;; notmuch-hello.el --- welcome to notmuch, a frontend
;;
;; Copyright © David Edmondson
;;
;; 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>

(eval-when-compile (require 'cl))
(require 'widget)
(require 'wid-edit) ; For `widget-forward'.

(require 'notmuch-lib)
(require 'notmuch-mua)

(declare-function notmuch-search "notmuch" (query &optional oldest-first target-thread target-line continuation))
(declare-function notmuch-poll "notmuch" ())

(defvar notmuch-hello-search-bar-marker nil
  "The position of the search bar within the notmuch-hello buffer.")

(defcustom notmuch-recent-searches-max 10
  "The number of recent searches to store and display."
  :type 'integer
  :group 'notmuch)

(defcustom notmuch-show-empty-saved-searches nil
  "Should saved searches with no messages be listed?"
  :type 'boolean
  :group 'notmuch)

(defun notmuch-sort-saved-searches (alist)
  "Generate an alphabetically sorted saved searches alist."
  (sort alist (lambda (a b) (string< (car a) (car b)))))

(defcustom notmuch-saved-search-sort-function nil
  "Function used to sort the saved searches for the notmuch-hello view.

This variable controls how saved searches should be sorted. No
sorting (nil) displays the saved searches in the order they are
stored in `notmuch-saved-searches'. Sort alphabetically sorts the
saved searches in alphabetical order. Custom sort function should
be a function or a lambda expression that takes the saved
searches alist as a parameter, and returns a new saved searches
alist to be used."
  :type '(choice (const :tag "No sorting" nil)
		 (const :tag "Sort alphabetically" notmuch-sort-saved-searches)
		 (function :tag "Custom sort function"
			   :value notmuch-sort-saved-searches))
  :group 'notmuch)

(defvar notmuch-hello-indent 4
  "How much to indent non-headers.")

(defcustom notmuch-show-logo t
  "Should the notmuch logo be shown?"
  :type 'boolean
  :group 'notmuch)

(defcustom notmuch-show-all-tags-list nil
  "Should all tags be shown in the notmuch-hello view?"
  :type 'boolean
  :group 'notmuch)

(defcustom notmuch-hello-tag-list-make-query nil
  "Function or string to generate queries for the all tags list.

This variable controls which query results are shown for each tag
in the \"all tags\" list. If nil, it will use all messages with
that tag. If this is set to a string, it is used as a filter for
messages having that tag (equivalent to \"tag:TAG and (THIS-VARIABLE)\").
Finally this can be a function that will be called for each tag and
should return a filter for that tag, or nil to hide the tag."
  :type '(choice (const :tag "All messages" nil)
		 (const :tag "Unread messages" "tag:unread")
		 (const :tag "Custom filter" string)
		 (const :tag "Custom filter function" function))
  :group 'notmuch)

(defcustom notmuch-hello-hide-tags nil
  "List of tags to be hidden in the \"all tags\"-section."
  :type '(repeat string)
  :group 'notmuch)

(defface notmuch-hello-logo-background
  '((((class color)
      (background dark))
     (:background "#5f5f5f"))
    (((class color)
      (background light))
     (:background "white")))
  "Background colour for the notmuch logo."
  :group 'notmuch)

(defcustom notmuch-column-control t
  "Controls the number of columns for saved searches/tags in notmuch view.

This variable has three potential sets of values:

- t: automatically calculate the number of columns possible based
  on the tags to be shown and the window width,
- an integer: a lower bound on the number of characters that will
  be used to display each column,
- a float: a fraction of the window width that is the lower bound
  on the number of characters that should be used for each
  column.

So:
- if you would like two columns of tags, set this to 0.5.
- if you would like a single column of tags, set this to 1.0.
- if you would like tags to be 30 characters wide, set this to
  30.
- if you don't want to worry about all of this nonsense, leave
  this set to `t'."
  :group 'notmuch
  :type '(choice
	  (const :tag "Automatically calculated" t)
	  (integer :tag "Number of characters")
	  (float :tag "Fraction of window")))

(defcustom notmuch-decimal-separator ","
  "The string used as a decimal separator.

Typically \",\" in the US and UK and \".\" in Europe."
  :group 'notmuch
  :type 'string)

(defcustom notmuch-hello-mode-hook nil
  "Functions called after entering `notmuch-hello-mode'."
  :group 'notmuch
  :type 'hook)

(defvar notmuch-hello-url "http://notmuchmail.org"
  "The `notmuch' web site.")

