;; notmuch-tree.el --- displaying notmuch forests.
;;
;; Copyright © Carl Worth
;; Copyright © David Edmondson
;; Copyright © Mark Walters
;;
;; This file is part of Notmuch.
;;
;; Notmuch 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.
;;
;; Notmuch 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 Notmuch.  If not, see <http://www.gnu.org/licenses/>.
;;
;; Authors: David Edmondson <dme@dme.org>
;;          Mark Walters <markwalters1009@gmail.com>

(require 'mail-parse)

(require 'notmuch-lib)
(require 'notmuch-query)
(require 'notmuch-show)
(require 'notmuch-tag)
(require 'notmuch-parser)

(eval-when-compile (require 'cl))
(declare-function notmuch-search "notmuch" (&optional query oldest-first target-thread target-line))
(declare-function notmuch-call-notmuch-process "notmuch" (&rest args))
(declare-function notmuch-read-query "notmuch" (prompt))
(declare-function notmuch-search-find-thread-id "notmuch" (&optional bare))
(declare-function notmuch-search-find-subject "notmuch" ())

;; the following variable is defined in notmuch.el
(defvar notmuch-search-query-string)

(defgroup notmuch-tree nil
  "Showing message and thread structure."
  :group 'notmuch)

(defcustom notmuch-tree-show-out nil
  "View selected messages in new window rather than split-pane."
  :type 'boolean
  :group 'notmuch-tree)

(defcustom notmuch-tree-result-format
  `(("date" . "%12s  ")
    ("authors" . "%-20s")
    ((("tree" . "%s")("subject" . "%s")) ." %-54s ")
    ("tags" . "(%s)"))
  "Result formatting for Tree view. Supported fields are: date,
        authors, subject, tree, tags.  Tree means the thread tree
        box graphics. The field may also be a list in which case
        the formatting rules are applied recursively and then the
        output of all the fields in the list is inserted
        according to format-string.

Note the author string should not contain
        whitespace (put it in the neighbouring fields instead).
        For example:
        (setq notmuch-tree-result-format \(\(\"authors\" . \"%-40s\"\)
                                             \(\"subject\" . \"%s\"\)\)\)"
  :type '(alist :key-type (string) :value-type (string))
  :group 'notmuch-tree)

;; Faces for messages that match the query.
(defface notmuch-tree-match-face
  '((t :inherit default))
  "Default face used in tree mode face for matching messages"
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-match-date-face
  nil
  "Face used in tree mode for the date in messages matching the query."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-match-author-face
  '((((class color)
      (background dark))
     (:foreground "OliveDrab1"))
    (((class color)
      (background light))
     (:foreground "dark blue"))
    (t
     (:bold t)))
  "Face used in tree mode for the date in messages matching the query."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-match-subject-face
  nil
  "Face used in tree mode for the subject in messages matching the query."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-match-tree-face
  nil
  "Face used in tree mode for the thread tree block graphics in messages matching the query."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-match-tag-face
  '((((class color)
      (background dark))
     (:foreground "OliveDrab1"))
    (((class color)
      (background light))
     (:foreground "navy blue" :bold t))
    (t
     (:bold t)))
  "Face used in tree mode for tags in messages matching the query."
  :group 'notmuch-tree
  :group 'notmuch-faces)

;; Faces for messages that do not match the query.
(defface notmuch-tree-no-match-face
  '((t (:foreground "gray")))
  "Default face used in tree mode face for non-matching messages"
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-no-match-date-face
  nil
  "Face used in tree mode for non-matching dates."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-no-match-subject-face
  nil
  "Face used in tree mode for non-matching subjects."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-no-match-tree-face
  nil
  "Face used in tree mode for the thread tree block graphics in messages matching the query."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-no-match-author-face
  nil
  "Face used in tree mode for the date in messages matching the query."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defface notmuch-tree-no-match-tag-face
  nil
  "Face used in tree mode face for non-matching tags."
  :group 'notmuch-tree
  :group 'notmuch-faces)

(defvar notmuch-tree-previous-subject
  "The subject of the most recent result shown during the async display")
(make-variable-buffer-local 'notmuch-tree-previous-subject)

(defvar notmuch-tree-basic-query nil
  "A buffer local copy of argument query to the function notmuch-tree")
(make-variable-buffer-local 'notmuch-tree-basic-query)

(defvar notmuch-tree-query-context nil
  "A buffer local copy of argument query-context to the function notmuch-tree")
(make-variable-buffer-local 'notmuch-tree-query-context)

(defvar notmuch-tree-target-msg nil
  "A buffer local copy of argument target to the function notmuch-tree")
(make-variable-buffer-local 'notmuch-tree-target-msg)

(defvar notmuch-tree-open-target nil
  "A buffer local copy of argument open-target to the function notmuch-tree")
(make-variable-buffer-local 'notmuch-tree-open-target)

(defvar notmuch-tree-message-window nil
  "The window of the message pane.

