;; jao-maildir.el -- Utilities for reading maildirs -*- lexical-binding: t; -*-

;; Copyright (c) 2019, 2020, 2021 jao

;; Author: jao <mail@jao.io>
;; Start date: Sun Dec 01, 2019 15:48
;; Keywords: mail

;; This file 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, or (at your option)
;; any later version.

;; This file 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 GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Comentary:

;; Inspecting the contents of maildirs and reporting it.

;;; Code:

(require 'seq)
(require 'jao-minibuffer)

(defvar jao-maildir-debug-p nil)
(defvar jao-maildir-echo-p t)
(defvar jao-maildir-tracked-maildirs nil)
(defvar jao-maildir-info-string "")
(defvar jao-maildir-home (expand-file-name "~/var/mail"))
(defvar jao-maildir-news-home (expand-file-name "~/var/news"))

(defgroup jao-maildir-faces nil "Faces"
  :group 'faces)
(defun jao-maildir--maildir-new (mbox) (expand-file-name "new" mbox))

(defun jao-maildir--maildir-new-count (mbox)
  (- (length (directory-files (jao-maildir--maildir-new mbox))) 2))

(defface jao-maildir-emph '((t :inherit font-lock-keyword-face))
  "Face used to highlihgt non-boring tracked maildirs"
  :group 'jao-maildir-faces)

(defvar jao-maildir--maildirs nil)
(defvar jao-maildir--counts nil)
(defvar jao-maildir--label-mboxes nil)
(defvar jao-maildir--trackers nil)
(defvar jao-maildir--track-strings ())

(defun jao-maildir--update-counts ()
  (dolist (mbox jao-maildir--maildirs)
    (puthash mbox (jao-maildir--maildir-new-count mbox) jao-maildir--counts)))

(defun jao-maildir--init-counts (maildirs)
  (setq jao-maildir--counts (make-hash-table :test 'equal))
  (setq jao-maildir--maildirs maildirs)
  (jao-maildir--update-counts))

(defun jao-maildir--set-trackers (maildirs tracked-maildirs)
  (jao-maildir--init-counts maildirs)
  (let* ((label-mboxes (make-hash-table :test 'equal))
         (trackers (seq-map-indexed
                    (lambda (track idx)
                      (puthash (car track) () label-mboxes)
                      (let ((tr (seq-take track 2))
                            (l (elt track 2)))
                        (append tr
                                (cond ((eq l t) '(jao-maildir-emph))
                                      ((null l) '(default))
                                      (t (list l)))
                                (list (or (elt track 3) idx)))))
                           tracked-maildirs)))
    (dolist (mbox maildirs)
      (let ((lb (seq-find (lambda (lb) (when lb (string-match-p lb mbox)))
                          (hash-table-keys label-mboxes))))
        (puthash lb (cons mbox (gethash lb label-mboxes)) label-mboxes)))
    (setq jao-maildir--label-mboxes label-mboxes)
    (setq jao-maildir--trackers trackers)))

(defun jao-maildir--tracked-count (track)
  (seq-reduce (lambda (c k) (+ c (gethash k jao-maildir--counts 0)))
              (gethash (car track) jao-maildir--label-mboxes)
              0))

(defun jao-maildir--update-track-string (mbox)
  (when-let ((track (seq-find (lambda (td) (string-match-p (car td) mbox))
                              jao-maildir--trackers)))
    (let* ((label (cadr track))
           (other (assoc-delete-all label jao-maildir--track-strings))
           (cnt (jao-maildir--tracked-count track)))
      (if (> cnt 0)
          (let* ((face (car (last (butlast track))))
                 (order (car (last track)))
                 (str (propertize (format "%s%s" label cnt) 'face face))
                 (str (cons label (cons order str))))
            (setq jao-maildir--track-strings (cons str other)))
        (setq jao-maildir--track-strings other)))))

