;;; +browse-url.el  -*- lexical-binding: t; -*-

(require 'browse-url)
(require 'cl-lib)
(require 'seq)
(require 'url-util)

(defgroup +browse-url nil
  "My `browse-url' extras."
  :group 'browse-url)

;;; External URL handlers

(cl-defmacro +browse-url-make-external-viewer-handler
    (viewer
     &key
     args
     (prompt "URL: ")
     (program (executable-find (format "%s" viewer)))
     (name (intern (format "+browse-url-with-%s" viewer)))
     doc
     (var (intern (format "%s-args" name)))
     vardoc
     (custom-group '+browse-url)
     (fallback '(function browse-url-generic)))
  "Create a `browse-url' handler function calling PROGRAM on the URL.
This macro also creates a `customize' setting in CUSTOM-GROUP for
PROGRAM's command-line arguments.  ARGS specifies the
default arguments for this user option.

PROGRAM defaults to the result of calling `executable-find' on VIEWER.

PROMPT is shown to the user in the function's `interactive' spec, as an argument
to `browse-url-interactive-arg'.

The resulting function is named NAME, which defaults to
`+browse-url-with-VIEWER'.  The custom variable is named VAR, which defaults
to `NAME-args'.  If DOC or VARDOC are provided, they'll be the documentation of
the function and variable respectively; otherwise a basic default doc-string is
used.

If FALLBACK is non-nil (the default is `browse-url-generic'), the
generated function will call FALLBACK if unable to start PROGRAM
for some reason."
  (declare (indent 1))
  `(progn
     (defcustom ,var ,args
       ,(or vardoc (format "Arguments to pass to %s in `%s'."
                           viewer name))
       :type '(repeat :tag "Command-line argument" string)
       :group ',custom-group)
     (defun ,name (url &optional new-window)
       ,(or doc (format "Open URL in %s." viewer))
       (interactive (browse-url-interactive-arg ,prompt))
       (let* ((url (browse-url-encode-url url))
              (process-environment (browse-url-process-environment)))
         (message ,(format "Opening %%s in %s..." viewer) url)
         (unless (ignore-errors (apply #'start-process
                                       (format "%s %s" ',viewer url)
                                       nil
                                       ,program
                                       (append ,var (list url))))
           ,@(cond
              (fallback `((funcall ,fallback url new-window)))
              (:else `((message "Can't find viewer: %s" ,viewer)
                       nil))))))))

;; Some default handlers

(+browse-url-make-external-viewer-handler mpv
  :args '("--cache-pause-wait=15"
          "--cache-pause-initial=yes")
  :prompt "Video URL: ")

(+browse-url-make-external-viewer-handler mpv-image
  :program (executable-find "mpv")
  :args '("--image-display-duration=inf")
  :prompt "Image URL: ")

;;; Downloading

(defcustom +browse-url-download-open t
  "Whether to open downloaded files after downloading."
  :type 'boolean)

(defun +browse-url-download (url &rest _)
  "Download URL to `eww-download-directory'."
  (interactive "sDownload URL: ")
  (let ((dir eww-download-directory))
    (when (functionp dir) (setq dir (funcall dir)))
    (make-directory dir :parents)
    (url-retrieve url
                  (lambda (s u d)
                    (let ((file (+browse-url-download-callback s u d)))
                      (when +browse-url-download-open
                        (browse-url-xdg-open file))))
                  (list url dir))))

(defun +browse-url-download-callback (status url dir)
  ;; A slight change to `eww-download-callback' that returns the downloaded
  ;; filename.
  (unless (plist-get status :error)
    (let* ((obj (url-generic-parse-url url))
           (path (directory-file-name (car (url-path-and-query obj))))
           (file (eww-make-unique-file-name
                  (eww-decode-url-file-name (file-name-nondirectory path))
                  dir)))
      (goto-char (point-min))
      (re-search-forward "\r?\n\r?\n")
      (let ((coding-system-for-write 'no-conversion))
        (write-region (point) (point-max) file))
      (message "Saved %s" file)
      file)))

;;; URL matcher generators

(defun +browse-url-matches (&rest regexps)
  "Return a lambda that will determine if a url matches REGEXPS.
Each regexp will be tested in turn.  The first one that matches
is returned by the lambda.

This is a good function to use in key positions in `browse-url-handlers'."
  `(lambda (url &optional new-window)
     (cl-loop for regexp in ',regexps
              if (string-match-p regexp url)
              return regexp)))

;;; External domains
;; Some domains just don't open well in `eww'.  The following function and user
;; option define an easy way to automatically open those.

(defcustom +browse-url-external-domains nil
  "Domains to open in `browse-url-secondary-browser-function'.
This is just a list of strings.  They'll be regexp-escaped and
passed to `+browse-url-external-url-p', which is a good function
to put in `browse-url-handlers'.

If an item in this list is a list itself, it should contain one string, a valid
regexp that will not be regexp-quoted when matching against a url."
  :type '(repeat (choice
                  (list :tag "Regexp" regexp)
                  (string :tag "Literal string"))))

(defun +browse-url-external-url-p (url)
  "Return t if URL is a member of `+browse-url-external-domains'.
This function only tests URL's domain."
  (let ((host (url-host (url-generic-parse-url url))))
    (cl-loop for domain in +browse-url-external-domains
             if (string-match-p (if (stringp domain)
                                    (regexp-quote domain)
                                  (car domain))
                                host)
             return t)))

;;; Switch to an external browser from an Emacs browser

(defmacro +browse-url-switch-external-browser (mode url-fetcher-form)
  "Create a function for MODE to open an external browser.
URL-FETCHER-FORM will be used to get the URL of the current visited page."
  (declare (indent 1))
  `(defun ,(intern (format "+browse-url-external-from-%s" mode))
       (&optional url)
     "Browse URL with `browse-url-secondary-browser-function'.
This will close the current buffer."
     (interactive nil ,mode)
     (condition-case e
         (funcall browse-url-secondary-browser-function
                  (or url ,url-fetcher-form))
       (:success (when (null url) (quit-window))) ; Interactive use
       (t (signal (car e) (cdr e))))))

;;; Mark `browse-url-browser-function' as safe

(defcustom +browse-url-other-safe-browser-functions nil
  "Other safe browser functions."
  :type '(repeat function))

(defun +browse-url-browser-function-safe-p (f)
  "Return t if F is a safe browser function."
  (memq f (append +browse-url-other-safe-browser-functions
                  (mapcar (lambda (i)
                            (plist-get (cdr i) :value))
                          (seq-filter (lambda (i)
                                        (eq (car i) 'function-item))
                                      (cdr (get 'browse-url-browser-function
                                                'custom-type)))))))

(provide '+browse-url)
;;; +browse-url.el ends here