It is set in both the tree buffer and the child show buffer. It
is used to try and close the message pane when quitting tree view
or the child show buffer.")
(make-variable-buffer-local 'notmuch-tree-message-window)
(put 'notmuch-tree-message-window 'permanent-local t)

(defvar notmuch-tree-message-buffer nil
  "The buffer name of the show buffer in the message pane.

This is used to try and make sure we don't close the message pane
if the user has loaded a different buffer in that window.")
(make-variable-buffer-local 'notmuch-tree-message-buffer)
(put 'notmuch-tree-message-buffer 'permanent-local t)

(defun notmuch-tree-to-message-pane (func)
  "Execute FUNC in message pane.

This function returns a function (so can be used as a keybinding)
which executes function FUNC in the message pane if it is
open (if the message pane is closed it does nothing)."
  `(lambda ()
      ,(concat "(In message pane) " (documentation func t))
     (interactive)
     (when (window-live-p notmuch-tree-message-window)
       (with-selected-window notmuch-tree-message-window
	 (call-interactively #',func)))))

(defun notmuch-tree-button-activate (&optional button)
  "Activate BUTTON or button at point

This function does not give an error if there is no button."
  (interactive)
  (let ((button (or button (button-at (point)))))
    (when button (button-activate button))))

(defun notmuch-tree-close-message-pane-and (func)
  "Close message pane and execute FUNC.

This function returns a function (so can be used as a keybinding)
which closes the message pane if open and then executes function
FUNC."
  `(lambda ()
      ,(concat "(Close message pane and) " (documentation func t))
     (interactive)
     (notmuch-tree-close-message-window)
     (call-interactively #',func)))

(defvar notmuch-tree-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map notmuch-common-keymap)
    ;; The following override the global keymap.
    ;; Override because we want to close message pane first.
    (define-key map [remap notmuch-help] (notmuch-tree-close-message-pane-and #'notmuch-help))
    ;; Override because we first close message pane and then close tree buffer.
    (define-key map [remap notmuch-kill-this-buffer] 'notmuch-tree-quit)
    ;; Override because we close message pane after the search query is entered.
    (define-key map [remap notmuch-search] 'notmuch-tree-to-search)
    ;; Override because we want to close message pane first.
    (define-key map [remap notmuch-mua-new-mail] (notmuch-tree-close-message-pane-and #'notmuch-mua-new-mail))

    ;; these use notmuch-show functions directly
    (define-key map "|" 'notmuch-show-pipe-message)
    (define-key map "w" 'notmuch-show-save-attachments)
    (define-key map "v" 'notmuch-show-view-all-mime-parts)
    (define-key map "c" 'notmuch-show-stash-map)

    ;; these apply to the message pane
    (define-key map (kbd "M-TAB") (notmuch-tree-to-message-pane #'notmuch-show-previous-button))
    (define-key map (kbd "<backtab>")  (notmuch-tree-to-message-pane #'notmuch-show-previous-button))
    (define-key map (kbd "TAB") (notmuch-tree-to-message-pane #'notmuch-show-next-button))
    (define-key map "e" (notmuch-tree-to-message-pane #'notmuch-tree-button-activate))

    ;; bindings from show (or elsewhere) but we close the message pane first.
    (define-key map "f" (notmuch-tree-close-message-pane-and #'notmuch-show-forward-message))
    (define-key map "r" (notmuch-tree-close-message-pane-and #'notmuch-show-reply-sender))
    (define-key map "R" (notmuch-tree-close-message-pane-and #'notmuch-show-reply))
    (define-key map "V" (notmuch-tree-close-message-pane-and #'notmuch-show-view-raw-message))

