snix/init/functions.el

(require 's)
;; A few handy functions I use in init.el (or not, but they're nice to
;; have)

(defun custom-download-theme (url filename)
  "Downloads a theme through HTTP and places it in ~/.emacs.d/themes"

  ;; Ensure the directory exists
  (unless (file-exists-p "~/.emacs.d/themes")
    (make-directory "~/.emacs.d/themes"))

  ;; Adds the themes folder to the theme load path (if not already
  ;; there)
  (unless (member "~/.emacs.d/themes" custom-theme-load-path)
    (add-to-list 'custom-theme-load-path "~/.emacs.d/themes"))

  ;; Download file if it doesn't exist.

  (let ((file
         (concat "~/.emacs.d/themes/" filename)))
    (unless (file-exists-p file)
      (url-copy-file url file))))

(defun custom-download-script (url filename)
  "Downloads an Elisp script, places it in ~/.emacs/other and then loads it"

  ;; Ensure the directory exists
  (unless (file-exists-p "~/.emacs.d/other")
    (make-directory "~/.emacs.d/other"))

  ;; Download file if it doesn't exist.
  (let ((file
         (concat "~/.emacs.d/other/" filename)))
    (unless (file-exists-p file)
      (url-copy-file url file))

    (load file)))

(defun keychain-password (account &optional keychain)
  "Returns the password for the account, by default it's looked up in the Login.keychain but a
   different keychain can be specified."
  (let ((k (if keychain keychain "Login.keychain")))
    (replace-regexp-in-string
     "\n" ""
     (shell-command-to-string (concat  "security find-generic-password -w -a "
                                       account
                                       " "
                                       k)))))

;; This clones a git repository to 'foldername in .emacs.d
;; if there isn't already a folder with that name
(defun custom-clone-git (url foldername)
  "Clones a git repository to .emacs.d/foldername"
  (let ((fullpath (concat "~/.emacs.d/" foldername)))
    (unless (file-exists-p fullpath)
      (async-shell-command (concat "git clone " url " " fullpath)))))

(defun load-file-if-exists (filename)
  (if (file-exists-p filename)
      (load filename)))

(defun goto-line-with-feedback ()
  "Show line numbers temporarily, while prompting for the line number input"
  (interactive)
  (unwind-protect
      (progn
        (setq-local display-line-numbers t)
        (let ((target (read-number "Goto line: ")))
          (avy-push-mark)
          (goto-line target)))
    (setq-local display-line-numbers nil)))


(defun untabify-buffer ()
  (interactive)
  (untabify (point-min) (point-max)))

(defun indent-buffer ()
  (interactive)
  (indent-region (point-min) (point-max)))

(defun cleanup-buffer ()
  "Perform a bunch of operations on the whitespace content of a buffer.
Including indent-buffer, which should not be called automatically on save."
  (interactive)
  (untabify-buffer)
  (delete-trailing-whitespace)
  (indent-buffer))

;; These come from the emacs starter kit

(defun esk-add-watchwords ()
  (font-lock-add-keywords
   nil '(("\\<\\(FIX\\(ME\\)?\\|TODO\\|DEBUG\\|HACK\\|REFACTOR\\|NOCOMMIT\\)"
          1 font-lock-warning-face t))))

(defun esk-sudo-edit (&optional arg)
  (interactive "p")
  (if (or arg (not buffer-file-name))
      (find-file (concat "/sudo:root@localhost:" (read-file-name "File: ")))
    (find-alternate-file (concat "/sudo:root@localhost:" buffer-file-name))))

;; Open Fefes blog
(defun fefes-blog ()
  (interactive)
  (eww "https://blog.fefe.de/"))

;; Open this machines NixOS config
(defun nix-config ()
  (interactive)
  (find-file "/etc/nixos/configuration.nix"))

;; Open local emacs configuration
(defun emacs-config ()
  (interactive)
  (dired "~/.emacs.d/"))

;; Get the nix store path for a given derivation.
;; If the derivation has not been built before, this will trigger a build.
(defun nix-store-path (derivation)
  (let ((expr (concat "with import <nixos> {}; " derivation)))
    (s-chomp (shell-command-to-string (concat "nix-build -E '" expr "'")))))

(defun insert-nix-store-path ()
  (interactive)
  (let ((derivation (read-string "Derivation name (in <nixos>): ")))
    (insert (nix-store-path derivation))))

(defun toggle-force-newline ()
  "Buffer-local toggle for enforcing final newline on save."
  (interactive)
  (setq-local require-final-newline (not require-final-newline))
  (message "require-final-newline in buffer %s is now %s"
           (buffer-name)
           require-final-newline))

;; Helm includes a command to run external applications, which does
;; not seem to exist in ivy. This implementation uses some of the
;; logic from Helm to provide similar functionality using ivy.
(defun list-external-commands ()
  "Creates a list of all external commands available on $PATH
  while filtering NixOS wrappers."
  (cl-loop
   for dir in (split-string (getenv "PATH") path-separator)
   when (and (file-exists-p dir) (file-accessible-directory-p dir))
   for lsdir = (cl-loop for i in (directory-files dir t)
                        for bn = (file-name-nondirectory i)
                        when (and (not (s-contains? "-wrapped" i))
                                  (not (member bn completions))
                                  (not (file-directory-p i))
                                  (file-executable-p i))
                        collect bn)
   append lsdir into completions
   finally return (sort completions 'string-lessp)))

(defun ivy-run-external-command ()
  "Prompts the user with a list of all installed applications and
  lets them select one to launch."

  (interactive)
  (let ((external-commands-list (list-external-commands)))
    (ivy-read "Command:" external-commands-list
              :require-match t
              :history 'external-commands-history
              :action (lambda (cmd)
                        (message "Starting %s..." cmd)
                        (set-process-sentinel
                         (start-process-shell-command cmd nil cmd)
                         (lambda (process event)
                           (when (string= event "finished\n")
                             (message "%s process finished." process))))))))

(provide 'functions)