;;; aggressive-indent.el --- Minor mode to aggressively keep your code always indented

;; Copyright (C) 2014 Free Software Foundation, Inc.

;; Author: Artur Malabarba <emacs@endlessparentheses.com>
;; URL: https://github.com/Malabarba/aggressive-indent-mode
;; Version: 1.7
;; Package-Requires: ((emacs "24.1") (cl-lib "0.5"))
;; Keywords: indent lisp maint tools
;; Prefix: aggressive-indent
;; Separator: -

;;; Commentary:
;;
;; `electric-indent-mode' is enough to keep your code nicely aligned when
;; all you do is type.  However, once you start shifting blocks around,
;; transposing lines, or slurping and barfing sexps, indentation is bound
;; to go wrong.
;;
;; `aggressive-indent-mode' is a minor mode that keeps your code always
;; indented.  It reindents after every change, making it more reliable
;; than `electric-indent-mode'.
;;
;; ### Instructions ###
;;
;; This package is available fom Melpa, you may install it by calling
;;
;;     M-x package-install RET aggressive-indent
;;
;; Then activate it with
;;
;;     (add-hook 'emacs-lisp-mode-hook #'aggressive-indent-mode)
;;     (add-hook 'css-mode-hook #'aggressive-indent-mode)
;;
;; You can use this hook on any mode you want, `aggressive-indent' is not
;; exclusive to emacs-lisp code.  In fact, if you want to turn it on for
;; every programming mode, you can do something like:
;;
;;     (global-aggressive-indent-mode 1)
;;     (add-to-list 'aggressive-indent-excluded-modes 'html-mode)
;;
;; ### Manual Installation ###
;;
;; If you don't want to install from Melpa, you can download it manually,
;; place it in your `load-path' and require it with
;;
;;     (require 'aggressive-indent)

;;; Instructions:
;;
;; INSTALLATION
;;
;; This package is available fom Melpa, you may install it by calling
;; M-x package-install RET aggressive-indent.
;;
;; Then activate it with
;;     (add-hook 'emacs-lisp-mode-hook #'aggressive-indent-mode)
;;
;; You can also use an equivalent hook for another mode,
;; `aggressive-indent' is not exclusive to emacs-lisp code.
;;
;; Alternatively, you can download it manually, place it in your
;; `load-path' and require it with
;;
;;     (require 'aggressive-indent)

;;; License:
;;
;; This file is NOT part of GNU Emacs.
;;
;; 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
;; of the License, 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.
;;

;;; Code:

(require 'cl-lib)

(defgroup aggressive-indent nil
  "Customization group for aggressive-indent."
  :prefix "aggressive-indent-"
  :group 'electricity
  :group 'indent)

(defun aggressive-indent-bug-report ()
  "Opens github issues page in a web browser.  Please send any bugs you find.
Please include your Emacs and `aggressive-indent' versions."
  (interactive)
  (message "Your `aggressive-indent-version' is: %s, and your emacs version is: %s.
Please include this in your report!"
           (eval-when-compile
             (ignore-errors
               (require 'lisp-mnt)
               (lm-version)))
           emacs-version)
  (browse-url "https://github.com/Malabarba/aggressive-indent-mode/issues/new"))

(defvar aggressive-indent-mode)

;;; Configuring indentarion
(defcustom aggressive-indent-dont-electric-modes '(ruby-mode)
  "List of major-modes where `electric-indent' should be disabled."
  :type '(choice
          (const :tag "Never use `electric-indent-mode'." t)
          (repeat :tag "List of major-modes to avoid `electric-indent-mode'." symbol))
  :package-version '(aggressive-indent . "0.3.1"))

(defcustom aggressive-indent-excluded-modes
  '(
    bibtex-mode
    cider-repl-mode
    coffee-mode
    comint-mode
    conf-mode
    Custom-mode
    diff-mode
    doc-view-mode
    dos-mode
    erc-mode
    jabber-chat-mode
    haml-mode
    haskell-mode
    haskell-interactive-mode
    image-mode
    makefile-mode
    makefile-gmake-mode
    minibuffer-inactive-mode
    netcmd-mode
    python-mode
    sass-mode
    slim-mode
    special-mode
    shell-mode
    snippet-mode
    eshell-mode
    tabulated-list-mode
    term-mode
    TeX-output-mode
    text-mode
    yaml-mode
    )
  "Modes in which `aggressive-indent-mode' should not be activated.
This variable is only used if `global-aggressive-indent-mode' is
active.  If the minor mode is turned on with the local command,
`aggressive-indent-mode', this variable is ignored."
  :type '(repeat symbol)
  :package-version '(aggressive-indent . "0.3.1"))

