gptel/gptel-transient.el

;;; gptel-transient.el --- Transient menu for GPTel  -*- lexical-binding: t; -*-

;; Copyright (C) 2023  Karthik Chikmagalur

;; Author: Karthik Chikmagalur <karthikchikmagalur@gmail.com>
;; Keywords: convenience

;; SPDX-License-Identifier: GPL-3.0-or-later

;; 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 <https://www.gnu.org/licenses/>.

;;; Commentary:

;;

;;; Code:
(require 'cl-lib)
(require 'gptel)
(require 'transient)

(declare-function ediff-regions-internal "ediff")
(declare-function ediff-make-cloned-buffer "ediff-utils")


;; * Helper functions

(defun gptel--refactor-or-rewrite ()
  "Rewrite should be refactored into refactor.

Or is it the other way around?"
  (if (derived-mode-p 'prog-mode)
      "Refactor" "Rewrite"))

(defvar-local gptel--rewrite-message nil)
(defun gptel--rewrite-message ()
  "Set a generic refactor/rewrite message for the buffer."
  (if (derived-mode-p 'prog-mode)
      (format "You are a %s programmer. Refactor the following code. Generate only code, no explanation."
              (substring (symbol-name major-mode) nil -5))
    (format "You are a prose editor. Rewrite the following text to be more professional.")))

(defvar gptel--crowdsourced-prompts-url
  "https://github.com/f/awesome-chatgpt-prompts/raw/main/prompts.csv"
  "URL for crowdsourced LLM system prompts.")

(defvar gptel--crowdsourced-prompts
  (make-hash-table :test #'equal)
  "Crowdsourced LLM system prompts.")

(defun gptel--crowdsourced-prompts ()
  "Acquire and read crowdsourced LLM system prompts.

These are stored in the variable `gptel--crowdsourced-prompts',
which see."
  (when (hash-table-p gptel--crowdsourced-prompts)
    (when (hash-table-empty-p gptel--crowdsourced-prompts)
      (unless gptel-crowdsourced-prompts-file
        (run-at-time 0 nil #'gptel-system-prompt)
        (user-error "No crowdsourced prompts available"))
      (unless (and (file-exists-p gptel-crowdsourced-prompts-file)
                   (time-less-p
                    (time-subtract (current-time) (days-to-time 14))
                    (file-attribute-modification-time
                     (file-attributes gptel-crowdsourced-prompts-file))))
        (when (y-or-n-p
               (concat
                "Fetch crowdsourced system prompts from "
                (propertize "https://github.com/f/awesome-chatgpt-prompts" 'face 'link)
                "?"))
          ;; Fetch file
          (message "Fetching prompts...")
          (let ((dir (file-name-directory gptel-crowdsourced-prompts-file)))
            (unless (file-exists-p dir) (mkdir dir 'create-parents))
            (if (url-copy-file gptel--crowdsourced-prompts-url
                               gptel-crowdsourced-prompts-file
                               'ok-if-already-exists)
		(message "Fetching prompts... done.")
              (message "Could not retrieve new prompts.")))))
      (if (not (file-readable-p gptel-crowdsourced-prompts-file))
          (progn (message "No crowdsourced prompts available")
                 (call-interactively #'gptel-system-prompt))
        (with-temp-buffer
          (insert-file-contents gptel-crowdsourced-prompts-file)
          (goto-char (point-min))
          (forward-line 1)
          (while (not (eobp))
            (when-let ((act (read (current-buffer))))
              (forward-char)
              (save-excursion
                (while (re-search-forward "\"\"" (line-end-position) t)
                  (replace-match "\\\\\"")))
              (when-let ((prompt (read (current-buffer))))
                (puthash act prompt gptel--crowdsourced-prompts)))
            (forward-line 1)))))
    gptel--crowdsourced-prompts))


;; * Transient Prefixes

(define-obsolete-function-alias 'gptel-send-menu 'gptel-menu "0.3.2")

