From 9fd2b4699d9697b87fabcf982184ce6c381634f0 Mon Sep 17 00:00:00 2001
From: Cadence Ember <cadence@disroot.org>
Date: Sun, 4 Dec 2022 23:46:24 +1300
Subject: [PATCH] Optimise update-tree-wiki somewhat

---
 src/page-wiki.rkt    | 233 +------------------------------------
 src/tree-updater.rkt | 267 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 272 insertions(+), 228 deletions(-)
 create mode 100644 src/tree-updater.rkt

diff --git a/src/page-wiki.rkt b/src/page-wiki.rkt
index 2cd14dc..6f22ad8 100644
--- a/src/page-wiki.rkt
+++ b/src/page-wiki.rkt
@@ -19,6 +19,7 @@
          "data.rkt"
          "pure-utils.rkt"
          "syntax.rkt"
+         "tree-updater.rkt"
          "xexpr-utils.rkt"
          "url-utils.rkt")
 
@@ -30,51 +31,19 @@
  preprocess-html-wiki)
 
 (module+ test
-  (require rackunit)
-  (define wiki-document
-    '(*TOP*
-      (div (@ (class "mw-parser-output"))
-           (aside (@ (role "region") (class "portable-infobox pi-theme-wikia pi-layout-default"))
-                  (h2 (@ (class "pi-item pi-title") (data-source "title"))
-                      "Infobox Title")
-                  (figure (@ (class "pi-item pi-image") (data-source "image"))
-                          (a (@ (href "https://static.wikia.nocookie.net/nice-image.png") (class "image image-thumbnail") (title ""))
-                             (img (@ (src "https://static.wikia.nocookie.net/nice-image-thumbnail.png") (class "pi-image-thumbnail")))))
-                  (div (@ (class "pi-item pi-data") (data-source "description"))
-                       (h3 (@ (class "pi-data-label"))
-                           "Description")
-                       (div (@ (class "pi-data-value"))
-                            "Mystery infobox!")))
-           (div (@ (data-test-collapsesection) (class "collapsible collapsetoggle-inline collapsed"))
-                (i (b "This section is hidden for dramatic effect."))
-                (div (@ (class "collapsible-content"))
-                     (p "Another page link: "
-                        (a (@ (data-test-wikilink) (href "https://test.fandom.com/wiki/Another_Page") (title "Another Page"))
-                           "Another Page"))))
-           (figure (@ (class "thumb tnone"))
-                   (a (@ (href "https://static.wikia.nocookie.net/nice-image.png") (class "image") (data-test-figure-a))
-                      (img (@ (src "data:image/gif;base64,R0lGODlhAQABAIABAAAAAP///yH5BAEAAAEALAAAAAABAAEAQAICTAEAOw%3D%3D")
-                              (data-src "https://static.wikia.nocookie.net/nice-image-thumbnail.png")
-                              (class "thumbimage lazyload"))))
-                   (noscript
-                    (a (@ (href "https://static.wikia.nocookie.net/nice-image.png") (class "image"))
-                       (img (@ (src "https://static.wikia.nocookie.net/nice-image-thumbnail.png")
-                               (data-src "https://static.wikia.nocookie.net/nice-image-thumbnail.png")
-                               (class "thumbimage")))))
-                   (figcaption "Test figure!"))
