;;; majjit.el --- Clone jujutsu repositories with Magit's interface -*- lexical-binding: t -*-

;; Author: Lucien Cartier-Tilet <lucien@phundrak.com>
;; Maintainer: Lucien Cartier-Tilet <lucien@phundrak.com>
;; Version: 0.1.0
;; Package-Requires: ((emacs "28.1") (magit "4.5.0"))
;; Homepage: https://labs.phundrak.com/phundrak/majjit
;; Keywords: git tools vcs


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


;;; Commentary:

;; commentary

;;; Code:

(require 'magit)

(defgroup majjit nil
  "Clone your jj repositories with Magit."
  :group 'tools
  :prefix "majjit-"
  :link '(url-link :tag "https://labs.phundrak.com/phundrak/majjit"))

(defcustom majjit-default-directory nil
  "See `magit-clone-default-directory'."
  :package-version '(majjit . "0.1.0")
  :group 'majjit
  :type '(choice (const     :tag "Value of default-directory")
                 (directory :tag "Constant directory")
                 (function  :tag "Function's value")))

(defcustom majjit-executable "jj"
  "Local executable of jj."
  :package-version '(majjit . "0.1.0")
  :group 'majjit
  :type 'path)

(defcustom majjit-remote-executable "jj"
  "Remote executable of jj."
  :package-version '(majjit . "0.1.0")
  :group 'majjit
  :type 'path)

(defcustom majjit-global-arguments
  '("--color=never")
  "Global jj arguments."
  :package-version '(majjit . "0.1.0")
  :group 'majjit
  :type '(repeat string))

(defun majjit-sentinel (process event)
  "Default sentinel used by `majjit-run-jj-async'."
  (when (memq (process-status process) '(exit signal))
    (setq event (substring event 0 -1))
    (when (string-match "^finished" event)
      (message (concat (process-name process) " finished")))
    (when (eq process magit-this-process)
      (setq magit-this-process nil))))

(defun majjit-executable ()
  "Return executable for jj.

See `magit-git-executable'."
  (if (file-remote-p default-directory)
      majjit-remote-executable
    majjit-executable))

(defun majjit-run-jj-async (directory &rest args)
  "Start jujutsu and return the process object.

ARGS is flattened and then used as arguments to jujutsu. Once cloning is
done, open DIRECTORY with `find-file'.

Inspired by `magit-start-git'."
  (let ((default-process-coding-system (magit--process-coding-system))
        (magit-git-global-arguments majjit-global-arguments))
    (apply #'magit-start-process
           (majjit-executable)
           nil
           (magit-process-git-arguments args))
    ;; Don't refresh the buffer we're calling from.
    (process-put magit-this-process 'inhibit-refresh t)
    (set-process-sentinel magit-this-process
                          (lambda (process event)
                            (majjit-sentinel process event)
                            (find-file directory)))))

(defun majjit-read-args ()
  "Get all the necessary args for cloning the repository."
  (let* ((magit-clone-default-directory majjit-default-directory)
         (magit-args (magit-clone-read-args)))
    (list (car magit-args)
          (cadr magit-args)
          (yes-or-no-p "Colocate the repository? "))))

(defun majjit--check-valid-clone-directory (repository directory)
  "Check whether the target DIRECTORY is a valid target.

Taken from `magit-clone-internal'. Refer to it for use of REPOSITORY and
DIRECTORY."
  (let ((directory (file-name-as-directory (expand-file-name directory))))
    (when (file-exists-p directory)
      (if (file-directory-p directory)
          (when (length> (directory-files directory) 2)
            (let ((name (magit-clone--url-to-name repository)))
              (unless (and name
                           (setq directory (file-name-as-directory
                                            (expand-file-name name directory)))
                           (not (file-exists-p directory)))
                (user-error "%s already exists" directory))))
        (user-error "%s already exists and is not a directory" directory)))))

(defun majjit--internal (repository directory colocate-p)
  "Clone REPOSITORY to DIRECTORY using jj.

If COLOCATE-P is t, colocate the repository with git."
  (let ((directory (file-name-as-directory (expand-file-name directory))))
    (majjit--check-valid-clone-directory repository directory)
    (majjit-run-jj-async directory
                                 "git"
                                 "clone"
                                 (if colocate-p "--colocate" nil)
                                 "--"
                                 repository
                                 (magit-convert-filename-for-git directory))))

;;;###autoload
(defun majjit-clone-from-url (url)
  "Clone a repository from a known URL."
  (let ((directory (read-directory-name
                    "Clone to: "
                    (if (functionp majjit-default-directory)
                        (funcall majjit-default-directory)
                      majjit-default-directory)
                    nil nil
                    (magit-clone--url-to-name url)))
        (colocate-p (yes-or-no-p "Colocate? ")))
    (majjit--internal url directory colocate-p)))

;;;###autoload
(defun majjit-clone (repository directory colocate-p)
  "Clone a git REPOSITORY using jujutsu into a DIRECTORY.

If COLOCATE-P is t, then colocate the repository with git.

Depends on Magit. Inspired by `magit-clone-regular'."
  (interactive (majjit-read-args))
  (majjit--internal repository directory colocate-p))

(provide 'majjit)

;;; majjit.el ends here