;; BUG: The `:incompatible' spec doesn't work if there's a `:description' below it.
;;;###autoload (autoload 'gptel-menu "gptel-transient" nil t)
(transient-define-prefix gptel-menu ()
  "Change parameters of prompt to send to the LLM."
  ;; :incompatible '(("-m" "-n" "-k" "-e"))
  [:description
   (lambda () (format "Directive:  %s"
                 (truncate-string-to-width
                  gptel--system-message (max (- (window-width) 14) 20) nil nil t)))
   ("h" "Set directives for chat" gptel-system-prompt :transient t)]
  [["Session Parameters"
    (gptel--infix-provider)
    ;; (gptel--infix-model)
    (gptel--infix-max-tokens)
    (gptel--infix-num-messages-to-send)
    (gptel--infix-temperature)]
   ["Prompt from"
    ("p" "Minibuffer instead" "p")
    ("y" "Kill-ring instead" "y")
    ""
    ("i" "Replace/Delete prompt" "i")]
    ["Response to"
    ("m" "Minibuffer instead" "m")
    ("g" "gptel session" "g"
     :class transient-option
     :prompt "Existing or new gptel session: "
     :reader
     (lambda (prompt _ _history)
       (read-buffer
        prompt (generate-new-buffer-name
                (concat "*" (gptel-backend-name gptel-backend) "*"))
        nil (lambda (buf-name)
              (if (consp buf-name) (setq buf-name (car buf-name)))
              (let ((buf (get-buffer buf-name)))
                (and (buffer-local-value 'gptel-mode buf)
                     (not (eq (current-buffer) buf))))))))
    ("b" "Any buffer" "b"
     :class transient-option
     :prompt "Output to buffer: "
     :reader
     (lambda (prompt _ _history)
       (read-buffer prompt (buffer-name (other-buffer)) nil)))
    ("k" "Kill-ring" "k")]]
  [["Send"
    (gptel--suffix-send)
    ("M-RET" "Regenerate" gptel--regenerate :if gptel--in-response-p)]
   [:description gptel--refactor-or-rewrite
    :if use-region-p
    ("r"
     ;;FIXME: Transient complains if I use `gptel--refactor-or-rewrite' here. It
     ;;reads this function as a suffix instead of a function that returns the
     ;;description.
     (lambda () (if (derived-mode-p 'prog-mode)
               "Refactor" "Rewrite"))
     gptel-rewrite-menu)]
   ["Tweak Response" :if gptel--in-response-p :pad-keys t
    ("SPC" "Mark" gptel--mark-response)
    ("P" "Previous variant" gptel--previous-variant
     :if gptel--at-response-history-p
     :transient t)
    ("N" "Next variant" gptel--previous-variant
     :if gptel--at-response-history-p
     :transient t)
    ("E" "Ediff previous" gptel--ediff
     :if gptel--at-response-history-p)]]
  (interactive)
  (gptel--sanitize-model)
  (transient-setup 'gptel-menu))

;; ** Prefix for setting the system prompt.
(defun gptel-system-prompt--setup (_)
  "Set up suffixes for system prompt."
  (transient-parse-suffixes
   'gptel-system-prompt
   (cl-loop for (type . prompt) in gptel-directives
       with taken
       with width = (window-width)
       for name = (symbol-name type)
       for key =
       (let ((idx 0) pos)
         (while (or (not pos) (member pos taken))
           (setq pos (substring name idx (1+ idx)))
           (cl-incf idx))
         (push pos taken)
         pos)
       ;; The explicit declaration ":transient transient--do-return" here
       ;; appears to be required for Transient v0.5 and up.  Without it, these
       ;; are treated as suffixes when invoking `gptel-system-prompt' directly,
       ;; and infixes when going through `gptel-menu'.
       ;; TODO: Raise an issue with Transient.
       collect (list (key-description key)
                     (concat (capitalize name) " "
                             (propertize " " 'display '(space :align-to 20))
                             (propertize
                              (concat
                               "("
                               (string-replace
                                "\n" " "
                                (truncate-string-to-width prompt (- width 30) nil nil t))
                               ")")
                              'face 'shadow))
                     `(lambda () (interactive)
                        (message "Directive: %s" ,prompt)
                        (setq gptel--system-message ,prompt))
		     :transient 'transient--do-return)
       into prompt-suffixes
       finally return
       (nconc
        (list (list 'gptel--suffix-system-message))
        prompt-suffixes
        (list (list "SPC" "Pick crowdsourced prompt"
                    'gptel--read-crowdsourced-prompt
		    ;; NOTE: Quitting the completing read when picking a
		    ;; crowdsourced prompt will cause the transient to exit
		    ;; instead of returning to the system prompt menu.
                    :transient 'transient--do-exit))))))

