config.phundrak.com/docs/emacs/keybinding-managers.org

#+title: Emacs — Keybinding Managers
#+setupfile: ../headers
#+property: header-args:emacs-lisp  :mkdirp yes :lexical t :exports code
#+property: header-args:emacs-lisp+ :tangle ~/.config/emacs/lisp/keybinding-managemers.el
#+property: header-args:emacs-lisp+ :mkdirp yes :noweb no-export

* Keybinding Managers
** Which-key
Which key is, I think, one of my favorite quality of life package.
When you begin a keybind, Emacs will show you all keybinds you can
follow the first one with in order to form a full keychord. Very
useful when you have a lot of keybinds and don’t remember exactly what
is what.
#+begin_src emacs-lisp
(use-package which-key
  :straight (:build t)
  :defer t
  :init (which-key-mode)
  :diminish which-key-mode
  :config
  (setq which-key-idle-delay 1))
#+end_src

** General
General is an awesome package for managing keybindings. Not only is it
oriented towards keychords by default (which I love), but it also
provides some integration with evil so that we can declare keybindings
for certain states only! This is a perfect replacement for ~define-key~,
~evil-define-key~, and any other function for defining keychords. And it
is also possible to declare a prefix for my keybindings! By default,
all keybinds will be prefixed with ~SPC~ and keybinds related to a
specific mode (often major modes) will be prefixed by a comma ~,~ (and
by ~C-SPC~ and ~M-m~ respectively when in ~insert-mode~ or ~emacs-mode~). You
can still feel some influence from my Spacemacs years here.
#+begin_src emacs-lisp
(use-package general
  :straight (:build t)
  :init
  (general-auto-unbind-keys)
  :config
  (general-create-definer phundrak/undefine
    :keymaps 'override
    :states '(normal emacs))
  (general-create-definer phundrak/evil
    :states '(normal))
  (general-create-definer phundrak/leader-key
    :states '(normal insert visual emacs)
    :keymaps 'override
    :prefix "SPC"
    :global-prefix "C-SPC")
  (general-create-definer phundrak/major-leader-key
    :states '(normal insert visual emacs)
    :keymaps 'override
    :prefix ","
    :global-prefix "M-m"))
#+end_src

** Evil
Evil emulates most of vim’s keybinds, because let’s be honest here,
they are much more comfortable than Emacs’.
#+begin_src emacs-lisp
(use-package evil
  :straight (:build t)
  :after (general)
  :init
  (setq evil-want-integration t
        evil-want-keybinding nil
        evil-want-C-u-scroll t
        evil-want-C-i-jump nil)
  (require 'evil-vars)
  (evil-set-undo-system 'undo-tree)
  :config
  <<evil-undefine-keys>>
  <<evil-bepo>>
  (evil-mode 1)
  (setq evil-want-fine-undo t) ; more granular undo with evil
  (evil-set-initial-state 'messages-buffer-mode 'normal)
  (evil-set-initial-state 'dashboard-mode 'normal))
#+end_src

I want to undefine some default keybinds of Evil because it does not
match my workflow. Namely, I use the space key and the comma as
leaders for my keybinds, and I’m way too used to Emacs’ ~C-t~, ~C-a~, ~C-e~,
and ~C-y~.
#+name: evil-undefine-keys
#+begin_src emacs-lisp :tangle no
(evil-global-set-key 'motion "t" 'evil-next-visual-line)
(evil-global-set-key 'motion "s" 'evil-previous-visual-line)

(general-define-key
 :keymaps 'evil-motion-state-map
 "SPC" nil
 ","   nil)
(general-define-key
 :keymaps 'evil-insert-state-map
 "C-t" nil)
(general-define-key
 :keymaps 'evil-insert-state-map
 "U"   nil
 "C-a" nil
 "C-y" nil
 "C-e" nil)
#+end_src

