;;; w3m-session.el --- Functions to operate session of w3m -*- coding: iso-2022-7bit; -*-

;; Copyright (C) 2001-2003, 2005-2013, 2017, 2018
;; TSUCHIYA Masatoshi <tsuchiya@namazu.org>

;; Author: Hideyuki SHIRAI <shirai@meadowy.org>
;; Keywords: w3m, WWW, hypermedia
;; Homepage: http://emacs-w3m.namazu.org/

;; This program 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 2, or (at your option)
;; any later version.

;; This program 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 this program; see the file COPYING.  If not, write to
;; the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; w3m-session.el is an add-on program of emacs-w3m to save, load,
;; delete, and rename sessions or their selected tabs.

;; You need not load or restore an entire session.  You can examine and
;; manage the contents (individual tabs) of any session, including
;; deleting, renaming, or loading them one at a time.

;; A session is any collection of buffers (tabs) open at any given
;; time.  Be aware, however, that unfortunately much of the code and
;; documentation uses the terms session and buffer interchangeably.
;; There is also a term 'session-group' which is identical to a
;; session which has more than buffer.  Yes, this does need to be
;; refactored!

;; Session management does its best to automatically keep track of the
;; current collection of w3m buffers so that should a catastrophic
;; crash occur, the entire session can be restored.  Upon restarting
;; emacs-w3m after a crash, the user will be prompted whether to
;; recover the prior session.  Additionally, the user may at any time
;; manually save the current session, or restore the tabs of a prior
;; session.  Note that restoring a prior session is not destructive; it
;; only adds new tabs into the current session for each tab of the
;; saved session.

;; Session information is also saved when one quits emacs-w3m using
;; the `w3m-quit' command, bound by default to `Q'.

;; The session information for all sessions are stored as a single
;; elisp object, by default in file ~/.w3m/.session.  Tab content is
;; NOT stored.  What is stored for each tab is the url, title, cursor
;; position, and tab history.  Even so, this can eventually become a
;; monstrously large data structure, and probably needlessly, if one
;; accumulates large history records for each tab.

;;;; Typical usage and tutorial

;; One enters session management by evaluating `w3m-session-select'
;; (M-s).  Typically, there will be at least one session automatically
;; present, either labeled as a crash recovery session or an
;; automatically saved one.  Next to each session name will be a number
;; in brackets representing the number of tab (buffers) in the
;; session.  There will also be column entries for the session
;; timestamp, and summary URL entries.  One exits session management
;; with either `q' or `C-g'.

;; From any emacs-w3m buffer one may save a session by evaluating
;; `w3m-session-save' (M-S).

;; From within session management, one can rename (`r') or delete
;; (`d') any session.  Selecting a session using the RET key will load
;; ALL of that session's tabs.  You can examine the details of a
;; session by pressing `M-s' (the same key binding you used to enter
;; the session management).  At this point, you can rename, delete, or
;; load any individual tab.  Note that the first entry on the list
;; gives you a second chance to load ALL the tabs.  Quitting returns
;; you to the session list.

;; All changes are saved to disk immediately.


;;; Code:
(eval-when-compile (require 'cl))
(require 'w3m-util)

(eval-when-compile
  (defvar w3m-async-exec)
  (defvar w3m-async-exec-with-many-urls)
  (defvar w3m-current-title)
  (defvar w3m-current-url)
  (defvar w3m-history)
  (defvar w3m-history-flat)
  (defvar w3m-language)
  (defvar w3m-mode-map)
  (defvar w3m-profile-directory)
  (autoload 'w3m-goto-url-new-session "w3m")
  (autoload 'w3m-history-tree "w3m-hist")
  (autoload 'w3m-load-list "w3m")
  (autoload 'w3m-save-list "w3m"))

(defvar w3m-session-group-open nil
  "Which session-group is open.

If a session-group is currently open, i.e., when displaying a
list of buffers for an individual session, this should be set
to the session (session-group) number.

There is a legacy terminology problem that needs to be addressed
here.  The documentation and symbol names currently confuse
'sessions', 'buffers`, and 'session-groups'.  A 'session-group'
is identical to a 'session' that has more than one 'buffer'.")

(defcustom w3m-session-file
  (expand-file-name ".sessions" w3m-profile-directory)
  "*File name to keep sessions."
  :group 'w3m
  :type 'file)

(defcustom w3m-session-autosave t
  "*Non-nil means save automatically when w3m quit."
  :group 'w3m
  :type 'boolean)

(defcustom w3m-session-deleted-save t
  "*Non-nil means save deleted sessions."
  :group 'w3m
  :type 'boolean)

(defcustom w3m-session-crash-recovery t
  "If non-nil, recover session by auto-saved one when emacs-w3m crashes."
  :group 'w3m
  :type 'boolean)

(defcustom w3m-session-time-format
  (if (and (equal "Japanese" w3m-language)
	   (not (featurep 'xemacs)))
      "%Y年%m月%d日(%a) %H:%M"
    "%Y-%m-%d (%a) %H:%M")
  "*Format of saved time."
  :group 'w3m
  :type 'string)

