;;; visual-regexp.el --- A regexp/replace command for Emacs with interactive visual feedback

;; Copyright (C) 2013-2016 Marko Bencun

;; Author: Marko Bencun <mbencun@gmail.com>
;; URL: https://github.com/benma/visual-regexp.el/
;; Version: 1.0
;; Package-Requires: ((cl-lib "0.2"))
;; Keywords: regexp, replace, visual, feedback

;; This file is part of visual-regexp.

;; visual-regexp 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.

;; visual-regexp 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 visual-regexp.  If not, see <http://www.gnu.org/licenses/>.

;;; WHAT'S NEW
;; 1.0: Add support for one prompt for search/replace, using query-replace-from-to-separator
;;      (query-replace history like in Emacs 25).
;;      Breaking changes:
;;       - vr/minibuffer-(regexp|replace)-keymap have been collapsed to vr/minibuffer-keymap
;;       - vr/minibuffer-help-(regexp|replace) have been replaced by vr--minibuffer-help-text
;; 0.9: Fix warnings regarding free variables.
;; 0.8: Error handling for vr--get-regexp-string. Bug-fixes regarding error display.
;; 0.7: Customizable separator (arrow) string and face.
;; 0.6: distinguish prompts in vr/replace, vr/query-replace, vr/mc-mark.
;; 0.5: emulate case-conversion of replace-regexp.
;; 0.4: vr/mc-mark: interface to multiple-cursors.
;; 0.3: use the same history as the regular Emacs replace commands;
;; 0.2: support for lisp expressions in the replace string, same as in (query-)replace-regexp
;; 0.1: initial release

;;; Tip Jar
;; If you found this useful, please consider donating.
;; BTC: 1BxauiLGMQPb2pavkkQkuFe5CgrGMrUat2

;;; What's This?

;; visual-regexp for Emacs is like `replace-regexp`, but with live  visual feedback directly in the buffer.
;; While constructing the regexp in the minibuffer, you get live visual feedback for the matches, including group matches.
;; While constructing the replacement in the minibuffer, you get live visual feedback for the replacements.
;; It can be used to replace all matches in one go (like `replace-regexp`), or a decision can be made on each match (like `query-replace-regexp`).
;; Thanks to Detlev Zundel for his re-builder.

;;; Where does visual-regexp come from?
;;
;; I was not happy with the way I used emacs' replace-regexp before. Constructing the regular expression is error prone and emacs' regular expressions are limited
;; (for example, no lookaheads, named groups, etc.).
;; Using re-builder to interactively build regular expressions was a step into the right direction, but manually copying over the regexp
;; to the minibuffer is cumbersome.
;; Using the idea of interactive feedback of re-builder, this package makes it possible to use just the minibuffer to construct (with live visual feedback) the regexp and replacement,
;; using Emacs style regular expressions, or optionally, regular expressions powered by other (mode modern) engines, for the replacement. For the latter part, see the package visual-regexp-steroids.

;;; Installation

;; If you are using Emacs 24, you can get visual-regexp from [melpa](https://melpa.org/) with the package manager.
;; Add the following code to your init file. Of course you can select your own key bindings.
;; ----------------------------------------------------------
;; (add-to-list 'load-path "folder-in-which-visual-regexp-files-are-in/") ;; if the files are not already in the load path
;; (require 'visual-regexp)
;; (define-key global-map (kbd "C-c r") 'vr/replace)
;; (define-key global-map (kbd "C-c q") 'vr/query-replace)
;; ;; if you use multiple-cursors, this is for you:
;; (define-key global-map (kbd "C-c m") 'vr/mc-mark)
;; ----------------------------------------------------------
;; To customize, use `M-x customize-group [RET] visual-regexp`.

;;; Code:
(unless (fboundp 'make-overlay)
  (require 'overlay))

;; cl is used for the (loop ...) macro
(require 'cl-lib)

;;; faces

(defcustom vr/match-separator-use-custom-face nil
  "If activated, vr/match-separator-face is used to display the separator. Otherwise, use the same face as the current match."
  :type 'boolean
  :group 'visual-regexp)

(defface vr/match-separator-face
  '((((class color))
     :foreground "red"
     :bold t)
    (t
     :inverse-video t))
  "Face for the arrow between match and replacement. To use this, you must activate vr/match-separator-use-custom-face"
  :group 'visual-regexp)

;; For Emacs < 25.0, this variable is not yet defined.
;; Copy pasted from Emacs 25.0 replace.el.
(unless (boundp 'query-replace-from-to-separator)
  (defcustom query-replace-from-to-separator
    (propertize (if (char-displayable-p ?→) " → " " -> ")
		'face 'minibuffer-prompt)
    "String that separates FROM and TO in the history of replacement pairs."
    ;; Avoids error when attempt to autoload char-displayable-p fails
    ;; while preparing to dump, also stops customize-rogue listing this.
    :initialize 'custom-initialize-delay
    :type 'sexp))

(defcustom vr/match-separator-string
  (progn
    (custom-reevaluate-setting 'query-replace-from-to-separator)
    (substring-no-properties query-replace-from-to-separator))
  "This string is used to separate a match from the replacement during feedback."
  :type 'sexp
  :initialize 'custom-initialize-delay
  :group 'visual-regexp)