;;;###autoload
(defun jao-maildir-update-info-string (&optional mbox)
  (cond ((eq mbox t)
         (seq-do 'jao-maildir--update-track-string jao-maildir--maildirs))
        ((stringp mbox)
         (puthash mbox (jao-maildir--maildir-new-count mbox) jao-maildir--counts)
         (jao-maildir--update-track-string mbox)))
  (let* ((s (seq-sort-by #'cadr #'< jao-maildir--track-strings))
         (s (mapconcat 'identity (mapcar 'cddr s) " ")))
    (setq jao-maildir-info-string (if (string-blank-p s) "" (concat s " "))))
  (when jao-maildir-echo-p (jao-minibuffer-refresh)))

(defvar jao-maildir--watches nil)

(defun jao-maildir-cancel-watchers ()
  (dolist (w jao-maildir--watches) (file-notify-rm-watch w))
  (setq jao-maildir--watches nil))

(defun jao-maildir--log-watch (mbox e)
  (when jao-maildir-debug-p
    (message "[%s] watch: %s: %s" (current-time-string) mbox e)))

(defun jao-maildir--watcher (mbox cb)
  (lambda (e)
    (jao-maildir--log-watch e mbox)
    (when (memq (cadr e) '(created deleted))
      (jao-maildir-update-info-string mbox)
      (when cb (funcall cb mbox)))))

(defun jao-maildir--setup-watches (cb)
  (jao-maildir-cancel-watchers)
  (setq jao-maildir--watches
        (mapcar (lambda (mbox)
                  (file-notify-add-watch (jao-maildir--maildir-new mbox)
                                         '(change)
                                         (jao-maildir--watcher mbox cb)))
                jao-maildir--maildirs)))

;;;###autoload
(defun jao-maildir-setup (maildirs trackers mode-line &optional cb)
  (jao-maildir--set-trackers maildirs trackers)
  (cond ((eq 'mode-line mode-line)
         (add-to-list 'global-mode-string 'jao-maildir-info-string t))
        ((numberp mode-line)
         (jao-minibuffer-add-variable 'jao-maildir-info-string mode-line)
         (jao-maildir-update-info-string t))
        (t (error "Invalid mode-line value")))
  (jao-maildir--setup-watches cb))

;;;###autoload
(defun jao-maildir-file-to-group (file &optional maildir newsdir)
  "Calculate the Gnus group name from the given file name.
Example:

  IN: /home/jao/var/mail/jao/foo/cur/1259184569.M4818P3384.localhost,W=6921:2,S
  OUT: nnml:jao.foo

  IN: /home/jao/.emacs.d/gnus/Mail/jao.trove/32570, /home/jao/.emacs.d/gnus/Mail/
  OUT: nnml:jao.trove

  IN: /home/jao/var/mail/gmane/foo/bar/100
  OUT: nntp:gmane.foo.bar

  IN: /home/jao/var/mail/bigml/cur/1259176906.M17483P24679.localhost,W=2488:2,S
  OUT:nnimap:bigml/inbox"
  (let* ((g (directory-file-name (file-name-directory file)))
         (g (replace-regexp-in-string
             (file-name-as-directory (or maildir jao-maildir-home)) "" g))
         (g (replace-regexp-in-string
             (file-name-as-directory (or newsdir jao-maildir-news-home)) "" g))
         (nntp (string-match-p "^\\(gmane\\|gwene\\)/" g))
         (g (cond (nntp (concat "nntp:" g))
                  ((file-name-directory g)
                   (replace-regexp-in-string "^\\([^/]+\\)/" "nnml:\\1/"
                                             (file-name-directory g) t))
                  (t (concat "nnml:" g))))
         (g (replace-regexp-in-string "/" "." g))
         (g (replace-regexp-in-string "[/.]$" "" g)))
    (cond ((string-match ":$" g) (concat g "inbox"))
          (nntp g)
          (t (replace-regexp-in-string ":\\." ":" g)))))

(provide 'jao-maildir)
;;; jao-maildir.el ends here