;;; news-to-texi.scm — Convert a GNU-style NEWS file to Texinfo
;;;
;;; Usage: guile news-to-texi.scm NEWS > version-history.texi
;;;
;;; The NEWS format is:
;;;
;;;   Version X.Y (date)
;;;
;;;     * First item.
;;;     * Second item, possibly
;;;       continued on the next line.
;;;
;;; Lines before the first "Version" heading (title, copyright notice)
;;; are skipped.

(use-modules (ice-9 rdelim)
             (ice-9 regex)
             (ice-9 match))

(define (news->texi port out)
  (let loop ((line      (read-line port))
             (in-version? #f)
             (in-item?    #f))
    (cond
     ((eof-object? line)
      ;; Close any open item/version.
      (when in-item?
        (display "\n" out))
      (when in-version?
        (format out "@end itemize~%~%")))

     ;; Version heading: "Version X.Y ..."
     ((string-match "^Version " line)
      ;; Close previous version if open.
      (when in-item?
        (display "\n" out))
      (when in-version?
        (format out "@end itemize~%~%"))
      (format out "@item ~a~%" line)
      (format out "@itemize~%" )
      (loop (read-line port) #t #f))

     ;; Bullet item: "  * text"
     ((string-match "^  \\* (.+)" line)
      =>
      (lambda (m)
        ;; Close previous item if open.
        (when in-item?
          (display "\n" out))
        (format out "@item~%")
        (display (match:substring m 1) out)
        (loop (read-line port) in-version? #t)))

     ;; Continuation line: "    text" (indented, no bullet)
     ((and in-item? (string-match "^    (.+)" line))
      =>
      (lambda (m)
        (display "\n" out)
        (display (match:substring m 1) out)
        (loop (read-line port) in-version? #t)))

     ;; Blank or preamble line — skip.
     (else
      (loop (read-line port) in-version? in-item?)))))

(match (command-line)
  ((_ news-file)
   (call-with-input-file news-file
     (lambda (in)
       (news->texi in (current-output-port)))))
  ((_ . _)
   (format (current-error-port) "Usage: guile news-to-texi.scm NEWS~%")
   (exit 1)))