Emacs Package Updates

#!/bin/sh

# <xbar.title>Emacs Package Updates</xbar.title>
# <xbar.version>v1.2</xbar.version>
# <xbar.author>Takashi Masuda</xbar.author>
# <xbar.author.github>masutaka</xbar.author.github>
# <xbar.desc>List available updates from Emacs package</xbar.desc>
# <xbar.image>http://i.imgur.com/SBlrP2t.png</xbar.image>
# <xbar.dependencies>emacs</xbar.dependencies>

EMACS=$(command -v emacs)

exit_with_error() {
  echo "🐮err | color=red";
  exit 1;
}

cat <<EOE > /tmp/emacs-package-updates.el
(require 'package)

(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
(package-initialize)

(defun melpa-archive-contents ()
  (let ((archive-contents (expand-file-name "elpa/archives/melpa/archive-contents"
                                            user-emacs-directory))
        lisp)
    (when (file-readable-p archive-contents)
      (with-temp-buffer
        (progn
          (insert-file-contents archive-contents)
          (setq lisp
                (condition-case nil
                    (read (current-buffer))
                  (error ()))))))
    lisp))

(catch 'success
  (let ((retry-count 0))
    (while (< retry-count 3)
      (list-packages)
      (if (last (melpa-archive-contents))
          (throw 'success "list-packages() succeeded.")
        (setq retry-count (+ retry-count 1)))
      (sleep-for 3))
    (error (format "list-packages() failed with retry count %d." retry-count))))

(defun my-package-version (pkg-desc)
  (package-version-join (package-desc-version pkg-desc)))

(let ((upgrades (with-current-buffer "*Packages*"
                  (package-menu--find-upgrades)))
      pkg-desc pkg-name)
  (message "🐮%d" (length upgrades))
  (message "---")
  (dolist (upgrade upgrades)
    (setq pkg-desc (cdr upgrade))
    (setq pkg-name (package-desc-name pkg-desc))
    (message "%s (%s < %s)"
             pkg-name
             (my-package-version (cadr (assoc pkg-name package-alist)))
             (my-package-version pkg-desc)))
  (message "---")
  (message "Refresh... | refresh=true"))
EOE

($EMACS -Q --batch -l /tmp/emacs-package-updates.el 2>&1 || exit_with_error) | sed -ne '/🐮/,$p'