(defcustom w3m-session-automatic-title
  (if (equal "Japanese" w3m-language)
      "自動保存"
    "Automatic saved sessions")
  "*String of title to save session automatically."
  :group 'w3m
  :type 'string)

(defcustom w3m-session-deleted-title
  (if (equal "Japanese" w3m-language)
      "削除セッション"
    "Removed sessions")
  "*String of title to save session when buffer delete."
  :group 'w3m
  :type 'string)

(defcustom w3m-session-crash-recovery-title
  (if (equal "Japanese" w3m-language)
      "クラッシュ回復"
    "Crash recovery sessions")
  "*String of title to save session to use for crash recovering."
  :group 'w3m
  :type 'string)

(defcustom w3m-session-deleted-keep-number 5
  "*Number to keep sessions when buffers delete."
  :group 'w3m
  :type 'integer)

(defcustom w3m-session-automatic-keep-number 5
  "*Number to keep sessions automatically."
  :group 'w3m
  :type 'integer)

(defcustom w3m-session-unknown-title "<Unknown Title>"
  "*String of title to use when title is not specified."
  :group 'w3m
  :type 'string)

(defcustom w3m-session-load-last-sessions nil
  "*Whether to re-load the most recent session when emacs-w3m
starts."
  :group 'w3m
  :type
  '(radio
    (const :format "Re-load the last session automatically." t)
    (const :format "Ask whether to re-load the last session." ask)
    (const :format "Never re-load the last session automatically." nil)))

(defcustom w3m-session-load-crashed-sessions 'ask
  "*Whether to re-load a crashed session when emacs-w3m starts.
This is used when emacs-w3m determines that the most recent session crashed."
  :group 'w3m
  :type
  '(radio
    (const :format "RelLoad the crashed session automatically." t)
    (const :format "Ask whether to re-load the crashed session." ask)
    (const :format "Never re-load the crashed session automatically." nil)))

(defface w3m-session-select
  `((((class color) (background light) (type nil))
     (:foreground "black"))
    (((class color) (background dark) (type nil))
     (:foreground "cyan"))
    (((class color) (background light))
     (:foreground "dark blue"))
    (((class color) (background dark))
     (:foreground "white"))
    (t nil))
  "Face of w3m-session."
  :group 'w3m)
;; backward-compatibility alias
(put 'w3m-session-select-face 'face-alias 'w3m-session-select)

(defface w3m-session-selected
  `((((class color) (background light) (type nil))
     (:foreground "blue" :bold t :underline t))
    (((class color) (background dark) (type nil))
     (:foreground "cyan" :bold t :underline t))
    (((class color) (background light))
     (:foreground "dark blue" :bold t :underline t))
    (((class color) (background dark))
     (:foreground "white" :bold t :underline t))
    (t (:bold t :underline t)))
  "Face of selected w3m-session."
  :group 'w3m)
;; backward-compatibility alias
(put 'w3m-session-selected-face 'face-alias 'w3m-session-selected)

(defun w3m-session-history-to-save ()
  "Return a copy of `w3m-history-flat' without current page data."
  (let ((pos (cadar w3m-history)))
    (apply
     'append
     (mapcar (lambda (x)
	       (unless (equal (nth 2 x) pos)
		 (list x)))
	     (copy-sequence (w3m-history-slimmed-history-flat))))))

;; format of session file.
;; '((sessiontitle1 time1 ((url11 pos11 hflat11 urltitle11)
;;                         (url12 pos12 hflat12 urltitle12) ...) current1)
;;   ...

(defmacro w3m-session-ignore-errors (&rest forms)
  "Run FORMS.  Remove `w3m-session-file' and quit if any error happens."
  `(condition-case err
       (progn ,@forms)
     (error
      (if (and (file-exists-p w3m-session-file)
	       (yes-or-no-p (format
			     "An error was found in \"%s\"; may we remove it? "
			     ,(if (featurep 'xemacs)
				  '(abbreviate-file-name w3m-session-file t)
				'(abbreviate-file-name w3m-session-file)))))
	  (progn
	    (delete-file w3m-session-file)
	    (run-at-time 0.1 nil #'message
			 "\"%s\" has been removed; try again."
			 (abbreviate-file-name w3m-session-file))
	    (keyboard-quit))
	(signal (car err) (cdr err))))))

;;;###autoload
(defun w3m-session-save ()
  "Save the current session (all currently open emacs-w3m buffers).

