;;; jao-doc-view.el -- extensions for doc-view -*- lexical-binding: t; -*-

;; Copyright (c) 2013, 2015, 2017, 2018, 2019, 2021, 2022 Jose Antonio Ortega Ruiz

;; 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 of the License, 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 this program.  If not, see <http://www.gnu.org/licenses/>.

;; Author: Jose Antonio Ortega Ruiz <jao@gnu.org>
;; Start date: Fri Feb 15, 2013 01:21

(require 'doc-view)
(require 'jao-pdf)

;;; Utilities

(defmacro jao-doc-view--funcall (a b &rest args)
  `(cond ((derived-mode-p 'pdf-view-mode) (,a ,@args))
         ((derived-mode-p 'doc-view-mode) (,b ,@args))))

(defun jao-doc-view-current-page ()
  (jao-doc-view--funcall pdf-view-current-page doc-view-current-page))

(defun jao-doc-view-goto-page (page &optional height)
  (when page
    (jao-doc-view--funcall pdf-view-goto-page doc-view-goto-page page))
  (when (and height (derived-mode-p 'pdf-view-mode))
    (image-set-window-vscroll
     (round (/ (* height (cdr (pdf-view-image-size))) (frame-char-height))))))

;;; imenu
(defun jao-doc-view-enable-imenu (file-name goto-page)
  (let ((ifun (lambda () (doc-view-imenu-index file-name goto-page)))
        (doc-view-imenu-enabled t))
    (doc-view-imenu-setup)
    (setq-local imenu-create-index-function ifun)))

;;; Page trailing
(defvar-local jao-doc-view--trail-back ())
(defvar-local jao-doc-view--trail-fwd ())

(defun jao-doc-view--trail-push (dest-page)
  (when-let (page (jao-doc-view-current-page))
    (unless (eq (car jao-doc-view--trail-back) page)
      (push page jao-doc-view--trail-back))))

(defun jao-doc-view-back ()
  (interactive nil doc-view-mode)
  (if-let (p (pop jao-doc-view--trail-back))
      (progn (push (jao-doc-view-current-page) jao-doc-view--trail-fwd)
             (jao-doc-view-goto-page p))
    (message "No more back marks.")))

(defun jao-doc-view-forward ()
  (interactive nil doc-view-mode)
  (if-let (p (pop jao-doc-view--trail-fwd))
      (progn (push (jao-doc-view-current-page) jao-doc-view--trail-back)
             (jao-doc-view-goto-page p))
    (message "No more forward marks.")))

(advice-add 'doc-view-goto-page :before #'jao-doc-view--trail-push)

;;; Extract text
(defun jao-doc-view-page-text (&optional re-render no-select)
  (interactive "P")
  (let* ((pno (doc-view-current-page))
         (in buffer-file-name)
         (cdir (or (doc-view--current-cache-dir) "/tmp"))
         (out (format "%s/p%s.txt" cdir pno)))
    (when (and (file-exists-p out) re-render)
      (delete-file out))
    (unless (file-exists-p out)
      (shell-command-to-string (format "mutool convert -o %s %s %s" out in pno)))
    (if no-select
        out
      (find-file out)
      (view-mode))))

(define-key doc-view-mode-map "t" #'jao-doc-view-page-text)

;;; Find URLs
(defun jao-doc-view--full-txt ()
  (expand-file-name "doc.txt" (doc-view--current-cache-dir)))

(defun jao-doc-view--collect-urls (file)
  (with-current-buffer (find-file-noselect file)
    (goto-char (point-min))
    (let ((urls nil))
      (while (re-search-forward "https?://" nil t)
        (push (thing-at-point-url-at-point) urls))
      urls)))

(defun jao-doc-view--page-urls (&optional all)
  (let ((txt (jao-doc-view--full-txt)))
    (cond ((and all (not (file-exists-p txt)))
           (message "Full text not extracted yet: doing so!")
           (doc-view-doc->txt txt (lambda () (message "Text extracted")))
           'wait)
          (all (jao-doc-view--collect-urls txt))
          (t (jao-doc-view--collect-urls (jao-doc-view-page-text nil t))))))

(defun jao-doc-view-visit-url (all)
  "Visit URL displayed in this page."
  (interactive "P")
  (let ((urls (jao-doc-view--page-urls all)))
    (cond ((eq 'wait urls) (message "Extracting text, please wait and retry."))
          ((zerop (length urls))
           (message "No URLs in this %s" (if all "document" "page")))
          (t (when-let (url (completing-read "URL: " urls nil nil
                                             (when (null (cdr urls)) (car urls))))
               (browse-url url))))))

;;; .
(provide 'jao-doc-view)