be a board object generated with `sbbs-make-board'."
(let (boards)
(dolist (b (sbbs--list-boards))
(push (cons (format "/%s/ (%s)"
(sbbs--board-name b)
(sbbs--board-domain b))
b)
boards))
(cdr (assoc (completing-read "Board: " boards nil t) boards))))
;; UTILITY FUNCTIONS
(defun sbbs--reload-thread (&optional _ignore-auto _noconfirm)
"Function to reload an opened thread."
(when sbbs--thread-id (sbbs-view-open sbbs--thread-id)))
(defun sbbs--reload-board ()
"Function to regenerate thread index.
Called by `tabulated-list-mode' hooks."
(when sbbs--board (sbbs-browse sbbs--board t)))
(defun sbbs--parse-number-range (desc limit)
"Generate list of numbers, as specified by DESC.
To avoid memory overflows, limit number of entries to LIMIT."
(save-match-data
(apply #'nconc
(mapcar
(lambda (range)
(cond ((string-match "\\`\\([[:digit:]]+\\)-\\([[:digit:]]+\\)\\'" range)
(number-sequence (string-to-number (match-string 1 range))
(min limit (string-to-number (match-string 2 range)))))
((string-match "\\`\\([[:digit:]]+\\)\\'" range)
(list (string-to-number (match-string 1 range))))
(t (error "invalid range"))))
(split-string desc ",")))))
(defun sbbs--read-jump-to (nr)
"Set point to first character of post with number NR."
(let ((up (point-min)) (down (point-max)) current)
(while (progn
(goto-char (+ up (/ (- down up) 2)))
(setq current (get-text-property (point) 'sbbs-thread-nr))
(/= nr current))
(cond ((< nr current) (setq down (point)))
((> nr current) (setq up (point))))))
(unless (and (eq 'highlight (get-text-property (point) 'face))
(looking-at-p "\\`#[[:digit:]]+"))
;; in case we are on the first character of a post, we shouldn't
;; jump back, since that would mean setting to point to NR-1.
(sbbs-read-previous 1)))
;; UI GENERATOR
(defconst sbbs--link-regexp
(rx-to-string
`(: bos
(or (: "/" (group-n 2 (+ alnum))
"/" (group-n 3 (+ digit))
"/" (group-n 4 (: (+ digit) (? "-" (+ digit)))
(* "," (+ digit) (? "-" (+ digit)))))
(: "http" (? "s") "://"
(group-n 1 (or ,@(mapcar #'sbbs--board-domain
(sbbs--list-boards))))
"/" (group-n 2 (+ alnum))
"/" (group-n 3 (+ digit))
(? "#t" (backref 3)
"p" (group-n 4 (+ digit)))))
eos))
"Regular expression to destruct internal links.")
(defun sbbs--limit-to-range (spec &optional no-push-p)
"Hide all posts in the current thread, that aren't in SPEC.
Unless NO-PUSH-P is non-nil, SPEC will be pushed onto
`sbbs--limit-stack', as to be popped off again by
`sbbs-show-pop'."
(let ((inhibit-read-only t))
(remove-list-of-text-properties
(point-min) (point-max) '(invisible intangible))
(when spec
(unless no-push-p
(push (cons (point) spec) sbbs--limit-stack))
(save-excursion
(let ((last (point-max)))
(goto-char last)
(while (not (bobp))
(sbbs-read-previous 1)
(unless (memq (get-text-property (point) 'sbbs-thread-nr)
spec)
(add-text-properties
(point) last '(invisible t intangible t)))
(setq last (point)))))
(goto-char (point-min))
(when spec
(sbbs--read-jump-to (car spec)))
(let ((point (point)))
(when sbbs-jump-to-link
(forward-button 1)
(when (invisible-p (point))
(goto-char point)))))))
(defun sbbs--insert-link (text link)
"Insert link to LINK as TEXT into buffer.
If LINK is a (board, thread or site) local link, modify opening
behaviour accordingly."