(transient-define-prefix gptel-system-prompt ()
  "Change the LLM system prompt.

The \"system\" prompt establishes directives for the chat
session. Some examples of system prompts are:

You are a helpful assistant. Answer as concisely as possible.
Reply only with shell commands and no prose.
You are a poet. Reply only in verse.

Customize `gptel-directives' for task-specific prompts."
  [:description
   (lambda () (format "Current directive: %s"
                 (truncate-string-to-width
                  gptel--system-message 100 nil nil t)))
   :class transient-column
   :setup-children gptel-system-prompt--setup
   :pad-keys t])

;; ** Prefix for rewriting/refactoring

(transient-define-prefix gptel-rewrite-menu ()
  "Rewrite or refactor text region using an LLM."
  [:description
   (lambda ()
     (format "Directive:  %s"
             (truncate-string-to-width
              (or gptel--rewrite-message (gptel--rewrite-message))
              (max (- (window-width) 14) 20) nil nil t)))
   (gptel--infix-rewrite-prompt)]
  [[:description "Diff Options"
   ("-w" "Wordwise diff" "-w")]
   [:description
    (lambda () (if (derived-mode-p 'prog-mode)
              "Refactor" "Rewrite"))
    (gptel--suffix-rewrite)
    (gptel--suffix-rewrite-and-replace)
    (gptel--suffix-rewrite-and-ediff)]]
  (interactive)
  (unless gptel--rewrite-message
    (setq gptel--rewrite-message (gptel--rewrite-message)))
  (transient-setup 'gptel-rewrite-menu))


;; * Transient Infixes

;; ** Infixes for model parameters

(defun gptel--transient-read-variable (prompt initial-input history)
  "Read value from minibuffer and interpret the result as a Lisp object.

PROMPT, INITIAL-INPUT and HISTORY are as in the Transient reader
documention."
  (ignore-errors
    (read-from-minibuffer prompt initial-input read-expression-map t history)))

(transient-define-infix gptel--infix-num-messages-to-send ()
  "Number of recent messages to send with each exchange.

By default, the full conversation history is sent with every new
prompt. This retains the full context of the conversation, but
can be expensive in token size. Set how many recent messages to
include."
  :description "Number of past messages to send"
  :class 'transient-lisp-variable
  :variable 'gptel--num-messages-to-send
  :key "-n"
  :prompt "Number of past messages to include for context (leave empty for all): "
  :reader 'gptel--transient-read-variable)

(transient-define-infix gptel--infix-max-tokens ()
  "Max tokens per response.

This is roughly the number of words in the response. 100-300 is a
reasonable range for short answers, 400 or more for longer
responses."
  :description "Response length (tokens)"
  :class 'transient-lisp-variable
  :variable 'gptel-max-tokens
  :key "-c"
  :prompt "Response length in tokens (leave empty: default, 80-200: short, 200-500: long): "
  :reader 'gptel--transient-read-variable)

(defclass gptel-provider-variable (transient-lisp-variable)
  ((model       :initarg :model)
   (model-value :initarg :model-value)
   (always-read :initform t)
   (set-value :initarg :set-value :initform #'set))
  "Class used for gptel-backends.")