(defface vr/match-0
  '((((class color) (background light))
     :background "lightblue")
    (((class color) (background dark))
     :background "steelblue4")
    (t
     :inverse-video t))
  "First face for displaying a whole match."
  :group 'visual-regexp)

(defface vr/match-1
  '((((class color) (background light))
     :background "pale turquoise")
    (((class color) (background dark))
     :background "dodgerblue4")
    (t
     :inverse-video t))
  "Second face for displaying a whole match."
  :group 'visual-regexp)

(defface vr/group-0
  '((((class color) (background light))
     :background "aquamarine")
    (((class color) (background dark))
     :background "blue3")
    (t
     :inverse-video t))
  "First face for displaying a matching group."
  :group 'visual-regexp)

(defface vr/group-1
  '((((class color) (background light))
     :background "springgreen")
    (((class color) (background dark))
     :background "chartreuse4")
    (t
     :inverse-video t))
  "Second face for displaying a matching group."
  :group 'visual-regexp)

(defface vr/group-2
  '((((min-colors 88) (class color) (background light))
     :background "yellow1")
    (((class color) (background light))
     :background "yellow")
    (((class color) (background dark))
     :background "sienna4")
    (t
     :inverse-video t))
  "Third face for displaying a matching group."
  :group 'visual-regexp)

;;; variables

(defcustom vr/auto-show-help t
  "Show help message automatically when the minibuffer is entered."
  :type 'boolean
  :group 'visual-regexp)

(defcustom vr/default-feedback-limit 50
  "Limit number of matches shown in visual feedback.
If nil, don't limit the number of matches shown in visual feedback."
  :type 'integer
  :group 'visual-regexp)

(defcustom vr/default-replace-preview nil
  "Preview of replacement activated by default? If activated, the original is not shown alongside the replacement."
  :type 'boolean
  :group 'visual-regexp)

(defcustom vr/query-replace-from-history-variable query-replace-from-history-variable
  "History list to use for the FROM argument. The default is to use the same history as Emacs' query-replace commands."
  :type 'symbol
  :group 'visual-regexp)

(defcustom vr/query-replace-to-history-variable query-replace-to-history-variable
  "History list to use for the TO argument. The default is to use the same history as Emacs' query-replace commands."
  :type 'symbol
  :group 'visual-regexp)

(setq vr--is-emacs24 (version< emacs-version "25"))

(defvar vr--query-replace-defaults nil
  "Same as query-replace-defaults from Emacs 25, for compatibility with Emacs 24.")

(defcustom vr/query-replace-defaults-variable
  (if vr--is-emacs24
      'vr--query-replace-defaults
    'query-replace-defaults)
  "History of search/replace pairs"
  :type 'symbol
  :group 'visual-regexp)

(defvar vr/initialize-hook nil
  "Hook called before vr/replace and vr/query-replace")

;;; private variables

(defconst vr--match-faces '(vr/match-0 vr/match-1)
  "Faces in list for convenience")

(defconst vr--group-faces '(vr/group-0 vr/group-1 vr/group-2)
  "Faces in list for convenience")

(defconst vr--overlay-priority 1001
  "Starting priority of visual-regexp overlays.")

(defvar vr--in-minibuffer nil
  "Is visual-regexp currently being used?")

(defvar vr--calling-func nil
  "Which function invoked vr--interactive-get-args?")

(defvar vr--last-minibuffer-contents nil
  "Keeping track of minibuffer changes")

(defvar vr--target-buffer-start nil
  "Starting position in target buffer.")

(defvar vr--target-buffer-end nil
  "Ending position in target buffer.")

(defvar vr--limit-reached)

(defvar vr--regexp-string nil
  "Entered regexp.")

(defvar vr--replace-string nil
  "Entered replacement.")

(defvar vr--feedback-limit nil
  "Feedback limit currently in use.")

(defvar vr--replace-preview nil
  "Preview of replacement activated?")

(defvar vr--target-buffer nil
  "Buffer to which visual-regexp is applied to.")

(defvar vr--overlays (make-hash-table :test 'equal)
  "Overlays used in target buffer.")

(defvar vr--visible-overlays (list)
  "Overlays currently visible.")

(defvar vr--minibuffer-message-overlay nil)

;;; keymap

(defvar vr/minibuffer-keymap
  (let ((map (copy-keymap minibuffer-local-map)))
    (define-key map (kbd "C-c ?") 'vr--minibuffer-help)
    (define-key map (kbd "C-c a") 'vr--shortcut-toggle-limit)
    (define-key map (kbd "C-c p") 'vr--shortcut-toggle-preview)
    map)
  "Keymap used while using visual-regexp,")

;;; helper functions

(defun vr--shortcut-toggle-preview ()
  (interactive)
  (when (vr--in-replace)
    (setq vr--replace-preview (not vr--replace-preview))
    (vr--update-minibuffer-prompt)
    (vr--do-replace-feedback)))

(defun vr--shortcut-toggle-limit ()
  "Toggle the limit of overlays shown (default limit / no limit)"
  (interactive)
  (if vr--feedback-limit
      (setq vr--feedback-limit nil)
    (setq vr--feedback-limit vr/default-feedback-limit))
  (vr--show-feedback))

