;;; winum.el --- Navigate windows and frames using numbers.
;;
;; Copyright (c) 2006-2015 Nikolaj Schumacher
;; Copyright (c) 2016 Thomas Chauvot de Beauchêne
;;
;; 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 3 of the License, 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.  If not, see <http://www.gnu.org/licenses/>.
;;
;; Author: Thomas de Beauchêne <thomas.de.beauchene@gmail.com>
;; Version: 2.2.0
;; Keywords: convenience, frames, windows, multi-screen
;; URL: http://github.com/deb0ch/winum.el
;; Created: 2016
;; Compatibility: GNU Emacs 24.x
;; Package-requires: ((cl-lib "0.5") (dash "2.13.0"))
;;
;; This file is NOT part of GNU Emacs.
;;
;;; Commentary:
;;
;; Window numbers for Emacs: Navigate your windows and frames using numbers.
;;
;; This package is an extended and actively maintained version of the
;; https://github.com/nschum/window-numbering.el package by Nikolaj Schumacher,
;; with some ideas and code taken from https://github.com/abo-abo/ace-window.
;;
;; This version brings, among other things, support for number sets across multiple
;; frames, giving the user a smoother experience of multi-screen Emacs.
;;
;;; Code:
;;
;; FIXME: The mode-line's window number is not always up to date in all frames.
;;

(eval-when-compile (require 'cl-lib))
(require 'dash)

;; Configuration variables -----------------------------------------------------

(defgroup winum nil
  "Navigate and manage windows using numbers."
  :group 'convenience)

(defcustom winum-scope 'global
  "Frames affected by a number set."
  :group 'winum
  :type  '(choice
           (const :tag "frame local" frame-local)
           (const :tag "visible frames" visible)
           (const :tag "global" global)))

(defcustom winum-reverse-frame-list nil
  "If t, order frames by reverse order of creation.
Has effect only when `winum-scope' is not 'frame-local."
  :group 'winum
  :type  'boolean)

(defcustom winum-minibuffer-auto-assign 0
  "If non-nil, `winum-mode' automatically assigns this index to the minibuffer."
  :group 'winum
  :type  'sexp)

(defcustom winum-assign-func nil
  "Function called for each window by `winum-mode'.
This is called before automatic assignment begins.  The function should
return an index to have it assigned to the current-window, nil otherwise.

Example: always assign *Calculator* the number 9 and *NeoTree* the number 0:

  (defun my-winum-assign-func ()
    (cond
     ((equal (buffer-name) \"*Calculator*\")
      9)
     ((string-match-p (buffer-name) \".*\\*NeoTree\\*.*\")
      0)
     (t
      nil)))

  (setq winum-assign-func 'my-winum-assign-func)"
  :group 'winum
  :type  'function)

(make-obsolete-variable 'winum-assign-func 'winum-assign-functions "2.0.0")

(defcustom winum-assign-functions nil
  "List of functions called for each window by `winum-mode'.

These functions allow for deterministic assignment of indices to windows. Each
function is called for every window. A function should return the index to be
assigned to a window or nil. The *first* function to output a value for a
given window will determine this window's number.

If the list is empty or if every functions returns nil for a given window winum
will proceed to automatic assignment.

Since this list is meant to allow custom window assignment for *mutiple*
packages at once it should never be directly set, only added to and removed
from.

Example: always assign *Calculator* the number 9, *Flycheck-errors* the number 8
and *NeoTree* the number 0:

  (defun winum-assign-9-to-calculator-8-to-flycheck-errors ()
    (cond
     ((equal (buffer-name) \"*Calculator*\") 9)
     ((equal (buffer-name) \"*Flycheck errors*\") 8)))

  (defun winum-assign-0-to-neotree ()
    (when (string-match-p (buffer-name) \".*\\*NeoTree\\*.*\") 10))

  (add-to-list
    'winum-assign-functions #'winum-assign-9-to-calculator-8-to-flycheck-errors)
  (add-to-list
    'winum-assign-functions #'winum-assign-0-to-neotree)"
  :group 'winum
  :type  '(repeat function))

(defcustom winum-auto-assign-function #'winum--auto-assign
  "The function called to auto-assign indices to windows.

This function is called after `winum-assign-functions' to automatically assign
indices to the remaining windows. It must take in a list of windows and call
the function `winum--assign' to assign an index to each, while avoiding
assigning any indices already taken (stored in `winum--assigned-indices').
Members of this list should be tested for using `equal'.