-           (iframe (@ (src "https://example.com/iframe-src")))))))
+  (require rackunit))
 
 (define (preprocess-html-wiki html)
-  (define (rr* find replace contents)
+  (define ((rr* find replace) contents)
     (regexp-replace* find contents replace))
   ((compose1
     ; fix navbox list nesting
     ; navbox on right of page has incorrect html "<td ...><li>" and the xexpr parser puts the <li> much further up the tree
     ; add a <ul> to make the parser happy
     ; usage: /fallout/wiki/Fallout:_New_Vegas_achievements_and_trophies
-    (curry rr* #rx"(<td[^>]*>\n?)(<li>)" "\\1<ul>\\2")
+    (rr* #rx"(<td[^>]*>\n?)(<li>)" "\\1<ul>\\2")
     ; change <figcaption><p> to <figcaption><span> to make the parser happy
-    (curry rr* #rx"(<figcaption[^>]*>)[ \t]*<p class=\"caption\">([^<]*)</p>" "\\1<span class=\"caption\">\\2</span>"))
+    (rr* #rx"(<figcaption[^>]*>)[ \t]*<p class=\"caption\">([^<]*)</p>" "\\1<span class=\"caption\">\\2</span>"))
    html))
 (module+ test
   (check-equal? (preprocess-html-wiki "<td class=\"va-navbox-column\" style=\"width: 33%\">\n<li>Hey</li>")
@@ -82,198 +51,6 @@
   (check-equal? (preprocess-html-wiki "<figure class=\"thumb tright\" style=\"width: 150px\"><a class=\"image\"><img></a><noscript><a><img></a></noscript><figcaption class=\"thumbcaption\"> 	<p class=\"caption\">Caption text.</p></figcaption></figure>")
                 "<figure class=\"thumb tright\" style=\"width: 150px\"><a class=\"image\"><img></a><noscript><a><img></a></noscript><figcaption class=\"thumbcaption\"><span class=\"caption\">Caption text.</span></figcaption></figure>"))
 
-(define (update-tree-wiki tree wikiname)
-  (update-tree
-   (λ (element element-type attributes children)
-     ;; replace whole element?
-     (cond
-       ; wrap tables in a div.table-scroller
-       [(and (eq? element-type 'table)
-             (has-class? "wikitable" attributes)
-             (not (dict-has-key? attributes 'data-scrolling)))
-        `(div
-          ((class "table-scroller"))
-          ((,element-type (@ (data-scrolling) ,@attributes)
-                          ,@children)))]
-       ; exclude empty figcaptions
-       [(and (eq? element-type 'figcaption)
-             (or (eq? (length (filter element-is-element? children)) 0)
-                 ((query-selector (λ (element-type attributes children)
-                                    (eq? element-type 'use))
-                                  element))))
-        return-no-element]
-       ; exclude infobox items that are videos, and gallery items that are videos
-       [(and (or (has-class? "pi-item" attributes)
-                 (has-class? "wikia-gallery-item" attributes))
-             ((query-selector (λ (element-type attributes children)
-                                (has-class? "video-thumbnail" attributes))
-                              element)))
-        return-no-element]
-       ; exclude the invisible brackets after headings
-       [(and (eq? element-type 'span)
-             (has-class? "mw-editsection" attributes))
-        return-no-element]
-       ; display a link instead of an iframe
-       [(eq? element-type 'iframe)
-        (define src (car (dict-ref attributes 'src null)))
-        `(a
-          ((class "iframe-alternative") (href ,src))
-          (,(format "Embedded media: ~a" src)))]
-       ; remove noscript versions of images because they are likely lower quality than the script versions
-       [(and (eq? element-type 'noscript)
-             (match children
-               ; either the noscript has a.image as a first child...
