#+TITLE: Editor
#+AUTHOR: Christopher James Hayward
#+EMAIL: chris@chrishayward.xyz

#+PROPERTY: header-args:emacs-lisp :tangle editor.el :comments org
#+PROPERTY: header-args            :results silent :eval no-export :comments org

#+OPTIONS: num:nil toc:nil todo:nil tasks:nil tags:nil
#+OPTIONS: skip:nil author:nil email:nil creator:nil timestamp:nil

Configuration and imrpovements to the editor experience within Emacs. *Vim*[fn:1] user? This module extends the keybindings by implementing *Evil*[fn:2]. *Doom*[fn:3], *Spacemacs*[fn:4]? The all powerful leader key is also implemented right here!

* Keys

Offer =ESC= as an alternative to quit (most) prompts, instead of the default =C-g=.

#+begin_src emacs-lisp
(global-set-key (kbd "<escape>") 'keyboard-escape-quit)
#+end_src

** Completions

Emacs has *a lot of keybindings*, sometimes it's useful to just start mashing keys and see what happens. This behaviour exists in a third-party package called *which-key*[fn:5]. It displays the current incomplete keybinding input in a mini-buffer, showing available completion options with their corresponding keybindings.

#+begin_src emacs-lisp
(use-package which-key
  :diminish which-key-mode
  :custom (which-key-idle-delay dotfiles/idle)
  :config (which-key-mode))
#+end_src

** Turn Emacs into Vim

Emacs has *some strange default keybindings*, they're not like any other editor you've likely ever used. To overcome this nearly show-stopping hurdle, we turn Emacs into Vim[fn:1] with *Evil Mode - The Extensible VI Layer for Emacs*[fn:2].

#+begin_src emacs-lisp
(use-package evil
  :custom (evil-want-integration t)  ;; Required for `evil-collection'.
          (evil-want-keybinding nil) ;; Same as above
  :config (evil-mode +1))
#+end_src

While covering substantial ground towards our goal, the default keybindings implemented in *Evil*[fn:2] alone are *lacking* compared to what you would expect from *Vim*[fn:1]. There's, of course, a communicated curated package *evil-collection*[fn:6] that does a much better job implementing the proper keybindings.

#+begin_src emacs-lisp
(use-package evil-collection
  :after evil
  :config (evil-collection-init))
#+end_src

*** Surround text

Whether it's on purpose, or more likely, you forgot an opening brace; *evil-surround*[fn:7] surrounds highlighted blocks of text with functions, quotations, and any symbol you can input.

#+begin_src emacs-lisp
(use-package evil-surround
  :after evil
  :config (global-evil-surround-mode 1))
#+end_src

*** Toggle comments

When you're in deep with errors, or just trying some new code, it's useful to be able to toggle large comment sections in a language agnostic manner. In comes *evil-nerd-commentor*[fn:8], with a custom binding to =M-;=. What is =M-= ? Typically that refers to the =Alt= key, called the =Meta= key in Emacs. 

#+begin_src emacs-lisp
(use-package evil-nerd-commenter
  :after evil
  :bind ("M-;" . evilnc-comment-or-uncomment-lines))
#+end_src

** Implementing the leader key

If you're like me and started with Emacs using a framework like *Doom*[fn:3] or *Spacemacs*[fn:4], you probably have a lot of muscle memory for using =SPC= as a leader key. This behaviour is actually not difficult to implement, especially when using *general.el*[fn:9].

+ =SPC= in most situations as a prefix key
+ =C-SPC= when using the [[file:desktop.org][Desktop]] module within an =X= buffer

#+begin_src emacs-lisp
(use-package general
  :after evil
  :config
  (general-create-definer dotfiles/leader
    :states '(normal motion)
    :keymaps 'override
    :prefix dotfiles/leader-key
    :global-prefix dotfiles/leader-key-global))
#+end_src

** Transient bindings

Create transient keybindings with a shared prefix through *Hydra*[fn:10]. This is also used by a number of third-party packages as a completion system. An implementation example is available in the *Font* section of the [[file:interface.org][Interface]] module.

+ Defer loading for performance

#+begin_src emacs-lisp
(use-package hydra
  :defer t)
#+end_src

Place runtime tweaks behind =SPC t=

#+begin_src emacs-lisp
(dotfiles/leader
  "t" '(:ignore t :which-key "Tweaks"))
#+end_src

** Cherry picked shortcuts

Implement shortcut bindings, cherry picked from *Doom*[fn:3].

+ Close buffers with =SPC c=
+ Find files with =SPC , (comma)=

#+begin_src emacs-lisp
(dotfiles/leader
  "." '(find-file :which-key "Files")
  "c" '(kill-buffer-and-window :which-key "Close"))
#+end_src

*** Managing windows

Window management with =SPC w=

+ Swap with =w=
+ Close with =c=
+ Move with =h,j,k,l=
+ Split with =s - <motion>=

#+begin_src emacs-lisp
(dotfiles/leader
  "w" '(:ignore t :which-key "Window")
  "ww" '(window-swap-states :which-key "Swap")
  "wc" '(delete-window :which-key "Close")
  "wh" '(windmove-left :which-key "Left")
  "wj" '(windmove-down :which-key "Down")
  "wk" '(windmove-up :which-key "Up")
  "wl" '(windmove-right :which-key "Right")
  "ws" '(:ignore t :which-key "Split")
  "wsj" '(split-window-below :which-key "Down")
  "wsl" '(split-window-right :which-key "Right"))
#+end_src

*** Quitting Emacs

Quit Emacs with =SPC q=

  + Save and quit =q=
  + Quit without saving =w=
  + Exit the Frame (daemon) =f=

#+begin_src emacs-lisp
(dotfiles/leader
  "q" '(:ignore t :which-key "Quit")
  "qq" '(save-buffers-kill-emacs :which-key "Save")
  "qw" '(kill-emacs :which-key "Now")
  "qf" '(delete-frame :which-key "Frame"))
#+end_src

* Help

Use the built-in ~describe-*~ functionality of Emacs to quickly access documentation for packages, variables, and functions. 