(defun vr--get-regexp-string-full ()
  (if (equal vr--in-minibuffer 'vr--minibuffer-regexp)
      (minibuffer-contents)
    vr--regexp-string))

(defun vr--query-replace--split-string (string)
  "Copy/paste of query-replace--split-string, removing the assertion."
  (let* ((length (length string))
         (split-pos (text-property-any 0 length 'separator t string)))
    (if (not split-pos)
        (substring-no-properties string)
      (cons (substring-no-properties string 0 split-pos)
            (substring-no-properties string (1+ split-pos) length)))))

(defun vr--in-from ()
  "Returns t if the we are in the regexp prompt. Returns nil if we are in the replace prompt. Call only if (and vr--in-minibuffer (minibufferp))"
  (equal vr--in-minibuffer 'vr--minibuffer-regexp))

(defun vr--in-replace ()
  "Returns t if we are either in the replace prompt, or in the regexp prompt containing a replacement (separated by query-replace-from-to-separator)"
  (or (not (vr--in-from))
      (consp (vr--query-replace--split-string (vr--get-regexp-string-full)))))

(defun vr--get-regexp-string (&optional for-display)
  (let ((split (vr--query-replace--split-string (vr--get-regexp-string-full))))
    (if (consp split) (car split) split)))

(defun vr--get-replace-string ()
  (if (equal vr--in-minibuffer 'vr--minibuffer-replace)
      (minibuffer-contents-no-properties)
    (let ((split (vr--query-replace--split-string (vr--get-regexp-string-full))))
      (if (consp split) (cdr split) vr--replace-string))))

(defun vr--format-error (err)
  (if (eq (car err) 'error)
      (car (cdr err))
    (format "%s" err)))

;;; minibuffer functions

(defun vr--set-minibuffer-prompt ()
  (let ((prompt (cond ((equal vr--calling-func 'vr--calling-func-query-replace)
                       "Query replace")
                      ((equal vr--calling-func 'vr--calling-func-mc-mark)
                       "Mark")
                      (t
                       "Replace"))))
    (when (and (vr--in-replace) vr--replace-preview)
      (setq prompt (concat prompt " (preview)")))
    (when (not (vr--in-from))
      (setq prompt (concat prompt " " (vr--get-regexp-string t))))
    (setq prompt (concat prompt (if (vr--in-from) ": " " with: ")))
    prompt))

(defun vr--update-minibuffer-prompt ()
  (when (and vr--in-minibuffer (minibufferp))
    (let ((inhibit-read-only t)
          (prompt (vr--set-minibuffer-prompt)))
      (put-text-property (point-min) (minibuffer-prompt-end) 'display prompt))))


(defun vr--minibuffer-message (message &rest args)
  "Adaptation of minibuffer-message that does not use sit-for
to make the message disappear. The problem with this was that during sit-for,
 the cursor was shown at the beginning of the message regardless of whether
 the point was actually there or not. Workaround: we let the message stay
visible all the time in the minibuffer."
  (if (not (and vr--in-minibuffer (minibufferp (current-buffer))))
      ;; fallback
      (apply 'minibuffer-message message args)
    ;; Clear out any old echo-area message to make way for our new thing.
    (message nil)
    (setq message (concat " [" message "]"))
    (when args (setq message (apply 'format message args)))
    (unless (zerop (length message))
      ;; The current C cursor code doesn't know to use the overlay's
      ;; marker's stickiness to figure out whether to place the cursor
      ;; before or after the string, so let's spoon-feed it the pos.
      (put-text-property 0 1 'cursor t message))
    (unless (overlayp vr--minibuffer-message-overlay)
      (setq vr--minibuffer-message-overlay (make-overlay (point-max) (point-max) nil t t)))
    (move-overlay vr--minibuffer-message-overlay (point-max) (point-max))
    (overlay-put vr--minibuffer-message-overlay 'after-string message)))

(defun vr--minibuffer-help-text ()
  (let ((help ""))
    (setq help (concat help (substitute-command-keys "\\<vr/minibuffer-keymap>\\[vr--minibuffer-help]: help, \\[vr--shortcut-toggle-limit]: toggle show all")))
    (when (vr--in-replace)
      (setq help (concat help (substitute-command-keys ", \\[vr--shortcut-toggle-preview]: toggle preview"))))
    help
    ))

(defun vr--minibuffer-help ()
  (interactive)
  (vr--minibuffer-message (vr--minibuffer-help-text)))

;;; overlay functions

(defun vr--get-overlay (i j)
  "i: match index, j: submatch index"
  (let (overlay)
    (setq overlay (gethash (list i j) vr--overlays))
    (unless overlay ;; create new one if overlay does not exist yet
      (setq overlay (make-overlay 0 0))
      (if (= 0 j)
          (overlay-put overlay 'face (nth (mod i (length vr--match-faces)) vr--match-faces))
        (overlay-put overlay 'face (nth (mod j (length vr--group-faces)) vr--group-faces)))
      (overlay-put overlay 'priority (+ vr--overlay-priority (if (= j 0) 0 1)))
      (overlay-put overlay 'vr-ij (list i j))
      (puthash (list i j) overlay vr--overlays))
    overlay))

