;;; notmuch-jump.el --- User-friendly shortcut keys  -*- lexical-binding: t -*-
;;
;; Copyright © Austin Clements
;;
;; 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 <https://www.gnu.org/licenses/>.
;;
;; Authors: Austin Clements <aclements@csail.mit.edu>
;;          David Edmondson <dme@dme.org>

;;; Code:

(require 'notmuch-lib)
(require 'notmuch-hello)

;;;###autoload
(defun notmuch-jump-search ()
  "Jump to a saved search by shortcut key.

This prompts for and performs a saved search using the shortcut
keys configured in the :key property of `notmuch-saved-searches'.
Typically these shortcuts are a single key long, so this is a
fast way to jump to a saved search from anywhere in Notmuch."
  (interactive)
  ;; Build the action map
  (let (action-map)
    (dolist (saved-search notmuch-saved-searches)
      (let* ((saved-search (notmuch-hello-saved-search-to-plist saved-search))
	     (key (plist-get saved-search :key)))
	(when key
	  (let ((name (plist-get saved-search :name))
		(query (plist-get saved-search :query))
		(oldest-first
		 (cl-case (plist-get saved-search :sort-order)
		   (newest-first nil)
		   (oldest-first t)
		   (otherwise (default-value 'notmuch-search-oldest-first)))))
	    (push (list key name
			(cond
			 ((eq (plist-get saved-search :search-type) 'tree)
			  (lambda () (notmuch-tree query)))
			 ((eq (plist-get saved-search :search-type) 'unthreaded)
			  (lambda () (notmuch-unthreaded query)))
			 (t
			  (lambda () (notmuch-search query oldest-first)))))
		  action-map)))))
    (setq action-map (nreverse action-map))
    (if action-map
	(notmuch-jump action-map "Search: ")
      (error "To use notmuch-jump, %s"
	     "please customize shortcut keys in notmuch-saved-searches."))))

(defface notmuch-jump-key
  '((t :inherit minibuffer-prompt))
  "Default face used for keys in `notmuch-jump' and related."
  :group 'notmuch-faces)

(defvar notmuch-jump--action nil)

;;;###autoload
(defun notmuch-jump (action-map prompt)
  "Interactively prompt for one of the keys in ACTION-MAP.

Displays a summary of all bindings in ACTION-MAP in the
minibuffer, reads a key from the minibuffer, and performs the
corresponding action.  The prompt can be canceled with C-g or
RET.  PROMPT must be a string to use for the prompt.  PROMPT
should include a space at the end.

ACTION-MAP must be a list of triples of the form
  (KEY LABEL ACTION)
where KEY is a key binding, LABEL is a string label to display in
the buffer, and ACTION is a nullary function to call.  LABEL may
be null, in which case the action will still be bound, but will
not appear in the pop-up buffer."
  (let* ((items (notmuch-jump--format-actions action-map))
	 ;; Format the table of bindings and the full prompt
	 (table
	  (with-temp-buffer
	    (notmuch-jump--insert-items (window-body-width) items)
	    (buffer-string)))
	 (full-prompt
	  (concat table "\n\n"
		  (propertize prompt 'face 'minibuffer-prompt)))
	 ;; By default, the minibuffer applies the minibuffer face to
	 ;; the entire prompt.  However, we want to clearly
	 ;; distinguish bindings (which we put in the prompt face
	 ;; ourselves) from their labels, so disable the minibuffer's
	 ;; own re-face-ing.
	 (minibuffer-prompt-properties
	  (notmuch-plist-delete
	   (copy-sequence minibuffer-prompt-properties)
	   'face))
	 ;; Build the keymap with our bindings
	 (minibuffer-map (notmuch-jump--make-keymap action-map prompt))
	 ;; The bindings save the the action in notmuch-jump--action
	 (notmuch-jump--action nil))
    ;; Read the action
    (read-from-minibuffer full-prompt nil minibuffer-map)
    ;; If we got an action, do it
    (when notmuch-jump--action
      (funcall notmuch-jump--action))))

(defun notmuch-jump--format-actions (action-map)
  "Format the actions in ACTION-MAP.

Returns a list of strings, one for each item with a label in
ACTION-MAP.  These strings can be inserted into a tabular
buffer."
  ;; Compute the maximum key description width
  (let ((key-width 1))
    (pcase-dolist (`(,key ,_desc) action-map)
      (setq key-width
	    (max key-width
		 (string-width (format-kbd-macro key)))))
    ;; Format each action
    (mapcar (pcase-lambda (`(,key ,desc))
	      (setq key (format-kbd-macro key))
	      (concat (propertize key 'face 'notmuch-jump-key)
		      (make-string (- key-width (length key)) ? )
		      " " desc))
	    action-map)))

(defun notmuch-jump--insert-items (width items)
  "Make a table of ITEMS up to WIDTH wide in the current buffer."
  (let* ((nitems (length items))
	 (col-width (+ 3 (apply #'max (mapcar #'string-width items))))
	 (ncols (if (> (* col-width nitems) width)
		    (max 1 (/ width col-width))
		  ;; Items fit on one line.  Space them out
		  (setq col-width (/ width nitems))
		  (length items))))
    (while items
      (dotimes (col ncols)
	(when items
	  (let ((item (pop items)))
	    (insert item)
	    (when (and items (< col (- ncols 1)))
	      (insert (make-string (- col-width (string-width item)) ? ))))))
      (when items
	(insert "\n")))))

(defvar notmuch-jump-minibuffer-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map minibuffer-local-map)
    ;; Make this like a special-mode keymap, with no self-insert-command
    (suppress-keymap map)
    (define-key map (kbd "DEL") 'exit-minibuffer)
    map)
  "Base keymap for notmuch-jump's minibuffer keymap.")

(defun notmuch-jump--make-keymap (action-map prompt)
  "Translate ACTION-MAP into a minibuffer keymap."
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map notmuch-jump-minibuffer-map)
    (pcase-dolist (`(,key ,_name ,fn) action-map)
      (when (= (length key) 1)
	(define-key map key
	  (lambda ()
	    (interactive)
	    (setq notmuch-jump--action fn)
	    (exit-minibuffer)))))
    ;; By doing this in two passes (and checking if we already have a
    ;; binding) we avoid problems if the user specifies a binding which
    ;; is a prefix of another binding.
    (pcase-dolist (`(,key ,_name ,_fn) action-map)
      (when (> (length key) 1)
	(let* ((key (elt key 0))
	       (keystr (string key))
	       (new-prompt (concat prompt (format-kbd-macro keystr) " "))
	       (action-submap nil))
	  (unless (lookup-key map keystr)
	    (pcase-dolist (`(,k ,n ,f) action-map)
	      (when (= key (elt k 0))
		(push (list (substring k 1) n f) action-submap)))
	    ;; We deal with backspace specially
	    (push (list (kbd "DEL")
			"Backup"
			(apply-partially #'notmuch-jump action-map prompt))
		  action-submap)
	    (setq action-submap (nreverse action-submap))
	    (define-key map keystr
	      (lambda ()
		(interactive)
		(setq notmuch-jump--action
		      (apply-partially #'notmuch-jump
				       action-submap
				       new-prompt))
		(exit-minibuffer)))))))
    map))

(provide 'notmuch-jump)

;;; notmuch-jump.el ends here