#+title: Emacs Configuration
#+author: Geir Okkenhaug Jerstad 
#+email: geir@geokkjer.eu
#+options: toc:nil num:nil
#+PROPERTY: header-args:emacs-lisp :tangle ~/.emacs.d/init.el


* About
My attempt at a litterate configuration for Emacs.
to tangle this file, run the following command in Emacs:
#+BEGIN_SRC emacs-lisp
(org-babel-tangle)
#+END_SRC
or keyboard shortcut `C-c C-v t` (org-babel-tangle) in Emacs.
This will generate the `~/.emacs.d/init.el` file with the configuration.

* Prep  

** Copilot Authentication
To use GitHub Copilot, you need to authenticate with your GitHub account. This is done by running the following command in Emacs:
after installing the copilot package:
Try to trigger the GitHub OAuth flow from within Emacs:

#+BEGIN_SRC emacs-lisp :eval yes
(call-interactively 'copilot-auth)
#+END_SRC

* Configuration

** Setup lexical binding
Here we set up lexical binding, which is a feature in Emacs Lisp that allows for more efficient variable scoping and function closures. This is recommended for performance reasons.
#+BEGIN_SRC emacs-lisp
;; enable lexical binding
(setq lexical-binding t)
#+END_SRC

** Set automatic update of packages

We set up Emacs to automatically update packages on startup. This ensures that we always have the latest versions of the packages we use.
#+BEGIN_SRC emacs-lisp
(defun geokkjer/display-startup-time ()
  (message "Emacs loaded in %s with %d grabage collections."
           (format "%.2f seconds"
                   (float-time
                    (time-subtract after-init-time before-init-time)))
           gcs-done))

(add-hook 'emacs-startup-hook #'geokkjer/display-startup-time)

(setq gc-cons-threshold (* 50 1000 1000))
#+END_SRC

** Customize UI
Here we set up the UI to our liking. We disable the menu bar, tool bar, and scroll bar, and set the font size to 14pt.
#+BEGIN_SRC emacs-lisp
;; disable startup screen
(setq inhibit-startup-screen t)
;; disable menu bar
(menu-bar-mode -1)
;; disable tool bar
(tool-bar-mode -1)
;; disable scroll bar
(scroll-bar-mode -1)
;; set font size
(set-face-attribute 'default nil :height 140)
#+END_SRC
Set up doom modeline, which is a nice status line for Emacs. We set it up to show the current buffer name and the current line number.
#+BEGIN_SRC emacs-lisp
;; install doom-modeline if not already installed
(unless (package-installed-p 'doom-modeline)
  (package-refresh-contents)
  (package-install 'doom-modeline))
(require 'doom-modeline)
;; enable doom-modeline
(doom-modeline-mode 1)
;; set up doom-modeline to show the current buffer name and line number
(setq doom-modeline-buffer-file-name-style 'truncate-with-project)
#+END_SRC

** Set up package management
#+BEGIN_SRC emacs-lisp
;; set up package archives
(require 'package)
(setq package-archives
      '(("melpa" . "https://melpa.org/packages/")
        ("gnu"   . "https://elpa.gnu.org/packages/")))
(package-initialize)
#+END_SRC

** Install use-package
#+BEGIN_SRC emacs-lisp
;; install use-package if not already installed
(unless (package-installed-p 'use-package)
  (package-refresh-contents)
  (package-install 'use-package))
(require 'use-package)
;; ensure that use-package is always used
(setq use-package-always-ensure t)
#+END_SRC

** Org Mode
Configure Org-mode for literate programming and note-taking.

#+BEGIN_SRC emacs-lisp
;; ensure org-mode is installed and up to date
(use-package org
  :ensure t
  :mode ("\\.org\\'" . org-mode)
  :config
  ;; enable syntax highlighting in code blocks
  (setq org-src-fontify-natively t)
  ;; preserve indentation in code blocks
  (setq org-src-preserve-indentation t)
  ;; enable babel for code execution
  (org-babel-do-load-languages
   'org-babel-load-languages
   '((emacs-lisp . t)
     (shell . t)
     (python . t)
     (nix . t)))
  ;; don't ask for confirmation when evaluating code blocks
  (setq org-confirm-babel-evaluate nil))
#+END_SRC

* Code Completion and ide features
** LSP Mode
Here we install lsp-mode and lsp-ui, which are the core components of the LSP (Language Server Protocol) support in Emacs. We also set up keybindings for common LSP commands.
#+BEGIN_SRC emacs-lisp
;; install lsp-mode and lsp-ui if not already installed
(unless (package-installed-p 'lsp-mode)
  (package-refresh-contents)
  (package-install 'lsp-mode))
(unless (package-installed-p 'lsp-ui)
  (package-refresh-contents)
  (package-install 'lsp-ui))
(require 'lsp-mode)
(require 'lsp-ui)
;; enable lsp-mode in programming buffers
(add-hook 'prog-mode-hook #'lsp)
#+END_SRC
** GitHub Copilot

Here we install from MELPA, enable it in all prog-modes and bind keys for completion:

#+BEGIN_SRC emacs-lisp
;; ensure Copilot is installed
(unless (package-installed-p 'copilot)
  (package-refresh-contents)
  (package-install 'copilot))

(require 'copilot)
;; turn on in programming buffers
(add-hook 'prog-mode-hook #'copilot-mode)

;; keybindings: M-TAB to trigger, TAB to accept
(define-key copilot-mode-map       (kbd "M-TAB") #'copilot-complete)
(define-key copilot-completion-map (kbd "<tab>")   #'copilot-accept-completion)
#+END_SRC

** Language support
Here we install and configure support for various programming languages. We use the `use-package` macro to ensure that the packages are installed and configured correctly.



** NixOS from Emacs
Editing Nix files and doing NixOS admin stuff like nixos-rebuild boot --upgrade
Run the commands with M-x shell-command

#+BEGIN_SRC emacs-lisp 
;; NixOS commands   
(defun nixos-upgrade ()
  "Run 'nixos-rebuild boot --upgrade' in a shell."
  (interactive)
  (shell-command "nixos-rebuild boot --upgrade"))

(defun nixos-switch ()
  "Run 'nixos-rebuild switch' in a shell."
  (interactive)
  (shell-command "nixos-rebuild switch"))
#+END_SRC


#+BEGIN_SRC emacs-lisp
;; install nix-mode
(use-package nix-mode
  :ensure t
  :mode "\\.nix\\'")
;; install nix-repl
(use-package nix-repl
  :ensure t
  :mode "\\.nix\\'")
;; install nixpkgs
(use-package nixpkgs
  :ensure t
  :mode "\\.nix\\'")
#+END_SRC