;;; package-management.el --- Initialize package management.  -*- lexical-binding: t; -*-

;; Time-stamp: <2020-03-11T16:10:53+0100>

;;; Commentary:
;; * Set up package sources and their priorities.
;; * Set up use-package.
;; * Compile elisp files.
;; * Update keyring.
;; * Update packages.
;; * Set up quelpa.

;;; Code:

(require 'package)
(add-to-list 'package-archives
             '("melpa-stable" . "https://stable.melpa.org/packages/") t)
(add-to-list 'package-archives
             '("melpa" . "https://melpa.org/packages/") t)
(setq package-archive-priorities '(("melpa-stable" . 30)
                                   ("gnu"          . 20)
                                   ("melpa"        . 10)))

;; Workaround for 26.2 <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=34341>.
(when (< emacs-major-version 27)
  (defvar gnutls-algorithm-priority "NORMAL:-VERS-TLS1.3"))

(when (< emacs-major-version 27)
  (package-initialize))

;; Add path for custom packages.
(add-to-list 'load-path (concat user-emacs-directory "custom-packages/"))

;; Install use-package if necessary.
(unless (package-installed-p 'use-package)
  (package-refresh-contents)
  (package-install 'use-package))
(eval-when-compile
  (require 'use-package))

;; Always install packages if they are not present.
(use-package use-package
  :custom (use-package-always-ensure t))

;; Autocompile files on load.
(use-package auto-compile
  :custom (load-prefer-newer t)         ; Use uncompiled file if it is newer.
  :config (auto-compile-on-load-mode))

;; Tool for updating the GNU ELPA keyring.
(use-package gnu-elpa-keyring-update
  :config
  (defvar my/keyring-last-access
    (time-to-seconds
     (file-attribute-access-time
      (file-attributes gnu-elpa-keyring-update--keyring)))
    "Last access time for the GNU ELPA keyring.")

  ;; Only update keyring if atime (mtime with relatime) is > 1 week ago.
  (if (> (- (time-to-seconds) my/keyring-last-access) (* 60 60 24 7))
      (gnu-elpa-keyring-update)))

;; Update packages if at least 7 days have passed.
(use-package auto-package-update
  :after (quelpa)
  :demand t
  :defines (quelpa-cache)
  :custom ((auto-package-update-delete-old-versions t)
           (auto-package-update-interval 7)
           (auto-package-update-hide-results nil))
  :config (progn
            (auto-package-update-maybe)
            (defvar my/tmp--package-activated-list nil)
            (defun my/apu-delete-quelpa-packages ()
              "Delete quelpa packages from `package-activated-list'."
              (setq my/tmp--package-activated-list package-activated-list)
              (dolist (package quelpa-cache)
                (let ((package-name (car package)))
                  (setq package-activated-list
                        (delq package-name package-activated-list)))))
            (defun my/apu-restore-quelpa-packages ()
              "Restore quelpa packages to `package-activated-list'."
              (if my/tmp--package-activated-list
                  (setq package-activated-list my/tmp--package-activated-list)
                (message "Error: Could not restore `package-activated-list'."))
              (setq my/tmp--package-activated-list nil)))
  :hook ((auto-package-update-before . my/apu-delete-quelpa-packages)
         (auto-package-update-after  . my/apu-restore-quelpa-packages)))

;; Install Emacs packages directly from source.
(use-package quelpa
  :demand t
  :custom ((quelpa-self-upgrade-p nil)
           (quelpa-update-melpa-p nil)
           (quelpa-checkout-melpa-p nil)
           (quelpa-upgrade-interval 7))
  :hook (after-init . quelpa-upgrade-all-maybe))

;; Use :quelpa in use-package configurations.
(use-package quelpa-use-package
  :after (use-package quelpa)
  ; Override `use-package-always-ensure' for quelpa-packages.
  :config (quelpa-use-package-activate-advice))

(provide 'basics/package-management)
;;; package-management.el ends here