;;; use-package.el --- A use-package declaration for simplifying your .emacs

;; Copyright (C) 2012 John Wiegley

;; Author: John Wiegley <jwiegley@gmail.com>
;; Created: 17 Jun 2012
;; Version: 1.0
;; Package-Requires: ((bind-key "1.0") (diminish "0.44"))
;; Keywords: dotemacs startup speed config package
;; X-URL: https://github.com/jwiegley/use-package

;; This program is free software; you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation; either version 2, or (at
;; your option) any later version.

;; This program is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; The `use-package' declaration macro allows you to isolate package
;; configuration in your ".emacs" in a way that is performance-oriented and,
;; well, just tidy.  I created it because I have over 80 packages that I use
;; in Emacs, and things were getting difficult to manage.  Yet with this
;; utility my total load time is just under 1 second, with no loss of
;; functionality!
;;
;; Please see README.md from the same repository for documentation.

;;; Code:

(require 'bind-key)
(require 'bytecomp)
(require 'diminish nil t)

(when (fboundp 'declare-function)
  (declare-function package-installed-p 'package))

(defgroup use-package nil
  "A use-package declaration for simplifying your `.emacs'."
  :group 'startup)

(defcustom use-package-verbose nil
  "Whether to report about loading and configuration details."
  :type 'boolean
  :group 'use-package)

(defcustom use-package-minimum-reported-time 0.01
  "Minimal load time that will be reported"
  :type 'number
  :group 'use-package)

(defmacro with-elapsed-timer (text &rest forms)
  (let ((body `(progn ,@forms)))
    (if use-package-verbose
        (let ((nowvar (make-symbol "now")))
          `(let ((,nowvar (current-time)))
             (message "%s..." ,text)
             (prog1 ,body
               (let ((elapsed
                      (float-time (time-subtract (current-time) ,nowvar))))
                 (if (> elapsed ,use-package-minimum-reported-time)
                     (message "%s...done (%.3fs)" ,text elapsed)
                   (message "%s...done" ,text))))))
      body)))

(put 'with-elapsed-timer 'lisp-indent-function 1)

(defvar use-package-idle-timer nil)
(defvar use-package-idle-forms nil)

(defun use-package-start-idle-timer ()
  "Ensure that the idle timer is running."
  (unless use-package-idle-timer
    (setq use-package-idle-timer
          (run-with-idle-timer
           3 t
           'use-package-idle-eval))))

(defun use-package-init-on-idle (form)
  "Add a new form to the idle queue."
  (use-package-start-idle-timer)
  (if use-package-idle-forms
      (add-to-list 'use-package-idle-forms
                   form t)
    (setq use-package-idle-forms (list form))))

(defun use-package-idle-eval()
  "Start to eval idle-commands from the idle queue."
  (let ((next (pop use-package-idle-forms)))
    (if next
        (progn
          (when use-package-verbose
            (message "use-package idle:%s" next))

          (condition-case e
              (funcall next)
            (error
             (message
              "Failure on use-package idle. Form: %s, Error: %s"
              next e)))
          ;; recurse after a bit
          (when (sit-for 3)
            (use-package-idle-eval)))
      ;; finished (so far!)
      (cancel-timer use-package-idle-timer)
      (setq use-package-idle-timer nil))))

(defun use-package-ensure-elpa (package)
  (when (not (package-installed-p package))
    (package-install package)))

(defvar use-package-keywords
  '(
     :bind
     :commands
     :config
     :defer
     :defines
     :demand
     :diminish
     :disabled
     :ensure
     :idle
     :if
     :init
     :interpreter
     :load-path
     :mode
     :pre-init
     :pre-load
     :requires
  )
  "Keywords recognized by `use-package'.")

(defun plist-keys (plist)
  "Return a list containing all the keys in PLIST."
  (when plist
    (cons
      (car plist)
      (plist-keys
        (cddr plist)))))

(defun use-package-validate-keywords (args)
  "Error if any keyword given in ARGS is not recognized.
Return the list of recognized keywords."
  (mapc
    (function
      (lambda (keyword)
        (unless (memq keyword use-package-keywords)
          (error "Unrecognized keyword: %s" keyword))))
    (plist-keys args)))

(defun plist-get-value (plist prop)
  "Return the value of PROP in PLIST as if it was backquoted."
  (eval (list '\` (plist-get plist prop))))

(defmacro use-package (name &rest args)
  "Use a package with configuration options.

For full documentation. please see commentary.

  (use-package package-name
     :keyword option)

:init Code to run when `use-package' form evals.
:bind Perform key bindings, and define autoload for bound
      commands.
:commands Define autoloads for given commands.
:pre-load Code to run when `use-package' form evals and before
       anything else. Unlike :init this form runs before the
       package is required or autoloads added.
:mode Form to be added to `auto-mode-alist'.
:interpreter Form to be added to `interpreter-mode-alist'.
:defer Defer loading of package -- automatic
       if :commands, :bind, :mode or :interpreter are used.
:demand Prevent deferred loading in all cases.
:config Runs if and when package loads.
:if Conditional loading.
:disabled Ignore everything.
:defines Define vars to silence byte-compiler.
:load-path Add to `load-path' before loading.
:diminish Support for diminish package (if it's installed).
:idle adds a form to run on an idle timer
:ensure loads package using package.el if necessary."
  (use-package-validate-keywords args) ; error if any bad keyword, ignore result
  (let* ((commands (plist-get args :commands))
         (pre-init-body (plist-get args :pre-init))
         (pre-load-body (plist-get args :pre-load))
         (init-body (plist-get args :init))
         (config-body (plist-get args :config))
         (diminish-var (plist-get-value args :diminish))
         (defines (plist-get-value args :defines))
         (idle-body (plist-get args :idle))
         (keybindings-alist (plist-get-value args :bind))
         (mode (plist-get-value args :mode))
         (mode-alist
          (if (stringp mode) (cons mode name) mode))
         (interpreter (plist-get-value args :interpreter))
         (interpreter-alist
          (if (stringp interpreter) (cons interpreter name) interpreter))
         (predicate (plist-get args :if))
         (pkg-load-path (plist-get-value args :load-path))
         (defines-eval (if (null defines)
                           nil
                         (if (listp defines)
                             (mapcar (lambda (var) `(defvar ,var)) defines)
                           `((defvar ,defines)))))
         (requires (plist-get-value args :requires))
         (requires-test (if (null requires)
                            t
                          (if (listp requires)
                              `(not (member nil (mapcar #'featurep
                                                        (quote ,requires))))
                            `(featurep (quote ,requires)))))
         (name-string (if (stringp name) name (symbol-name name)))
         (name-symbol (if (stringp name) (intern name) name)))