The default auto-assign function is `winum--auto-assign', which assigns strictly
increasing integers to each window."
  :group 'winum
  :type 'function)

(defcustom winum-auto-setup-mode-line t
  "When nil, `winum-mode' will not display window numbers in the mode-line.
You might want this to be nil if you use a package that already manages window
numbers in the mode-line."
  :group 'winum
  :type  'boolean)

(defcustom winum-mode-line-position 1
  "The position in the mode-line `winum-mode' displays the number."
  :group 'winum
  :type  'integer)

(defcustom winum-mode-line-p #'integerp
  "A predicate that determines when to display a window index on the mode-line.
By default, only integers are displayed."
  :group 'winum
  :type 'function)

(defcustom winum-format " %s "
  "Format string defining how the window number looks like in the mode-line.
This string is passed to the `format' function along with the index."
  :group 'winum
  :type  'string)

(defcustom winum-ignored-buffers '(" *which-key*")
  "List of buffers to ignore when assigning indices."
  :group 'winum
  :type  '(repeat string))

(defcustom winum-ignored-buffers-regexp '()
  "List of regexps for buffer names to ignore when assigning indices.
See Info node `(emacs) Regexps' or Info node `(elisp) Regular Expressions'"
  :group 'winum
  :type '(repeat string)
  :risky t)

(defface winum-face '()
  "Face used for the index in the mode-line."
  :group 'winum)

(defvar winum-base-map
  (let ((map (make-sparse-keymap)))
    (define-key map (kbd "`") 'winum-select-window-by-index)
    (define-key map (kbd "²") 'winum-select-window-by-index)
    (define-key map (kbd "0") 'winum-select-window-0-or-10)
    (define-key map (kbd "1") 'winum-select-window-1)
    (define-key map (kbd "2") 'winum-select-window-2)
    (define-key map (kbd "3") 'winum-select-window-3)
    (define-key map (kbd "4") 'winum-select-window-4)
    (define-key map (kbd "5") 'winum-select-window-5)
    (define-key map (kbd "6") 'winum-select-window-6)
    (define-key map (kbd "7") 'winum-select-window-7)
    (define-key map (kbd "8") 'winum-select-window-8)
    (define-key map (kbd "9") 'winum-select-window-9)
    map)
  "Keymap to be used under the prefix provided by `winum-keymap-prefix'.")

(defvar winum-mode-map (let ((map (make-sparse-keymap)))
                         (define-key map (kbd "C-x w") winum-base-map)
                         map)
  "Keymap used for `winum-mode'.")

;; Internal variables ----------------------------------------------------------

(defvar winum--max-frames 16
  "Maximum number of frames that can be numbered.")

(defvar winum--assigned-indices nil
  "List of indices that have already been assigned by `winum-assign-functions'.")

(defvar winum--window-table nil
  "Hash table with indices as keys and windows as values.
Used internally by winum to get a window provided an index.")

(defvar winum--index-table nil
  "Hash table with windows as keys and indices as values.
Used internally by winum to get an index provided a window.")

(defvar winum--frames-table nil
  "Table linking windows to indices and indices to windows for each frame.

Used only when `winum-scope' is 'frame-local to keep track of
separate window index sets in every frame.

It is a hash table using Emacs frames as keys and cons of the form
\(`winum--window-table' . `winum--index-table')
as values.

To get a window given an index, use the `car' of a value.
To get an index given a window, use the `cdr' of a value.

Such a structure allows for per-frame bidirectional fast access.")

(defvar winum--mode-line-segment
  '(:eval (let ((index (winum-get-index)))
            (when (funcall winum-mode-line-p index)
              (propertize (format winum-format index) 'face 'winum-face))))
  "What is pushed into `mode-line-format' when setting it up automatically.")

(defvar winum--last-used-scope winum-scope
  "Tracks the last used `winum-scope'.
Needed to detect scope changes at runtime.")