    ;; The main tree view bindings
    (define-key map (kbd "RET") 'notmuch-tree-show-message)
    (define-key map [mouse-1] 'notmuch-tree-show-message)
    (define-key map "x" 'notmuch-tree-quit)
    (define-key map "A" 'notmuch-tree-archive-thread)
    (define-key map "a" 'notmuch-tree-archive-message-then-next)
    (define-key map "=" 'notmuch-tree-refresh-view)
    (define-key map "z" 'notmuch-tree-to-tree)
    (define-key map "n" 'notmuch-tree-next-matching-message)
    (define-key map "p" 'notmuch-tree-prev-matching-message)
    (define-key map "N" 'notmuch-tree-next-message)
    (define-key map "P" 'notmuch-tree-prev-message)
    (define-key map (kbd "M-p") 'notmuch-tree-prev-thread)
    (define-key map (kbd "M-n") 'notmuch-tree-next-thread)
    (define-key map "-" 'notmuch-tree-remove-tag)
    (define-key map "+" 'notmuch-tree-add-tag)
    (define-key map "*" 'notmuch-tree-tag-thread)
    (define-key map " " 'notmuch-tree-scroll-or-next)
    (define-key map "b" 'notmuch-tree-scroll-message-window-back)
    map))
(fset 'notmuch-tree-mode-map notmuch-tree-mode-map)

(defun notmuch-tree-get-message-properties ()
  "Return the properties of the current message as a plist.

Some useful entries are:
:headers - Property list containing the headers :Date, :Subject, :From, etc.
:tags - Tags for this message"
  (save-excursion
    (beginning-of-line)
    (get-text-property (point) :notmuch-message-properties)))

;; XXX This should really be a lib function but we are trying to
;; reduce impact on the code base.
(defun notmuch-show-get-prop (prop &optional props)
  "This is a tree view overridden version of notmuch-show-get-prop

It gets property PROP from PROPS or, if PROPS is nil, the current
message in either tree or show. This means that several functions
in notmuch-show now work unchanged in tree as they just need the
correct message properties."
  (let ((props (or props
		   (cond ((eq major-mode 'notmuch-show-mode)
			  (notmuch-show-get-message-properties))
			 ((eq major-mode 'notmuch-tree-mode)
			  (notmuch-tree-get-message-properties))))))
    (plist-get props prop)))

(defun notmuch-tree-set-message-properties (props)
  (save-excursion
    (beginning-of-line)
    (put-text-property (point) (+ (point) 1) :notmuch-message-properties props)))

(defun notmuch-tree-set-prop (prop val &optional props)
  (let ((inhibit-read-only t)
	(props (or props
		   (notmuch-tree-get-message-properties))))
    (plist-put props prop val)
    (notmuch-tree-set-message-properties props)))

(defun notmuch-tree-get-prop (prop &optional props)
  (let ((props (or props
		   (notmuch-tree-get-message-properties))))
    (plist-get props prop)))

(defun notmuch-tree-set-tags (tags)
  "Set the tags of the current message."
  (notmuch-tree-set-prop :tags tags))

(defun notmuch-tree-get-tags ()
  "Return the tags of the current message."
  (notmuch-tree-get-prop :tags))

(defun notmuch-tree-get-message-id (&optional bare)
  "Return the message id of the current message."
  (let ((id (notmuch-tree-get-prop :id)))
    (if id
	(if bare
	    id
	  (notmuch-id-to-query id))
      nil)))

(defun notmuch-tree-get-match ()
  "Return whether the current message is a match."
  (interactive)
  (notmuch-tree-get-prop :match))

(defun notmuch-tree-refresh-result ()
  "Redisplay the current message line.

This redisplays the current line based on the messages
properties (as they are now). This is used when tags are
updated."
  (let ((init-point (point))
	(end (line-end-position))
	(msg (notmuch-tree-get-message-properties))
	(inhibit-read-only t))
    (beginning-of-line)
    ;; This is a little tricky: we override
    ;; notmuch-tree-previous-subject to get the decision between
    ;; ... and a subject right and it stops notmuch-tree-insert-msg
    ;; from overwriting the buffer local copy of
    ;; notmuch-tree-previous-subject if this is called while the
    ;; buffer is displaying.
    (let ((notmuch-tree-previous-subject (notmuch-tree-get-prop :previous-subject)))
      (delete-region (point) (1+ (line-end-position)))
      (notmuch-tree-insert-msg msg))
    (let ((new-end (line-end-position)))
      (goto-char (if (= init-point end)
		     new-end
		   (min init-point (- new-end 1)))))))

(defun notmuch-tree-tag-update-display (&optional tag-changes)
  "Update display for TAG-CHANGES to current message.