(defun vr--delete-overlays ()
  "Delete all visible overlays."
  (mapc (lambda (overlay)
          (delete-overlay overlay))
        vr--visible-overlays)
  (setq vr--visible-overlays (list)))

(defun vr--delete-overlay-display (overlay)
  (overlay-put overlay 'display nil)
  (overlay-put overlay 'after-string nil)
  (overlay-put overlay 'priority vr--overlay-priority))

(defun vr--delete-overlay-displays ()
  "Delete the display of all visible overlays. Call before vr--delete-overlays."
  (mapc (lambda (overlay)
          (cl-multiple-value-bind (i j) (overlay-get overlay 'vr-ij)
            (when (= 0 j)
              (vr--delete-overlay-display overlay))))
        vr--visible-overlays))

;;; hooks

(defun vr--show-feedback ()
  (if (vr--in-replace)
      (vr--do-replace-feedback)
    (vr--feedback)))

(defun vr--after-change (beg end len)
  (when (and vr--in-minibuffer (minibufferp))
    ;; minibuffer-up temporarily deletes minibuffer contents before inserting new one.
    ;; don't do anything then as the messages shown by visual-regexp are irritating while browsing the history.
    (unless (and (string= "" (minibuffer-contents-no-properties))
                 (equal last-command 'previous-history-element))
      ;; do something when minibuffer contents changes
      (unless (string= vr--last-minibuffer-contents (minibuffer-contents-no-properties))
        (setq vr--last-minibuffer-contents (minibuffer-contents-no-properties))
        ;; minibuffer contents has changed, update visual feedback.
        ;; not using after-change-hook because this hook applies to the whole minibuffer, including minibuffer-messages
        ;; that disappear after a while.
        (vr--update-minibuffer-prompt)
        (vr--show-feedback)))))
(add-hook 'after-change-functions 'vr--after-change)

(defun vr--minibuffer-setup ()
  "Setup prompt and help when entering minibuffer."
  (when vr--in-minibuffer
    (progn
      (vr--update-minibuffer-prompt)
      (when vr/auto-show-help (vr--minibuffer-help)))))
(add-hook 'minibuffer-setup-hook 'vr--minibuffer-setup)

;;; helper functions

(defun vr--target-window ()
  (if vr--target-buffer
      (get-buffer-window vr--target-buffer)
    nil))

(defun vr--compose-messages (&rest msgs)
  (mapconcat 'identity (delq nil (mapcar (lambda (msg) (if (or (not msg) (string= "" msg)) nil msg)) msgs)) " - "))

;;; show feedback functions
(defun vr--feedback-function (regexp-string forward feedback-limit callback)
  "Feedback function for emacs-style regexp search"
  (let ((message-line "")
        (err))
    (with-current-buffer vr--target-buffer
      (save-excursion
        (goto-char (if forward vr--target-buffer-start vr--target-buffer-end))
        (let ((i 0)
              (looping t))
          (while (and looping
                      (condition-case err
                          (if forward
                              (re-search-forward regexp-string vr--target-buffer-end t)
                            (re-search-backward regexp-string vr--target-buffer-start t))
                        (invalid-regexp (progn (setq message-line (car (cdr err))) nil))))
            (when (or (not feedback-limit) (< i feedback-limit)) ;; let outer loop finish so we can get the matches count
              (cl-loop for (start end) on (match-data) by 'cddr
                       for j from 0
                       when (and start end)
                       do
                       (funcall callback i j start end)))
            (when (= (match-beginning 0) (match-end 0))
              (cond ;; don't get stuck on zero-width matches
               ((and forward (> vr--target-buffer-end (point))) (forward-char))
               ((and (not forward) (< vr--target-buffer-start (point))) (backward-char))
               (t (setq looping nil))))
            (setq i (1+ i)))
          (if (string= "" message-line)
              (setq message-line (format "%s matches" i))))))
    message-line))

(defun vr--feedback-match-callback (i j begin end)
  (with-current-buffer vr--target-buffer
    (save-excursion
      (when (= 0 i) ;; make first match visible
        (with-selected-window (vr--target-window)
          (goto-char end)))
      (let ((overlay (vr--get-overlay i j)))
        (move-overlay overlay begin end vr--target-buffer)
        (if (and (= 0 j) (= begin end)) ;; empty match; indicate by a pipe
            (overlay-put overlay 'after-string (propertize "|" 'face (nth (mod i (length vr--match-faces)) vr--match-faces) 'help-echo "empty match"))
          (overlay-put overlay 'after-string nil))
        (setq vr--visible-overlays (cons overlay vr--visible-overlays)))
      ;; mark if we have reached the specified feedback limit
      (when (and vr--feedback-limit (= vr--feedback-limit (1+ i)) )
        (setq vr--limit-reached t)))))

