;;; diredy.el --- Flexible grouping for files in Dired buffers  -*- lexical-binding: t; -*-

;; Copyright (C) 2021  Free Software Foundation, Inc.

;; Author: Adam Porter <adam@alphapapa.net>
;; Maintainer: Adam Porter <adam@alphapapa.net>
;; Keywords: convenience

;; 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:

;; This library provides a command, `diredy', that rearranges a Dired
;; buffer into a hierarchy by file size and MIME type.

;;; Code:

;;;; Requirements

(require 'taxy)
(require 'taxy-magit-section)

(require 'dired)
(require 'mailcap)

;;;; Variables

(defvar diredy-taxy
  (cl-labels ((file-name
               (string) (let* ((start (text-property-not-all 0 (length string) 'dired-filename nil string))
                               (end (text-property-any start (length string) 'dired-filename nil string)))
                          (substring string start end)))
              (file-extension
               (filename) (file-name-extension filename))
              (file-type (string)
                         (when-let ((extension (file-extension (file-name string))))
                           (mailcap-extension-to-mime extension)))
              (file-size
               (filename) (file-attribute-size (file-attributes filename)))
              (file-size-group
               (string) (pcase (file-size (file-name string))
                          ('nil "No size")
                          ((pred (> 1024))
                           "< 1K")
                          ((pred (> 102400))
                           "< 100K")
                          ((pred (> 1048576))
                           "< 1M")
                          ((pred (> 10485760))
                           "< 10M")
                          (_ ">= 10M")))
              (file-dir? (string) (if (file-directory-p (file-name string))
                                      "Directory" "File"))
	      (make-fn (&rest args)
		       (apply #'make-taxy-magit-section
			      :make #'make-fn
			      :level-indent 1
			      :item-indent 2
			      args)))
    (make-fn
     :name "Diredy"
     :make #'make-fn
     :take (apply-partially #'taxy-take-keyed (list #'file-dir? #'file-size-group #'file-type)))))

(defvar dired-mode)

;;;; Customization


;;;; Commands

(defun diredy ()
  "Apply grouping to current Dired buffer."
  (interactive)
  (cl-assert (eq 'dired-mode major-mode))
  (use-local-map (make-composed-keymap (list dired-mode-map magit-section-mode-map)))
  (save-excursion
    (goto-char (point-min))
    (forward-line 2)
    (let* ((lines (save-excursion
		    (cl-loop until (eobp)
			     collect (string-trim (buffer-substring (point-at-bol) (point-at-eol)))
			     do (forward-line 1))))
	   (filled-taxy (thread-last diredy-taxy
			  taxy-emptied
			  (taxy-fill lines)
			  (taxy-mapc* (lambda (taxy)
					(setf (taxy-taxys taxy)
					      (cl-sort (taxy-taxys taxy) #'string<
						       :key #'taxy-name))))))
	   (inhibit-read-only t))
      (delete-region (point) (point-max))
      (taxy-magit-section-insert filled-taxy :items 'last
	:initial-depth 0 :blank-between-depth 1))))

;;;; Functions


;;;; Footer

(provide 'diredy)

;;; diredy.el ends here
