;;; holy-mode.el --- Enter the church of Emacs

;; Copyright (c) 2015-2020 Sylvain Benner
;;
;; Author: Sylvain Benner <sylvain.benner@gmail.com>
;; Keywords: convenience editing
;; Created: 18 Mar 2015
;; Version: 1.00
;; Package-Requires: ((emacs "24") (evil "1.0.9"))
;; URL: https://github.com/syl20bnr/spacemacs

;; 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 3 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.

;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; Code:

(defadvice evil-insert-state (around holy-insert-to-emacs-state disable)
  "Forces Emacs state."
  (if (equal -1 (ad-get-arg 0))
      ad-do-it
    (evil-emacs-state)))

(defadvice evil-motion-state (around holy-motion-to-emacs-state disable)
  "Forces Emacs state."
  (if (equal -1 (ad-get-arg 0))
      ad-do-it
    (evil-emacs-state)))

(defadvice evil-normal-state (around holy-normal-to-emacs-state disable)
  "Forces Emacs state."
  (if (equal -1 (ad-get-arg 0))
      ad-do-it
    (evil-emacs-state)))

;;;###autoload
(define-minor-mode holy-mode
  "Global minor mode to repulse the evil from spacemacs.

The `insert state' is replaced by the `emacs state'."
  :global t
  :lighter " holy"
  :group 'spacemacs
  (if holy-mode
      (in-nomine-patris-et-filii-et-spiritus-sancti)
    (amen)))

(defun in-nomine-patris-et-filii-et-spiritus-sancti ()
  "Enter the church of Emacs (wash your hands)."
  ;; make all buffers' initial state emacs
  (push '("." . emacs) evil-buffer-regexps)
  ;; replace evil states by `emacs state'
  (ad-enable-advice 'evil-insert-state 'around 'holy-insert-to-emacs-state)
  (ad-enable-advice 'evil-motion-state 'around 'holy-motion-to-emacs-state)
  (ad-enable-advice 'evil-normal-state 'around 'holy-normal-to-emacs-state)
  (ad-activate 'evil-insert-state)
  (ad-activate 'evil-motion-state)
  (ad-activate 'evil-normal-state)
  ;; key bindings hooks for dynamic switching of editing styles
  (run-hook-with-args 'spacemacs-editing-style-hook 'emacs)
  ;; initiate `emacs state' and enter the church
  (holy-mode//update-states-for-current-buffers 'emacs))

(defun amen ()
  "May the force be with you my son (or not)."
  ;; restore defaults
  (setq evil-buffer-regexps (delete '("." . emacs) evil-buffer-regexps))
  ;; restore evil states
  (ad-disable-advice 'evil-insert-state 'around 'holy-insert-to-emacs-state)
  (ad-disable-advice 'evil-motion-state 'around 'holy-motion-to-emacs-state)
  (ad-disable-advice 'evil-normal-state 'around 'holy-normal-to-emacs-state)
  (ad-activate 'evil-insert-state)
  (ad-activate 'evil-motion-state)
  (ad-activate 'evil-normal-state)
  ;; restore key bindings
  (run-hook-with-args 'spacemacs-editing-style-hook 'vim)
  ;; restore the states
  (holy-mode//update-states-for-current-buffers 'vim))

(defun holy-mode//update-states-for-current-buffers (style)
  "Update the active state in all current buffers given current STYLE."
  (dolist (buffer (buffer-list))
    (with-current-buffer buffer
      (cond
       ((eq 'emacs style) (evil-emacs-state))
       ((and (eq 'vim style)
             (eq 'emacs evil-state))
        (cond
         ((memq major-mode evil-evilified-state-modes) (evil-evilified-state))
         ((memq major-mode evil-motion-state-modes) (evil-motion-state))
         (t (evil-normal-state))))))))