;;; wiki-utils.el -- wiki utility functions -*- lexical-binding: t -*-

;; Copyright (C) 2023 Free Software Foundation.

;; Author: Yuchen Pei <id@ypei.org>
;; Package-Requires: ((emacs "28.2"))

;; This file is part of wiki.el.

;; wiki.el 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.

;; wiki.el 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 wiki.el.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; wiki utility functions.

;;; Code:
(require 'url-parse)

(defvar wiki-local-dir (locate-user-emacs-file "wiki")
  "Path to local directory of wiki files.")

(defvar wiki-fetch-prefer-local t
  "If non-nil, visit the local file if exists when instructed for
fetching.")

(defun wiki-fetch-url (url dir &optional callback title)
  "Fetch URL asynchronously.

Then calls CALLBACK which is a closure taking no argument."
  (interactive "sURL: ")
  (let ((file-name (expand-file-name
                    (or title (wiki-make-file-name-from-url url))
                    dir))
        (cb (lambda (status file-name)
              (wiki-fetch-url-save-and-switch status file-name)
              (when callback (funcall callback)))))
    (url-retrieve url cb (list file-name)))
  )

(defun wiki-fetch-url-save-and-switch (status file-name)
  (when (plist-get status :error)
    (error "Wiki fetch failed: %s" (plist-get status :error)))
  (wiki-delete-http-header)
  (let ((to-insert (buffer-string))
        (buffer (find-file-noselect file-name))
        (coding-system-for-write 'utf-8))
    (kill-buffer)
    (with-current-buffer buffer
      (insert to-insert)
      (goto-char (point-min))
      (save-buffer)
      (revert-buffer t t))
    (switch-to-buffer buffer))
  )

(defun wiki-delete-http-header ()
  (delete-region (point-min) (progn (wiki-skip-http-header) (point))))

(defun wiki-skip-http-header ()
  (goto-char (point-min))
  (re-search-forward "\r?\n\r?\n"))

(defun wiki-make-file-name-from-url (url)
  (file-name-nondirectory
   (directory-file-name
    (car (url-path-and-query (url-generic-parse-url
                              (url-unhex-string url)))))))

;; TODO: add wikihow; generalise fandom
;; TODO: default engine to mediawiki
(defvar wiki-sites
  '((local)
    (archwiki :base-url "https://wiki.archlinux.org/title/"
              :engine mediawiki
              :display-name "ArchWiki")
    (debian-wiki :base-url "https://wiki.debian.org/"
                 :engine moinmoin
                 :display-name "Debian Wiki")
    (emacswiki :base-url "https://www.emacswiki.org/emacs/"
               :engine oddmuse
               :display-name "EmacsWiki")
    (esp :base-url "https://wiki.endsoftwarepatents.org/wiki/"
         :engine mediawiki
         :display-name "ESP Wiki")
    (fandom-recipes :base-url "https://recipes.fandom.com/wiki/"
                    :engine mediawiki
                    :display-name "Fandom Recipes Wiki")
    (fsd :base-url "https://directory.fsf.org/wiki/"
         :engine mediawiki
         :display-name "Free Software Directory")
    (haskell-wiki :base-url "https://wiki.haskell.org/"
                  :engine mediawiki
                  :display-name "Haskell Wiki")
    (libreplanet :base-url "https://libreplanet.org/wiki/"
                 :engine mediawiki
                 :display-name "Libreplanet Wiki")
    (oddmuse :base-url "https://oddmuse.org/wiki/"
             :engine oddmuse
             :display-name "Oddmuse")
    (parabolawiki :base-url "https://wiki.parabola.nu/"
                  :engine mediawiki
                  :display-name "ParabolaWiki")
    (python-wiki :base-url "https://wiki.python.org/moin/"
                 :engine moinmoin
                 :display-name "Python Wiki")
    (termux-wiki :base-url "https://wiki.termux.com/wiki/"
                 :engine mediawiki
                 :display-name "Termux Wiki")
    (ubuntu-wiki :base-url "https://wiki.ubuntu.com/"
                 :engine moinmoin
                 :display-name "Ubuntu Wiki")
    (ubuntu-community-help-wiki
     :base-url "https://help.ubuntu.com/community/"
     :engine moinmoin
     :display-name "Ubuntu Community Help Wiki")
    (wikiindex :base-url "https://wikiindex.org/"
               :engine mediawiki
               :display-name "WikiIndex")
    (wikipedia-en :base-url "https://en.wikipedia.org/wiki/"
                  :engine mediawiki
                  :display-name "Wikipedia EN")
    (wikipedia-zh :base-url "https://zh.wikipedia.org/wiki/"
                  :engine mediawiki
                  :display-name "Wikipedia ZH")
    (wikivoyage-en :base-url "https://en.wikivoyage.org/wiki/"
                   :engine mediawiki
                   :display-name "Wikivoyage EN")
    (wiktionary-en :base-url "https://en.wiktionary.org/wiki/"
                   :engine mediawiki
                   :display-name "Wiktionary EN")
    )
  "Alist of wiki sites.

Each item is in the form of (identifier . properties), where
identifier is a symbol, and properties is a plist of the site.
One of the sites is (local), meaning a local filesystem.")

(defun wiki-site-fetcher (wiki-site)
  (if wiki-site
      (intern (format "wiki-%s-fetch" wiki-site))
    'wiki-find-file))

(provide 'wiki-utils)
;;; wiki-utils.el ends here