Does NOT change the database."
  (let* ((current-tags (notmuch-tree-get-tags))
	 (new-tags (notmuch-update-tags current-tags tag-changes)))
    (unless (equal current-tags new-tags)
      (notmuch-tree-set-tags new-tags)
      (notmuch-tree-refresh-result))))

(defun notmuch-tree-tag (tag-changes)
  "Change tags for the current message"
  (interactive
   (list (notmuch-read-tag-changes (notmuch-tree-get-tags) "Tag message")))
  (notmuch-tag (notmuch-tree-get-message-id) tag-changes)
  (notmuch-tree-tag-update-display tag-changes))

(defun notmuch-tree-add-tag (tag-changes)
  "Same as `notmuch-tree-tag' but sets initial input to '+'."
  (interactive
   (list (notmuch-read-tag-changes (notmuch-tree-get-tags) "Tag message" "+")))
  (notmuch-tree-tag tag-changes))

(defun notmuch-tree-remove-tag (tag-changes)
  "Same as `notmuch-tree-tag' but sets initial input to '-'."
  (interactive
   (list (notmuch-read-tag-changes (notmuch-tree-get-tags) "Tag message" "-")))
  (notmuch-tree-tag tag-changes))

;; The next two functions close the message window before calling
;; notmuch-search or notmuch-tree but they do so after the user has
;; entered the query (in case the user was basing the query on
;; something in the message window).

(defun notmuch-tree-to-search ()
  "Run \"notmuch search\" with the given `query' and display results."
  (interactive)
  (let ((query (notmuch-read-query "Notmuch search: ")))
    (notmuch-tree-close-message-window)
    (notmuch-search query)))

(defun notmuch-tree-to-tree ()
  "Run a query and display results in Tree view"
  (interactive)
  (let ((query (notmuch-read-query "Notmuch tree view search: ")))
    (notmuch-tree-close-message-window)
    (notmuch-tree query)))

(defun notmuch-tree-message-window-kill-hook ()
  "Close the message pane when exiting the show buffer."
  (let ((buffer (current-buffer)))
    (when (and (window-live-p notmuch-tree-message-window)
	       (eq (window-buffer notmuch-tree-message-window) buffer))
      ;; We do not want an error if this is the sole window in the
      ;; frame and I do not know how to test for that in emacs pre
      ;; 24. Hence we just ignore-errors.
      (ignore-errors
	(delete-window notmuch-tree-message-window)))))

(defun notmuch-tree-show-message-in ()
  "Show the current message (in split-pane)."
  (interactive)
  (let ((id (notmuch-tree-get-message-id))
	(inhibit-read-only t)
	buffer)
    (when id
      ;; We close and reopen the window to kill off un-needed buffers
      ;; this might cause flickering but seems ok.
      (notmuch-tree-close-message-window)
      (setq notmuch-tree-message-window
	    (split-window-vertically (/ (window-height) 4)))
      (with-selected-window notmuch-tree-message-window
	;; Since we are only displaying one message do not indent.
	(let ((notmuch-show-indent-messages-width 0)
	      (notmuch-show-only-matching-messages t))
	  (setq buffer (notmuch-show id))))
      ;; We need the `let' as notmuch-tree-message-window is buffer local.
      (let ((window notmuch-tree-message-window))
	(with-current-buffer buffer
	  (setq notmuch-tree-message-window window)
	  (add-hook 'kill-buffer-hook 'notmuch-tree-message-window-kill-hook)))
      (when notmuch-show-mark-read-tags
	(notmuch-tree-tag-update-display notmuch-show-mark-read-tags))
      (setq notmuch-tree-message-buffer buffer))))

(defun notmuch-tree-show-message-out ()
  "Show the current message (in whole window)."
  (interactive)
  (let ((id (notmuch-tree-get-message-id))
	(inhibit-read-only t)
	buffer)
    (when id
      ;; We close the window to kill off un-needed buffers.
      (notmuch-tree-close-message-window)
      (notmuch-show id))))

(defun notmuch-tree-show-message (arg)
  "Show the current message.

