#(define-markup-command (print-songinfo layout props) ()
  (define (songinfo-from songId key)
    (let ((song (if (defined? 'SONG_DATA) (assoc-ref SONG_DATA songId) #f)))
      (if song
        (assoc-ref song key)
        (ly:warning (ly:format "song with id ~a not found" songId)))))

  (define (format-author authorId)
    (let ((author (if (defined? 'AUTHOR_DATA) (assoc-ref AUTHOR_DATA authorId) #f)))
      (if author
        (markup
          #:override (cons 'author:name (assoc-ref author "name"))
          #:override (cons 'author:trail_name (assoc-ref author "trail_name"))
          #:override (cons 'author:birth_year (assoc-ref author "birth_year"))
          #:override (cons 'author:death_year (assoc-ref author "death_year"))
          #:override (cons 'author:organization (assoc-ref author "organization"))
          (ly:output-def-lookup layout 'authorMarkup))
        (ly:warning (ly:format "author with id ~a not found" authorId)))))

  (define (format-poet poetId)
    (markup #:override (cons 'author (format-author poetId)) (ly:output-def-lookup layout 'poetMarkup)))

  (define (format-composer composerId)
    (markup #:override (cons 'author (format-author composerId)) (ly:output-def-lookup layout 'composerMarkup)))

  (define (format-poet-and-composer authorId)
    (markup #:override (cons 'author (format-author authorId)) (ly:output-def-lookup layout 'poetAndComposerEqualMarkup)))

  (interpret-markup layout props
    (if (chain-assoc-get 'page:is-bookpart-last-page props #f)
    (let* ((songId (chain-assoc-get 'header:songId props #f))
           (poetId (chain-assoc-get 'header:poetId props (if songId (songinfo-from songId "poet") #f)))
           (composerId (chain-assoc-get 'header:composerId props (if songId (songinfo-from songId "composer") #f)))
           (poet-and-composer-same (equal? poetId composerId)))
      (let ((blockwidth (* (chain-assoc-get 'header:songinfo-size-factor props 0.9) (ly:output-def-lookup layout 'line-width)))
            (infotext (chain-assoc-get 'header:infotext props (chain-assoc-get 'header:songinfo props #f)))
            (poet-maybe-with-composer (chain-assoc-get 'header:poet props (if poetId (if poet-and-composer-same (format-poet-and-composer poetId) (format-poet poetId)) #f)))
            (composer (chain-assoc-get 'header:composer props (if (and composerId (not poet-and-composer-same)) (format-composer composerId) #f)))
            (copyright (chain-assoc-get 'header:copyright props #f))
            (translation (chain-assoc-get 'header:translation props #f))
            (spelling (chain-assoc-get 'header:spelling props #f))
            (year_text (chain-assoc-get 'header:year_text props #f))
            (year_melody (chain-assoc-get 'header:year_melody props #f)))
            (markup
              #:override (cons 'songinfo:poet-maybe-with-composer
                (if (and poet-maybe-with-composer (not (and (string? poet-maybe-with-composer) (string-null? poet-maybe-with-composer)))) poet-maybe-with-composer #f))
              #:override (cons 'songinfo:composer
                (if (and composer (not (and (string? composer) (string-null? composer)))) composer #f))
              #:override (cons 'songinfo:copyright
                (if (and copyright (not (and (string? copyright) (string-null? copyright)))) copyright #f))
              #:override (cons 'songinfo:infotext
                (if (and infotext (not (and (string? infotext) (string-null? infotext)))) infotext #f))
              #:override (cons 'songinfo:translation
                (if (and translation (not (and (string? translation) (string-null? translation)))) translation #f))
              #:override (cons 'songinfo:spelling
                (if (and spelling (not (and (string? spelling) (string-null? spelling)))) spelling #f))
              #:override (cons 'songinfo:year_text
                (if (and year_text (not (and (string? year_text) (string-null? year_text)))) year_text #f))
              #:override (cons 'songinfo:year_melody
                (if (and year_melody (not (and (string? year_melody) (string-null? year_melody)))) year_melody #f))
              #:override '(baseline-skip . 3.0)
              #:override `(line-width . ,blockwidth)
              #:fontsize songInfoFontSize
              #:sans
              (ly:output-def-lookup layout 'songinfoMarkup)
            )))
      (make-null-markup)))
)

#(define-markup-command (print-pagenumber layout props)()
  (let ((label (chain-assoc-get 'header:myindexlabel props #f)))
   (interpret-markup layout props
     (markup #:large #:bold
        (if label
         (make-custom-page-number-markup label (chain-assoc-get 'page:page-number props 0))
         (make-fromproperty-markup 'page:page-number-string)
        )
   ))))

\paper {
  print-first-page-number = ##t
  first-page-number = #0

  oddFooterMarkup = \markup {
    \fill-line {
      \line { \null }
      \line { \general-align #Y #DOWN \print-songinfo }
      \line { \if \should-print-page-number \print-pagenumber }
    }
  }
  evenFooterMarkup  = \markup {
    \fill-line {
      \line { \if \should-print-page-number \print-pagenumber }
      \line { \general-align #Y #DOWN \print-songinfo }
      \line { \null }
    }
  }
}