This is (will be) my Emacs literate configuration file. A self
contained file with all my configuration is useful for documentation
purposes. It will be modeled using the technique described by
Protesilaos for his own Emacs config file:
<https://protesilaos.com/emacs/dotemacs>.

This method consists in generating all files /a priori/, after modifying
this file, and *not* at load time, as that would be too slow.

#+begin_src emacs-lisp :tangle no :results none
(org-babel-tangle)
#+end_src

* Overview of files and directories

- =early-init.el=: quoting the [[https://www.gnu.org/software/emacs/manual/html_node/emacs/Early-Init-File.html][Emacs documentation]], this file is "loaded
  before the package system and GUI is initialized, so in it you can
  customize variables that affect the package initialization process"
- =init.el=: the skeleton of my configuration framework. It will load
  the rest of the modules.
- =rul-emacs-modules/=: a directory with Emacs modules specific to my
  configuration. Modules group code related to a topic or theme of
  configuration. For example, =rul-prog.el= contains code related to
  programming, and =rul-org.el= contains code related to org-mode. If a
  module gets too big, I can create a smaller module under the same
  topic; for example, =rul-org-agenda.el=.
- =rul-post-init.el=: this file will be loaded after =init.el=, and will
  normally live in other git repository. Here I normally add overrides
  needed in my work computer.
- =rul-emacs.org=: this file. It (will) generate the rest of the structure.

* Early configuration file (=early-init.el=)
** Graphical aspects
Customization of graphical aspects of Emacs, such as size, panels, etc.

#+begin_src emacs-lisp :tangle "early-init.el"
;; I don't use any of these
(menu-bar-mode -1)
(tool-bar-mode -1)
(scroll-bar-mode -1)

;; Avoid initial flash of light.
;; Inspired on prot-emacs-avoid-initial-flash-of-light.
(setq mode-line-format nil)
(set-face-attribute 'default nil :background "#000000" :foreground "#ffffff")
(set-face-attribute 'mode-line nil :background "#000000" :foreground "#ffffff" :box 'unspecified)
#+end_src

** Frame configuration
I like to keep a few frames open all the time. A main frame, where I
open my org files, code, etc. A frame for communication and reading,
such as email and feeds, and a frame for terminals.

Currently, the frames are all the same, but I will add configuration
to distinguish them so I can automate their placement in my desktop
environment.

#+begin_src emacs-lisp :tangle "early-init.el"
;; Do not resize when font size changes
(setq frame-resize-pixelwise t)

;; By default, start maximized
(add-to-list 'default-frame-alist '(fullscreen . maximized))

;; No need for titlebar
(modify-frame-parameters nil '((undecorated . t)))

;; Name frames to ease switching between them
(add-hook 'after-init-hook (lambda () (set-frame-name "main")))
#+end_src

** Miscellany
#+begin_src emacs-lisp :tangle "early-init.el"
;; Initialise installed packages, otherwise, basic functions are not
;; available during the initialization stage.
(setq package-enable-at-startup t)

;; Do not report warnings. It's too noisy.
(setq native-comp-async-report-warnings-errors 'silent)

;; Keep things minimal
(setq inhibit-startup-screen t)
(setq inhibit-startup-echo-area-message user-login-name)
#+end_src

* Main configuration file (=init.el=)
** Package matters

I use package from both stable and bleeding-edge Melpa.

#+begin_src emacs-lisp :tangle "init.el"
(add-to-list 'package-archives
             '("melpa-stable" . "https://stable.melpa.org/packages/") t)

(add-to-list 'package-archives
             '("melpa" . "https://melpa.org/packages/") t)
#+end_src
** Backups
Emacs tends to clutter the filesystem with backup files. A backup file is normally the filename with a =~= suffix. I rather have my filesystem clean, and centralize all backups in a single directory.

#+begin_src emacs-lisp :tangle "init.el"
(if (file-directory-p "~/.backup")
    (setq backup-directory-alist '(("." . "~/.backup")))
  (message "Directory does not exist: ~/.backup"))

(setq
 backup-by-copying t    ; Don't delink hardlinks
 delete-old-versions t  ; Clean up the backups
 kept-new-versions 3    ; keep some new versions
 kept-old-versions 2   ; and some old ones, too
 version-control t)      ; Use version numbers on backups
#+end_src
** Customizations
Customizations don't place nicely with version control, so I do them in a random file that won't get persisted.