;; Interactive functions -------------------------------------------------------

;;;###autoload
(define-minor-mode winum-mode
  "A minor mode that allows for managing windows based on window numbers."
  :lighter nil
  :global t
  (if winum-mode
      (winum--init)
    (winum--deinit)))

;;;###autoload
(defun winum-select-window-0-or-10 (&optional arg)
  "Jump to window 0, or window 10 if 0 is not assigned.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (let ((n (if (winum-get-window-by-index 0) 0 10)))
    (if arg
        (winum-delete-window-by-index n)
      (winum-select-window-by-index n))))

;;;###autoload
(defun winum-select-window-0 (&optional arg)
  "Jump to window 0.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 0)
    (winum-select-window-by-index 0)))

;;;###autoload
(defun winum-select-window-1 (&optional arg)
  "Jump to window 1.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 1)
    (winum-select-window-by-index 1)))

;;;###autoload
(defun winum-select-window-2 (&optional arg)
  "Jump to window 2.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 2)
    (winum-select-window-by-index 2)))

;;;###autoload
(defun winum-select-window-3 (&optional arg)
  "Jump to window 3.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 3)
    (winum-select-window-by-index 3)))

;;;###autoload
(defun winum-select-window-4 (&optional arg)
  "Jump to window 4.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 4)
    (winum-select-window-by-index 4)))

;;;###autoload
(defun winum-select-window-5 (&optional arg)
  "Jump to window 5.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 5)
    (winum-select-window-by-index 5)))

;;;###autoload
(defun winum-select-window-6 (&optional arg)
  "Jump to window 6.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 6)
    (winum-select-window-by-index 6)))

;;;###autoload
(defun winum-select-window-7 (&optional arg)
  "Jump to window 7.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 7)
    (winum-select-window-by-index 7)))

;;;###autoload
(defun winum-select-window-8 (&optional arg)
  "Jump to window 8.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 8)
    (winum-select-window-by-index 8)))

;;;###autoload
(defun winum-select-window-9 (&optional arg)
  "Jump to window 9.
If prefix ARG is given, delete the window instead of selecting it."
  (interactive "P")
  (if arg
      (winum-delete-window-by-index 9)
    (winum-select-window-by-index 9)))

;;;###autoload
(defun winum-select-window-by-index (&optional arg)
  "Select window whose index is specified by ARG.
There are several ways to provide the value:
- if called from elisp with an argument, use it.
- if called from elisp without an argument, use current window.
- if called interactively with a numeric prefix argument, use it.
- if called interactively with the default prefix argument, use current window.
- if called interactively and no argument is provided, read from minibuffer."
  (interactive "P")
  (let* ((i (if (called-interactively-p 'any)
                (cond
                 ((integerp arg) arg)
                 (arg (winum-get-index))
                 (t (read--expression "Window: ")))
              (or arg (winum-get-index))))
         (w (winum-get-window-by-index i)))
    (if w
        (winum--switch-to-window w)
      (user-error "No window with index %S" i))))

;;;###autoload
(defun winum-delete-window-by-index (&optional arg)
  "Delete window whose index is specified by ARG.
There are several ways to provide the value:
- if called from elisp with an argument, use it.
- if called from elisp without an argument, use current window.
- if called interactively with a numeric prefix argument, use it.
- if called interactively with the default prefix argument, use current window.
- if called interactively and no argument is provided, read from minibuffer."
  (interactive "P")
  (let* ((i (if (called-interactively-p 'any)
                (cond
                 ((integerp arg) arg)
                 (arg (winum-get-index))
                 (t (read--expression "Window: ")))
              (or arg (winum-get-index))))
         (w (winum-get-window-by-index i)))
    (if w
        (delete-window w)
      (user-error "No window with index %S" i))))

;; Public API ------------------------------------------------------------------

;;;###autoload
(defun winum-set-keymap-prefix (prefix)
  "Set key bindings prefix for `winum-keymap' based on `winum-base-map'.
This function overrides the value of `winum-keymap', so you
should call it before customization of `winum-keymap' and/or
after customization of `winum-base-map'.
PREFIX must be a key sequence, like the ones returned by `kbd'."
  (setq winum-keymap (when prefix (let ((map (make-sparse-keymap)))
                                    (define-key map prefix winum-base-map)
                                    map)))
  (setcdr (assoc 'winum-mode minor-mode-map-alist)
          winum-keymap))

;;;###autoload
(defun winum-get-window-by-index (index)
  "Return window INDEX if exists, nil otherwise."
  (let ((window-table (winum--get-window-table)))
    (gethash index window-table)))

;;;###autoload
(defun winum-get-index (&optional window)
  "Get the index of WINDOW or the current window."
  (let ((w (or window (selected-window))))
    (gethash w (winum--get-index-table))))