(save-match-data
(let ((match (string-match sbbs--link-regexp link))
range id)
(when match
(when (match-string 4 link)
(setq range (sbbs--parse-number-range (match-string 4 link) 300)))
(setq id (string-to-number (match-string 3 link))))
(let* ((board sbbs--board)
(domain (sbbs--board-domain board))
(name (sbbs--board-name board))
(other (sbbs-make-board (match-string 1 link)
(match-string 2 link)
(string-match-p "\\`https://" link)))
(func (lambda (&optional _)
(cond ((not match) (browse-url link))
;; other supported board
((or (and (sbbs--board-domain other)
(not (string= (sbbs--board-domain other)
domain)))
(not (string= name (sbbs--board-name other))))
(let ((sbbs--board other))
(sbbs-view-open id range)))
;; other thread
((/= id sbbs--thread-id)
(let ((sbbs--board board))
(sbbs-view-open id range)))
;; this thread
(range (sbbs--limit-to-range range))))))
(insert-button text 'action func)))))
(defun sbbs--insert-sxml-par (sxml)
"Insert paragraph contents SXML at point."
(dolist (it sxml)
(cond ((stringp it)
(insert (propertize it 'face 'variable-pitch)))
((eq (car it) 'br)
(newline))
((eq (car it) 'b)
(insert (propertize (cadr it) 'face '(bold variable-pitch))))
((eq (car it) 'i)
(insert (propertize (cadr it) 'face '(italic variable-pitch))))
((eq (car it) 'code)
(insert (propertize (cadr it) 'face 'fixed-pitch)))
((eq (car it) 'del)
(insert (propertize (cadr it) 'face 'sbbs--spoiler-face)))
((eq (car it) 'a)
(let* ((text (caddr it))
(link (plist-get (cadadr it) 'href)))
(sbbs--insert-link text link)))
(t (insert (prin1-to-string it)))))
(insert ?\n))
(defun sbbs--insert-sxml (sxml)
"Insert top level SXML into buffer at point."
(dolist (par sxml)
(cond ((eq (car par) 'p)
(sbbs--insert-sxml-par (cdr par)))
((eq (car par) 'blockquote)
(let ((start (point))
(comment-start "> "))
(sbbs--insert-sxml-par (cdadr par))
(comment-region start (point))
(add-face-text-property start (point)
'font-lock-comment-face)))
((eq (car par) 'pre)
(let ((start (point)))
(insert (propertize (cadadr par)
'face 'fixed-pitch))
(newline)
(add-face-text-property start (point) 'sbbs--code-face)))
(t (error "Unknown top-level element")))
(insert ?\n)))
(defun sbbs--thread-insert-post (post)
"Prepare and Insert header and contents of POST at point."
(let ((start (point)))
(insert (format "#%d\t%s" (car post)
(cdr (assq 'date (cdr post)))))
(when (cdr (assq 'vip (cdr post)))
(insert " (VIP)"))
(newline 2)
(add-text-properties start (1- (point)) '(face highlight))
(set-text-properties (1- (point)) (point) nil)
(sbbs--insert-sxml (cdr (assq 'content (cdr post))))
(add-text-properties start (point) (list 'sbbs-thread-nr (car post)))))
;; URL.EL CALLBACKS
(defun sbbs--board-loader (status buf)
"Callback function for `url-retrieve' when loading board.
Load results into buffer BUF. STATUS is used to check for
errors."
(when (buffer-live-p buf)
(when (plist-get status :error)
(error "Error while loading: %s"
(cdr (plist-get status :error))))
(decode-coding-region (point-min) (point-max) 'utf-8)
(forward-paragraph)
(let ((list (read (current-buffer))))
(kill-buffer)
(with-current-buffer buf
(let (ent)
(dolist (thread list)
(push (list (car thread)
(vector (substring (cdr (assq 'date (cdr thread)))
0 16)
(number-to-string
(cdr (assq 'messages (cdr thread))))
(propertize
(cdr (assq 'headline (cdr thread)))
'face 'variable-pitch)))
ent))
(setq-local tabulated-list-entries ent)
(tabulated-list-print t t)
(hl-line-highlight))))))
(defun sbbs--thread-loader (status id buf range)
"Callback function for `url-retrieve' when loading thread.