(cl-defmethod transient-format-value ((obj gptel-provider-variable))
  (propertize (concat (gptel-backend-name (oref obj value)) ":"
                      (buffer-local-value (oref obj model) transient--original-buffer))
              'face 'transient-value))

(cl-defmethod transient-infix-set ((obj gptel-provider-variable) value)
  (pcase-let ((`(,backend-value ,model-value) value))
    (funcall (oref obj set-value)
             (oref obj variable)
             (oset obj value backend-value))
    (funcall (oref obj set-value)
             (oref obj model)
             (oset obj model-value model-value))))

(transient-define-infix gptel--infix-provider ()
  "AI Provider for Chat."
  :description "GPT Model: "
  :class 'gptel-provider-variable
  :prompt "Model provider: "
  :variable 'gptel-backend
  :model 'gptel-model
  :key "-m"
  :reader (lambda (prompt &rest _)
            (let* ((backend-name
                    (if (<= (length gptel--known-backends) 1)
                        (caar gptel--known-backends)
                      (completing-read
                       prompt
                       (mapcar #'car gptel--known-backends))))
                   (backend (alist-get backend-name gptel--known-backends
                                nil nil #'equal))
                   (backend-models (gptel-backend-models backend))
                   (model-name (if (= (length backend-models) 1)
                                   (car backend-models)
                                 (completing-read
                                  "Model: " backend-models))))
              (list backend model-name))))

(transient-define-infix gptel--infix-model ()
  "AI Model for Chat."
  :description "GPT Model: "
  :class 'transient-lisp-variable
  :variable 'gptel-model
  :key "-m"
  :choices '("gpt-3.5-turbo" "gpt-3.5-turbo-16k" "gpt-4" "gpt-4-1106-preview")
  :reader (lambda (prompt &rest _)
            (completing-read
             prompt
             '("gpt-3.5-turbo" "gpt-3.5-turbo-16k" "gpt-4" "gpt-4-1106-preview"))))

(transient-define-infix gptel--infix-temperature ()
  "Temperature of request."
  :description "Randomness (0 - 2.0)"
  :class 'transient-lisp-variable
  :variable 'gptel-temperature
  :key "-t"
  :prompt "Set temperature (0.0-2.0, leave empty for default): "
  :reader 'gptel--transient-read-variable)

;; ** Infix for the refactor/rewrite system message

(transient-define-infix gptel--infix-rewrite-prompt ()
  "Chat directive (system message) to use for rewriting or refactoring."
  :description (lambda () (if (derived-mode-p 'prog-mode)
                         "Set directives for refactor"
                       "Set directives for rewrite"))
  :format "%k %d"
  :class 'transient-lisp-variable
  :variable 'gptel--rewrite-message
  :key "h"
  :prompt "Set directive for rewrite: "
  :reader (lambda (prompt _ history)
            (read-string
             prompt (gptel--rewrite-message) history)))


;; * Transient Suffixes

;; ** Suffix to send prompt

(transient-define-suffix gptel--suffix-send (args)
  "Send ARGS."
  :key "RET"
  :description "Send prompt"
  (interactive (list (transient-args transient-current-command)))
  (let ((stream gptel-stream)
        (in-place (and (member "i" args) t))
        (output-to-other-buffer-p)
        (backend gptel-backend)
        (model gptel-model)
        (backend-name (gptel-backend-name gptel-backend))
        (buffer) (position)
        (callback) (gptel-buffer-name)
        ;; Input redirection: grab prompt from elsewhere?
        (prompt
         (cond
          ((member "p" args)
           (read-string
            (format "Ask %s: " (gptel-backend-name gptel-backend))
            (apply #'buffer-substring-no-properties
                   (if (use-region-p)
                       (list (region-beginning) (region-end))
                     (list (line-beginning-position) (line-end-position))))))
          ((member "y" args)
           (unless (car-safe kill-ring)
             (user-error "`kill-ring' is empty!  Nothing to send"))
           (if current-prefix-arg
               (read-from-kill-ring "Prompt from kill-ring: ")
             (current-kill 0))))))