Something else that really bugs me is I use the bépo layout, which is
not at all like the qwerty layout. For instance, ~hjkl~ becomes ~ctsr~.
Thus, I need some bépo-specific changes.
#+name: evil-bepo
#+begin_src emacs-lisp :tangle no
(dolist (key '("c" "C" "t" "T" "s" "S" "r" "R" "h" "H" "j" "J" "k" "K" "l" "L"))
  (general-define-key :states 'normal key nil))

(general-define-key
 :states 'motion
 "h" 'evil-replace
 "H" 'evil-replace-state
 "j" 'evil-find-char-to
 "J" 'evil-find-char-to-backward
 "k" 'evil-substitute
 "K" 'evil-smart-doc-lookup
 "l" 'evil-change
 "L" 'evil-change-line

 "c" 'evil-backward-char
 "C" 'evil-window-top
 "t" 'evil-next-visual-line
 "T" 'evil-join
 "s" 'evil-previous-visual-line
 "S" 'evil-lookup
 "r" 'evil-forward-char
 "R" 'evil-window-bottom)
#+end_src

This package enables and integrates Evil into a lot of different
modes, such as org-mode, dired, mu4e, etc. Again, I need some
additional code compared to most people due to the bépo layout.
#+begin_src emacs-lisp
(use-package evil-collection
  :after evil
  :straight (:build t)
  :config
  ;; bépo conversion
  (defun my/bépo-rotate-evil-collection (_mode mode-keymaps &rest _rest)
    (evil-collection-translate-key 'normal mode-keymaps
      ;; bépo ctsr is qwerty hjkl
      "c" "h"
      "t" "j"
      "s" "k"
      "r" "l"
      ;; add back ctsr
      "h" "c"
      "j" "t"
      "k" "s"
      "l" "r"))
  (add-hook 'evil-collection-setup-hook #'my/bépo-rotate-evil-collection)
  (evil-collection-init))
#+end_src

~undo-tree~ is my preferred way of undoing and redoing stuff. The main
reason is it doesn’t create a linear undo/redo history, but rather a
complete tree you can navigate to see your complete editing history.
One of the two obvious things to do are to tell Emacs to save all its
undo history files in a dedicated directory, otherwise we’d risk
littering all of our directories. The second thing is to simply
globally enable its mode.
#+begin_src emacs-lisp
(use-package undo-tree
  :defer t
  :straight (:build t)
  :custom
  (undo-tree-history-directory-alist
   `(("." . ,(expand-file-name (file-name-as-directory "undo-tree-hist")
                               user-emacs-directory))))
  :init
  (global-undo-tree-mode)
  :config
  <<undo-tree-ignore-text-properties>>
  <<undo-tree-compress-files>>
  (setq undo-tree-visualizer-diff       t
        undo-tree-visualizer-timestamps t
        undo-tree-auto-save-history     t
        undo-tree-enable-undo-in-region t
        undo-limit        (* 800 1024)
        undo-strong-limit (* 12 1024 1024)
        undo-outer-limit  (* 128 1024 1024)))
#+end_src

An interesting behaviour from DoomEmacs is to compress the history
files with ~zstd~ when it is present on the system. Not only do we enjoy
much smaller files (according to DoomEmacs, we get something like 80%
file savings), Emacs can load them much faster than the regular files.
Sure, it uses more CPU time uncompressing these files, but it’s
insignificant, and it’s still faster than loading a heavier file.
#+name: undo-tree-compress-files
#+begin_src emacs-lisp :tangle no
(when (executable-find "zstd")
  (defun my/undo-tree-append-zst-to-filename (filename)
    "Append .zst to the FILENAME in order to compress it."
    (concat filename ".zst"))
  (advice-add 'undo-tree-make-history-save-file-name
              :filter-return
              #'my/undo-tree-append-zst-to-filename))
#+end_src

** Hydra
[[https://github.com/abo-abo/hydra][Hydra]] is a simple menu creator for keybindings.
#+begin_src emacs-lisp
(use-package hydra
  :straight (:build t)
  :defer t)
#+end_src