    ;; force this immediately -- one off cost
    (unless (plist-get args :disabled)

      (let* ((ensure (plist-get args :ensure))
             (package-name
              (or (and (eq ensure t)
                       name)
                  ensure)))

        (when package-name
          (require 'package)
          (use-package-ensure-elpa package-name)))


      (if diminish-var
          (setq config-body
                `(progn
                   ,config-body
                   (ignore-errors
                     ,@(cond
                        ((stringp diminish-var)
                         `((diminish (quote ,(intern (concat name-string "-mode")))
                                     ,diminish-var)))
                        ((symbolp diminish-var)
                         `((diminish (quote ,diminish-var))))
                        ((and (consp diminish-var) (stringp (cdr diminish-var)))
                         `((diminish (quote ,(car diminish-var)) ,(cdr diminish-var))))
                        (t      ; list of symbols or (symbol . "string") pairs
                         (mapcar (lambda (var)
                                   (if (listp var)
                                       `(diminish (quote ,(car var)) ,(cdr var))
                                     `(diminish (quote ,var))))
                                 diminish-var)))))))

      (if (and commands (symbolp commands))
          (setq commands (list commands)))


      (when idle-body
        (setq init-body
              `(progn
                 (require 'use-package)
                 (use-package-init-on-idle (lambda () ,idle-body))
                 ,init-body)))


      (let ((init-for-commands
             (lambda (func sym-or-list)
               (let ((cons-list (if (and (consp sym-or-list)
                                         (stringp (car sym-or-list)))
                                    (list sym-or-list)
                                  sym-or-list)))
                 (if cons-list
                     (setq init-body
                           `(progn
                              ,init-body
                              ,@(mapcar #'(lambda (elem)
                                            (push (cdr elem) commands)
                                            (funcall func elem))
                                        cons-list))))))))

        (funcall init-for-commands
                 #'(lambda (binding)
                     `(bind-key ,(car binding)
                                (quote ,(cdr binding))))
                 keybindings-alist)

        (funcall init-for-commands
                 #'(lambda (mode)
                     `(add-to-list 'auto-mode-alist
                                   (quote ,mode)))
                 mode-alist)

        (funcall init-for-commands
                 #'(lambda (interpreter)
                     `(add-to-list 'interpreter-mode-alist
                                   (quote ,interpreter)))
                 interpreter-alist))

      `(progn
         ,pre-load-body
         ,@(mapcar
            #'(lambda (path)
                `(add-to-list 'load-path
                              ,(if (file-name-absolute-p path)
                                   path
                                 (expand-file-name path user-emacs-directory))))
            (cond ((stringp pkg-load-path)
                   (list pkg-load-path))
                  ((functionp pkg-load-path)
                   (funcall pkg-load-path))
                  (t
                   pkg-load-path)))

         (eval-when-compile
           (when (bound-and-true-p byte-compile-current-file)
             ,@defines-eval
             ,(if (stringp name)
                  `(load ,name t)
                `(require ',name nil t))))

         ,(if (and (or commands (plist-get args :defer))
                   (not (plist-get args :demand)))
              (let (form)
                (mapc #'(lambda (command)
                          (push `(autoload (function ,command)
                                   ,name-string nil t) form))
                      commands)

                `(when ,(or predicate t)
                   ,pre-init-body
                   ,@form
                   ,init-body
                   ,(unless (null config-body)
                      `(eval-after-load ,(if (stringp name) name `',name)
                         `(,(lambda ()
                              (if ,requires-test
                                  (with-elapsed-timer
                                      ,(format "Configuring package %s" name-string)
                                    ,config-body))))))
                   t))
            `(if (and ,(or predicate t)
                      ,requires-test)
                 (with-elapsed-timer
                     ,(format "Loading package %s" name-string)
                   (if (not ,(if (stringp name)
                                 `(load ,name t)
                               `(require ',name nil t)))
                       (message "Could not load package %s" ,name-string)
                     ,pre-init-body
                     ,init-body
                     ,config-body
                     t))))))))

(put 'use-package 'lisp-indent-function 'defun)

(defconst use-package-font-lock-keywords
  '(("(\\(use-package\\)\\_>[ \t']*\\(\\(?:\\sw\\|\\s_\\)+\\)?"
     (1 font-lock-keyword-face)
     (2 font-lock-constant-face nil t))))

(font-lock-add-keywords 'emacs-lisp-mode use-package-font-lock-keywords)

(provide 'use-package)
;; Local Variables:
;; indent-tabs-mode: nil
;; End:
;;; use-package.el ends here