;; For backwards compatibility
;;;###autoload
(defun winum-get-number-string (&optional window)
  "Get the current or specified window's current number as a propertized string.
WINDOW: if specified, the window of which we want to know the number.
        If not specified, the number of the currently selected window is
        returned."
  (let* ((n (winum-get-index window))
         (s (if (funcall winum-mode-line-p n)
                (format "%s" n)
              "")))
    (propertize s 'face 'winum-face)))

;; Internal functions ----------------------------------------------------------

(defun winum--init ()
  "Initialize winum-mode."
  (if (eq winum-scope 'frame-local)
      (setq winum--frames-table (make-hash-table :size winum--max-frames))
    (setq winum--window-table (make-hash-table :test 'equal)
          winum--index-table (make-hash-table :test 'equal)))
  (when winum-auto-setup-mode-line
    (winum--install-mode-line))
  (add-hook 'minibuffer-setup-hook 'winum--update)
  (add-hook 'window-configuration-change-hook 'winum--update)
  (dolist (frame (frame-list))
    (select-frame frame)
    (winum--update)))

(defun winum--deinit ()
  "Actions performed when turning off winum-mode."
  (when winum-auto-setup-mode-line
    (winum--clear-mode-line))
  (remove-hook 'minibuffer-setup-hook 'winum--update)
  (remove-hook 'window-configuration-change-hook 'winum--update)
  (setq winum--frames-table nil))

(defun winum--install-mode-line (&optional position)
  "Install the window index from `winum-mode' to the mode-line.
POSITION: position in the mode-line."
  (let ((mode-line (default-value 'mode-line-format))
        res)
    (dotimes (i (min (or position winum-mode-line-position 1)
                     (length mode-line)))
      (push (pop mode-line) res))
    (unless (equal (car mode-line) winum--mode-line-segment)
      (push winum--mode-line-segment res))
    (while mode-line
      (push (pop mode-line) res))
    (let ((nres (nreverse res)))
      (setq mode-line-format nres)
      (setq-default mode-line-format nres)))
  (force-mode-line-update t))

(defun winum--clear-mode-line ()
  "Remove the window index of `winum-mode' from the mode-line."
  (let ((mode-line (default-value 'mode-line-format))
        res)
    (while mode-line
      (let ((item (pop mode-line)))
        (unless (equal item winum--mode-line-segment)
          (push item res))))
    (let ((nres (nreverse res)))
      (setq mode-line-format nres)
      (setq-default mode-line-format nres)))
  (force-mode-line-update t))

(defun winum--update ()
  "Update window indices."
  (let ((windows (winum--window-list)))
    (setq winum--assigned-indices nil)
    (clrhash (winum--get-window-table))
    (clrhash (winum--get-index-table))
    (when winum-assign-functions
      (--each (-copy windows) (when (winum--try-to-find-custom-index it)
                                (setq windows (delq it windows)))))
    (when (and winum-minibuffer-auto-assign
               (active-minibuffer-window)
               (not (winum-get-window-by-index winum-minibuffer-auto-assign)))
      (winum--assign (active-minibuffer-window) winum-minibuffer-auto-assign)
      (push winum-minibuffer-auto-assign winum--assigned-indices))
    ;; Auto-assign remaining windows
    (when windows
      (funcall winum-auto-assign-function windows))))

(defun winum--auto-assign (windows)
  "The default auto-assign function for assigning indices to windows.
Takes in the list of windows WINDOWS and uses `winum--assign' to assign
increasing integers to it."
  (let ((index 1))
    (dolist (w windows)
      (while (member index winum--assigned-indices)
        (setq index (1+ index)))
      (winum--assign w index)
      (setq index (1+ index)))))

(defun winum--try-to-find-custom-index (window)
  "Try to find and assign a custom index for WINDOW.
Do so by trying every function in `winum-assign-functions' and assign the
*first* non nil value.
When multiple functions assign an index to a window log a warning and use the
first index anyway."
  (with-selected-window window
    (with-current-buffer (window-buffer window)
      (when-let* ((inds (->> winum-assign-functions
                             (--map (cons it (funcall it)))
                             (--remove (null (cdr it)))))
                  (ind (-> inds (cl-first) (cdr))))
        (when (> (length inds) 1)
          (message "Winum conflict - window %s was assigned an index by multiple custom assign functions: '%s'"
                   window (--map (format "%s -> %S" (car it) (cdr it)) inds)))
        (winum--assign window ind)
        (push ind winum--assigned-indices)))))