(defvar notmuch-hello-recent-searches nil)

(defun notmuch-hello-remember-search (search)
  (if (not (member search notmuch-hello-recent-searches))
      (push search notmuch-hello-recent-searches))
  (if (> (length notmuch-hello-recent-searches)
	 notmuch-recent-searches-max)
      (setq notmuch-hello-recent-searches (butlast notmuch-hello-recent-searches))))

(defun notmuch-hello-nice-number (n)
  (let (result)
    (while (> n 0)
      (push (% n 1000) result)
      (setq n (/ n 1000)))
    (setq result (or result '(0)))
    (apply #'concat
     (number-to-string (car result))
     (mapcar (lambda (elem)
	      (format "%s%03d" notmuch-decimal-separator elem))
	     (cdr result)))))

(defun notmuch-hello-trim (search)
  "Trim whitespace."
  (if (string-match "^[[:space:]]*\\(.*[^[:space:]]\\)[[:space:]]*$" search)
      (match-string 1 search)
    search))

(defun notmuch-hello-search (search)
  (let ((search (notmuch-hello-trim search)))
    (notmuch-hello-remember-search search)
    (notmuch-search search notmuch-search-oldest-first nil nil #'notmuch-hello-search-continuation)))

(defun notmuch-hello-add-saved-search (widget)
  (interactive)
  (let ((search (widget-value
		 (symbol-value
		  (widget-get widget :notmuch-saved-search-widget))))
	(name (completing-read "Name for saved search: "
			       notmuch-saved-searches)))
    ;; If an existing saved search with this name exists, remove it.
    (setq notmuch-saved-searches
	  (loop for elem in notmuch-saved-searches
		if (not (equal name
			       (car elem)))
		collect elem))
    ;; Add the new one.
    (customize-save-variable 'notmuch-saved-searches
			     (add-to-list 'notmuch-saved-searches
					  (cons name search) t))
    (message "Saved '%s' as '%s'." search name)
    (notmuch-hello-update)))

(defun notmuch-hello-longest-label (tag-alist)
  (or (loop for elem in tag-alist
	    maximize (length (car elem)))
      0))

(defun notmuch-hello-reflect-generate-row (ncols nrows row list)
  (let ((len (length list)))
    (loop for col from 0 to (- ncols 1)
	  collect (let ((offset (+ (* nrows col) row)))
		    (if (< offset len)
			(nth offset list)
		      ;; Don't forget to insert an empty slot in the
		      ;; output matrix if there is no corresponding
		      ;; value in the input matrix.
		      nil)))))

(defun notmuch-hello-reflect (list ncols)
  "Reflect a `ncols' wide matrix represented by `list' along the
diagonal."
  ;; Not very lispy...
  (let ((nrows (ceiling (length list) ncols)))
    (loop for row from 0 to (- nrows 1)
	  append (notmuch-hello-reflect-generate-row ncols nrows row list))))

(defun notmuch-hello-widget-search (widget &rest ignore)
  (notmuch-search (widget-get widget
			      :notmuch-search-terms)
		  notmuch-search-oldest-first
		  nil nil #'notmuch-hello-search-continuation))

(defun notmuch-saved-search-count (search)
  (car (process-lines notmuch-command "count" search)))

(defun notmuch-hello-tags-per-line (widest)
  "Determine how many tags to show per line and how wide they
should be. Returns a cons cell `(tags-per-line width)'."
  (let ((tags-per-line
	 (cond
	  ((integerp notmuch-column-control)
	   (max 1
		(/ (- (window-width) notmuch-hello-indent)
		   ;; Count is 9 wide (8 digits plus space), 1 for the space
		   ;; after the name.
		   (+ 9 1 (max notmuch-column-control widest)))))

	  ((floatp notmuch-column-control)
	   (let* ((available-width (- (window-width) notmuch-hello-indent))
		  (proposed-width (max (* available-width notmuch-column-control) widest)))
	     (floor available-width proposed-width)))

	  (t
	   (max 1
		(/ (- (window-width) notmuch-hello-indent)
		   ;; Count is 9 wide (8 digits plus space), 1 for the space
		   ;; after the name.
		   (+ 9 1 widest)))))))