Shows in split pane or whole window according to value of
`notmuch-tree-show-out'. A prefix argument reverses the choice."
  (interactive "P")
  (if (or (and notmuch-tree-show-out  (not arg))
	  (and (not notmuch-tree-show-out) arg))
      (notmuch-tree-show-message-out)
    (notmuch-tree-show-message-in)))

(defun notmuch-tree-scroll-message-window ()
  "Scroll the message window (if it exists)"
  (interactive)
  (when (window-live-p notmuch-tree-message-window)
    (with-selected-window notmuch-tree-message-window
      (if (pos-visible-in-window-p (point-max))
	  t
	(scroll-up)))))

(defun notmuch-tree-scroll-message-window-back ()
  "Scroll the message window back(if it exists)"
  (interactive)
  (when (window-live-p notmuch-tree-message-window)
    (with-selected-window notmuch-tree-message-window
      (if (pos-visible-in-window-p (point-min))
	  t
	(scroll-down)))))

(defun notmuch-tree-scroll-or-next ()
  "Scroll the message window. If it at end go to next message."
  (interactive)
  (when (notmuch-tree-scroll-message-window)
    (notmuch-tree-next-matching-message)))

(defun notmuch-tree-quit ()
  "Close the split view or exit tree."
  (interactive)
  (unless (notmuch-tree-close-message-window)
    (kill-buffer (current-buffer))))

(defun notmuch-tree-close-message-window ()
  "Close the message-window. Return t if close succeeds."
  (interactive)
  (when (and (window-live-p notmuch-tree-message-window)
	     (eq (window-buffer notmuch-tree-message-window) notmuch-tree-message-buffer))
    (delete-window notmuch-tree-message-window)
    (unless (get-buffer-window-list notmuch-tree-message-buffer)
      (kill-buffer notmuch-tree-message-buffer))
    t))

(defun notmuch-tree-archive-message (&optional unarchive)
  "Archive the current message.

Archive the current message by applying the tag changes in
`notmuch-archive-tags' to it. If a prefix argument is given, the
message will be \"unarchived\", i.e. the tag changes in
`notmuch-archive-tags' will be reversed."
  (interactive "P")
  (when notmuch-archive-tags
    (notmuch-tree-tag (notmuch-tag-change-list notmuch-archive-tags unarchive))))

(defun notmuch-tree-archive-message-then-next (&optional unarchive)
  "Archive the current message and move to next matching message."
  (interactive "P")
  (notmuch-tree-archive-message unarchive)
  (notmuch-tree-next-matching-message))

(defun notmuch-tree-next-message ()
  "Move to next message."
  (interactive)
  (forward-line)
  (when (window-live-p notmuch-tree-message-window)
    (notmuch-tree-show-message-in)))

(defun notmuch-tree-prev-message ()
  "Move to previous message."
  (interactive)
  (forward-line -1)
  (when (window-live-p notmuch-tree-message-window)
    (notmuch-tree-show-message-in)))

(defun notmuch-tree-prev-matching-message ()
  "Move to previous matching message."
  (interactive)
  (forward-line -1)
  (while (and (not (bobp)) (not (notmuch-tree-get-match)))
    (forward-line -1))
  (when (window-live-p notmuch-tree-message-window)
    (notmuch-tree-show-message-in)))

(defun notmuch-tree-next-matching-message ()
  "Move to next matching message."
  (interactive)
  (forward-line)
  (while (and (not (eobp)) (not (notmuch-tree-get-match)))
    (forward-line))
  (when (window-live-p notmuch-tree-message-window)
    (notmuch-tree-show-message-in)))

(defun notmuch-tree-refresh-view ()
  "Refresh view."
  (interactive)
  (let ((inhibit-read-only t)
	(basic-query notmuch-tree-basic-query)
	(query-context notmuch-tree-query-context)
	(target (notmuch-tree-get-message-id)))
    (erase-buffer)
    (notmuch-tree-worker basic-query
			 query-context
			 target)))

(defun notmuch-tree-thread-top ()
  (when (notmuch-tree-get-message-properties)
    (while (not (or (notmuch-tree-get-prop :first) (eobp)))
      (forward-line -1))))

(defun notmuch-tree-prev-thread ()
  (interactive)
  (forward-line -1)
  (notmuch-tree-thread-top))

(defun notmuch-tree-next-thread ()
  (interactive)
  (forward-line 1)
  (while (not (or (notmuch-tree-get-prop :first) (eobp)))
    (forward-line 1)))