Configurations that need persisting will be added to =custom-set-variables= and =custom-set-faces=.

#+begin_src emacs-lisp :tangle "init.el"
;; Do not persist customizations
(setq custom-file (make-temp-file "emacs-custom-"))
#+end_src

** Editor interface
General configurations related to text editing across all modes.

#+begin_src emacs-lisp :tangle "init.el"
(setq fill-column 79) ; Wrap lines
(setq mouse-yank-at-point t) ; Do not follow mouse curors when mouse-yanking

(setq-default indent-tabs-mode nil) ; No tabs when indenting
(setq-default tab-width 4) ; How many spaces a tab represents

(setq initial-scratch-message "")

(defalias 'yes-or-no-p 'y-or-n-p)

;; Only flash the mode line
(setq ring-bell-function
      (lambda ()
        (let ((orig-fg (face-foreground 'mode-line)))
          (set-face-foreground 'mode-line "#F2804F")
          (run-with-idle-timer 0.1 nil
                               (lambda (fg) (set-face-foreground 'mode-line fg))
                               orig-fg))))

;; Highlight parens
(setq show-paren-delay 0)
(show-paren-mode 1)

(savehist-mode 1) ; Save histories, including minibuffer

(save-place-mode 1) ; Remember and restore cursor information

(setq auto-save-no-message t) ; Do not print a message when auto-saving

(pixel-scroll-precision-mode 1) ; Precision scrolling
#+end_src
** Emacs server
I used to run Emacs as a systemd daemon, but it was not too deterministic as sometimes it would break.

  https://rbenencia.name/blog/emacs-daemon-as-a-systemd-service/

Now, I simply start it from Emacs itself. This approach works well for me.

#+begin_src emacs-lisp :tangle "init.el"
;; Server
(require 'server)
(setq server-client-instructions nil) ; Keep it quiet when opening an ec

(unless (server-running-p)
  (server-start))
#+end_src
** Modules machinery
#+begin_src emacs-lisp :tangle "init.el"
(dolist (path '("~/.emacs.d/rul-lisp/packages"))
  (add-to-list 'load-path path))

(when-let* ((file (locate-user-emacs-file "rul-pre-init.el"))
            ((file-exists-p file)))
  (load-file file))

(require 'rul-themes)
(require 'rul-bindings)
(require 'rul-completion)
(require 'rul-elfeed)
(require 'rul-fm)
(require 'rul-fonts)
(require 'rul-mail)
(require 'rul-media)
(require 'rul-modeline)
(require 'rul-org)
(require 'rul-prog)
(require 'rul-terminals)
(require 'rul-vc)
(require 'rul-wm)
(require 'rul-write)

(when-let* ((file (locate-user-emacs-file "rul-post-init.el"))
            ((file-exists-p file)))
  (load-file file))

;; init.el ends here
#+end_src

* Modules
I group my configuration in logical modules. In general, a module
contains configuration for more than one package.

** The =themes= module
The =themes= module contains code pertaining to Emacs themes. 

#+begin_src emacs-lisp :tangle "rul-lisp/packages/rul-themes.el"
(use-package ef-themes :ensure t)
(use-package modus-themes
  :ensure t
  :config
  (setq
   modus-themes-mode-line '(accented borderless padded)
   modus-themes-region '(bg-only)
   modus-themes-bold-constructs t
   modus-themes-italic-constructs t
   modus-themes-paren-match '(bold intense)
   modus-themes-headings (quote ((1 . (rainbow variable-pitch 1.3))
                                 (2 . (rainbow 1.1))
                                 (t . (rainbow))))
   modus-themes-org-blocks 'tinted))
#+end_src


Additionally, this module subscribes to =org.freedesktop.appearance color-theme=
to detect what color theme is preferred, and set our Emacs theme accordingly.