(defcustom aggressive-indent-protected-commands '(undo undo-tree-undo undo-tree-redo whitespace-cleanup)
  "Commands after which indentation will NOT be performed.
Aggressive indentation could break things like `undo' by locking
the user in a loop, so this variable is used to control which
commands will NOT be followed by a re-indent."
  :type '(repeat symbol)
  :package-version '(aggressive-indent . "0.1"))

(defcustom aggressive-indent-comments-too nil
  "If non-nil, aggressively indent in comments as well."
  :type 'boolean
  :package-version '(aggressive-indent . "0.3"))

(defcustom aggressive-indent-modes-to-prefer-defun
  '(emacs-lisp-mode lisp-mode scheme-mode clojure-mode)
  "List of major-modes in which indenting defun is preferred.
Add here any major modes with very good definitions of
`end-of-defun' and `beginning-of-defun', or modes which bug out
if you have `after-change-functions' (such as paredit).

If current major mode is derived from one of these,
`aggressive-indent' will call `aggressive-indent-indent-defun'
after every command.  Otherwise, it will call
`aggressive-indent-indent-region-and-on' after every buffer
change."
  :type '(repeat symbol)
  :package-version '(aggressive-indent . "0.3"))

;;; Preventing indentation
(defvar aggressive-indent--internal-dont-indent-if
  '((memq this-command aggressive-indent-protected-commands)
    (region-active-p)
    buffer-read-only
    undo-in-progress
    (null (buffer-modified-p))
    (and (boundp 'smerge-mode) smerge-mode)
    (let ((line (thing-at-point 'line)))
      (and (stringp line)
           ;; If the user is starting to type a comment.
           (stringp comment-start)
           (string-match (concat "\\`[[:blank:]]*"
                                 (substring comment-start 0 1)
                                 "[[:blank:]]*$")
                         line)))
    (let ((sp (syntax-ppss)))
      ;; Comments.
      (or (and (not aggressive-indent-comments-too) (elt sp 4))
          ;; Strings.
          (elt sp 3))))
  "List of forms which prevent indentation when they evaluate to non-nil.
This is for internal use only.  For user customization, use
`aggressive-indent-dont-indent-if' instead.")

(eval-after-load 'yasnippet
  '(when (boundp 'yas--active-field-overlay)
     (add-to-list 'aggressive-indent--internal-dont-indent-if
                  '(and
                    (overlayp yas--active-field-overlay)
                    (overlay-end yas--active-field-overlay))
                  'append)))
(eval-after-load 'company
  '(when (boundp 'company-candidates)
     (add-to-list 'aggressive-indent--internal-dont-indent-if
                  'company-candidates)))
(eval-after-load 'auto-complete
  '(when (boundp 'ac-completing)
     (add-to-list 'aggressive-indent--internal-dont-indent-if
                  'ac-completing)))
(eval-after-load 'multiple-cursors-core
  '(when (boundp 'multiple-cursors-mode)
     (add-to-list 'aggressive-indent--internal-dont-indent-if
                  'multiple-cursors-mode)))
(eval-after-load 'iedit
  '(when (boundp 'iedit-mode)
     (add-to-list 'aggressive-indent--internal-dont-indent-if
                  'iedit-mode)))
(eval-after-load 'evil
  '(when (boundp 'iedit-mode)
     (add-to-list 'aggressive-indent--internal-dont-indent-if
                  'iedit-mode)))
(eval-after-load 'coq
  '(add-to-list 'aggressive-indent--internal-dont-indent-if
                '(and (derived-mode-p 'coq-mode)
                      (not (string-match "\\.[[:space:]]*$"
                                         (thing-at-point 'line))))))

(defcustom aggressive-indent-dont-indent-if '()
  "List of variables and functions to prevent aggressive indenting.
This variable is a list where each element is a Lisp form.
As long as any one of these forms returns non-nil,
aggressive-indent will not perform any indentation.