(defun notmuch-tree-thread-mapcar (function)
  "Iterate through all messages in the current thread
 and call FUNCTION for side effects."
  (save-excursion
    (notmuch-tree-thread-top)
    (loop collect (funcall function)
	  do (forward-line)
	  while (and (notmuch-tree-get-message-properties)
		     (not (notmuch-tree-get-prop :first))))))

(defun notmuch-tree-get-messages-ids-thread-search ()
  "Return a search string for all message ids of messages in the current thread."
  (mapconcat 'identity
	     (notmuch-tree-thread-mapcar 'notmuch-tree-get-message-id)
	     " or "))

(defun notmuch-tree-tag-thread (tag-changes)
  "Tag all messages in the current thread"
  (interactive
   (let ((tags (apply #'append (notmuch-tree-thread-mapcar
				(lambda () (notmuch-tree-get-tags))))))
     (list (notmuch-read-tag-changes tags "Tag thread"))))
  (when (notmuch-tree-get-message-properties)
    (notmuch-tag (notmuch-tree-get-messages-ids-thread-search) tag-changes)
    (notmuch-tree-thread-mapcar
     (lambda () (notmuch-tree-tag-update-display tag-changes)))))

(defun notmuch-tree-archive-thread (&optional unarchive)
  "Archive each message in thread.

Archive each message currently shown by applying the tag changes
in `notmuch-archive-tags' to each. If a prefix argument is given,
the messages will be \"unarchived\", i.e. the tag changes in
`notmuch-archive-tags' will be reversed.

Note: This command is safe from any race condition of new messages
being delivered to the same thread. It does not archive the
entire thread, but only the messages shown in the current
buffer."
  (interactive "P")
  (when notmuch-archive-tags
    (notmuch-tree-tag-thread
     (notmuch-tag-change-list notmuch-archive-tags unarchive))))

;; Functions below here display the tree buffer itself.

(defun notmuch-tree-clean-address (address)
  "Try to clean a single email ADDRESS for display. Return
AUTHOR_NAME if present, otherwise return AUTHOR_EMAIL. Return
unchanged ADDRESS if parsing fails."
  (let* ((clean-address (notmuch-clean-address address))
	 (p-address (car clean-address))
	 (p-name (cdr clean-address)))

    ;; If we have a name return that otherwise return the address.
    (or p-name p-address)))

(defun notmuch-tree-format-field (field format-string msg)
  "Format a FIELD of MSG according to FORMAT-STRING and return string"
  (let* ((headers (plist-get msg :headers))
	 (match (plist-get msg :match)))
    (cond
     ((listp field)
      (format format-string (notmuch-tree-format-field-list field msg)))

     ((string-equal field "date")
      (let ((face (if match
		      'notmuch-tree-match-date-face
		    'notmuch-tree-no-match-date-face)))
	(propertize (format format-string (plist-get msg :date_relative)) 'face face)))

     ((string-equal field "tree")
      (let ((tree-status (plist-get msg :tree-status))
	    (face (if match
		      'notmuch-tree-match-tree-face
		    'notmuch-tree-no-match-tree-face)))

	(propertize (format format-string
			    (mapconcat #'identity (reverse tree-status) ""))
		    'face face)))

     ((string-equal field "subject")
      (let ((bare-subject (notmuch-show-strip-re (plist-get headers :Subject)))
	    (previous-subject notmuch-tree-previous-subject)
	    (face (if match
		      'notmuch-tree-match-subject-face
		    'notmuch-tree-no-match-subject-face)))

	(setq notmuch-tree-previous-subject bare-subject)
	(propertize (format format-string
			    (if (string= previous-subject bare-subject)
				" ..."
			      bare-subject))
		    'face face)))

     ((string-equal field "authors")
      (let ((author (notmuch-tree-clean-address (plist-get headers :From)))
	    (len (length (format format-string "")))
	    (face (if match
		      'notmuch-tree-match-author-face
		    'notmuch-tree-no-match-author-face)))
	(when (> (length author) len)
	  (setq author (substring author 0 len)))
	(propertize (format format-string author) 'face face)))

     ((string-equal field "tags")
      (let ((tags (plist-get msg :tags))
	    (face (if match
		      'notmuch-tree-match-tag-face
		    'notmuch-tree-no-match-tag-face)))
	(format format-string (notmuch-tag-format-tags tags face)))))))