The attribute ID determines what thread from board BOARD to
load. STATUS is used to check for errors."
(when (buffer-live-p buf)
(when (plist-get status :error)
(error "Error while loading: %s"
(cdr (plist-get status :error))))
(prog-mode)
(forward-paragraph)
(decode-coding-region (point) (point-max) 'utf-8)
(save-excursion
(save-match-data
(while (search-forward "#f" nil t)
(unless (cadddr (syntax-ppss))
(replace-match "nil")))))
(save-excursion
(save-match-data
(while (search-forward "#f" nil t)
(unless (cadddr (syntax-ppss))
(replace-match "t")))))
(let ((thread (read (current-buffer))))
(kill-buffer)
(with-current-buffer buf
(let ((buffer-read-only nil))
(erase-buffer)
(setq header-line-format
(format "Thread %d: %s" id
(cdr (assq 'headline thread))))
(dolist (post (cadr (assq 'posts thread)))
(sbbs--thread-insert-post post))
(delete-blank-lines)
(when range
(sbbs--limit-to-range range))
(goto-char (point-min)))))))
;; INTERACTIVE FUNCTIONS
(defun sbbs-show-all ()
"Show all hidden posts."
(interactive)
(sbbs-show-pop -1))
(defun sbbs-show-pop (&optional n)
"Show all hidden posts.
A prefix argument N, repeats this N times. If negative or zero,
pop all the way up."
(interactive "P")
(let ((n (or n 1)))
(dotimes (_ (if (> n 0) n (length sbbs--limit-stack)))
(let ((point (car (pop sbbs--limit-stack))))
(sbbs--limit-to-range (cdar sbbs--limit-stack) t)
(when point (goto-char point))))))
(defun sbbs-view-open (id &optional range)
"Open thread ID in new buffer."
(interactive (list (tabulated-list-get-id)))
(let ((url (sbbs--board-url (format "/%d" id) t))
(headline (or (and (not (tabulated-list-get-entry))
header-line-format)
(substring-no-properties
(aref (tabulated-list-get-entry) 2))))
(board sbbs--board)
(buf (get-buffer-create
(format "*reading /%s/%d*"
(sbbs--board-name sbbs--board)
id))))
(with-current-buffer buf
(sbbs-read-mode)
(when headline
(setq header-line-format (format "Thread %d: %s" id headline)))
(setq sbbs--board board
sbbs--thread-id id))
(url-retrieve url #'sbbs--thread-loader (list id buf range))
(switch-to-buffer buf)))
(defun sbbs-view-compose ()
"Create buffer to start a new thread."
(interactive)
(let ((board sbbs--board))
(with-current-buffer (generate-new-buffer "*new thread*")
(sbbs-compose-mode)
(setq sbbs--board board)
(switch-to-buffer (current-buffer)))))
(defun sbbs-read-reply (arg)
"Create buffer to start a reply in current thread.
With \\[universal-argument] interactivly, or a non-nil ARG, add a
reply reference to thread at point."
(interactive "P")
(let ((id sbbs--thread-id)
(nr (get-text-property (point) 'sbbs-thread-nr))
(board sbbs--board))
(with-current-buffer (generate-new-buffer "*new response*")
(sbbs-compose-mode)
(when (and arg (= (car arg) 4))
(insert (format ">>%d" nr))
(newline))
(setq header-line-format (format "Responding to Thread %d" id)
sbbs--thread-id id
sbbs--board board)
(switch-to-buffer (current-buffer)))))
(defun sbbs-compose-create ()
"Upload response or thread to board."