See `aggressive-indent--internal-dont-indent-if' for usage examples."
  :type '(repeat sexp)
  :package-version '(aggressive-indent . "0.2"))

(defvar aggressive-indent--error-message "One of the forms in `aggressive-indent-dont-indent-if' had the following error, I've disabled it until you fix it: %S"
  "Error message thrown by `aggressive-indent-dont-indent-if'.")

(defvar aggressive-indent--has-errored nil
  "Keep track of whether `aggressive-indent-dont-indent-if' is throwing.
This is used to prevent an infinite error loop on the user.")

(defun aggressive-indent--run-user-hooks ()
  "Safely run forms in `aggressive-indent-dont-indent-if'.
If any of them errors out, we only report it once until it stops
erroring again."
  (and aggressive-indent-dont-indent-if
       (condition-case er
           (prog1 (eval (cons 'or aggressive-indent-dont-indent-if))
             (setq aggressive-indent--has-errored nil))
         (error (unless aggressive-indent--has-errored
                  (setq aggressive-indent--has-errored t)
                  (message aggressive-indent--error-message er))))))

;;; Indenting defun
;;;###autoload
(defun aggressive-indent-indent-defun (&optional l r)
  "Indent current defun.
Throw an error if parentheses are unbalanced.
If L and R are provided, use them for finding the start and end of defun."
  (interactive)
  (let ((p (point-marker)))
    (set-marker-insertion-type p t)
    (indent-region
     (save-excursion
       (when l (goto-char l))
       (beginning-of-defun 1) (point))
     (save-excursion
       (when r (goto-char r))
       (end-of-defun 1) (point)))
    (goto-char p)))

(defun aggressive-indent--softly-indent-defun (&optional l r)
  "Indent current defun unobstrusively.
Like `aggressive-indent-indent-defun', but without errors or
messages.  L and R passed to `aggressive-indent-indent-defun'."
  (cl-letf (((symbol-function 'message) #'ignore))
    (ignore-errors (aggressive-indent-indent-defun l r))))

;;; Indenting region
;;;###autoload
(defun aggressive-indent-indent-region-and-on (l r)
  "Indent region between L and R, and then some.
Call `indent-region' between L and R, and then keep indenting
until nothing more happens."
  (interactive "r")
  (let ((p (point-marker))
        was-begining-of-line)
    (set-marker-insertion-type p t)
    (unwind-protect
        (progn
          (unless (= l r)
            (when (= (char-before r) ?\n)
              (cl-decf r)))
          ;; If L is at the end of a line, skip that line.
          (unless (= l r)
            (when (= (char-after l) ?\n)
              (cl-incf l)))
          ;; Indent the affected region.
          (goto-char r)
          (unless (= l r) (indent-region l r))
          ;; And then we indent each following line until nothing happens.
          (forward-line 1)
          (skip-chars-forward "[:blank:]\n\r\xc")
          (let* ((eod (ignore-errors
                        (save-excursion (end-of-defun)
                                        (point-marker))))
                 (point-limit (if (and eod (< (point) eod))
                                  eod (point-max-marker))))
            (while (and (null (eobp))
                        (let ((op (point))
                              (np (progn (indent-according-to-mode)
                                         (point))))
                          ;; As long as we're indenting things to the
                          ;; left, keep indenting.
                          (or (< np op)
                              ;; If we're indenting to the right, or
                              ;; not at all, stop at the limit.
                              (< (point) point-limit))))
              (forward-line 1)
              (skip-chars-forward "[:blank:]\n\r\f"))))
      (goto-char p))))

(defun aggressive-indent--softly-indent-region-and-on (l r &rest _)
  "Indent region between L and R, and a bit more.
Like `aggressive-indent-indent-region-and-on', but without errors
or messages."
  (cl-letf (((symbol-function 'message) #'ignore))
    (ignore-errors (aggressive-indent-indent-region-and-on l r))))

;;; Tracking changes
(defvar aggressive-indent--changed-list nil
  "List of (left right) limit of regions changed in the last command loop.")
(make-variable-buffer-local 'aggressive-indent--changed-list)

(defvar aggressive-indent--balanced-parens t
  "Non-nil if the current-buffer has balanced parens.")
(make-variable-buffer-local 'aggressive-indent--balanced-parens)