+ Run helper functions with =SPC h=
  * Packages =p=
  * Variables =v=
  * Functions =f=

#+begin_src emacs-lisp
(dotfiles/leader
  "h" '(:ignore t :which-key "Help")
  "hp" '(describe-package :which-key "Package")
  "hv" '(describe-variable :which-key "Variable")
  "hf" '(describe-function :which-key "Function"))
#+end_src

* Files

Emacs has some really cool built-in packages, *Dired*[fn:11] is one of them. It's not perfect out of the box though, there's work to do.

** Navigating to the current directory

I don't want to have to press =RET= twice to navigate to the current directory. Avoid this behaviour with ~jump~, included in the =dired-x= package that ships with *Dired*[fn:11].

+ Open a new dired buffer with =SPC d=.

#+begin_src emacs-lisp
(require 'dired-x)
(dotfiles/leader
  "d" '(dired-jump :which-key "Dired"))
#+end_src

** Reusing the same buffer

By default *Dired*[fn:11] will create a new buffer every time you press =RET= over a directory. This leads to unwanted buffers all over the place. Avoid this behaviour with *Dired Single*[fn:12], reusing the same dired buffer.

+ Move up a directory with =h=
+ Open a single buffer with =l=

#+begin_src emacs-lisp
(use-package dired-single
  :config (evil-collection-define-key 'normal 'dired-mode-map
            "h" 'dired-single-up-directory
            "l" 'dired-single-buffer))
#+end_src

* Shell

Another really incredible piece of kit, shipped with Emacs. *Eshell*[fn:15] is a fully POSIX compliant shell written entirely in Emacs Lisp. While not a traditional terminal emulator, it provides me with all of the functionality I expect and require from one. The infamous lambda prompt implemented with the *Eshell Prompt Extras*[fn:16] package.

#+begin_src emacs-lisp
(use-package eshell-prompt-extras
  :custom (eshell-highlight-prompt nil)
          (eshell-prefer-lisp-functions nil)
	        (eshell-prompt-function 'epe-theme-lambda))
#+end_src

Open an =eshell= buffer with =SPC e=.

#+begin_src emacs-lisp
(dotfiles/leader
  "e" '(eshell :which-key "Shell"))
#+end_src

* Magit

#+ATTR_ORG: :width 420px
#+ATTR_HTML: :width 420px
#+ATTR_LATEX: :width 420px
[[../docs/images/2021-02-13-example-magit.gif]]

Yet another hallmark feature of Emacs: *Magit*[fn:17] with the *darling* name, the developer stresses it's supposed to be *Magic* but with *Git*[fn:19]. It's a complete *Git*[fn:19] porcelain within Emacs.

#+begin_src emacs-lisp
(use-package magit
  :commands magit-status
  :custom (magit-display-buffer-function
           #'magit-display-buffer-same-window-except-diff-v1))
#+end_src

Open the *status* page for the current repository with =SPC g=.

#+begin_src emacs-lisp
(dotfiles/leader
  "g" '(magit-status :which-key "Magit"))
#+end_src

** GitHub integration

Interact with *Git*[fn:19] forges from *Magit*[fn:17] and Emacs using *Forge*[fn:18], requiring only a *GitHub*[fn:20] token to get started. If you're not sure what *GitHub*[fn:20] is, it's to *Git*[fn:19] what *Porn* is to *PornHub*. No citations!

+ Requires a valid ~$GITHUB_TOKEN~

#+begin_src emacs-lisp
(use-package forge
  :after magit)
#+end_src

* Resources

[fn:1] https://vim.org
[fn:2] https://evil.readthedocs.io/en/latest/index.html
[fn:3] https://github.com/hlissner/doom-emacs/
[fn:4] https://spacemacs.org
[fn:5] https://github.com/justbur/emacs-which-key/
[fn:6] https://github.com/emacs-evil/evil-collection
[fn:7] https://github.com/emacs-evil/evil-surround
[fn:8] https://github.com/redguardtoo/evil-nerd-commenter
[fn:9] https://github.com/noctuid/general.el
[fn:10] https://github.com/abo-abo/hydra
[fn:11] https://en.wikipedia.org/wiki/Dired
[fn:12] https://github.com/crocket/dired-single
[fn:15] https://gnu.org/software/emacs/manual/html_node/eshell/index.html
[fn:16] https://github.com/zwild/eshell-prompt-extras
[fn:17] https://github.com/magit/magit
[fn:18] https://github.com/magit/forge
[fn:19] https://git-scm.com
[fn:20] https://github.com