The user will be prompted for a name for the saved session.  The
saved session information will include, for each currently open
emacs-w3m buffer: the current url and page title, and the
buffer's url history."
  (interactive)
  (w3m-session-ignore-errors
   (let ((sessions (w3m-load-list w3m-session-file))
	 (bufs (w3m-list-buffers))
	 (prompt "New session title: ")
	 (cnum 0)
	 (i 0)
	 title titles urls len buf cbuf)
     (mapc (lambda (x)
	     (setq titles (cons (cons (car x) (car x)) titles)))
	   sessions)
     (setq title (or w3m-current-title
		     (with-current-buffer (car bufs)
		       w3m-current-title)))
     (setq titles (cons (cons title title) titles))
     (catch 'loop
       (while t
	 ;; A devious way to emulate INITIAL-INPUT that is deprecated.
	 (let ((minibuffer-setup-hook (lambda nil (insert title))))
	   (setq title (completing-read prompt titles nil nil nil nil title)))
	 (if (or (string= title "")
		 (and (assoc title sessions)
		      (not (y-or-n-p (format "\"%s\" exists.  Overwrite? "
					     title)))))
	     (setq prompt "New session title: ")
	   (throw 'loop t))))
     (setq cbuf (current-buffer))
     (save-current-buffer
       (while (setq buf (car bufs))
	 (setq bufs (cdr bufs))
	 (set-buffer buf)
	 (when w3m-current-url
	   (when (eq cbuf (current-buffer))
	     (setq cnum i))
	   (setq i (1+ i))
	   (setq urls (cons (list w3m-current-url
				  (copy-sequence (caar w3m-history))
				  (w3m-session-history-to-save)
				  w3m-current-title)
			    urls)))))
     (if (not urls)
	 (message "%s: no buffers saved...done" title)
       (setq len (length urls))
       (setq urls (nreverse urls))
       (when (assoc title sessions)
	 (setq sessions (delq (assoc title sessions) sessions)))
       (setq sessions (cons (list title (current-time) urls cnum) sessions))
       (w3m-save-list w3m-session-file sessions)
       (message "%s: %d buffer%s saved...done" title len (if (= len 1) "" "s"))
       (when (and (setq buf (get-buffer " *w3m-session select*"))
		  (get-buffer-window buf 'visible))
	 (save-selected-window (w3m-session-select)))))))

(defun w3m-session-automatic-save ()
  "Save list of displayed session automatically."
  (when w3m-session-autosave
    (w3m-session-ignore-errors
     (let ((sessions (w3m-load-list w3m-session-file))
	   (bufs (w3m-list-buffers))
	   (title (concat w3m-session-automatic-title "-1"))
	   (titleregex (concat "^"
			       (regexp-quote w3m-session-automatic-title)
			       "-[0-9]+$"))
	   (cnum 0)
	   (i 0)
	   urls buf cbuf session
	   tmp tmptitle tmptime tmpurls)
       (when bufs
	 (setq cbuf (current-buffer))
	 (save-current-buffer
	   (while (setq buf (car bufs))
	     (setq bufs (cdr bufs))
	     (set-buffer buf)
	     (when w3m-current-url
	       (when (eq cbuf (current-buffer))
		 (setq cnum i))
	       (setq i (1+ i))
	       (setq urls (cons (list w3m-current-url
				      (copy-sequence (caar w3m-history))
				      (w3m-session-history-to-save)
				      w3m-current-title)
				urls)))))
	 (when urls
	   (setq i 2)
	   (while (setq session (car sessions))
	     (setq sessions (cdr sessions))
	     (if (string-match titleregex (nth 0 session))
		 (when (<= i w3m-session-automatic-keep-number)
		   (setq tmptitle (format (concat w3m-session-automatic-title
						  "-%d") i))
		   (setq tmptime (nth 1 session))
		   (setq tmpurls (nth 2 session))
		   (setq tmp (cons (list tmptitle tmptime tmpurls nil) tmp))
		   (setq i (1+ i)))
	       (setq tmp (cons session tmp))))
	   (setq sessions (nreverse tmp))
	   (setq urls (nreverse urls))
	   (setq sessions (cons (list title (current-time) urls cnum)
				sessions))
	   (w3m-save-list w3m-session-file sessions)))))))

(defun w3m-session-deleted-save (buffers)
  "Save list of deleted session."
  (when w3m-session-deleted-save
    (w3m-session-ignore-errors
     (let ((sessions (w3m-load-list w3m-session-file))
	   (title (concat w3m-session-deleted-title "-1"))
	   (titleregex (concat "^"
			       (regexp-quote w3m-session-deleted-title)
			       "-[0-9]+$"))
	   (bufs (copy-sequence buffers))
	   (i 2)
	   urls buf session
	   tmp tmptitle tmptime tmpurls)
       (when bufs
	 (setq bufs (sort bufs 'w3m-buffer-name-lessp))
	 (save-current-buffer
	   (while (setq buf (car bufs))
	     (setq bufs (cdr bufs))
	     (set-buffer buf)
	     (when w3m-current-url
	       (setq urls (cons (list w3m-current-url
				      (copy-sequence (caar w3m-history))
				      (w3m-session-history-to-save)
				      w3m-current-title)
				urls)))))
	 (when urls
	   (while (setq session (car sessions))
	     (setq sessions (cdr sessions))
	     (if (string-match titleregex (nth 0 session))
		 (when (<= i w3m-session-deleted-keep-number)
		   (setq tmptitle (format (concat w3m-session-deleted-title
						  "-%d") i))
		   (setq tmptime (nth 1 session))
		   (setq tmpurls (nth 2 session))
		   (setq tmp (cons (list tmptitle tmptime tmpurls nil) tmp))
		   (setq i (1+ i)))
	       (setq tmp (cons session tmp))))
	   (setq sessions (nreverse tmp))
	   (setq urls (nreverse urls))
	   (setq sessions (cons (list title (current-time) urls nil) sessions))
	   (w3m-save-list w3m-session-file sessions)))))))