    (cons tags-per-line (/ (max 1
				(- (window-width) notmuch-hello-indent
				   ;; Count is 9 wide (8 digits plus
				   ;; space), 1 for the space after the
				   ;; name.
				   (* tags-per-line (+ 9 1))))
			   tags-per-line))))

(defun notmuch-hello-insert-tags (tag-alist widest target)
  (let* ((tags-and-width (notmuch-hello-tags-per-line widest))
	 (tags-per-line (car tags-and-width))
	 (widest (cdr tags-and-width))
	 (count 0)
	 (reordered-list (notmuch-hello-reflect tag-alist tags-per-line))
	 ;; Hack the display of the buttons used.
	 (widget-push-button-prefix "")
	 (widget-push-button-suffix "")
	 (found-target-pos nil))
    ;; dme: It feels as though there should be a better way to
    ;; implement this loop than using an incrementing counter.
    (mapc (lambda (elem)
	    ;; (not elem) indicates an empty slot in the matrix.
	    (when elem
	      (let* ((name (car elem))
		     (query (cdr elem))
		     (formatted-name (format "%s " name)))
		(widget-insert (format "%8s "
				       (notmuch-hello-nice-number
					(string-to-number (notmuch-saved-search-count query)))))
		(if (string= formatted-name target)
		    (setq found-target-pos (point-marker)))
		(widget-create 'push-button
			       :notify #'notmuch-hello-widget-search
			       :notmuch-search-terms query
			       formatted-name)
		;; Insert enough space to consume the rest of the
		;; column.  Because the button for the name is `(1+
		;; (length name))' long (due to the trailing space) we
		;; can just insert `(- widest (length name))' spaces -
		;; the column separator is included in the button if
		;; `(equal widest (length name)'.
		(widget-insert (make-string (max 1
						 (- widest (length name)))
					    ? ))))
	    (setq count (1+ count))
	    (if (eq (% count tags-per-line) 0)
		(widget-insert "\n")))
	  reordered-list)

    ;; If the last line was not full (and hence did not include a
    ;; carriage return), insert one now.
    (if (not (eq (% count tags-per-line) 0))
	(widget-insert "\n"))
    found-target-pos))

(defun notmuch-hello-goto-search ()
  "Put point inside the `search' widget."
  (interactive)
  (goto-char notmuch-hello-search-bar-marker))

(defimage notmuch-hello-logo ((:type png :file "notmuch-logo.png")))

(defun notmuch-hello-search-continuation()
  (notmuch-hello-update t))

(defun notmuch-hello-update (&optional no-display)
  "Update the current notmuch view."
  ;; Lazy - rebuild everything.
  (interactive)
  (notmuch-hello no-display))

(defun notmuch-hello-poll-and-update ()
  "Invoke `notmuch-poll' to import mail, then refresh the current view."
  (interactive)
  (notmuch-poll)
  (notmuch-hello-update))


(defvar notmuch-hello-mode-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map widget-keymap)
    (define-key map "v" '(lambda () "Display the notmuch version" (interactive)
                           (message "notmuch version %s" (notmuch-version))))
    (define-key map "?" 'notmuch-help)
    (define-key map "q" 'notmuch-kill-this-buffer)
    (define-key map "=" 'notmuch-hello-update)
    (define-key map "G" 'notmuch-hello-poll-and-update)
    (define-key map (kbd "<C-tab>") 'widget-backward)
    (define-key map "m" 'notmuch-mua-new-mail)
    (define-key map "s" 'notmuch-hello-goto-search)
    map)
  "Keymap for \"notmuch hello\" buffers.")
(fset 'notmuch-hello-mode-map notmuch-hello-mode-map)

(defun notmuch-hello-mode ()
 "Major mode for convenient notmuch navigation. This is your entry portal into notmuch.