(defun vr--feedback (&optional inhibit-message)
  "Show visual feedback for matches."
  (vr--delete-overlays)
  (setq vr--limit-reached nil)
  (let (message-line)
    (setq message-line
          (condition-case err
              (progn
                (vr--feedback-function (vr--get-regexp-string) t vr--feedback-limit 'vr--feedback-match-callback))
            (error (vr--format-error err))))
    (unless inhibit-message
      (let ((msg (vr--compose-messages message-line (when vr--limit-reached (format "%s matches shown, hit C-c a to show all" vr--feedback-limit)))))
        (unless (string= "" msg)
          (vr--minibuffer-message msg))))))

(defun vr--get-replacement (replacement match-data i)
  (with-current-buffer vr--target-buffer
    (let*
        ;; emulate case-conversion of (perform-replace)
        ((case-fold-search (if (and case-fold-search search-upper-case)
                               (ignore-errors (isearch-no-upper-case-p (vr--get-regexp-string) t))
                             case-fold-search))
         (nocasify (not (and case-replace case-fold-search))))
      ;; we need to set the match data again, s.t. match-substitute-replacement works correctly. 
      ;; (match-data) could have been modified in the meantime, e.g. by vr--get-regexp-string->pcre-to-elisp.
      (set-match-data match-data)
      (if (stringp replacement)
          (match-substitute-replacement replacement nocasify)
        (match-substitute-replacement (funcall (car replacement) (cdr replacement) i) nocasify)))))

(defun vr--do-replace-feedback-match-callback (replacement match-data i)
  (let ((begin (cl-first match-data))
        (end (cl-second match-data))
        (replacement (vr--get-replacement replacement match-data i)))
    (let* ((overlay (vr--get-overlay i 0))
           (empty-match (= begin end)))
      (move-overlay overlay begin end vr--target-buffer)
      (vr--delete-overlay-display overlay)
      (let ((current-face (nth (mod i (length vr--match-faces)) vr--match-faces)))
        (if (or empty-match vr--replace-preview)
            (progn
              (overlay-put overlay (if empty-match 'after-string 'display) (propertize replacement 'face current-face))
              (overlay-put overlay 'priority (+ vr--overlay-priority 2)))
          (progn
            (overlay-put overlay 'after-string
                         (concat (propertize vr/match-separator-string 'face
                                             (if vr/match-separator-use-custom-face
                                                 'vr/match-separator-face
                                               current-face))
                                 (propertize replacement 'face current-face)))
            (overlay-put overlay 'priority (+ vr--overlay-priority 0))))))))

(defun vr--get-replacements (feedback feedback-limit)
  "Get replacements using emacs-style regexp."
  (setq vr--limit-reached nil)
  (let ((regexp-string)
        (replace-string (vr--get-replace-string))
        (message-line "")
        (i 0)
        (replacements (list))
        (err)
        (buffer-contents (with-current-buffer vr--target-buffer
                           (buffer-substring-no-properties (point-min) (point-max)))))

    (condition-case err
        (progn
          ;; can signal invalid-regexp
          (setq regexp-string (vr--get-regexp-string))

          (with-current-buffer vr--target-buffer
            (goto-char vr--target-buffer-start)
            (let ((looping t))
              (while (and
                      looping
                      (condition-case err
                          (re-search-forward regexp-string vr--target-buffer-end t)
                        ('invalid-regexp (progn (setq message-line (car (cdr err))) nil))))
                (condition-case err
                    (progn
                      (if (or (not feedback) (not feedback-limit) (< i feedback-limit))
                          (setq replacements (cons
                                              (let ((match-data (mapcar 'marker-position (match-data))))
                                                (list (query-replace-compile-replacement replace-string t) match-data i))
                                              replacements))
                        (setq vr--limit-reached t))
                      (when (= (match-beginning 0) (match-end 0))
                        (if (> vr--target-buffer-end (point))
                            (forward-char) ;; don't get stuck on zero-width matches
                          (setq looping nil)))
                      (setq i (1+ i)))
                  ('error (progn
                            (setq message-line (vr--format-error err))
                            (setq replacements (list))
                            (setq looping nil))))))))
      (invalid-regexp (setq message-line (car (cdr err))))
      (error (setq message-line (vr--format-error err))))
    (if feedback
        (if (string= "" message-line)
            (setq message-line (vr--compose-messages (format "%s matches" i) (when vr--limit-reached (format "%s matches shown, hit C-c a to show all" feedback-limit)))))
      (setq message-line (format "replaced %d matches" i)))
    (list replacements message-line)))

(defun vr--do-replace-feedback ()
  "Show visual feedback for replacements."
  (vr--feedback t) ;; only really needed when regexp has not been changed from default (=> no overlays have been created)
  (custom-reevaluate-setting 'vr/match-separator-string)
  (cl-multiple-value-bind (replacements message-line) (vr--get-replacements t vr--feedback-limit)
    ;; visual feedback for matches
    (condition-case err
        (mapc (lambda (replacement-info) (apply 'vr--do-replace-feedback-match-callback replacement-info)) replacements)
      ('error (setq message-line (vr--format-error err))))
    (unless (string= "" message-line)
      (vr--minibuffer-message message-line))))