    ;; Output redirection: Send response elsewhere?
    (cond
     ((member "m" args)
      (setq stream nil)
      (setq callback
            (lambda (resp info)
              (if resp
                  (message "%s response: %s" backend-name resp)
                (message "%s response error: %s" backend-name (plist-get info :status))))))
     ((member "k" args)
      (setq stream nil)
      (setq callback
            (lambda (resp info)
              (if (not resp)
                  (message "%s response error: %s" backend-name (plist-get info :status))
                (kill-new resp)
                (message "%s response: \"%s\" copied to kill-ring."
                         backend-name
                         (truncate-string-to-width resp 30))))))
     ((setq gptel-buffer-name
            (cl-some (lambda (s) (and (string-prefix-p "g" s)
                                 (substring s 1)))
                     args))
      (setq output-to-other-buffer-p t)
      (let ((reduced-prompt             ;For inserting into the gptel buffer as
                                        ;context, not the prompt used for the
                                        ;request itself
             (or prompt
                 (if (use-region-p)
                     (buffer-substring-no-properties (region-beginning)
                                                     (region-end))
                   (buffer-substring-no-properties
                    (save-excursion
                      (text-property-search-backward
                       'gptel 'response
                       (when (get-char-property (max (point-min) (1- (point)))
                                                'gptel)
                         t))
                      (point))
                    (gptel--at-word-end (point)))))))
        (cond
         ((buffer-live-p (get-buffer gptel-buffer-name))
          ;; Insert into existing gptel session
          (progn
            (setq buffer (get-buffer gptel-buffer-name))
            (with-current-buffer buffer
              (goto-char (point-max))
              (unless (or buffer-read-only
                          (get-char-property (point) 'read-only))
                (insert reduced-prompt))
              (setq position (point))
              (when gptel-mode
                (gptel--update-status " Waiting..." 'warning)))))
         ;; Insert into new gptel session
         (t (setq buffer
                  (gptel gptel-buffer-name
                         (condition-case nil
                             (gptel--get-api-key)
                           ((error user-error)
                            (setq gptel-api-key
                                  (read-passwd
                                   (format "%s API key: "
                                           (gptel-backend-name
                                            gptel-backend))))))
                         reduced-prompt))
            ;; Set backend and model in new session from current buffer
            (with-current-buffer buffer
              (setq gptel-backend backend)
              (setq gptel-model model)
              (gptel--update-status " Waiting..." 'warning)
              (setq position (point)))))))
     ((setq gptel-buffer-name
            (cl-some (lambda (s) (and (string-prefix-p "b" s)
                                 (substring s 1)))
                     args))
      (setq output-to-other-buffer-p t)
      (setq buffer (get-buffer-create gptel-buffer-name))
      (with-current-buffer buffer (setq position (point)))))

    ;; Create prompt, unless doing input-redirection above
    (unless prompt
      (setq prompt (gptel--create-prompt (gptel--at-word-end (point)))))

    (when in-place
      ;; Kill the latest prompt
      (let ((beg
             (if (use-region-p)
                 (region-beginning)
               (save-excursion
                 (text-property-search-backward
                  'gptel 'response
                  (when (get-char-property (max (point-min) (1- (point)))
                                           'gptel)
                    t))
                 (point))))
            (end (if (use-region-p) (region-end) (point))))
        (unless output-to-other-buffer-p
          ;; store the killed text in gptel-history
          (gptel--attach-response-history
           (list (buffer-substring-no-properties beg end))))
        (kill-region beg end)))