Complete list of currently available key bindings:

\\{notmuch-hello-mode-map}"
 (interactive)
 (kill-all-local-variables)
 (use-local-map notmuch-hello-mode-map)
 (setq major-mode 'notmuch-hello-mode
       mode-name "notmuch-hello")
 (run-mode-hooks 'notmuch-hello-mode-hook)
 ;;(setq buffer-read-only t)
)

(defun notmuch-hello-generate-tag-alist ()
  "Return an alist from tags to queries to display in the all-tags section."
  (notmuch-remove-if-not
   #'cdr
   (mapcar (lambda (tag)
	     (cons tag
		   (cond
		    ((functionp notmuch-hello-tag-list-make-query)
		     (concat "tag:" tag " and ("
			     (funcall notmuch-hello-tag-list-make-query tag) ")"))
		    ((stringp notmuch-hello-tag-list-make-query)
		     (concat "tag:" tag " and ("
			     notmuch-hello-tag-list-make-query ")"))
		    (t (concat "tag:" tag)))))
	   (notmuch-remove-if-not
	    (lambda (tag)
	      (not (member tag notmuch-hello-hide-tags)))
	    (process-lines notmuch-command "search-tags")))))

;;;###autoload
(defun notmuch-hello (&optional no-display)
  "Run notmuch and display saved searches, known tags, etc."
  (interactive)

  ; Jump through a hoop to get this value from the deprecated variable
  ; name (`notmuch-folders') or from the default value.
  (if (not notmuch-saved-searches)
    (setq notmuch-saved-searches (notmuch-saved-searches)))

  (if no-display
      (set-buffer "*notmuch-hello*")
    (switch-to-buffer "*notmuch-hello*"))

  (let ((target (if (widget-at)
		   (widget-value (widget-at))
		 (condition-case nil
		     (progn
		       (widget-forward 1)
		       (widget-value (widget-at)))
		   (error nil))))
	(inhibit-read-only t))

    ;; delete all editable widget fields
    (let ((all widget-field-list))
      (mapc 'widget-delete all))

    (erase-buffer)

    (unless (eq major-mode 'notmuch-hello-mode)
      (notmuch-hello-mode))

    (let ((all (overlay-lists)))
      ;; Delete all the overlays.
      (mapc 'delete-overlay (car all))
      (mapc 'delete-overlay (cdr all)))

    (when notmuch-show-logo
      (let ((image notmuch-hello-logo))
	;; The notmuch logo uses transparency. That can display poorly
	;; when inserting the image into an emacs buffer (black logo on
	;; a black background), so force the background colour of the
	;; image. We use a face to represent the colour so that
	;; `defface' can be used to declare the different possible
	;; colours, which depend on whether the frame has a light or
	;; dark background.
	(setq image (cons 'image
			  (append (cdr image)
				  (list :background (face-background 'notmuch-hello-logo-background)))))
	(insert-image image))
      (widget-insert "  "))

    (widget-insert "Welcome to ")
    ;; Hack the display of the links used.
    (let ((widget-link-prefix "")
	  (widget-link-suffix ""))
      (widget-create 'link
		     :notify (lambda (&rest ignore)
			       (browse-url notmuch-hello-url))
		     :help-echo "Visit the notmuch website."
		     "notmuch")
      (widget-insert ". ")
      (widget-insert "You have ")
      (widget-create 'link
		     :notify (lambda (&rest ignore)
			       (notmuch-hello-update))
		     :help-echo "Refresh"
		     (notmuch-hello-nice-number
		      (string-to-number (car (process-lines notmuch-command "count")))))
      (widget-insert " messages.\n"))

    (let ((found-target-pos nil)
	  (final-target-pos nil))
      (let* ((saved-alist
	      ;; Filter out empty saved searches if required.
	      (if notmuch-show-empty-saved-searches
		  notmuch-saved-searches
		(loop for elem in notmuch-saved-searches
		      if (> (string-to-number (notmuch-saved-search-count (cdr elem))) 0)
		      collect elem)))
	     (saved-widest (notmuch-hello-longest-label saved-alist))
	     (alltags-alist (if notmuch-show-all-tags-list (notmuch-hello-generate-tag-alist)))
	     (alltags-widest (notmuch-hello-longest-label alltags-alist))
	     (widest (max saved-widest alltags-widest)))

	(when saved-alist
	  ;; Sort saved searches if required.
	  (when notmuch-saved-search-sort-function
	    (setq saved-alist
		  (funcall notmuch-saved-search-sort-function saved-alist)))
	  (widget-insert "\nSaved searches: ")
	  (widget-create 'push-button
			 :notify (lambda (&rest ignore)
				   (customize-variable 'notmuch-saved-searches))
			 "edit")
	  (widget-insert "\n\n")
	  (setq final-target-pos (point-marker))
	  (let ((start (point)))
	    (setq found-target-pos (notmuch-hello-insert-tags saved-alist widest target))
	    (if found-target-pos
		(setq final-target-pos found-target-pos))
	    (indent-rigidly start (point) notmuch-hello-indent)))