-               [(list (list 'a (list '@ a-att ...) _)) (has-class? "image" a-att)]
-               ; or the noscript has img as a first child
-               [(list (list 'img _)) #t]
-               [_ #f]))
-        return-no-element]
-       [#t
-        (list element-type
-              ;; attributes
-              ((compose1
-                ; uncollapsing
-                (curry attribute-maybe-update 'class
-                       (λ (class)
-                         (string-join
-                          ((compose1
-                            ; uncollapse all navbox items (bottom of page mass navigation)
-                            (curry u
-                                   (λ (classlist) (and (eq? element-type 'table)
-                                                       (member "navbox" classlist)
-                                                       (member "collapsed" classlist)))
-                                   (λ (classlist) (filter (curry (negate equal?) "collapsed") classlist)))
-                            ; uncollapse portable-infobox sections
-                            (curry u
-                                   (λ (classlist) (and (eq? element-type 'section)
-                                                       (member "pi-collapse" classlist)))
-                                   (λ (classlist) (filter (λ (v)
-                                                            (and (not (equal? v "pi-collapse-closed"))
-                                                                 (not (equal? v "pi-collapse"))))
-                                                          classlist)))
-                            ; generic: includes article sections and tables, probably more
-                            (curry u
-                                   (λ (classlist) (and (member "collapsible" classlist)
-                                                       (member "collapsed" classlist)))
-                                   (λ (classlist) (filter (curry (negate equal?) "collapsed") classlist))))
-                           (string-split class " "))
-                          " ")))
-                ; change links to stay on the same wiki
-                (curry attribute-maybe-update 'href
-                       (λ (href)
-                         ((compose1
-                           (λ (href) (regexp-replace #rx"^(/wiki/.*)" href (format "/~a\\1" wikiname)))
-                           (λ (href) (regexp-replace (pregexp (format "^https://(~a)\\.fandom\\.com(/wiki/.*)" px-wikiname)) href "/\\1\\2")))
-                          href)))
-                ; add noreferrer to a.image
-                (curry u
-                       (λ (v) (and (eq? element-type 'a)
-                                   (has-class? "image" v)))
-                       (λ (v) (dict-update v 'rel (λ (s)
-                                                    (list (string-append (car s) " noreferrer")))
-                                           '(""))))
-                ; proxy images from inline styles, if strict_proxy is set
-                (curry u
-                       (λ (v) (config-true? 'strict_proxy))
-                       (λ (v) (attribute-maybe-update
-                               'style
-                               (λ (style)
-                                 (regexp-replace #rx"url\\(['\"]?(.*?)['\"]?\\)" style
-                                                 (λ (whole url)
-                                                   (string-append
-                                                    "url("
-                                                    (u-proxy-url url)
-                                                    ")")))) v)))
-                ; and also their links, if strict_proxy is set
-                (curry u
-                       (λ (v)
-                         (and (config-true? 'strict_proxy)
-                              (eq? element-type 'a)
-                              (or (has-class? "image-thumbnail" v)
-                                  (has-class? "image" v))))
-                       (λ (v) (attribute-maybe-update 'href u-proxy-url v)))
-                ; proxy images from src attributes, if strict_proxy is set
-                (curry u
-                       (λ (v) (config-true? 'strict_proxy))
-                       (λ (v) (attribute-maybe-update 'src u-proxy-url v)))
-                ; don't lazyload images
-                (curry u
-                       (λ (v) (dict-has-key? v 'data-src))
-                       (λ (v) (attribute-maybe-update 'src (λ (_) (car (dict-ref v 'data-src))) v)))
-                ; don't use srcset - TODO: use srcset?
-                (λ (v) (dict-remove v 'srcset)))
-               attributes)
-              ;; children
-              ((compose1
-                ; more uncollapsing - sample: bandori/wiki/BanG_Dream!_Wikia
-                (curry u
-                       (λ (v) (has-class? "mw-collapsible-content" attributes))
-                       (λ (v) (for/list ([element v])
-                                (u (λ (element) (pair? element))
-                                   (λ (element)
-                                     `(,(car element)
-                                       (@ ,@(attribute-maybe-update 'style (λ (a) (regexp-replace #rx"display: *none" a "display:inline")) (bits->attributes element)))
