(require 'w3m)

(defvar trac-url-prefix "http://example.com/trac/")
(defvar trac-login-url-suffix "/login")
(defvar trac-feed-url-suffix "/query")
(defvar trac-feed-query-parameter '((status . new) (status . assigned) (status . reopened) (format . rss) (order . priority)))
(defun trac-login-url (project)
  "URL for trac's login."
  (concat trac-url-prefix project trac-login-url-suffix))
(defun trac-feed-url (project)
  "URL for trac's RSS feed."
  (concat trac-url-prefix
          project
          trac-feed-url-suffix
          "?"
          (mapconcat (lambda (pair) (concat (symbol-name (car pair)) "=" (symbol-name (cdr pair)))) trac-feed-query-parameter "&")
          ))
(defvar trac-feed-content-type "application/rss+xml")
(defvar trac-temporary-file-prefix "/tmp/trac")
(defvar trac-convert-program "/home/tabe/bin/trac2howm.scm")

(defun trac-retrieve (project)
  (interactive "sProject: ")
  (catch 'failed
    (let ((use-cookies w3m-use-cookies)
          (temp-file (make-temp-file trac-temporary-file-prefix)))
      (unwind-protect
          (progn
            (setq w3m-use-cookies t)
            (with-temp-buffer
              (w3m-retrieve (w3m-retrieve (trac-login-url project))))
            (set-file-modes temp-file ?\600)
            (with-temp-file temp-file
              (let ((content-type (w3m-retrieve (trac-feed-url project) nil t)))
                (unless (equal trac-feed-content-type content-type)
                  (throw 'failed (message "failed. (%s)" (or content-type "nil"))))
                )
              )
            (call-process trac-convert-program temp-file t t project))
        (delete-file temp-file)
        (setq w3m-use-cookies use-cookies)
      ))))