(defun w3m-session-crash-recovery-save ()
  "Save list of displayed session."
  (when w3m-session-crash-recovery
    (w3m-session-ignore-errors
     (let ((sessions (w3m-load-list w3m-session-file))
	   (bufs (w3m-list-buffers))
	   (title w3m-session-crash-recovery-title)
	   urls buf tmp)
       (when bufs
	 (save-current-buffer
	   (while (setq buf (car bufs))
	     (setq bufs (cdr bufs))
	     (set-buffer buf)
	     (when w3m-current-url
	       (setq urls (cons (list w3m-current-url
				      (copy-sequence (caar w3m-history))
				      (w3m-session-history-to-save)
				      w3m-current-title)
				urls)))))
	 (when urls
	   (setq urls (nreverse urls))
	   (setq tmp (assoc title sessions))
	   (when tmp (setq sessions (delq tmp sessions)))
	   (setq sessions (cons (list title (current-time) urls nil) sessions))
	   (w3m-save-list w3m-session-file sessions)))))))

;;;###autoload
(defun w3m-session-crash-recovery-remove ()
  "Remove crash recovery session set."
  (when w3m-session-crash-recovery
    (w3m-session-ignore-errors
     (let* ((sessions (w3m-load-list w3m-session-file))
	    (item (assoc w3m-session-crash-recovery-title sessions)))
       (when item
	 (setq sessions (delq item sessions))
	 (w3m-save-list w3m-session-file sessions))))))

(defvar w3m-session-select-mode-map nil)
(unless w3m-session-select-mode-map
  (let ((map (make-keymap)))
    (suppress-keymap map)
    (define-key map "q" 'w3m-session-select-quit)
    (define-key map "Q" 'w3m-session-select-quit)
    (define-key map "\C-g" 'w3m-session-select-quit)
    (define-key map "\C-m" 'w3m-session-select-select)
    (define-key map "\M-s" 'w3m-session-select-open-session-group)
    (define-key map "d" 'w3m-session-select-delete)
    (define-key map "D" 'w3m-session-select-delete)
    (define-key map "s" 'w3m-session-select-save)
    (define-key map "S" 'w3m-session-select-save)
    (define-key map "r" 'w3m-session-select-rename)
    (define-key map "R" 'w3m-session-select-rename)
    (define-key map "n" 'w3m-session-select-next)
    (define-key map "j" 'w3m-session-select-next)
    (define-key map "\C-n" 'w3m-session-select-next)
    (define-key map [down] 'w3m-session-select-next)
    (define-key map "p" 'w3m-session-select-previous)
    (define-key map "k" 'w3m-session-select-previous)
    (define-key map "\C-p" 'w3m-session-select-previous)
    (define-key map [up] 'w3m-session-select-previous)
    (setq w3m-session-select-mode-map map)))

;;; Local variables
(defvar w3m-session-select-sessions nil)
(make-variable-buffer-local 'w3m-session-select-sessions)

(defun w3m-session-select-mode (&optional sessions)
  "Major mode for selecting emacs-w3m session.

\\<w3m-session-select-mode-map>
\\[w3m-session-select-select]	Select the session.
\\[w3m-session-select-open-session-group]	Open the session group.
\\[w3m-session-select-delete]	Delete the session.
\\[w3m-session-select-rename]	Rename the session.
\\[w3m-session-select-save]	Save the session.
\\[w3m-session-select-next]	Move the point to the next session.
\\[w3m-session-select-previous]	Move the point to the previous session.
\\[w3m-session-select-quit]	Exit selecting session.
"
  (w3m-session-ignore-errors
   (let ((sessions (or sessions
		       (w3m-load-list w3m-session-file))))
     (buffer-disable-undo)
     (setq mode-name "w3m session"
	   truncate-lines t
	   buffer-read-only nil
	   major-mode 'w3m-session-select-mode
	   w3m-session-select-sessions sessions
	   buffer-read-only t)
     (setq w3m-session-group-open nil)
     (use-local-map w3m-session-select-mode-map)
     (w3m-session-select-list-all-sessions))))