;;; vr/replace

(defun vr--do-replace (&optional silent)
  "Replace matches."
  (vr--delete-overlay-displays)
  (vr--delete-overlays)
  (cl-multiple-value-bind (replacements message-line) (vr--get-replacements nil nil)
    (let ((replace-count 0)
          (cumulative-offset 0)
          last-match-data)
      (cl-loop for replacement-info in replacements
               for counter from 0 do
               (setq replace-count (1+ replace-count))
               (cl-multiple-value-bind (replacement match-data i) replacement-info
                 ;; replace match
                 (let* ((replacement (vr--get-replacement replacement match-data i))
                        (begin (cl-first match-data))
                        (end (cl-second match-data)))
                   (with-current-buffer vr--target-buffer
                     (save-excursion
                       ;; first insert, then delete
                       ;; this ensures that if we had an active region before, the replaced match is still part of the region
                       (goto-char begin)
                       (insert replacement)
                       (setq cumulative-offset (+ cumulative-offset (- (point) end)))
                       (delete-char (- end begin))))
                   (when (= 0 counter)
                     (setq last-match-data match-data))
                   )))
      (unless (or silent (string= "" message-line))
        (vr--minibuffer-message message-line))
      ;; needed to correctly position the mark after query replace (finished with 'automatic ('!'))
      (set-match-data (mapcar (lambda (el) (+ cumulative-offset el)) last-match-data))
      replace-count)))

(defun vr--set-target-buffer-start-end ()
  (setq vr--target-buffer-start (if (region-active-p)
                                    (region-beginning)
                                  (point)))
  (setq vr--target-buffer-end (if (region-active-p)
                                  (region-end)
                                (point-max))))

(defun vr--set-regexp-string ()
  (save-excursion
    ;; deactivate mark so that we can see our faces instead of region-face.
    (deactivate-mark)
    (setq vr--in-minibuffer 'vr--minibuffer-regexp)
    (setq vr--last-minibuffer-contents "")
    (custom-reevaluate-setting 'query-replace-from-to-separator)
    (let* ((minibuffer-allow-text-properties t)
           (history-add-new-input nil)
           (text-property-default-nonsticky
            (cons '(separator . t) text-property-default-nonsticky))
           ;; seperator and query-replace-from-to-history copy/pasted from replace.el
           (separator
            (when query-replace-from-to-separator
              (propertize "\0"
                          'display query-replace-from-to-separator
                          'separator t)))
           (query-replace-from-to-history
            (append
             (when separator
               (mapcar (lambda (from-to)
                         (concat (query-replace-descr (car from-to))
                                 separator
                                 (query-replace-descr (cdr from-to))))
                       (symbol-value vr/query-replace-defaults-variable)))
             (symbol-value vr/query-replace-from-history-variable))))
      (setq vr--regexp-string
            (read-from-minibuffer
             " " ;; prompt will be set in vr--minibuffer-setup
             nil vr/minibuffer-keymap
             nil 'query-replace-from-to-history))
      (let ((split (vr--query-replace--split-string vr--regexp-string)))
        (if (not (consp split))
            (add-to-history vr/query-replace-from-history-variable vr--regexp-string nil t)
          (add-to-history vr/query-replace-from-history-variable (car split) nil t)
          (add-to-history vr/query-replace-to-history-variable (cdr split) nil t)
          (add-to-history vr/query-replace-defaults-variable split nil t))))))

(defun vr--set-replace-string ()
  (save-excursion
    ;; deactivate mark so that we can see our faces instead of region-face.
    (deactivate-mark)
    (let ((split (vr--query-replace--split-string vr--regexp-string)))
      (unless (consp split)
        (setq vr--in-minibuffer 'vr--minibuffer-replace)
        (setq vr--last-minibuffer-contents "")
        (let ((history-add-new-input nil))
          (setq vr--replace-string
                (read-from-minibuffer
                 " " ;; prompt will be set in vr--minibuffer-setup
                 nil vr/minibuffer-keymap
                 nil vr/query-replace-to-history-variable))
          (add-to-history vr/query-replace-to-history-variable vr--replace-string nil t)
          (add-to-history vr/query-replace-defaults-variable (cons vr--regexp-string vr--replace-string)))))))

(defun vr--interactive-get-args (mode calling-func)
  "Get interactive args for the vr/replace and vr/query-replace functions."
  (unwind-protect
      (progn
        (let ((buffer-read-only t)) ;; make target buffer
          (when vr--in-minibuffer (error "visual-regexp already in use."))
          (setq vr--calling-func calling-func)
          (setq vr--target-buffer (current-buffer))
          (vr--set-target-buffer-start-end)

          (run-hooks 'vr/initialize-hook)
          (setq vr--feedback-limit vr/default-feedback-limit)

          (setq vr--replace-preview vr/default-replace-preview)

          (vr--set-regexp-string)
          (when (equal mode 'vr--mode-regexp-replace)
            (vr--set-replace-string))
          
          ;; Successfully got the args, deactivate mark now. If the command was aborted (C-g), the mark (region) would remain active.
          (deactivate-mark)
          (cond ((equal mode 'vr--mode-regexp-replace)
                 (list vr--regexp-string
                       vr--replace-string
                       vr--target-buffer-start
                       vr--target-buffer-end))
                ((equal mode 'vr--mode-regexp)
                 (list vr--regexp-string
                       vr--target-buffer-start
                       vr--target-buffer-end)))))
    (progn ;; execute on finish
      (setq vr--in-minibuffer nil)
      (setq vr--calling-func nil)
      (unless (overlayp vr--minibuffer-message-overlay)
        (delete-overlay vr--minibuffer-message-overlay))
      (vr--delete-overlay-displays)
      (vr--delete-overlays))))