    (gptel-request
     prompt
     :buffer (or buffer (current-buffer))
     :position position
     :in-place (and in-place (not output-to-other-buffer-p))
     :stream stream
     :callback callback)
    (when output-to-other-buffer-p
      (message (concat "Prompt sent to buffer: "
                       (propertize gptel-buffer-name 'face 'help-key-binding)))
      (display-buffer
       buffer '((display-buffer-reuse-window
                 display-buffer-pop-up-window)
                (reusable-frames . visible))))))

;; ** Suffix to regenerate response

(defun gptel--regenerate ()
  "Regenerate gptel response at point."
  (interactive)
  (when (gptel--in-response-p)
    (pcase-let* ((`(,beg . ,end) (gptel--get-bounds))
                 (history (get-char-property (point) 'gptel-history))
                 (prev-responses (cons (buffer-substring-no-properties beg end)
                                       history)))
      (when gptel-mode                  ;Remove prefix/suffix
        (save-excursion
          (goto-char beg)
          (when (looking-back (concat "\n+" (regexp-quote (gptel-response-prefix-string)))
                              (point-min) 'greedy)
            (setq beg (match-beginning 0)))
          (goto-char end)
          (when (looking-at
                 (concat "\n+" (regexp-quote (gptel-prompt-prefix-string))))
            (setq end (match-end 0)))))
      (delete-region beg end)
      (gptel--attach-response-history prev-responses)
      (call-interactively #'gptel--suffix-send))))

;; ** Set system message
(defun gptel--read-crowdsourced-prompt ()
  "Pick a crowdsourced system prompt for gptel.

This uses the prompts in the variable
`gptel--crowdsourced-prompts', which see."
  (interactive)
  (if (not (hash-table-empty-p (gptel--crowdsourced-prompts)))
      (let ((choice
             (completing-read
              "Pick and edit prompt: "
              (lambda (str pred action)
                (if (eq action 'metadata)
                    `(metadata
                      (affixation-function .
                       (lambda (cands)
                         (mapcar
                          (lambda (c)
                            (list c ""
                             (concat (propertize " " 'display '(space :align-to 22))
                              " " (propertize (gethash c gptel--crowdsourced-prompts)
                               'face 'completions-annotations))))
                          cands))))
                  (complete-with-action action gptel--crowdsourced-prompts str pred)))
              nil t)))
        (when-let ((prompt (gethash choice gptel--crowdsourced-prompts)))
            (setq gptel--system-message prompt)
            (call-interactively #'gptel--suffix-system-message)))
    (message "No prompts available.")))

(transient-define-suffix gptel--suffix-system-message ()
  "Edit LLM directives."
  :transient 'transient--do-exit
  :description "Set custom directives"
  :key "h"
  (interactive)
  (let ((orig-buf (current-buffer))
        (msg-start (make-marker)))
    (with-current-buffer (get-buffer-create "*gptel-system*")
      (let ((inhibit-read-only t))
        (erase-buffer)
        (text-mode)
        (setq header-line-format
              (concat
               "Edit your system message below and press "
               (propertize "C-c C-c" 'face 'help-key-binding)
               " when ready, or "
               (propertize "C-c C-k" 'face 'help-key-binding)
               " to abort."))
        (insert
         "# Example: You are a helpful assistant. Answer as concisely as possible.\n"
         "# Example: Reply only with shell commands and no prose.\n"
         "# Example: You are a poet. Reply only in verse.\n\n")
        (add-text-properties
         (point-min) (1- (point))
         (list 'read-only t 'face 'font-lock-comment-face))
        ;; TODO: make-separator-line requires Emacs 28.1+.
        ;; (insert (propertize (make-separator-line) 'rear-nonsticky t))
        (set-marker msg-start (point))
        (save-excursion
          (insert (buffer-local-value 'gptel--system-message orig-buf))
          (push-mark nil 'nomsg))
        (activate-mark))
      (display-buffer (current-buffer)
                      `((display-buffer-below-selected)
                        (body-function . ,#'select-window)
                        (window-height . ,#'fit-window-to-buffer)))
      (let ((quit-to-menu
             (lambda ()
               (interactive)
               (local-unset-key (kbd "C-c C-c"))
               (local-unset-key (kbd "C-c C-k"))
               (quit-window)
               (display-buffer
                orig-buf
                `((display-buffer-reuse-window
                   display-buffer-use-some-window)
                  (body-function . ,#'select-window)))
               (call-interactively #'gptel-menu))))
        (local-set-key (kbd "C-c C-c")
                       (lambda ()
                         (interactive)
                         (let ((system-message
                                (buffer-substring msg-start (point-max))))
                           (with-current-buffer orig-buf
                             (setq gptel--system-message system-message)))
                         (funcall quit-to-menu)))
        (local-set-key (kbd "C-c C-k") quit-to-menu)))))