(defun aggressive-indent--proccess-changed-list-and-indent ()
  "Indent the regions in `aggressive-indent--changed-list'."
  (let ((inhibit-modification-hooks t)
        (inhibit-point-motion-hooks t)
        (indent-function
         (if (cl-member-if #'derived-mode-p aggressive-indent-modes-to-prefer-defun)
             #'aggressive-indent--softly-indent-defun #'aggressive-indent--softly-indent-region-and-on)))
    ;; Take the 10 most recent changes.
    (let ((cell (nthcdr 10 aggressive-indent--changed-list)))
      (when cell (setcdr cell nil)))
    ;; (message "----------")
    (while aggressive-indent--changed-list
      ;; (message "%S" (car aggressive-indent--changed-list))
      (apply indent-function (car aggressive-indent--changed-list))
      (setq aggressive-indent--changed-list
            (cdr aggressive-indent--changed-list)))))

(defun aggressive-indent--indent-if-changed ()
  "Indent any region that changed in the last command loop."
  (when (and aggressive-indent--changed-list aggressive-indent--balanced-parens)
    (save-excursion
      (save-selected-window
        (unless (or (run-hook-wrapped 'aggressive-indent--internal-dont-indent-if #'eval)
                    (aggressive-indent--run-user-hooks))
          (while-no-input
            (redisplay)
            (aggressive-indent--proccess-changed-list-and-indent)))))))

(defun aggressive-indent--check-parens ()
  "Check if parens are balanced in the current buffer.
Store result in `aggressive-indent--balanced-parens'."
  (setq aggressive-indent--balanced-parens
        (save-excursion
          (ignore-errors
            (zerop (car (syntax-ppss (point-max))))))))

(defun aggressive-indent--keep-track-of-changes (l r &rest _)
  "Store the limits (L and R) of each change in the buffer."
  (when aggressive-indent-mode
    (push (list l r) aggressive-indent--changed-list)
    (aggressive-indent--check-parens)))

;;; Minor modes
;;;###autoload
(define-minor-mode aggressive-indent-mode
  nil nil " =>"
  `((,(kbd "C-c C-q") . aggressive-indent-indent-defun)
    ([backspace]
     menu-item "maybe-delete-indentation" ignore :filter
     (lambda (&optional _)
       (when (and (looking-back "^[[:blank:]]+")
                  ;; Wherever we don't want to indent, we probably also
                  ;; want the default backspace behavior.
                  (not (run-hook-wrapped 'aggressive-indent--internal-dont-indent-if #'eval))
                  (not (aggressive-indent--run-user-hooks)))
         #'delete-indentation))))
  (if aggressive-indent-mode
      (if (and global-aggressive-indent-mode
               (or (cl-member-if #'derived-mode-p aggressive-indent-excluded-modes)
                   (memq major-mode '(text-mode fundamental-mode))
                   buffer-read-only))
          (aggressive-indent-mode -1)
        ;; Should electric indent be ON or OFF?
        (if (or (eq aggressive-indent-dont-electric-modes t)
                (cl-member-if #'derived-mode-p aggressive-indent-dont-electric-modes))
            (aggressive-indent--local-electric nil)
          (aggressive-indent--local-electric t))
        (aggressive-indent--check-parens)
        (add-hook 'after-change-functions #'aggressive-indent--keep-track-of-changes nil 'local)
        (add-hook 'before-save-hook #'aggressive-indent--proccess-changed-list-and-indent nil 'local)
        (add-hook 'post-command-hook #'aggressive-indent--indent-if-changed nil 'local))
    ;; Clean the hooks
    (remove-hook 'after-change-functions #'aggressive-indent--keep-track-of-changes 'local)
    (remove-hook 'before-save-hook #'aggressive-indent--proccess-changed-list-and-indent 'local)
    (remove-hook 'post-command-hook #'aggressive-indent--indent-if-changed 'local)
    (remove-hook 'post-command-hook #'aggressive-indent--softly-indent-defun 'local)))

(defun aggressive-indent--local-electric (on)
  "Turn variable `electric-indent-mode' on or off locally, as per boolean ON."
  (if (fboundp 'electric-indent-local-mode)
      (electric-indent-local-mode (if on 1 -1))
    (set (make-local-variable 'electric-indent-mode) on)))

;;;###autoload
(define-globalized-minor-mode global-aggressive-indent-mode
  aggressive-indent-mode aggressive-indent-mode)

;;;###autoload
(defalias 'aggressive-indent-global-mode
  #'global-aggressive-indent-mode)

(provide 'aggressive-indent)
;;; aggressive-indent.el ends here