(add-hook 'multiple-cursors-mode-enabled-hook
          ;; run vr/mc-mark once per cursor by default (do not ask the user)
          (lambda ()
            (when (boundp 'mc--default-cmds-to-run-once)
              (add-to-list 'mc--default-cmds-to-run-once 'vr/mc-mark))))

;;;###autoload
(defun vr/mc-mark (regexp start end)
  "Convert regexp selection to multiple cursors."
  (require 'multiple-cursors)
  (interactive
   (vr--interactive-get-args 'vr--mode-regexp 'vr--calling-func-mc-mark))
  (with-current-buffer vr--target-buffer
    (mc/remove-fake-cursors)
    (activate-mark)
    (let (;; disable deactivating of mark after buffer-editing commands
          ;; (which happens for example in visual-regexp-steroids/vr--parse-matches
          ;; during the callback).
          (deactivate-mark nil)
          (first-fake-cursor nil))
      (vr--feedback-function (vr--get-regexp-string) t nil (lambda (i j begin end)
                                                             (with-current-buffer vr--target-buffer
                                                               (goto-char end)
                                                               (push-mark begin)
                                                               ;; temporarily enable transient mark mode
                                                               (activate-mark)
                                                               (let ((fc (mc/create-fake-cursor-at-point)))
                                                                 (unless first-fake-cursor
                                                                   (setq first-fake-cursor fc))))))

      ;; one fake cursor too many, replace first one with
      ;; the regular cursor.
      (when first-fake-cursor
        (mc/pop-state-from-overlay first-fake-cursor)))
    (mc/maybe-multiple-cursors-mode)))

;;;###autoload
(defun vr/replace (regexp replace start end)
  "Regexp-replace with live visual feedback."
  (interactive
   (vr--interactive-get-args 'vr--mode-regexp-replace 'vr--calling-func-replace))
  (unwind-protect
      (progn
        (when vr--in-minibuffer (error "visual-regexp already in use."))
        (setq vr--target-buffer (current-buffer)
              vr--target-buffer-start start
              vr--target-buffer-end end
              vr--regexp-string regexp
              vr--replace-string replace)
        ;; do replacement
        (vr--do-replace))
    ;; execute on finish
    (setq vr--in-minibuffer nil)))

;; query-replace-regexp starts here

(defvar vr--query-replacements nil)
;; we redefine the help text from replace.el to remove the commands we don't support.

(defconst vr--query-replace-help
  "Type Space or `y' to replace one match, Delete or `n' to skip to next,
RET or `q' to exit, Period to replace one match and exit,
Comma to replace but not move point immediately,
p to preview the replacement (like 'C-c p' during construction of the regexp),
C-r [not supported in visual-regexp],
C-w [not supported in visual-regexp],
C-l to clear the screen, redisplay, and offer same replacement again,
! to replace all remaining matches with no more questions,
^ [not supported in visual-regexp],
E [not supported in visual-regexp]"
  "Help message while in `vr/query-replace'.")

(defvar vr--query-replace-map
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map query-replace-map)
    ;; the following replace.el commands are not supported by visual-regexp.
    (define-key map "e" nil)
    (define-key map "E" nil)
    (define-key map "\C-r" nil)
    (define-key map "\C-w" nil)
    (define-key map "^" nil)
    (define-key map "p" 'toggle-preview)
    map
    ))

;;;###autoload
(defun vr/query-replace (regexp replace start end)
  "Use vr/query-replace like you would use query-replace-regexp."
  (interactive
   (vr--interactive-get-args 'vr--mode-regexp-replace 'vr--calling-func-query-replace))
  (unwind-protect
      (progn
        (when vr--in-minibuffer (error "visual-regexp already in use."))
        (setq vr--target-buffer (current-buffer)
              vr--target-buffer-start start
              vr--target-buffer-end end
              vr--regexp-string regexp
              vr--replace-string replace)
        (vr--perform-query-replace))
    ;; execute on finish
    (setq vr--in-minibuffer nil)))

(defun vr--perform-query-replace ()
  ;; This function is a heavily modified version of (perform-replace) from replace.el.
  ;; The original plan was to use the original perform-replace, but various issues stood in the way.
  (and minibuffer-auto-raise
       (raise-frame (window-frame (minibuffer-window))))
  (let* ((from-string (vr--get-regexp-string))
         (map vr--query-replace-map)
         (vr--query-replacements (nreverse (car (vr--get-replacements nil nil))))
         (next-replacement nil) ;; replacement string for current match
         (keep-going t)
         (replace-count 0)
         ;; a match can be replaced by a longer/shorter replacement. cumulate the difference
         (cumulative-offset 0)
         (recenter-last-op nil) ; Start cycling order with initial position.
         (message
          (concat
           (propertize "Replacing " 'read-only t)
           (propertize "%s" 'read-only t 'face 'font-lock-keyword-face)
           (propertize " with " 'read-only t)
           (propertize "%s" 'read-only t 'face 'font-lock-keyword-face)
           (propertize (substitute-command-keys
                        " (\\<vr--query-replace-map>\\[help] for help) ")
                       'read-only t))))