(interactive)
(let ((board sbbs--board)
(url-request-method "POST")
(url-request-extra-headers
'(("Content-Type" . "application/x-www-form-urlencoded")))
(url-request-data
(url-build-query-string
`((epistula ,(buffer-string))
(ornamentum "") (name "") (message "")
(frontpage ,(if sbbs--thread-id "true" "false"))
. ,(and (not sbbs--thread-id)
`((titulus ,(read-string "Headline: ")))))))
(url (if sbbs--thread-id
(sbbs--board-url (format "%d/post" sbbs--thread-id))
(sbbs--board-url "/post"))))
(url-retrieve url (lambda (status buf)
(if (plist-get status :error)
(message "Error while submitting: %s"
(cdr (plist-get status :error)))
(kill-buffer buf)
(let ((sbbs--board board))
(sbbs--reload-thread))))
(list (current-buffer)))))
(defun sbbs-read-next (arg)
"Move point ARG posts forward."
(interactive "p")
(dotimes (_ arg)
(end-of-line)
(catch 'found
(while (search-forward-regexp "^#" nil t)
(when (and (eq 'highlight (get-text-property (point) 'face))
(not (get-text-property (point) 'invisible)))
(throw 'found t)))))
(beginning-of-line)
(when sbbs-recenter-to-top
(set-window-start (selected-window) (point))))
(defun sbbs-read-previous (arg)
"Move point ARG posts backwards."
(interactive "p")
(dotimes (_ arg)
(catch 'found
(while (search-backward-regexp "^#" nil t)
(when (and (eq 'highlight (get-text-property (point) 'face))
(not (get-text-property (point) 'invisible)))
(throw 'found t)))))
(beginning-of-line)
(when sbbs-recenter-to-top
(set-window-start (selected-window) (point))))
;;;###autoload
(defun sbbs-browse (board reload)
"Open thread overview for BOARD."
(interactive (list (sbbs-read-board) nil))
(let* ((name (format "*browsing /%s/*" (sbbs--board-name board)))
(url (sbbs--board-url "list" t board)))
(if (and (get-buffer name) (not reload))
(progn (switch-to-buffer name)
(sbbs--reload-board))
(with-current-buffer (get-buffer-create name)
(sbbs-view-mode)
(setq sbbs--board board)
(url-retrieve url #'sbbs--board-loader
(list (current-buffer)))
(switch-to-buffer (current-buffer))))))
;;;###autoload
(defalias 'sbbs #'sbbs-browse)
;; MAJOR MODES
(defvar sbbs-view-mode-map
(let ((map (make-sparse-keymap)))
(define-key map (kbd "RET") #'sbbs-view-open)
(define-key map (kbd "c") #'sbbs-view-compose)
map))
(define-derived-mode sbbs-view-mode tabulated-list-mode "SchemeBBS Browse"
"Major mode for browsing a SchemeBBS board."
(buffer-disable-undo)
(setq tabulated-list-format [("Date" 16 t)
("#" 3 t :right-align t)
("Headline" 0 nil)]
tabulated-list-sort-key '("Date" . t))
(add-hook 'tabulated-list-revert-hook
#'sbbs--reload-board nil t)
(tabulated-list-init-header)
(hl-line-mode t))
(defvar sbbs-read-mode-map
(let ((map (make-sparse-keymap)))
(suppress-keymap map)
(define-key map (kbd "<tab>") #'forward-button)
(define-key map (kbd "<backtab>") #'backward-button)
(define-key map (kbd "r") #'sbbs-read-reply)
(define-key map (kbd "n") #'sbbs-read-next)
(define-key map (kbd "p") #'sbbs-read-previous)
(define-key map (kbd "a") #'sbbs-show-pop)
(define-key map (kbd "A") #'sbbs-show-all)
map))
(define-derived-mode sbbs-read-mode special-mode "SchemeBBS Read"
"Major mode for reading a thread."
(buffer-disable-undo)
(visual-line-mode t)
(setq-local revert-buffer-function #'sbbs--reload-thread))
(defvar sbbs-compose-mode-map
(let ((map (make-sparse-keymap)))
(define-key map (kbd "C-c C-c") #'sbbs-compose-create)
map))
(define-derived-mode sbbs-compose-mode text-mode "SchemeBBS Compose"
"Major mode for composing replies and starting new threads."
(setq-local fill-column most-positive-fixnum)
(message "Press C-c C-c to send"))
(provide 'sbbs)
;;; sbbs.el ends here