;;; 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
(defvar-local jao-doc-view--imenu-file nil)
(defvar-local jao-doc-view--goer 'jao-doc-view-goto-page)

(defun jao-doc-view--enable-imenu (&optional file-name goto-page)
  (setq-local imenu-create-index-function #'jao-doc-view--imenu-create-index
              jao-doc-view--imenu-file (or file-name jao-doc-view--imenu-file)
              jao-doc-view--goer (or goto-page 'jao-doc-view-goto-page)))

(defun jao-doc-view--imenu-create-index ()
  (jao-pdf-imenu-index #'jao-doc-view--goer #jao-doc-view--imenu-file))

(add-hook 'doc-view-mode-hook #'jao-pdf-set-up-imenu)

;;; 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)

;;; Find URLs
(defun jao-doc-view--page-urls (&optional all)
  (if doc-view--current-converter-processes
      (message "DocView: please wait till conversion finished.")
    (let ((txt (expand-file-name "doc.txt" (doc-view--current-cache-dir)))
          (page (doc-view-current-page))
          (pd-rx "^")
          (urls))
      (if (file-readable-p txt)
          (with-current-buffer (find-file-noselect txt)
            (goto-char (point-min))
            (unless all (re-search-forward pd-rx nil t (1- page)))
            (let ((end (save-excursion
                         (if (and (not all) (re-search-forward pd-rx nil t))
                             (point)
                           (point-max)))))
              (while (re-search-forward "https?://" end t)
                (push (thing-at-point-url-at-point) urls))
              urls))
        (doc-view-doc->txt txt (lambda () (jao-doc-view--page-urls all)))
        'wait))))

(defun jao-doc-view-visit-url (all)
  "Visit URL displayed in this page."
  (interactive "P" doc-view-mode)
  (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 page"))
          (t (when-let (url (completing-read "URL: " urls nil nil
                                             (when (null (cdr urls)) (car urls))))
               (browse-url url))))))

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