To browse files associated with DocURLs

docurl.el

;; About DocURLs, see: http://f76.eu/a0
;;
;; Felix E. Klee <felix.klee@inka.de>

(defgroup docurl nil
  "Support for browsing DocURLs"
  :group 'communication)

(defcustom docurl-cache-filename
  "~/.local/share/docurl_cache"
  "Path of file that contains the DocURL cache"
  :type 'file)

(defcustom docurl-doc-dir
  "~"
  "Path of directory below which documents are found"
  :type 'file)

(defun docurlp (url)
  "Return t if URL is a DocURL."
  (let* ((urlobj (url-generic-parse-url url))
         (domain (url-domain urlobj))
         (path (url-filename urlobj)))
    (and
     (string-collate-equalp domain "f76.eu" "C" t)
     (not (or (string= path "") (string= path "/"))))))

(defun docurl-idp (object)
  "Return t is a valid DocURL ID."
  (let ((case-fold-search nil))
    (eq (string-match "^a[0-9a-zA-Z]+$" object) 0)))

(defun docurl-id (url)
  (let* ((urlobj (url-generic-parse-url url))
         (path-with-leading-slash (url-filename urlobj)))
    (substring path-with-leading-slash 1)))

(defun docurl-copy-relative-doc-filename ()
  "Copy relative filename of the current document into the kill
ring.  This function is useful when manually appending to the
cache file."
  (interactive)
  (let* ((base-dir (expand-file-name docurl-doc-dir))
         (regexp (concat "^" base-dir "\\(.*\\)$"))
         (filename (buffer-file-name)))
    (if (string-match regexp filename)
        (kill-new (match-string 1 filename)))))

(defun docurl-relative-doc-filename (id)
  "File name of document relative to document directory"
  (with-temp-buffer
    (insert-file-contents (expand-file-name docurl-cache-filename))
    (let ((case-fold-search nil))
      (search-forward-regexp (concat "^" id "[[:blank:]]+\\(.*\\)")))
    (match-string 1)))

(defun docurl-doc-filename (id)
  (expand-file-name
   (docurl-relative-doc-filename id)
   docurl-doc-dir))

(defun docurl-browse-by-id (id)
  (find-file-other-window (docurl-doc-filename id)))

(defun docurl-browse (url)
  "Opens the file associated with URL in a buffer."
  (let ((id (docurl-id url)))
    (docurl-browse-by-id id)))

(provide 'docurl)