;;; latex-flymake.el --- Flymake integration  -*- lexical-binding: t; -*-

;; Copyright (C), 2018 Free Software Foundation, Inc.

;; Author: Alex Branham <branham@utexas.edu>
;; Maintainer: auctex-devel@gnu.org
;; Created: 2018-02-11
;; Keywords: tex

;; This file is part of AUCTeX.

;; AUCTeX 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, or (at your option)
;; any later version.

;; AUCTeX 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 AUCTeX; see the file COPYING.  If not, write to the Free
;; Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
;; 02110-1301, USA.

;;; Commentary:

;; This file provides flymake integration for latex documents using
;; "chktex" as a backend.  You must be running Emacs 26 or newer.
;; Enable it by adding the following to your init file:

;;   (add-hook 'LaTeX-mode-hook #'flymake-mode)

;;; Code:

(eval-when-compile
  (require 'cl-lib))
(require 'flymake)

(defvar-local LaTeX--flymake-proc nil)

(defun LaTeX-flymake (report-fn &rest _args)
  "Setup flymake integration.

REPORT-FN is flymake's callback function."
  (unless (executable-find "chktex")
    (error "Cannot find chktex"))
  (when (process-live-p LaTeX--flymake-proc)
    (kill-process LaTeX--flymake-proc))
  (let ((source (current-buffer)))
    (save-restriction
      (widen)
      (setq
       LaTeX--flymake-proc
       (make-process
        :name "LaTeX-flymake" :noquery t :connection-type 'pipe
        :buffer (generate-new-buffer " *LaTeX-flymake*")
        :command '("chktex" "--verbosity=0" "--quiet" "--inputfiles")
        :sentinel
        (lambda (proc _event)
          (when (eq 'exit (process-status proc))
            (unwind-protect
                (if (with-current-buffer source (eq proc LaTeX--flymake-proc))
                    (with-current-buffer (process-buffer proc)
                      (goto-char (point-min))
                      (cl-loop
                       while (search-forward-regexp
                              (rx line-start "stdin:"
                                  ;; line
                                  (group-n 1 (one-or-more num))
                                  ":"
                                  ;; column
                                  (group-n 2 (one-or-more num))
                                  ":"
                                  ;; This is information about the
                                  ;; number of the warning, which we
                                  ;; probably don't care about:
                                  (one-or-more num)
                                  ":"
                                  ;; Warning message:
                                  (group-n 3 (one-or-more not-newline)) line-end)
                              nil t)
                       for msg = (match-string 3)
                       for (beg . end) = (flymake-diag-region
                                          source
                                          (string-to-number (match-string 1))
                                          (string-to-number (match-string 2)))
                       for type = :warning
                       collect (flymake-make-diagnostic source
                                                        beg
                                                        end
                                                        type
                                                        msg)
                       into diags
                       finally (funcall report-fn diags)))
                  (flymake-log :warning "Canceling obsolete check %s"
                               proc))
              (kill-buffer (process-buffer proc)))))))
      (process-send-region LaTeX--flymake-proc (point-min) (point-max))
      (process-send-eof LaTeX--flymake-proc))))

(provide 'latex-flymake)
;;; latex-flymake.el ends here