-                                       ,@(filter element-is-content? (cdr element))))
-                                   element))))
-                ; wrap blinking animated images in a slot so they can be animated with CSS
-                (curry u
-                       (λ (v) (and (has-class? "animated" attributes)
-                                   ((length v) . > . 1)))
-                       (λ (v)
-                         `((span (@ (class "animated-slot__outer") (style ,(format "--steps: ~a" (length v))))
-                                 (span (@ (class "animated-slot__inner"))
-                                       ,@v))))))
-               children))]))
-   tree))
-(module+ test
-  (define transformed
-    (parameterize ([(config-parameter 'strict_proxy) "true"])
-      (update-tree-wiki wiki-document "test")))
-  ; check that wikilinks are changed to be local
-  (check-equal? (get-attribute 'href (bits->attributes
-                                      ((query-selector
-                                        (λ (t a c) (dict-has-key? a 'data-test-wikilink))
-                                        transformed))))
-                "/test/wiki/Another_Page")
-  ; check that a.image has noreferrer
-  (check-equal? (get-attribute 'rel (bits->attributes
-                                     ((query-selector
-                                       (λ (t a c) (and (eq? t 'a)
-                                                       (has-class? "image" a)))
-                                       transformed))))
-                " noreferrer")
-  ; check that article collapse sections become uncollapsed
-  (check-equal? (get-attribute 'class (bits->attributes
-                                       ((query-selector
-                                         (λ (t a c) (dict-has-key? a 'data-test-collapsesection))
-                                         transformed))))
-                "collapsible collapsetoggle-inline")
-  ; check that iframes are gone
-  (check-false ((query-selector (λ (t a c) (eq? t 'iframe)) transformed)))
-  (check-equal? (let* ([alternative ((query-selector (λ (t a c) (has-class? "iframe-alternative" a)) transformed))]
-                       [link ((query-selector (λ (t a c) (eq? t 'a)) alternative))])
-                  (get-attribute 'href (bits->attributes link)))
-                "https://example.com/iframe-src")
-  ; check that images are proxied
-  (check-equal? (get-attribute 'src (bits->attributes
-                                     ((query-selector
-                                       (λ (t a c) (eq? t 'img))
-                                       transformed))))
-                "/proxy?dest=https%3A%2F%2Fstatic.wikia.nocookie.net%2Fnice-image-thumbnail.png")
-  ; check that links to images are proxied
-  (check-equal? (get-attribute 'href (bits->attributes
-                                      ((query-selector
-                                        (λ (t a c) (and (eq? t 'a) (has-class? "image-thumbnail" a)))
-                                        transformed))))
-                "/proxy?dest=https%3A%2F%2Fstatic.wikia.nocookie.net%2Fnice-image.png")
-  (check-equal? (get-attribute 'href (bits->attributes
-                                      ((query-selector
-                                        (λ (t a c) (member '(data-test-figure-a) a))
-                                        transformed))))
-                "/proxy?dest=https%3A%2F%2Fstatic.wikia.nocookie.net%2Fnice-image.png")
-  ; check that noscript images are removed
-  (check-equal? ((query-selector (λ (t a c) (eq? t 'noscript)) transformed)) #f))
-
 (define (page-wiki req)
   (define wikiname (path/param-path (first (url-path (request-uri req)))))
   (define user-cookies (user-cookies-getter req))
diff --git a/src/tree-updater.rkt b/src/tree-updater.rkt
new file mode 100644
index 0000000..815ef8a
--- /dev/null
+++ b/src/tree-updater.rkt
@@ -0,0 +1,267 @@
+#lang racket/base
+(require racket/dict
+         racket/function
+         racket/match
+         racket/string
+         "config.rkt"
+         "pure-utils.rkt"
+         "url-utils.rkt"
+         "xexpr-utils.rkt")
+
+(provide
+ update-tree-wiki)
+
+(module+ test
+  (require rackunit
+           html-parsing)
+  (define wiki-document
+    '(*TOP*
+      (div (@ (class "mw-parser-output"))
+           (aside (@ (role "region") (class "portable-infobox pi-theme-wikia pi-layout-default"))
+                  (h2 (@ (class "pi-item pi-title") (data-source "title"))
+                      "Infobox Title")
+                  (figure (@ (class "pi-item pi-image") (data-source "image"))
+                          (a (@ (href "https://static.wikia.nocookie.net/nice-image.png") (class "image image-thumbnail") (title ""))
+                             (img (@ (src "https://static.wikia.nocookie.net/nice-image-thumbnail.png") (class "pi-image-thumbnail")))))
+                  (div (@ (class "pi-item pi-data") (data-source "description"))
+                       (h3 (@ (class "pi-data-label"))
+                           "Description")
+                       (div (@ (class "pi-data-value"))
+                            "Mystery infobox!")))
+           (div (@ (data-test-collapsesection) (class "collapsible collapsetoggle-inline collapsed"))
+                (i (b "This section is hidden for dramatic effect."))