#+begin_src emacs-lisp :tangle "rul-lisp/packages/rul-themes.el"
(use-package dbus)
(defun mf/set-theme-from-dbus-value (value)
  "Set the appropiate theme according to the color-scheme setting value."
  (message "value is %s" value)
  (if (equal value '1)
      (progn (message "Switch to dark theme")
             (modus-themes-select 'modus-vivendi))
    (progn (message "Switch to light theme")
           (modus-themes-select 'modus-operandi))))

(defun mf/color-scheme-changed (path var value)
  "DBus handler to detect when the color-scheme has changed."
  (when (and (string-equal path "org.freedesktop.appearance")
             (string-equal var "color-scheme"))
    (mf/set-theme-from-dbus-value (car value))
    ))

;; Register for future changes
(dbus-register-signal
 :session "org.freedesktop.portal.Desktop"
 "/org/freedesktop/portal/desktop" "org.freedesktop.portal.Settings"
 "SettingChanged"
 #'mf/color-scheme-changed)

;; Request the current color-scheme
(dbus-call-method-asynchronously
 :session "org.freedesktop.portal.Desktop"
 "/org/freedesktop/portal/desktop" "org.freedesktop.portal.Settings"
 "Read"
 (lambda (value) (mf/set-theme-from-dbus-value (caar value)))
 "org.freedesktop.appearance"
 "color-scheme"
 )


(provide 'rul-themes)
#+end_src

** The =bindings= module
This module contains code pertaining to keybindings. It starts by
defining a set global keys.

#+begin_src emacs-lisp :tangle "rul-lisp/packages/rul-bindings.el"
;; Global keybindings
(global-set-key (kbd "C-c R") 'revert-buffer)
(global-set-key (kbd "C-c w") 'whitespace-cleanup)

(defun help/insert-em-dash ()
  "Inserts an EM-DASH (not a HYPEN, not an N-DASH)"
  (interactive)
  (insert "—"))

(global-set-key (kbd "C--") #'help/insert-em-dash)
#+end_src

Next, we define a few /hydras/. /Hydras/ are a way of grouping keybindings
together, offering a menu on the way.

#+begin_src emacs-lisp :tangle "rul-lisp/packages/rul-bindings.el"
(use-package hydra
  :ensure t
  :defer 1)

;; tab-bar
(defhydra hydra-tab-bar (:color amaranth)
  "Tab Bar Operations"
  ("t" tab-new "Create a new tab" :column "Creation" :exit t)
  ("d" dired-other-tab "Open Dired in another tab")
  ("f" find-file-other-tab "Find file in another tab")
  ("x" tab-close "Close current tab")
  ("m" tab-move "Move current tab" :column "Management")
  ("r" tab-rename "Rename Tab")
  ("<return>" tab-bar-select-tab-by-name "Select tab by name" :column "Navigation")
  ("l" tab-next "Next Tab")
  ("j" tab-previous "Previous Tab")
  ("q" nil "Exit" :exit t))

(global-set-key (kbd "C-x t") 'hydra-tab-bar/body)

;; Zoom
(defhydra hydra-zoom ()
  "zoom"
  ("g" text-scale-increase "in")
  ("l" text-scale-decrease "out"))

(global-set-key (kbd "C-c z") 'hydra-zoom/body)

;; Go
(defhydra hydra-go ()
  "zoom"
  ("=" gofmt :exit t)
  ("c" go-coverage :exit t))

;; vterm
(defhydra hydra-vterm ()
  "zoom"
  ("t" multi-vterm "Open a terminal" :exit t)
  ("d" multi-vterm-dedicated-open "Dedicated" :exit t)
  ("p" multi-vterm-prev "Previous terminal")
  ("n" multi-vterm-next "Next terminal")
  ("r" multi-vterm-rename-buffer "Rename buffer" :exit t)
  )

(global-set-key (kbd "C-c t") 'hydra-vterm/body)
(global-set-key (kbd "C-c m") 'hydra-go/body)
#+end_src

Finally, we make use of =which-key=, which will show a menu with all
keybinding options after a prefix is pressed. I think this package has
the potential to obsolete =hydra=, so I'll have to revisit that code.

#+begin_src emacs-lisp :tangle "rul-lisp/packages/rul-bindings.el"
(use-package which-key
  :ensure t
  :config
  (which-key-mode))

(provide 'rul-bindings)
#+end_src