;; ** Suffixes for rewriting/refactoring

(transient-define-suffix gptel--suffix-rewrite ()
  "Rewrite or refactor region contents."
  :key "r"
  :description #'gptel--refactor-or-rewrite
  (interactive)
  (let* ((prompt (buffer-substring-no-properties
                  (region-beginning) (region-end)))
         (stream gptel-stream)
         (gptel--system-message gptel--rewrite-message))
    (gptel-request prompt :stream stream)))

(transient-define-suffix gptel--suffix-rewrite-and-replace ()
  "Refactor region contents and replace it."
  :key "R"
  :description (lambda () (concat (gptel--refactor-or-rewrite) " in place"))
  (interactive)
  (let* ((prompt (buffer-substring-no-properties
                  (region-beginning) (region-end)))
         (stream gptel-stream)
         (gptel--system-message gptel--rewrite-message))
    (kill-region (region-beginning) (region-end))
    (message "Original text saved to kill-ring.")
    (gptel-request prompt :stream stream :in-place t)))

(transient-define-suffix gptel--suffix-rewrite-and-ediff (args)
  "Refactoring or rewrite region contents and run Ediff."
  :key "E"
  :description (lambda () (concat (gptel--refactor-or-rewrite) " and Ediff"))
  (interactive (list (transient-args transient-current-command)))
  (letrec ((prompt (buffer-substring-no-properties
                  (region-beginning) (region-end)))
           (gptel--system-message gptel--rewrite-message)
           ;; TODO: Technically we should save the window config at the time
           ;; `ediff-setup-hook' runs, but this will do for now.
           (cwc (current-window-configuration))
           (gptel--ediff-restore
            (lambda ()
              (when (window-configuration-p cwc)
                (set-window-configuration cwc))
              (remove-hook 'ediff-quit-hook gptel--ediff-restore))))
    (message "Waiting for response... ")
    (gptel-request
     prompt
     :context (cons (region-beginning) (region-end))
     :callback
     (lambda (response info)
       (if (not response)
           (message "ChatGPT response error: %s" (plist-get info :status))
         (let* ((gptel-buffer (plist-get info :buffer))
                (gptel-bounds (plist-get info :context))
                (buffer-mode
                 (buffer-local-value 'major-mode gptel-buffer)))
           (pcase-let ((`(,new-buf ,new-beg ,new-end)
                        (with-current-buffer (get-buffer-create "*gptel-rewrite-Region.B-*")
                          (let ((inhibit-read-only t))
                            (erase-buffer)
                            (funcall buffer-mode)
                            (insert response)
                            (goto-char (point-min))
                            (list (current-buffer) (point-min) (point-max))))))
             (require 'ediff)
             (add-hook 'ediff-quit-hook gptel--ediff-restore)
             (apply
              #'ediff-regions-internal
              (get-buffer (ediff-make-cloned-buffer gptel-buffer "-Region.A-"))
              (car gptel-bounds) (cdr gptel-bounds)
              new-buf new-beg new-end
              nil
              (if (transient-arg-value "-w" args)
                  (list 'ediff-regions-wordwise 'word-wise nil)
                (list 'ediff-regions-linewise nil nil))))))))))

(provide 'gptel-transient)
;;; gptel-transient.el ends here

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