    ;; show visual feedback for all matches
    (mapc (lambda (replacement-info)
            (cl-multiple-value-bind (replacement match-data i) replacement-info
              (vr--feedback-match-callback i 0 (cl-first match-data) (cl-second match-data))))
          vr--query-replacements)

    (goto-char vr--target-buffer-start)
    (push-mark)
    (undo-boundary)
    (unwind-protect
        ;; Loop finding occurrences that perhaps should be replaced.
        (while (and keep-going vr--query-replacements)
          ;; Advance replacement list
          (cl-multiple-value-bind (replacement match-data i) (car vr--query-replacements)
            (setq match-data (mapcar (lambda (el) (+ cumulative-offset el)) match-data))
            (let ((begin (cl-first match-data))
                  (end (cl-second match-data))
                  (next-replacement-orig replacement))
              (setq next-replacement (vr--get-replacement replacement match-data replace-count))
              (goto-char begin)
              (setq vr--query-replacements (cdr vr--query-replacements))

              ;; default for new occurrence: no preview
              (setq vr--replace-preview nil)

              (undo-boundary)
              (let (done replaced key def)
                ;; Loop reading commands until one of them sets done,
                ;; which means it has finished handling this
                ;; occurrence.
                (while (not done)
                  ;; show replacement feedback for current occurrence
                  (unless replaced
                    (vr--do-replace-feedback-match-callback next-replacement-orig match-data i))
                  ;; Bind message-log-max so we don't fill up the message log
                  ;; with a bunch of identical messages.
                  (let ((message-log-max nil))
                    (message message from-string next-replacement))
                  (setq key (read-event))
                  (setq key (vector key))
                  (setq def (lookup-key map key))

                  ;; can use replace-match afterwards
                  (set-match-data match-data)

                  ;; Restore the match data while we process the command.
                  (cond ((eq def 'help)
                         (with-output-to-temp-buffer "*Help*"
                           (princ
                            (concat "Query replacing visual-regexp "
                                    from-string " with "
                                    next-replacement ".\n\n"
                                    (substitute-command-keys
                                     vr--query-replace-help)))
                           (with-current-buffer standard-output
                             (help-mode))))
                        ((eq def 'exit)
                         (setq keep-going nil
                               done t))
                        ((eq def 'act)
                         (unless replaced
                           (replace-match next-replacement t t)
                           (setq replace-count (1+ replace-count)))
                         (setq done t
                               replaced t))
                        ((eq def 'act-and-exit)
                         (unless replaced
                           (replace-match next-replacement t t)
                           (setq replace-count (1+ replace-count)))
                         (setq keep-going nil
                               done t
                               replaced t))
                        ((eq def 'act-and-show)
                         (unless replaced
                           (replace-match next-replacement t t)
                           (setq replace-count (1+ replace-count))
                           (setq replaced t)))
                        ((eq def 'toggle-preview)
                         (setq vr--replace-preview (not vr--replace-preview)))
                        ((eq def 'automatic)
                         (setq vr--target-buffer-start (match-beginning 0)
                               vr--target-buffer-end (+ cumulative-offset vr--target-buffer-end))
                         (setq replace-count (+ replace-count (vr--do-replace t)))
                         (setq done t
                               replaced t
                               keep-going nil))
                        ((eq def 'skip)
                         (setq done t))
                        ((eq def 'recenter)
                         ;; `this-command' has the value `query-replace',
                         ;; so we need to bind it to `recenter-top-bottom'
                         ;; to allow it to detect a sequence of `C-l'.
                         (let ((this-command 'recenter-top-bottom)
                               (last-command 'recenter-top-bottom))
                           (recenter-top-bottom)))
                        (t
                         (setq this-command 'mode-exited)
                         (setq keep-going nil)
                         (setq unread-command-events
                               (append (listify-key-sequence key)
                                       unread-command-events))
                         (setq done t)))
                  (when replaced
                    (setq cumulative-offset (+ cumulative-offset (- (length next-replacement) (- end begin)))))
                  (unless (eq def 'recenter)
                    ;; Reset recenter cycling order to initial position.
                    (setq recenter-last-op nil))
                  ;; in case of 'act-and-show: delete overlay display or it will still be
                  ;; visible even though the replacement has been made
                  (when replaced (vr--delete-overlay-display (vr--get-overlay i 0)))))

              ;; occurrence has been handled
              ;; delete feedback overlay
              (delete-overlay (vr--get-overlay i 0)))))

      ;; unwind
      (progn
        (vr--delete-overlay-displays)
        (vr--delete-overlays)
        ;; (replace-dehighlight)
        ))
    (unless unread-command-events
      ;; point is set to the end of the last occurrence.
      (goto-char (match-end 0))
      (message "Replaced %d occurrence%s"
               replace-count
               (if (= replace-count 1) "" "s")))))

(provide 'visual-regexp)

;;; visual-regexp.el ends here
