;; mu4e-mark.el -- part of mu4e, the mu mail user agent
;;
;; Copyright (C) 2011-2013 Dirk-Jan C. Binnema

;; Author: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
;; Maintainer: Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>

;; This file is not part of GNU Emacs.
;;
;; GNU Emacs 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 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs 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 GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; In this file are function related to marking messages; they assume we are
;; currently in the headers buffer.

;; Code:
(require 'mu4e-proc)
(require 'mu4e-utils)
(require 'mu4e-message)

(eval-when-compile (byte-compile-disable-warning 'cl-functions))

;; keep byte-compiler happy
(declare-function mu4e~headers-mark "mu4e-headers")
(declare-function mu4e~headers-goto-docid "mu4e-headers")
(declare-function mu4e-headers-next "mu4e-headers")


(defcustom mu4e-headers-leave-behavior 'ask
  "What to do when user leaves the headers view.
That is when he e.g. quits, refreshes or does a new search.
Value is one of the following symbols:
- `ask'     ask user whether to ignore the marks
- `apply'   automatically apply the marks before doing anything else
- `ignore'  automatically ignore the marks without asking"
  :type '(choice (const ask    :tag "ask user whether to ignore marks")
		 (const apply  :tag "apply marks without asking")
		 (const ignore :tag "ignore marks without asking"))
  :group 'mu4e-headers)

(defvar mu4e-headers-show-target t
  "Whether to show targets (such as '-> delete', '-> /archive')
when marking message. Normally, this is useful information for the
user, however, when you often mark large numbers (thousands) of
message, showing the target makes this quite a bit slower (showing
the target uses an emacs feature called 'overlays', which aren't
particularly fast).")

;;; insert stuff;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defvar mu4e~mark-map nil
  "Map (hash) of docid->markinfo; when a message is marked, the
information is added here.
markinfo is a cons cell consisting of the following:
\(mark . target)
where
   MARK is the type of mark (move, trash, delete)
   TARGET (optional) is the target directory (for 'move')")

;; the mark-map is specific for the current header buffer
;; currently, there can't be more than one, but we never know what will
;; happen in the future

;; the fringe is the space on the left of headers, where we put marks below some
;; handy definitions; only `mu4e-mark-fringe-len' should be change (if ever),
;; the others follow from that.
(defconst mu4e~mark-fringe-len 2
  "Width of the fringe for marks on the left.")
(defconst mu4e~mark-fringe (make-string mu4e~mark-fringe-len ?\s)
  "The space on the left of message headers to put marks.")
(defconst mu4e~mark-fringe-format (format "%%-%ds" mu4e~mark-fringe-len)
  "Format string to set a mark and leave remaining space.")

(defun mu4e~mark-initialize ()
  "Initialize the marks subsystem."
  (set (make-local-variable 'mu4e~mark-map) (make-hash-table)))

(defun mu4e~mark-clear ()
  "Clear the marks subsystem."
  (clrhash mu4e~mark-map))

(defun mu4e~mark-find-headers-buffer ()
  "Find the headers buffer, if any."
  (find-if
    (lambda (b)
      (with-current-buffer b
	(eq major-mode 'mu4e-headers-mode)))
    (buffer-list)))
 
(defmacro mu4e~mark-in-context (&rest body)
  "Evaluate BODY in the context of the headers buffer in case this
is either a headers or view buffer."
  `(cond     
     ((eq major-mode 'mu4e-headers-mode) ,@body)
     ((eq major-mode 'mu4e-view-mode)  
       (when (buffer-live-p mu4e~view-headers-buffer)
	 (let* ((msg (mu4e-message-at-point))
		 (docid (mu4e-message-field msg :docid)))
	   (with-current-buffer mu4e~view-headers-buffer
	     (if (mu4e~headers-goto-docid docid)
	       ,@body
	       (mu4e-error "cannot find message in headers buffer.")))))) 
     (t
       ;; even in other modes (e.g. mu4e-main-mode we try to find
       ;; the headers buffer
       (let ((hbuf (mu4e~mark-find-headers-buffer)))
	 (if (buffer-live-p hbuf)
	   (with-current-buffer hbuf
	     ,@body)
	   (progn (mu4e-message "%S" major-mode) ,@body))))))  