(defun notmuch-tree-format-field-list (field-list msg)
  "Format fields of MSG according to FIELD-LIST and return string"
  (let ((face (if (plist-get msg :match)
		  'notmuch-tree-match-face
		'notmuch-tree-no-match-face))
	(result-string))
    (dolist (spec field-list result-string)
      (let ((field-string (notmuch-tree-format-field (car spec) (cdr spec) msg)))
	(setq result-string (concat result-string field-string))))
    (notmuch-apply-face result-string face t)))

(defun notmuch-tree-insert-msg (msg)
  "Insert the message MSG according to notmuch-tree-result-format"
  ;; We need to save the previous subject as it will get overwritten
  ;; by the insert-field calls.
  (let ((previous-subject notmuch-tree-previous-subject))
    (insert (notmuch-tree-format-field-list notmuch-tree-result-format msg))
    (notmuch-tree-set-message-properties msg)
    (notmuch-tree-set-prop :previous-subject previous-subject)
    (insert "\n")))

(defun notmuch-tree-goto-and-insert-msg (msg)
  "Insert msg at the end of the buffer. Move point to msg if it is the target"
  (save-excursion
    (goto-char (point-max))
    (notmuch-tree-insert-msg msg))
  (let ((msg-id (notmuch-id-to-query (plist-get msg :id)))
	(target notmuch-tree-target-msg))
    (when (or (and (not target) (plist-get msg :match))
	      (string= msg-id target))
      (setq notmuch-tree-target-msg "found")
      (goto-char (point-max))
      (forward-line -1)
      (when notmuch-tree-open-target
	(notmuch-tree-show-message-in)))))

(defun notmuch-tree-insert-tree (tree depth tree-status first last)
  "Insert the message tree TREE at depth DEPTH in the current thread.

A message tree is another name for a single sub-thread: i.e., a
message together with all its descendents."
  (let ((msg (car tree))
	(replies (cadr tree)))

      (cond
       ((and (< 0 depth) (not last))
	(push "├" tree-status))
       ((and (< 0 depth) last)
	(push "╰" tree-status))
       ((and (eq 0 depth) first last)
;;	  (push "─" tree-status)) choice between this and next line is matter of taste.
	(push " " tree-status))
       ((and (eq 0 depth) first (not last))
	  (push "┬" tree-status))
       ((and (eq 0 depth) (not first) last)
	(push "╰" tree-status))
       ((and (eq 0 depth) (not first) (not last))
	(push "├" tree-status)))

      (push (concat (if replies "┬" "─") "►") tree-status)
      (plist-put msg :first (and first (eq 0 depth)))
      (notmuch-tree-goto-and-insert-msg (plist-put msg :tree-status tree-status))
      (pop tree-status)
      (pop tree-status)

      (if last
	  (push " " tree-status)
	(push "│" tree-status))

    (notmuch-tree-insert-thread replies (1+ depth) tree-status)))

(defun notmuch-tree-insert-thread (thread depth tree-status)
  "Insert the collection of sibling sub-threads THREAD at depth DEPTH in the current forest."
  (let ((n (length thread)))
    (loop for tree in thread
	  for count from 1 to n

	  do (notmuch-tree-insert-tree tree depth tree-status (eq count 1) (eq count n)))))

(defun notmuch-tree-insert-forest-thread (forest-thread)
  "Insert a single complete thread."
  (let (tree-status)
    ;; Reset at the start of each main thread.
    (setq notmuch-tree-previous-subject nil)
    (notmuch-tree-insert-thread forest-thread 0 tree-status)))

(defun notmuch-tree-insert-forest (forest)
  "Insert a forest of threads.

This function inserts a collection of several complete threads as
passed to it by notmuch-tree-process-filter."
  (mapc 'notmuch-tree-insert-forest-thread forest))

(defun notmuch-tree-mode ()
  "Major mode displaying messages (as opposed to threads) of of a notmuch search.

This buffer contains the results of a \"notmuch tree\" of your
email archives. Each line in the buffer represents a single
message giving the relative date, the author, subject, and any
tags.

Pressing \\[notmuch-tree-show-message] on any line displays that message.