(defun w3m-session-select-list-all-sessions ()
  "List all saved sessions."
  (let ((sessions w3m-session-select-sessions)
	(num 0)
	(max 0)
	(inhibit-read-only t)
	title titles time times url urls wid pos)
    (if (not sessions)
	(progn
	  (message "No saved session")
	  (w3m-session-select-quit))
      (mapc (lambda (x)
	      (setq title (format "%s[%d]" (nth 0 x) (length (nth 2 x))))
	      (setq wid (string-width title))
	      (when (> wid max)
		(setq max wid))
	      (setq titles (cons title titles))
	      (setq times (cons (format-time-string w3m-session-time-format
						    (nth 1 x))
				times))
	      (setq urls (cons (mapconcat (lambda (url)
					    (if (stringp url)
						url
					      (car url)))
					  (nth 2 x) ", ")
			       urls)))
	    sessions)
      (setq titles (nreverse titles))
      (setq times (nreverse times))
      (setq urls (nreverse urls))
      (setq max (+ max 2))
      (erase-buffer)
      (insert "Select session:\n\n")
      (while (and (setq title (car titles))
		  (setq time (car times))
		  (setq url (car urls)))
	(setq titles (cdr titles))
	(setq times (cdr times))
	(setq urls (cdr urls))
	(setq pos (point))
	(insert title)
	(add-text-properties pos (point)
			     `(face w3m-session-select
				    w3m-session-number ,num))
	(setq num (1+ num))
	(insert (make-string (- max (string-width title)) ?\ ))
	(insert time "  " url "\n"))
      (goto-char (point-min))
      (goto-char (next-single-property-change
		  (point) 'w3m-session-number))
      (put-text-property (point)
			 (next-single-property-change
			  (point) 'w3m-session-number)
			 'face 'w3m-session-selected)
      (set-buffer-modified-p nil)
      (setq buffer-read-only t))))

(defun w3m-session-select-list-session-group (arg)
  "List all buffers (i.e., tabs) within a session.

The list can be acted upon similarly to a session list, i.e.,
entries can be individually deleted, renamed, or opened as a new
buffer in the current session."
  (let ((session (nth 2 (nth arg w3m-session-select-sessions)))
	(num 0)
	(max 0)
	(inhibit-read-only t)
	title url wid
	titles urls pos)
    (when session
      (mapc (lambda (x)
	      (setq title
		    (format "%s" (or (nth 3 x) w3m-session-unknown-title)))
	      (setq wid (string-width title))
	      (when (> wid max)
		(setq max wid))
	      (setq titles (cons title titles))
	      (setq urls (cons (nth 0 x)
			       urls)))
	    session)
      (setq titles (nreverse titles))
      (setq urls (nreverse urls))
      (setq max (+ max 2))
      (erase-buffer)
      (insert "Select session:\n\n")
      (setq pos (point))
      (insert "Open all sessions")
      (add-text-properties pos (point)
			   `(face w3m-session-selected
				  w3m-session-number ,arg))
      (insert "\n")
      (while (and (setq title (car titles))
		  (setq url (car urls)))
	(setq titles (cdr titles))
	(setq urls (cdr urls))
	(setq pos (point))
	(insert title)
	(add-text-properties pos (point)
			     `(face w3m-session-select
				    w3m-session-number ,(cons arg num)))
	(setq num (1+ num))
	(insert (make-string (- max (string-width title)) ?\ ))
	(insert url "\n"))
      (goto-char (point-min))
      (goto-char (next-single-property-change
		  (point) 'w3m-session-number)))
    (set-buffer-modified-p nil)
    (setq buffer-read-only t)))

(defun w3m-session-select-next (&optional arg)
  "Move the point to the next session."
  (interactive "p")
  (unless arg (setq arg 1))
  (let ((positive (< 0 arg))
	(inhibit-read-only t))
    (beginning-of-line)
    (put-text-property (point)
		       (next-single-property-change
			(point) 'w3m-session-number)
		       'face 'w3m-session-select)
    (while (not (zerop arg))
      (forward-line (if positive 1 -1))
      (unless (get-text-property (point) 'w3m-session-number)
	(if positive
	    (goto-char (next-single-property-change
			(point-min) 'w3m-session-number))
	  (goto-char (previous-single-property-change
		      (point-max) 'w3m-session-number))))
      (setq arg (if positive
		    (1- arg)
		  (1+ arg))))
    (beginning-of-line)
    (put-text-property (point)
		       (next-single-property-change
			(point) 'w3m-session-number)
		       'face 'w3m-session-selected)
    (set-buffer-modified-p nil)))

(defun w3m-session-select-previous (&optional arg)
  "the point to the previous session."
  (interactive "p")
  (w3m-session-select-next (- arg)))

(defun w3m-session-select-quit ()
  "Exit from w3m session select mode."
  (interactive)
  (if w3m-session-group-open
      (let ((num w3m-session-group-open))
	(setq w3m-session-group-open nil)
	(w3m-session-select-list-all-sessions))
    (let ((buffer (current-buffer)))
      (or (one-window-p) (delete-window))
      (kill-buffer buffer))))