+                (div (@ (class "collapsible-content"))
+                     (p "Another page link: "
+                        (a (@ (data-test-wikilink) (href "https://test.fandom.com/wiki/Another_Page") (title "Another Page"))
+                           "Another Page"))))
+           (figure (@ (class "thumb tnone"))
+                   (a (@ (href "https://static.wikia.nocookie.net/nice-image.png") (class "image") (data-test-figure-a))
+                      (img (@ (src "data:image/gif;base64,R0lGODlhAQABAIABAAAAAP///yH5BAEAAAEALAAAAAABAAEAQAICTAEAOw%3D%3D")
+                              (data-src "https://static.wikia.nocookie.net/nice-image-thumbnail.png")
+                              (class "thumbimage lazyload"))))
+                   (noscript
+                    (a (@ (href "https://static.wikia.nocookie.net/nice-image.png") (class "image"))
+                       (img (@ (src "https://static.wikia.nocookie.net/nice-image-thumbnail.png")
+                               (data-src "https://static.wikia.nocookie.net/nice-image-thumbnail.png")
+                               (class "thumbimage")))))
+                   (figcaption "Test figure!"))
+           (iframe (@ (src "https://example.com/iframe-src")))))))
+
+(define (updater wikiname)
+  (define classlist-updater
+    (compose1
+     ; uncollapse all navbox items (bottom of page mass navigation)
+     (curry u
+            (λ (classlist) (and ; removed due to scoping, would improve peformance (eq? element-type 'table)
+                            (member "navbox" classlist)
+                            (member "collapsed" classlist)))
+            (λ (classlist) (filter (curry (negate equal?) "collapsed") classlist)))
+     ; uncollapse portable-infobox sections
+     (curry u
+            (λ (classlist) (and ; removed due to scoping, would improve performance (eq? element-type 'section)
+                            (member "pi-collapse" classlist)))
+            (λ (classlist) (filter (λ (v)
+                                     (and (not (equal? v "pi-collapse-closed"))
+                                          (not (equal? v "pi-collapse"))))
+                                   classlist)))
+     ; generic: includes article sections and tables, probably more
+     (curry u
+            (λ (classlist) (and (member "collapsible" classlist)
+                                (member "collapsed" classlist)))
+            (λ (classlist) (filter (curry (negate equal?) "collapsed") classlist)))))
+
+  (define ((string-replace-curried from to) str)
+    (string-replace str from to))
+
+  (define class-updater
+    (compose1
+     (string-replace-curried " collapsed" "")
+     (string-replace-curried "pi-collapse-closed" "")
+     (string-replace-curried "pi-collapse" "")))
+
+  (define attributes-updater
+    (compose1
+     ; uncollapsing
+     #;(curry attribute-maybe-update 'class
+              (λ (class) (string-join (classlist-updater (string-split class " ")) " ")))
+     (curry attribute-maybe-update 'class class-updater)
+     ; change links to stay on the same wiki
+     (curry attribute-maybe-update 'href
+            (λ (href)
+              ((compose1
+                (λ (href) (regexp-replace #rx"^(/wiki/.*)" href (format "/~a\\1" wikiname)))
+                (λ (href) (regexp-replace (pregexp (format "^https://(~a)\\.fandom\\.com(/wiki/.*)" px-wikiname)) href "/\\1\\2")))
+               href)))
+     ; add noreferrer to a.image
+     (curry u
+            (λ (v) (and #;(eq? element-type 'a)
+                        (has-class? "image" v)))
+            (λ (v) (dict-update v 'rel (λ (s)
+                                         (list (string-append (car s) " noreferrer")))
+                                '(""))))
+     ; proxy images from inline styles, if strict_proxy is set
+     (curry u
+            (λ (v) (config-true? 'strict_proxy))
+            (λ (v) (attribute-maybe-update
+                    'style
+                    (λ (style)
+                      (regexp-replace #rx"url\\(['\"]?(.*?)['\"]?\\)" style
+                                      (λ (whole url)
+                                        (string-append
+                                         "url("
+                                         (u-proxy-url url)
+                                         ")")))) v)))
+     ; and also their links, if strict_proxy is set
+     (curry u
+            (λ (v)
+              (and (config-true? 'strict_proxy)
+                   #;(eq? element-type 'a)
+                   (or (has-class? "image-thumbnail" v)
+                       (has-class? "image" v))))
+            (λ (v) (attribute-maybe-update 'href u-proxy-url v)))
+     ; proxy images from src attributes, if strict_proxy is set
+     (curry u
+            (λ (v) (config-true? 'strict_proxy))
+            (λ (v) (attribute-maybe-update 'src u-proxy-url v)))
+     ; don't lazyload images
+     (curry u
+            (λ (v) (dict-has-key? v 'data-src))
+            (λ (v) (attribute-maybe-update 'src (λ (_) (car (dict-ref v 'data-src))) v)))
+     ; don't use srcset - TODO: use srcset?
