◊(Local Yarn Code "Diff")

(require racket/list
         racket/function
         racket/draw
         racket/class
         pollen/decode
         pollen/tag
         pollen/setup
         pollen/core
         net/uri-codec
         txexpr
         "dust.rkt")

(provide html-fn
         html-fndef)

           (is-newthought? (first (get-elements block-xpr))))
      (attr-set block-xpr 'class "pause-before")
      block-xpr))

;; Links
;;
;; Private use:
(define all-link-urls (make-hash))

;; Provided tag functions:
(define (html-link . args)
  `(link& [[ref ,(format "~a" (first args))]] ,@(rest args)))

(define (html-url ref url)
  (define page-path (hash-ref (current-metas) 'here-path))
  (define page-link-urls (hash-ref! all-link-urls page-path make-hash))
  (hash-set! page-link-urls (format "~a" ref) url) "")

;; Private use (by html-root):
(define (decode-link-urls tx)
  (define page-path (hash-ref (current-metas) 'here-path))
  (define page-link-urls (hash-ref! all-link-urls page-path make-hash))
  (cond [(eq? (get-tag tx) 'link&)
         (let* ([url-ref (attr-ref tx 'ref)]
                [url (or (hash-ref page-link-urls url-ref #f)
                         (format "Missing reference: ~a" url-ref))])
           `(a [[href ,url]] ,@(get-elements tx)))]
        [else tx]))

;; Fast link to another article
(define html-xref
  (case-lambda
    [(title) `(a [[href ,(format "~aarticles/~a.html" web-root (normalize title))]
                  [class "xref"]]
                 (i ,title))]
    [elems `(a [[href ,(format "~aarticles/~a.html" web-root (first elems))]
                [class "xref"]]
               ,@(rest elems))]))

;; Footnotes
;;
;; Private use:
(define all-fn-names (make-hash))
(define all-fn-definitions (make-hash))
(define (fn-id x) (here-id (string-append x "_fn")))
(define (fndef-id x) (here-id (string-append x "_fndef")))

;; Provided footnote tag functions:
(define (html-fn . args)
  (define name (format "~a" (first args)))
  (define page-path (hash-ref (current-metas) 'here-path))
  (define page-fn-names (cons name (hash-ref! all-fn-names page-path '())))
  (hash-set! all-fn-names page-path page-fn-names)
  
  (let* ([def-anchorlink (string-append "#" (fndef-id name))]
         [nth-ref        (number->string (count (curry string=? name) page-fn-names))]
         [ref-id         (string-append (fn-id name) nth-ref)]
         [fn-number      (+ 1 (index-of (remove-duplicates (reverse page-fn-names)) name))]
         [ref-text       (format "(~a)" fn-number)])
    (cond [(empty? (rest args)) `(sup (a [[href ,def-anchorlink] [id ,ref-id]] ,ref-text))]
          [else `(span [[class "links-footnote"] [id ,ref-id]]
                       ,@(rest args)
                       (sup (a [[href ,def-anchorlink]] ,ref-text)))])))

(define (html-fndef . elems)
  (define page-path (hash-ref (current-metas) 'here-path))
  (define page-fn-defs (hash-ref! all-fn-definitions page-path make-hash))
  (hash-set! page-fn-defs (format "~a" (first elems)) (rest elems)))

;; Private use (by html-root)
(define (html-footnote-block)
  (define page-path (hash-ref (current-metas) 'here-path))
  (define page-fn-names (hash-ref! all-fn-names page-path '()))
  (define page-fn-defs (hash-ref! all-fn-definitions page-path (make-hash)))
  (define note-items
    (for/list ([fn-name (in-list (remove-duplicates (reverse page-fn-names)))])
      (let* ([definition-text (or (hash-ref page-fn-defs fn-name #f)
                                  '((i "Missing footnote definition!")))]
             [backref-count (count (curry string=? fn-name) page-fn-names)]
             [backrefs (for/list ([fnref-num (in-range backref-count)])
                         `(a [[href ,(string-append "#"
                                                    (fn-id fn-name)
                                                    (format "~a" (+ 1 fnref-num)))]] "↩"))])
        `(li [[id ,(fndef-id fn-name)]] ,@definition-text ,@backrefs))))
  (cond [(null? note-items) ""]
        [else `(section ((class "footnotes")) (hr) (ol ,@note-items))]))

(define (html-note-with-srcline attrs elems)
  (txexpr 'note attrs (decode-hardwrapped-paragraphs elems)))