Complete list of currently available key bindings:

\\{notmuch-tree-mode-map}"

  (interactive)
  (kill-all-local-variables)
  (setq notmuch-buffer-refresh-function #'notmuch-tree-refresh-view)
  (use-local-map notmuch-tree-mode-map)
  (setq major-mode 'notmuch-tree-mode
	mode-name "notmuch-tree")
  (hl-line-mode 1)
  (setq buffer-read-only t
	truncate-lines t))

(defun notmuch-tree-process-sentinel (proc msg)
  "Add a message to let user know when \"notmuch tree\" exits"
  (let ((buffer (process-buffer proc))
	(status (process-status proc))
	(exit-status (process-exit-status proc))
	(never-found-target-thread nil))
    (when (memq status '(exit signal))
        (kill-buffer (process-get proc 'parse-buf))
	(if (buffer-live-p buffer)
	    (with-current-buffer buffer
	      (save-excursion
		(let ((inhibit-read-only t)
		      (atbob (bobp)))
		  (goto-char (point-max))
		  (if (eq status 'signal)
		      (insert "Incomplete search results (tree view process was killed).\n"))
		  (when (eq status 'exit)
		    (insert "End of search results.")
		    (unless (= exit-status 0)
		      (insert (format " (process returned %d)" exit-status)))
		    (insert "\n")))))))))

(defun notmuch-tree-process-filter (proc string)
  "Process and filter the output of \"notmuch show\" for tree view"
  (let ((results-buf (process-buffer proc))
        (parse-buf (process-get proc 'parse-buf))
        (inhibit-read-only t)
        done)
    (if (not (buffer-live-p results-buf))
        (delete-process proc)
      (with-current-buffer parse-buf
        ;; Insert new data
        (save-excursion
          (goto-char (point-max))
          (insert string))
	(notmuch-sexp-parse-partial-list 'notmuch-tree-insert-forest-thread
					 results-buf)))))

(defun notmuch-tree-worker (basic-query &optional query-context target open-target)
  "Insert the tree view of the search in the current buffer.

This is is a helper function for notmuch-tree. The arguments are
the same as for the function notmuch-tree."
  (interactive)
  (notmuch-tree-mode)
  (setq notmuch-tree-basic-query basic-query)
  (setq notmuch-tree-query-context query-context)
  (setq notmuch-tree-target-msg target)
  (setq notmuch-tree-open-target open-target)

  (erase-buffer)
  (goto-char (point-min))
  (let* ((search-args (concat basic-query
		       (if query-context (concat " and (" query-context ")"))
		       ))
	 (message-arg "--entire-thread"))
    (if (equal (car (process-lines notmuch-command "count" search-args)) "0")
	(setq search-args basic-query))
    (let ((proc (notmuch-start-notmuch
		 "notmuch-tree" (current-buffer) #'notmuch-tree-process-sentinel
		 "show" "--body=false" "--format=sexp"
		 message-arg search-args))
	  ;; Use a scratch buffer to accumulate partial output.
	  ;; This buffer will be killed by the sentinel, which
	  ;; should be called no matter how the process dies.
	  (parse-buf (generate-new-buffer " *notmuch tree parse*")))
      (process-put proc 'parse-buf parse-buf)
      (set-process-filter proc 'notmuch-tree-process-filter)
      (set-process-query-on-exit-flag proc nil))))

(defun notmuch-tree (&optional query query-context target buffer-name open-target)
  "Display threads matching QUERY in Tree View.

The arguments are:
  QUERY: the main query. This can be any query but in many cases will be
      a single thread. If nil this is read interactively from the minibuffer.
  QUERY-CONTEXT: is an additional term for the query. The query used
      is QUERY and QUERY-CONTEXT unless that does not match any messages
      in which case we fall back to just QUERY.
  TARGET: A message ID (with the id: prefix) that will be made
      current if it appears in the tree view results.
  BUFFER-NAME: the name of the buffer to display the tree view. If
      it is nil \"*notmuch-tree\" followed by QUERY is used.
  OPEN-TARGET: If TRUE open the target message in the message pane."
  (interactive)
  (if (null query)
      (setq query (notmuch-read-query "Notmuch tree view search: ")))
  (let ((buffer (get-buffer-create (generate-new-buffer-name
				    (or buffer-name
					(concat "*notmuch-tree-" query "*")))))
	(inhibit-read-only t))

    (switch-to-buffer buffer))
  ;; Don't track undo information for this buffer
  (set 'buffer-undo-list t)

  (notmuch-tree-worker query query-context target open-target)

  (setq truncate-lines t))


;;

(provide 'notmuch-tree)