(defun w3m-session-select-select ()
  "Select the session."
  (interactive)
  (beginning-of-line)
  (let* ((num (get-text-property
	       (point) 'w3m-session-number))
	 (item (if (consp num)
		   (nth (cdr num)
			(caddr (nth (car num)
				    w3m-session-select-sessions)))
		 (nth num w3m-session-select-sessions)))
	 (session (if (consp num)
		      (list (or (cadddr item) w3m-session-unknown-title)
			    nil
			    (list item)
			    nil)
		    item)))
    (w3m-session-select-quit)
    (w3m-session-goto-session session)))

(defun w3m-session-select-open-session-group (&optional arg)
  "Open the session group."
  (interactive)
  (beginning-of-line)
  (let ((num (or arg (get-text-property (point) 'w3m-session-number)))
	wheight)
    (if (consp num)
	(message "This is not a session group.")
      (setq w3m-session-group-open num)
      (setq wheight
	    (max (+ (length (caddr (nth num w3m-session-select-sessions))) 6)
		 window-min-height))
      (condition-case nil
	  (enlarge-window (- wheight (window-height)))
	(error nil))
      (w3m-session-select-list-session-group num))))

(defun w3m-session-select-save ()
  "Save the session."
  (interactive)
  (when (y-or-n-p "Save this session? ")
    (w3m-session-select-quit)
    (w3m-session-save)
    (w3m-session-select)))

(defun w3m-session-select-rename ()
  "Rename this session."
  (interactive)
  (beginning-of-line)
  (let ((num (get-text-property
	      (point) 'w3m-session-number))
	(sessions w3m-session-select-sessions))
    (w3m-session-rename sessions num)
    (if (not w3m-session-group-open)
	(w3m-session-select num)
      (w3m-session-select-open-session-group w3m-session-group-open))))

(defun w3m-session-select-delete ()
  "Delete an entry (either a session or a buffer)."
  (interactive)
  (when (y-or-n-p "Delete this entry? ")
    (beginning-of-line)
    (let ((num (get-text-property
		(point) 'w3m-session-number))
	  (sessions w3m-session-select-sessions))
      (w3m-session-delete sessions num)
      ;;(w3m-session-select)
      ;;(forward-line (min num (- (line-number-at-pos (point-max)) 4))))))
      (if (not w3m-session-group-open)
	  (w3m-session-select (min num (1- (length sessions))))
	(w3m-session-select-open-session-group w3m-session-group-open)
	(forward-line (min (cdr num)
			   (- (line-number-at-pos (point-max)) 4)))))))

;;;###autoload
(defun w3m-session-select (&optional n)
  "Select session from session list.
Position point at N-th session if N is given."
  (interactive)
  (w3m-session-ignore-errors
   (let ((sessions (w3m-load-list w3m-session-file))
	 (showbuf " *w3m-session select*")
	 window)
     (if sessions
	 (let ((wheight (max (+ (length sessions) 5) window-min-height))
	       last-window)
	   (setq last-window (previous-window
			      (w3m-static-if (fboundp 'frame-highest-window)
				  (frame-highest-window)
				(frame-first-window))))
	   (while (minibuffer-window-active-p last-window)
	     (setq last-window (previous-window last-window)))
	   (while (and
		   (not (one-window-p))
		   (or (< (window-width last-window)
			  (frame-width))
		       (< (window-height last-window)
			  (+ wheight window-min-height))))
	     (setq window last-window)
	     (setq last-window (previous-window window))
	     (delete-window window))
	   (select-window (split-window last-window))
	   (condition-case nil
	       (shrink-window (- (window-height) wheight))
	     (error nil))
	   (switch-to-buffer (w3m-get-buffer-create showbuf))
	   (w3m-session-select-mode sessions)
	   (when n (w3m-session-select-next n)))
       (when (setq showbuf (get-buffer showbuf))
	 (when (setq window (prog1 (get-buffer-window showbuf t)
			      (kill-buffer showbuf)))
	   (save-selected-window
	     (select-window window)
	     (or (one-window-p t t) (delete-window window)))))
       (message "No saved session")))))

(defun w3m-session-goto-session (session)
  "Goto URLs."
  (let ((title (nth 0 session))
	(urls (nth 2 session))
	(cnum (nth 3 session))
	(i 0)
	(w3m-async-exec (and w3m-async-exec-with-many-urls w3m-async-exec))
	url cbuf buf pos history)
    (message "Session goto(%s)..." title)
    (while (setq url (car urls))
      (setq urls (cdr urls))
      (unless (stringp url)
	(setq pos     (nth 1 url)
	      history (nth 2 url)
	      url     (nth 0 url)))
      (w3m-goto-url-new-session url)
      (setq buf (car (nreverse (w3m-list-buffers))))
      (when (or (and (numberp cnum) (= cnum i))
		(and (not cnum) (= i 0)))
	(setq cbuf buf))
      (when (and buf pos history)
	(set-buffer buf)
	(setq w3m-history-flat history)
	(w3m-history-tree pos))
      (setq i (1+ i)))
    (when (and cbuf (eq major-mode 'w3m-mode))
      (set-window-buffer (selected-window) cbuf))
    (message "Session goto(%s)...done" title)))

(defun w3m-session-rename (sessions num)
  "Rename an entry (either a session or a buffer).