(defun winum--assign (window index)
  "Assign to window WINDOW the index INDEX.
Returns the assigned index, or nil on error."
  (if (gethash index (winum--get-window-table))
      (progn
        (message "Index %S already assigned to %s, can't assign to %s"
                 index (gethash index (winum--get-window-table)) window)
        nil)
    (puthash index window (winum--get-window-table))
    (puthash window index (winum--get-index-table))
    index))

(defun winum--window-list ()
  "Return a list of interesting windows."
  (cl-remove-if
   #'winum--ignore-window-p
   (cl-case winum-scope
     (global
      (cl-mapcan 'winum--list-windows-in-frame
                 (if winum-reverse-frame-list
                     (frame-list)
                   (nreverse (frame-list)))))
     (visible
      (cl-mapcan 'winum--list-windows-in-frame
                 (if winum-reverse-frame-list
                     (visible-frame-list)
                   (nreverse (visible-frame-list)))))
     (frame-local
      (winum--list-windows-in-frame))
     (t
      (user-error "Invalid `winum-scope': %S" winum-scope)))))

(defun winum--ignore-window-p (window)
  "Non-nil if WINDOW should be ignored for indexing."
  (let ((f (window-frame window)))
    (or (not (and (frame-live-p f)
                  (frame-visible-p f)))
        (string= "initial_terminal" (terminal-name f))
        (member (buffer-name (window-buffer window)) winum-ignored-buffers)
        (cl-some
         (lambda (regex) (string-match regex (buffer-name (window-buffer window))))
         winum-ignored-buffers-regexp))))

(defun winum--list-windows-in-frame (&optional f)
  "List windows in frame F using natural Emacs ordering."
  (window-list f 0 (frame-first-window f)))

(defun winum--get-window-table ()
  "Return the window table used to get a window given an index.
This hashtable is not stored the same way depending on the value of
`winum-scope'."
  (winum--check-for-scope-change)
  (winum--check-frames-table)
  (if (eq winum-scope 'frame-local)
      (car (gethash (selected-frame) winum--frames-table))
    winum--window-table))

(defun winum--get-index-table ()
  "Return the index hashtable used to get an index given a window.
This hashtable is not stored the same way depending on the value of
`winum-scope'."
  (winum--check-for-scope-change)
  (winum--check-frames-table)
  (if (eq winum-scope 'frame-local)
      (cdr (gethash (selected-frame) winum--frames-table))
    winum--index-table))

(defun winum--check-frames-table ()
  "Make sure `winum--frames-table' exists and is correctly equipped.
Verifies 2 things (when `winum-scope' is frame local):
 * When `winum-scope' is frame-local for the first time it may be necessary to
   instantiate `winum--frames-table'.
 * A table entry for the current frame must be made when the frame has just
   been created."
  (when (eq winum-scope 'frame-local)
    (unless winum--frames-table
      (setq winum--frames-table (make-hash-table :size winum--max-frames)))
    (unless (gethash (selected-frame) winum--frames-table)
      (puthash (selected-frame) (cons
                                 (make-hash-table :test 'equal)
                                 (make-hash-table :test 'equal))
               winum--frames-table)
      (winum--update))))

(defun winum--switch-to-window (window)
  "Switch to the window WINDOW and switch input focus if on a different frame."
  (let ((frame (window-frame window)))
    (when (and (frame-live-p frame)
               (not (eq frame (selected-frame))))
      (select-frame-set-input-focus frame))
    (if (window-live-p window)
        (select-window window)
      (error "Got a dead window %S" window))))

(defun winum--check-for-scope-change ()
  "Check whether the `winum-scope' has been changed.
If a change is detected run `winum--init' to reinitialize all
internal data structures according to the new scope."
  (unless (eq winum-scope winum--last-used-scope)
    (setq winum--last-used-scope winum-scope)
    (winum--init)))

(defun winum--remove-deleted-frame-from-frames-table (frame)
  "Remove FRAME from `winum--frames-table' after it was deleted."
  (when winum--frames-table
    (remhash frame winum--frames-table)))

(add-hook 'delete-frame-functions #'winum--remove-deleted-frame-from-frames-table)

(provide 'winum)

;;; winum.el ends here