(defvar mu4e-marks nil
  "The list of all the possible marks.
This is an alist mapping mark symbols to their properties.  The
properties are:
  :char (string)  The character to display in the headers view
  :prompt (string) The prompt to use when asking for marks (used for
     example when marking a whole thread)
  :ask-target (function returning a string) Get the target.  This
     function run once per bulk-operation, and thus is suitable
     for user-interaction.  If nil, the target is nil.
  :dyn-target (function from (TARGET MSG) to string).  Compute
     the dynamic target.  This is run once per message, which is
     passed as MSG.  The default is to just return the target.
  :show-target (function from TARGET to string) How to display
     the target.
  :action (function taking (DOCID MSG TARGET)).  The action to
     apply on the message.
     ")

(unless mu4e-marks
  (setq mu4e-marks
'((refile
   :char       "r"
   :prompt     "refile"
   :dyn-target  (lambda (target msg) (mu4e-get-refile-folder msg))
   :action      (lambda (docid msg target) (mu4e~proc-move docid (mu4e~mark-check-target target) "-N")))
  (delete
   :char "D"
   :prompt "Delete"
   :show-target (lambda (target) "delete")
   :action (lambda (docid msg target) (mu4e~proc-remove docid)))
  (flag
   :char "+"
   :prompt "+flag"
   :show-target (lambda (target) "flag")
   :action (lambda (docid msg target) (mu4e~proc-move docid nil    "+F-u-N")))
  (move
   :char "m"
   :prompt "move"
   :ask-target  mu4e~mark-get-move-target
   :action (lambda (docid msg target) (mu4e~proc-move docid (mu4e~mark-check-target target) "-N")))
  (read
   :char       "!"
   :prompt "!read"
   :show-target (lambda (target) "read")
   :action (lambda (docid msg target) (mu4e~proc-move docid nil    "+S-u-N")))
  (trash
   :char      "d"
   :prompt "dtrash"
   :dyn-target (lambda (target msg) (mu4e-get-trash-folder msg))
   :action (lambda (docid msg target) (mu4e~proc-move docid (mu4e~mark-check-target target) "+T-N")))
  (unflag
   :char     "-"
   :prompt "-unflag"
   :show-target (lambda (target) "unflag")
   :action (lambda (docid msg target) (mu4e~proc-move docid nil    "-F-N")))
  (untrash
   :char    "="
   :prompt "=untrash"
   :show-target (lambda (target) "untrash")
   :action (lambda (docid msg target) (mu4e~proc-move docid nil    "-T")))
  (unread
   :char     "?"
   :prompt "?unread"
   :show-target (lambda (target) "unread")
   :action (lambda (docid msg target) (mu4e~proc-move docid nil    "-S+u-N")))
  (unmark
   :char     " "
   :prompt "unmark"
   :action (mu4e-error "No action for unmarking"))
  (something
   :char  "*"
   :prompt "*something"
   :action (mu4e-error "No action for deferred mark"))
  )))


(defun mu4e-mark-at-point (mark target)
  "Mark (or unmark) message at point.
MARK specifies the mark-type. For `move'-marks and `trash'-marks
the TARGET argument is non-nil and specifies to which
maildir the message is to be moved/trashed. The function works in
both headers buffers and message buffers.

The following marks are available, and the corresponding props:

   MARK       TARGET    description
   ----------------------------------------------------------
   `refile'    y	mark this message for archiving
   `something' n	mark this message for *something* (decided later)
   `delete'    n	remove the message
   `flag'      n	mark this message for flagging
   `move'      y	move the message to some folder
   `read'      n	mark the message as read
   `trash'     y	trash the message to some folder
   `unflag'    n	mark this message for unflagging
   `untrash'   n	remove the 'trashed' flag from a message
   `unmark'    n	unmark this message
   `unread'    n	mark the message as unread"
  (interactive)
  (let* ((msg (mu4e-message-at-point))
	  (docid (mu4e-message-field msg :docid))
	  ;; get a cell with the mark char and the 'target' 'move' already has a
	  ;; target (the target folder) the other ones get a pseudo "target", as
	  ;; info for the user.
	  (markdesc (cdr (or (assq mark mu4e-marks) (mu4e-error "Invalid mark %S" mark))))
	  (markkar (plist-get markdesc :char))
          (target (mu4e~mark-get-dyn-target mark target))
          (show-fct (plist-get markdesc :show-target))
	  (shown-target (if show-fct
                            (funcall show-fct target)
                          target)))
    (unless docid (mu4e-warn "No message on this line"))
    (unless (eq major-mode 'mu4e-headers-mode) (mu4e-error "Not in headers-mode"))
    (save-excursion
      (when (mu4e~headers-mark docid markkar)
	;; update the hash -- remove everything current, and if add the new stuff,
	;; unless we're unmarking
	(remhash docid mu4e~mark-map)
	;; remove possible overlays
	(remove-overlays (line-beginning-position) (line-end-position))
	;; now, let's set a mark (unless we were unmarking)
	(unless (eql mark 'unmark)
	  (puthash docid (cons mark target) mu4e~mark-map)
	  ;; when we have a target (ie., when moving), show the target folder in
	  ;; an overlay
	  (when (and shown-target mu4e-headers-show-target)
	    (let* ((targetstr (propertize (concat "-> " shown-target " ")
				'face 'mu4e-system-face))
		    ;; mu4e~headers-goto-docid docid t \will take us just after the
		    ;; docid cookie and then we skip the mu4e~mark-fringe
		    (start (+ (length mu4e~mark-fringe)
			     (mu4e~headers-goto-docid docid t)))
		    (overlay (make-overlay start (+ start (length targetstr)))))
	      (overlay-put overlay 'display targetstr)
	      docid)))))))


(defun mu4e~mark-get-move-target ()
  "Ask for a move target, and propose to create it if it does not exist."
  (interactive)
;;  (mu4e-message-at-point) ;; raises error if there is none
  (let* ((target (mu4e-ask-maildir "Move message to: "))
         (target (if (string= (substring target 0 1) "/")
		    target
		    (concat "/" target)))
	  (fulltarget (concat mu4e-maildir target)))
    (when (or (file-directory-p fulltarget)
	    (and (yes-or-no-p
		   (format "%s does not exist.  Create now?" fulltarget))
	      (mu4e~proc-mkdir fulltarget)))
      target)))

(defun mu4e~mark-ask-target (mark)
  "Ask the target for MARK, if the user should be asked the target."
  (let ((getter (plist-get (cdr (assq mark mu4e-marks)) :ask-target)))
    (and getter (funcall getter))))

(defun mu4e~mark-get-dyn-target (mark target)
  "Get the dynamic target for MARK.  The result may depend on the
message at point."
  (let ((getter (plist-get (cdr (assq mark mu4e-marks)) :dyn-target)))
    (if getter
        (funcall getter target (mu4e-message-at-point))
      target)))


(defun mu4e-mark-set (mark &optional target)
  "Mark the header at point, or, if region is active, mark all
headers in the region. Optionally, provide TARGET (for moves)."
  (unless target
    (setq target (mu4e~mark-ask-target mark)))
  (if (not (use-region-p))
    ;; single message
    (mu4e-mark-at-point mark target)
    ;; mark all messages in the region.
    (save-excursion
      (let ((cant-go-further) (eor (region-end)))
	(goto-char (region-beginning))
	(while (and (<= (point) eor) (not cant-go-further))
	  (mu4e-mark-at-point mark target)
	  (setq cant-go-further (not (mu4e-headers-next))))))))

(defun mu4e-mark-restore (docid)
  "Restore the visual mark for the message with DOCID."
  (let ((markcell (gethash docid mu4e~mark-map)))
    (when markcell
      (save-excursion
	(when (mu4e~headers-goto-docid docid)
	  (mu4e-mark-at-point (car markcell) (cdr markcell)))))))

(defun mu4e~mark-get-markpair (prompt &optional allow-something)
  "Ask user for a mark; return (MARK . TARGET).
If ALLOW-SOMETHING is non-nil, allow the 'something' pseudo mark
as well."
  (let* ((marks (mapcar (lambda (markdescr) (cons (plist-get (cdr markdescr) :prompt) (car markdescr))) mu4e-marks))
         (marks
          (if allow-something
	      marks
            (assq-delete-all 'something marks)))
	  (mark (mu4e-read-option prompt marks))
	  (target (mu4e~mark-ask-target mark)))
    (cons mark target)))