Rename session number NUM, when NUM is an integer.  NUM may also
be a cons cell, for which the car is a session number and the cdr
is a buffer entry (i.e., a tab) within that session.  In that case
rename the buffer entry."
  (let* ((default-prompt "Enter new session title (C-g to abort): ")
	 (prompt default-prompt)
	 overwrite
	 title
	 (group (if (consp num) (nth 2 (nth (car num) sessions)) nil))
	 (tmp  (if group (nth (cdr num) group) (nth num sessions)))
	 (otitle (if (consp num) (nth 2 (cdr tmp)) (car tmp))))
    (while (not title)
      ;; A devious way to emulate INITIAL-INPUT that is deprecated.
      (let ((minibuffer-setup-hook (lambda nil (insert otitle))))
	(setq title (read-from-minibuffer prompt nil nil nil nil otitle)))
      (cond
       ((string= title "")
	(setq title nil
	      prompt default-prompt))
       ((string= title otitle)
	(setq prompt (concat title
			     " is same as original title (C-g to abort): ")
	      title nil))
       ((and (not group) (assoc title sessions))
	(if (not (y-or-n-p (format "\"%s\" exists.  Overwrite? " title)))
	    (setq prompt default-prompt
		  title nil)
	  (setq sessions (delq (assoc title sessions) sessions))
	  (setq num (seq-position sessions (assoc otitle sessions)))))
       ((and group (member title (mapcar (lambda (x) (car (last x))) group)))
	;; handle *buffer* rename (overwrite existing)
	;; within a session ("session-group")
	(setq prompt "\
Not yet supported.  Manually delete the other entry, or try again. "
	      title nil))))
    ;; in this case, wrapper must decrement its copy of num
    ;; BB_2018-02-15: I don't understand that comment
    (cond
     (group ;; handle *buffer* rename within a session ("session-group")
      (setf (nth 2 (cdr tmp)) title)
      (setf (nth (cdr num) group) tmp)
      (setf (nth 2 (nth (car num) sessions)) group))
     ;; BB_2018-02-15: The good news is that this seems to be working;
     ;; the bad news is that an examination of the .sessions file
     ;; reveals a format difference, in that the original buffer name
     ;; was encoded with text properties, like so:
     ;;     #("w3m_home_page.html" 0 1 (idx 0))
     ;; and the replacement is just a string.  The text property may
     ;; just be cruft for the purpose of this file, but I'm not sure.
     (t
      (setcar tmp title)
      (setcar (nthcdr num sessions) tmp)))
    (w3m-save-list w3m-session-file sessions)))

(defun w3m-session-delete (sessions num)
  "Delete an entry (either a session or a buffer).

Delete session number NUM, when NUM is an integer.  NUM may also
be a cons cell, for which the car is a session number and the cdr
is a buffer entry (i.e., a tab) within that session.  In that case
delete the buffer entry."
  (if (consp num)
      (let* ((item (nth 2 (nth (car num) sessions)))
	     (tmp (delq (nth (cdr num) item) item)))
	(setf (nth 2 (nth (car num) sessions)) tmp))
    (setq sessions (delq (nth num sessions) sessions)))
  (if sessions
      (w3m-save-list w3m-session-file sessions)
    (let ((file (expand-file-name w3m-session-file)))
      (when (and (file-exists-p file) (file-writable-p file))
	(delete-file file)))))

(defvar w3m-session-menu-items
  `([,(w3m-make-menu-item "新しいセッションを作る..."
			  "Create New Session...")
     w3m-goto-new-session-url t]
    [,(w3m-make-menu-item "このセッションを複製する" "Copy This Session")
     w3m-copy-buffer w3m-current-url]
    "----" ;; separator
    [,(w3m-make-menu-item "前のセッションに移動する"
			  "Move Previous Session")
     w3m-previous-buffer
     (> (safe-length (w3m-list-buffers)) 1)]
    [,(w3m-make-menu-item "次のセッションに移動する" "Move Next Session")
     w3m-next-buffer
     (> (safe-length (w3m-list-buffers)) 1)]
    "----" ;; separator
    [,(w3m-make-menu-item "このセッションを閉じる" "Close This Session")
     w3m-delete-buffer
     (> (safe-length (w3m-list-buffers)) 1)]
    [,(w3m-make-menu-item "他のセッションを閉じる" "Close Other Sessions")
     w3m-delete-other-buffers
     (> (safe-length (w3m-list-buffers)) 1)]
    [,(w3m-make-menu-item "現在のセッションを保存する"
			  "Save Displayed Sessions")
     w3m-session-save t]
    [,(w3m-make-menu-item "セッションを選択する" "Select Sessions")
     w3m-session-select t])
  "*List of the session menu items.")

