%%%% Copyright (C) 2016 Knut Petersen <address@hidden>
%%%%
%%%% This file contains code derived from Lilypond's ly/event-listener.ly.
%%%% There the following copyright notice was included:
%%%%
%%%% Copyright (C) 2011--2015 Graham Percival <address@hidden>
%%%%
%%%% Other parts of this file are based on code provide by
%%%% Thomas Morley <address@hidden>, see
%%%% http://lilypond.1069038.n5.nabble.com/intercepting-implicit-explicit-page-breaks-td194196.html
%%%%
%%%% Needs at least lilypond version 2.19.23!
%%%%
%%%% This 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 of the License, or
%%%% (at your option) any later version.
%%%%
%%%% This file 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 LilyPond.  If not, see <http://www.gnu.org/licenses/>.
#(define out (open-output-file "videohelper.notes"))

% #(define lastmoment 0.000)

#(define (format-moment moment)
   (exact->inexact
    (/ (ly:moment-main-numerator moment)
       (ly:moment-main-denominator moment))))

#(define (moment-grace->string moment)
   "Prints a moment without grace note(s) as a float such as
0.25000.  Grace notes are written with the grace duration as a
separate \"dashed\" number, i.e. 0.25000-0.12500.  This allows any
program using the output of this function to interpret grace notes
however they want (half duration, quarter duration?  before beat,
after beat?  etc.)."
   (if
       (zero? (ly:moment-grace-numerator moment))
       (ly:format "~a" (format-moment moment))
       ;; grace notes have a negative numerator, so no "-" necessary
       (ly:format
         "~a~a"
         (format-moment moment)
         (format-moment
                       (ly:make-moment
                        (ly:moment-grace-numerator moment)
                        (ly:moment-grace-denominator moment))))))

#(define (make-output-string-line context values)
   "Constructs a tab-separated string beginning with the
score time (derived from the context) and then adding all the
values.  The string ends with a newline."
   (let* ((moment (ly:context-current-moment context)))
    (string-append
     (string-join
       (append
         (list (moment-grace->string moment))
         (map
             (lambda (x) (ly:format "~a" x))
             values))
       "\t")
     "\n")))


#(define (print-line context . values)
   "Prints the list of values (plus the score time) to a file, and
optionally outputs to the console as well.  context may be specified
as an engraver for convenience."
   (if (ly:translator? context)
       (set! context (ly:translator-context context)))
    (display (make-output-string-line context values) out)
    )

#(define (format-tempo engraver event)
   (if (ly:event-property  event 'metronome-count) 
       (print-line engraver "tempo"
         ( / 60
             (* (ly:event-property  event 'metronome-count)
                (format-moment (ly:duration-length (ly:event-property event 'tempo-unit))))))))
   
         

#(define (format-time engraver event)
   (print-line engraver "time"))

#(define (format-rest engraver event)
   (print-line engraver
               "rest"
               (format-moment (ly:duration-length
                               (ly:event-property event 'duration)))
               ))

#(define (format-note engraver event)
     (print-line engraver
                 "note"
                 (format-moment (ly:duration-length
                                 (ly:event-property event 'duration)))
                ))

\layout {
  \context {
  \Voice
  \consists #(make-engraver
              (listeners
               (tempo-change-event . format-tempo)
               (time-signature-event . format-time)
               (rest-event . format-rest)
               (note-event . format-note)))
  }
}

\paper {
        #(define (page-post-process layout pages) (print-pages-first-bar-numbers layout pages #t))
}

#(define* (print-pages-first-bar-numbers layout pages #:optional print-to-file)
  (let* ((lines (map (lambda (page) (ly:prob-property page 'lines)) pages))
         ;; list of systems of each pages
         (sys
           (map
             (lambda (line)
               (append-map
                 (lambda (l)
                   (let ((system-grob (ly:prob-property l 'system-grob)))
                     (if (not (null? system-grob))
                         (list system-grob)
                         system-grob))
                   )
                 line))
             lines))
         (sys-moment-location
           (map
             (lambda (m)
               (if (and (not (null? m)) (ly:grob? (car m)))
                   (grob::when (car m))
                   #f))
             sys))
         (formatted-output
           (map
             (lambda (page m)
               (if m
                   (format #f "~a page ~a\n" (format-moment m) page)
                   (format #f "page ~a contains no music\n" page))
                   )
             (iota (length pages) 1 1)
            sys-moment-location))
         )
    (if (not (null? sys-moment-location))
        (begin
           (for-each (lambda (i) (display i out)) formatted-output))
            (for-each display formatted-output)))

  ; (format out "lastmoment is ~a\n"  lastmoment)

  ) 

#(format out "~a~a~a" "LILYSOURCE=" (ly:parser-output-name) ".ly\n")

pdfforvideo = #(define-void-function () () (format out "~a~a~a" "VIDEOSOURCE=" current-outfile-name ".pdf\n"))

midiforvideo = #(define-void-function () () (format out "~a~a~a" "MIDISOURCE=" current-outfile-name ".midi\n"))