	(widget-insert "\nSearch: ")
	(setq notmuch-hello-search-bar-marker (point-marker))
	(widget-create 'editable-field
		       ;; Leave some space at the start and end of the
		       ;; search boxes.
		       :size (max 8 (- (window-width) notmuch-hello-indent
				       (length "Search: ")))
		       :action (lambda (widget &rest ignore)
				 (notmuch-hello-search (widget-value widget))))
	;; add an invisible space to make `widget-end-of-line' ignore
	;; trailine spaces in the search widget field
	(widget-insert " ")
	(put-text-property (1- (point)) (point) 'invisible t)
	(widget-insert "\n")

	(when notmuch-hello-recent-searches
	  (widget-insert "\nRecent searches: ")
	  (widget-create 'push-button
			 :notify (lambda (&rest ignore)
				   (setq notmuch-hello-recent-searches nil)
				   (notmuch-hello-update))
			 "clear")
	  (widget-insert "\n\n")
	  (let ((start (point))
		(nth 0))
	    (mapc '(lambda (search)
		     (let ((widget-symbol (intern (format "notmuch-hello-search-%d" nth))))
		       (set widget-symbol
			    (widget-create 'editable-field
				       ;; Don't let the search boxes be
				       ;; less than 8 characters wide.
				       :size (max 8
						  (- (window-width)
						     ;; Leave some space
						     ;; at the start and
						     ;; end of the
						     ;; boxes.
						     (* 2 notmuch-hello-indent)
						     ;; 1 for the space
						     ;; before the
						     ;; `[save]' button. 6
						     ;; for the `[save]'
						     ;; button.
						     1 6))
				       :action (lambda (widget &rest ignore)
						 (notmuch-hello-search (widget-value widget)))
				       search))
		       (widget-insert " ")
		       (widget-create 'push-button
				      :notify (lambda (widget &rest ignore)
						(notmuch-hello-add-saved-search widget))
				      :notmuch-saved-search-widget widget-symbol
				      "save"))
		     (widget-insert "\n")
		     (setq nth (1+ nth)))
		  notmuch-hello-recent-searches)
	    (indent-rigidly start (point) notmuch-hello-indent)))

	(when alltags-alist
	  (widget-insert "\nAll tags: ")
	  (widget-create 'push-button
			 :notify (lambda (widget &rest ignore)
				   (setq notmuch-show-all-tags-list nil)
				   (notmuch-hello-update))
			 "hide")
	  (widget-insert "\n\n")
	  (let ((start (point)))
	    (setq found-target-pos (notmuch-hello-insert-tags alltags-alist widest target))
	    (if (not final-target-pos)
		(setq final-target-pos found-target-pos))
	    (indent-rigidly start (point) notmuch-hello-indent)))

	(widget-insert "\n")

	(if (not notmuch-show-all-tags-list)
	    (widget-create 'push-button
			   :notify (lambda (widget &rest ignore)
				     (setq notmuch-show-all-tags-list t)
				     (notmuch-hello-update))
			   "Show all tags")))

      (let ((start (point)))
	(widget-insert "\n\n")
	(widget-insert "Type a search query and hit RET to view matching threads.\n")
	(when notmuch-hello-recent-searches
	  (widget-insert "Hit RET to re-submit a previous search. Edit it first if you like.\n")
	  (widget-insert "Save recent searches with the `save' button.\n"))
	(when notmuch-saved-searches
	  (widget-insert "Edit saved searches with the `edit' button.\n"))
	(widget-insert "Hit RET or click on a saved search or tag name to view matching threads.\n")
	(widget-insert "`=' refreshes this screen. `s' jumps to the search box. `q' to quit.\n")
	(let ((fill-column (- (window-width) notmuch-hello-indent)))
	  (center-region start (point))))

      (widget-setup)

      (when final-target-pos
	(goto-char final-target-pos)
	(unless (widget-at)
	  (widget-forward 1)))

      (unless (widget-at)
	(notmuch-hello-goto-search)))))

(defun notmuch-folder ()
  "Deprecated function for invoking notmuch---calling `notmuch' is preferred now."
  (interactive)
  (notmuch-hello))

;;

(provide 'notmuch-hello)