;;;###autoload
(defun w3m-setup-session-menu ()
  "Setup w3m session items in menubar."
  (w3m-static-if (featurep 'xemacs)
      (unless (car (find-menu-item current-menubar '("Session")))
	(easy-menu-define w3m-session-menu w3m-mode-map
	  "" '("Session" ["(empty)" ignore nil]))
	(easy-menu-add w3m-session-menu)
	(add-hook 'activate-menubar-hook 'w3m-session-menubar-update))
    (unless (lookup-key w3m-mode-map [menu-bar Session])
      (easy-menu-define w3m-session-menu w3m-mode-map "" '("Session"))
      (easy-menu-add w3m-session-menu)
      (add-hook 'menu-bar-update-hook 'w3m-session-menubar-update))))

(defvar w3m-session-menu-items-pre nil)
(defvar w3m-session-menu-items-time nil)

(defun w3m-session-menubar-update ()
  "Update w3m session menubar."
  (when (and (eq major-mode 'w3m-mode)
	     (w3m-static-if (featurep 'xemacs)
		 (frame-property (selected-frame) 'menubar-visible-p)
	       menu-bar-mode))
    (let ((items w3m-session-menu-items)
	  (pages (w3m-session-make-menu-items)))
      (easy-menu-define w3m-session-menu w3m-mode-map
	"The menu kepmap for the emacs-w3m session."
	(cons "Session" (if pages
			    (append items '("----") pages)
			  items)))
      (w3m-static-when (featurep 'xemacs)
	(when (setq items (car (find-menu-item current-menubar '("Session"))))
	  (setcdr items (cdr w3m-session-menu))
	  (set-buffer-menubar current-menubar))))))

(defun w3m-session-file-modtime ()
  "Return the modification time of the session file `w3m-session-file'.
The value is a list of two time values `(HIGH LOW)' if the session
file exists, otherwise nil."
  (nth 5 (file-attributes w3m-session-file)))

(defvar w3m-session-make-item-xmas
  (and (equal "Japanese" w3m-language) (featurep 'xemacs)))

(defun w3m-session-make-item (item)
  (if w3m-session-make-item-xmas
      (concat item "%_ ")
    item))

(defun w3m-session-make-menu-items ()
  "Create w3m session menu items."
  (if (and w3m-session-menu-items-pre
	   w3m-session-menu-items-time
	   (equal w3m-session-menu-items-time
		  (w3m-session-file-modtime)))
      w3m-session-menu-items-pre
    (w3m-session-ignore-errors
     (let ((sessions (w3m-load-list w3m-session-file)))
       (setq w3m-session-menu-items-time (w3m-session-file-modtime))
       (setq w3m-session-menu-items-pre
	     (and sessions
		  (mapcar
		   (lambda (entry)
		     (cons (w3m-session-make-item (car entry))
			   (cons (vector "Open all sessions"
					 `(w3m-session-goto-session
					   (quote ,entry)))
				 (mapcar
				  (lambda (item)
				    (let ((title
					   (w3m-session-make-item
					    (or (nth 3 item)
						w3m-session-unknown-title))))
				      (vector
				       title
				       `(w3m-session-goto-session
					 (quote
					  ,(list title
						 nil
						 (list item)
						 nil))))))
				  (nth 2 entry)))))
		   sessions)))))))

;;;###autoload
(defun w3m-session-last-autosave-session ()
  (when w3m-session-load-last-sessions
    (w3m-session-ignore-errors
     (let ((item
	    (let ((sessions (w3m-load-list w3m-session-file))
		  (n 1) x)
	      (catch 'loop
		(while t
		  (if (< w3m-session-automatic-keep-number n)
		      (throw 'loop nil)
		    (setq x (assoc (format "%s-%d"
					   w3m-session-automatic-title n)
				   sessions))
		    (when x (throw 'loop x)))
		  (setq n (1+ n)))))))
       (when (and item
		  (or (and (eq w3m-session-load-last-sessions 'ask)
			   (y-or-n-p "Load the last sessions? "))
		      w3m-session-load-last-sessions))
	 item)))))

;;;###autoload
(defun w3m-session-last-crashed-session ()
  (when (and w3m-session-crash-recovery w3m-session-load-crashed-sessions)
    (w3m-session-ignore-errors
     (let ((item (assoc w3m-session-crash-recovery-title
			(w3m-load-list w3m-session-file))))
       (when (and item
		  (or (and (eq w3m-session-load-crashed-sessions 'ask)
			   (y-or-n-p "Load the crashed sessions? "))
		      (eq w3m-session-load-crashed-sessions t)))
	 item)))))

(add-hook 'w3m-arrived-shutdown-functions 'w3m-session-crash-recovery-remove t)
(add-hook 'w3m-arrived-shutdown-functions 'w3m-session-automatic-save t)

(provide 'w3m-session)

;;; w3m-session.el ends here