;;; belf.el -- Bookshelf, ebook library management -*- lexical-binding: t -*-

;; Copyright (C) 2025  Free Software Foundation, Inc.

;; Author: Yuchen Pei <id@ypei.org>
;; Package-Requires: ((emacs "29.4"))

;; This file is part of dotted.

;; dotted is free software: you can redistribute it and/or modify it under
;; the terms of the GNU Affero General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; dotted 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 Affero General
;; Public License for more details.

;; You should have received a copy of the GNU Affero General Public
;; License along with dotted.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; Bookshelf, ebook library management.

;;; Code:

(require 'tabulated-list)
(require 'infobox)

(defvar-keymap belf-mode-map
  :parent tabulated-list-mode-map
  "F" #'belf-toggle-follow-mode
  "d" #'belf-show-in-dired
  "i" #'belf-book-infobox-at-point
  "n" #'belf-next-line
  "o" #'belf-open-book-other-window
  "p" #'belf-previous-line
  "RET" #'belf-open-book
  )

(define-derived-mode belf-mode tabulated-list-mode "Bookshelf"
  "Major mode for browsing a list of books."
  (setq tabulated-list-format
        [("Authors" 25 t)
         ("Title" 48 t)
         ("Year" 4 t)])
  (setq tabulated-list-padding 2)
  (tabulated-list-init-header)
  (setq revert-buffer-function #'belf-list-refresh-contents)
  (hl-line-mode))

(defun belf-list-books ()
  (interactive)
  (let ((buf (get-buffer-create "*Bookshelf*")))
    (with-current-buffer buf
      (belf-mode)
      (belf-list-refresh-contents))
    (pop-to-buffer-same-window buf)))

(defun belf-list-refresh-contents (&rest _)
  (setq-local tabulated-list-entries (belf-parse-all-file-names))
  (tabulated-list-print))

(defvar belf-dir "~/Documents" "Directory of books.")

(defun belf-parse-all-file-names ()
  (seq-filter
   #'identity
   (seq-map
    (lambda (f)
      (when-let ((parsed (belf-parse-file-name f)))
        (let-alist parsed
          (list f (vector .authors .title .year)))))
    (directory-files belf-dir t "\\.\\(epub\\|pdf\\|mobi\\|cbr\\|djvu\\)$"))))

(defun belf-parse-file-name (file-name)
  (let ((base (file-name-base file-name)))
    (when (string-match "^\\(.*?\\) - \\(.*\\) (\\([0-9]*\\))" base)
      `((authors . ,(match-string 1 base))
        (title . ,(match-string 2 base))
        (year . ,(match-string 3 base))))))

(defun belf-book-infobox (file-name)
  (interactive)
  (belf-book-render-info (belf-exiftool-info file-name) file-name))

(defvar belf-exiftool-program "exiftool" "The exiftool program.")

(defun belf-exiftool-info (file-name)
  "Given a video URL, return an alist of its properties."
  (with-temp-buffer
    (call-process belf-exiftool-program nil t nil "-j" file-name)
    (let ((start (point)))
      (call-process-region
       nil nil "jq" nil t nil
       ".[0]|pick(.Title, .Author, .Creator, .Keywords, .Subject, .Publisher, .Identifier, .Series, .Title_sort, .Author_sort, .PageCount, .ISBN, .Language, .FileType, .Description)")
      (goto-char start)
      (json-read)))
  )

(defun belf-book-cover (file-name)
  "Get book cover.

First look for an image file with the same file name.
Then for PDF, extract the first page.
For EPUB, looks for a cover image in the file. If not found, extract the first page."
  (cond ((file-exists-p (file-name-with-extension file-name "jpg"))
         (format "file://%s" (file-name-with-extension file-name "jpg")))
        (t nil)))

(defun belf-book-infobox-at-point ()
  (interactive)
  (let ((help-window-select (not belf-follow-mode)))
    (belf-book-infobox (tabulated-list-get-id)))
  )

(defun belf-book-render-info (info file-name)
  (setf (alist-get 'Title info)
        (concat (alist-get 'Title info)
                " -- "
                (buttonize
                 "xdg-open"
                 (lambda (_) (call-process "xdg-open" nil 0 nil file-name)))
                " " (buttonize "find-file" (lambda (_) (find-file file-name))))
        (alist-get 'Thumbnail info)
        (belf-book-cover file-name)
        (alist-get 'Description info)
        (when-let ((text (alist-get 'Description info)))
          (with-temp-buffer
            (insert text)
            (shr-render-region (point-min) (point-max))
            (goto-char (point-min))
            (insert "\n")
            (buffer-string))))
  (infobox-render
   (infobox-translate info (infobox-default-specs info))
   `(belf-book-infobox ,file-name)
   (called-interactively-p 'interactive)))

(defvar belf-follow-mode nil "Whether follow mode is on.")

(defun belf-toggle-follow-mode ()
  (interactive)
  (setq belf-follow-mode (not belf-follow-mode)))


(defun belf-previous-line ()
  (interactive)
  (previous-line)
  (when belf-follow-mode
    (belf-book-infobox-at-point)))

(defun belf-next-line ()
  (interactive)
  (next-line)
  (when belf-follow-mode
    (belf-book-infobox-at-point)))

(defun belf-show-in-dired ()
  (interactive)
  (dired-jump-other-window (tabulated-list-get-id)))

(defun belf-open-book ()
  (interactive)
  (find-file (tabulated-list-get-id)))

(defun belf-open-book-other-window ()
  (interactive)
  (find-file-other-window (tabulated-list-get-id)))

(provide 'belf)