(defun mu4e-mark-resolve-deferred-marks ()
  "Check if there are any deferred ('something') marks.
If there are such marks, replace them with a _real_ mark (ask the
user which one)."
  (interactive)
  (mu4e~mark-in-context
    (let ((markpair))
      (maphash
	(lambda (docid val)
	  (let ((mark (car val)) (target (cdr val)))
	    (when (eql mark 'something)
	      (unless markpair
		(setq markpair
		  (mu4e~mark-get-markpair "Set deferred mark(s) to: " nil)))
	      (save-excursion
		(when (mu4e~headers-goto-docid docid)
		  (mu4e-mark-set (car markpair) (cdr markpair)))))))
	mu4e~mark-map))))

(defun mu4e~mark-check-target (target)
  "Check if the target exists; if not, offer to create it."
  (let ((fulltarget (concat mu4e-maildir target)))
    (if (not (mu4e-create-maildir-maybe fulltarget))
      (mu4e-error "Target dir %s does not exist " fulltarget)
      target)))


(defun mu4e-mark-execute-all (&optional no-confirmation)
  "Execute the actions for all marked messages in this buffer.
After the actions have been executed succesfully, the affected
messages are *hidden* from the current header list. Since the
headers are the result of a search, we cannot be certain that the
messages no longer match the current one - to get that
certainty, we need to rerun the search, but we don't want to do
that automatically, as it may be too slow and/or break the user's
flow. Therefore, we hide the message, which in practice seems to
work well.

If NO-CONFIRMATION is non-nil, don't ask user for confirmation."
  (interactive)
  (mu4e~mark-in-context
    (let ((marknum (hash-table-count mu4e~mark-map)))
      (if (zerop marknum)
	(message "Nothing is marked")
	(mu4e-mark-resolve-deferred-marks)
	(when (or no-confirmation
		(y-or-n-p
		  (format "Are you sure you want to execute %d mark%s?"
		    marknum (if (> marknum 1) "s" ""))))
	  (maphash
	    (lambda (docid val)
	      (let* ((mark (car val)) (target (cdr val))
                     (markdescr (assq mark mu4e-marks))
                     (msg (save-excursion
                            (mu4e~headers-goto-docid docid)
                            (mu4e-message-at-point))))
		;; note: whenever you do something with the message,
		;; it looses its N (new) flag
                (if markdescr
                    (funcall (plist-get (cdr markdescr) :action) docid msg target)
                    (mu4e-error "Unrecognized mark %S" mark))))
	    mu4e~mark-map))
	(mu4e-mark-unmark-all)
	(message nil)))))

(defun mu4e-mark-unmark-all ()
  "Unmark all marked messages."
  (interactive)
  (mu4e~mark-in-context
    (when (or (null mu4e~mark-map) (zerop (hash-table-count mu4e~mark-map)))
      (mu4e-warn "Nothing is marked"))
    (maphash
      (lambda (docid val)
	(save-excursion
	  (when (mu4e~headers-goto-docid docid)
	    (mu4e-mark-set 'unmark))))
      mu4e~mark-map)
    ;; in any case, clear the marks map
    (mu4e~mark-clear)))

(defun mu4e-mark-docid-marked-p (docid)
  "Is the given docid marked?"
  (when (gethash docid mu4e~mark-map) t))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun mu4e-mark-marks-num ()
  "Return the number of marks in the current buffer."
  (if mu4e~mark-map (hash-table-count mu4e~mark-map) 0))
 

(defun mu4e-mark-handle-when-leaving ()
  "If there are any marks in the current buffer, handle those
according to the value of `mu4e-headers-leave-behavior'. This
function is to be called before any further action (like searching,
quiting the buffer) is taken; returning t means 'take the following
action', return nil means 'don't do anything'."
  (mu4e~mark-in-context 
    (let ((marknum (mu4e-mark-marks-num))
	   (what mu4e-headers-leave-behavior))
      (unless (zerop marknum) ;; nothing to do?
	(when (eq what 'ask)
	  (setq what (mu4e-read-option
		       (format  "There are %d existing mark(s); should we: " marknum)
		       '( ("apply marks"   . apply)
			  ("ignore marks?" . ignore)))))
	;; we determined what to do... now do it
	  (when (eq what 'apply)
	    (mu4e-mark-execute-all t))))))
    

(provide 'mu4e-mark)
;; End of mu4e-mark.el