+     (λ (v) (dict-remove v 'srcset))))
+
+  (define (children-updater attributes children)
+    ; more uncollapsing - sample: bandori/wiki/BanG_Dream!_Wikia
+    ((λ (children)
+       (u
+        (λ (v) (has-class? "mw-collapsible-content" attributes))
+        (λ (v) (for/list ([element v])
+                 (u (λ (element) (pair? element))
+                    (λ (element)
+                      `(,(car element)
+                        (@ ,@(attribute-maybe-update 'style (λ (a) (regexp-replace #rx"display: *none" a "display:inline")) (bits->attributes element)))
+                        ,@(filter element-is-content? (cdr element))))
+                    element)))
+        children))
+     ; wrap blinking animated images in a slot so they can be animated with CSS
+     ((λ (children)
+        (u
+         (λ (v) (and (has-class? "animated" attributes)
+                     ((length v) . > . 1)))
+         (λ (v)
+           `((span (@ (class "animated-slot__outer") (style ,(format "--steps: ~a" (length v))))
+                   (span (@ (class "animated-slot__inner"))
+                         ,@v))))
+         children))
+      children)))
+
+  (define (updater element element-type attributes children)
+    ;; replace whole element?
+    (cond
+      ; wrap tables in a div.table-scroller
+      [(and (eq? element-type 'table)
+            (has-class? "wikitable" attributes)
+            (not (dict-has-key? attributes 'data-scrolling)))
+       `(div
+         ((class "table-scroller"))
+         ((,element-type (@ (data-scrolling) ,@attributes)
+                         ,@children)))]
+      ; exclude empty figcaptions
+      [(and (eq? element-type 'figcaption)
+            (or (eq? (length (filter element-is-element? children)) 0)
+                ((query-selector (λ (element-type attributes children)
+                                   (eq? element-type 'use))
+                                 element))))
+       return-no-element]
+      ; exclude infobox items that are videos, and gallery items that are videos
+      [(and (or (has-class? "pi-item" attributes)
+                (has-class? "wikia-gallery-item" attributes))
+            ((query-selector (λ (element-type attributes children)
+                               (has-class? "video-thumbnail" attributes))
+                             element)))
+       return-no-element]
+      ; exclude the invisible brackets after headings
+      [(and (eq? element-type 'span)
+            (has-class? "mw-editsection" attributes))
+       return-no-element]
+      ; display a link instead of an iframe
+      [(eq? element-type 'iframe)
+       (define src (car (dict-ref attributes 'src null)))
+       `(a
+         ((class "iframe-alternative") (href ,src))
+         (,(format "Embedded media: ~a" src)))]
+      ; remove noscript versions of images because they are likely lower quality than the script versions
+      [(and (eq? element-type 'noscript)
+            (match children
+              ; either the noscript has a.image as a first child...
+              [(list (list 'a (list '@ a-att ...) _)) (has-class? "image" a-att)]
+              ; or the noscript has img as a first child
+              [(list (list 'img _)) #t]
+              [_ #f]))
+       return-no-element]
+      [#t
+       (list element-type
+             ;; attributes
+             (attributes-updater #; element-type attributes)
+             ;; children
+             (children-updater attributes children))]))
+
+  updater)
+
+(define (update-tree-wiki tree wikiname)
+  (update-tree (updater wikiname) tree))
+
+(module+ test
+  (define transformed
+    (parameterize ([(config-parameter 'strict_proxy) "true"])
+      (update-tree-wiki wiki-document "test")))
+  ; check that wikilinks are changed to be local
+  (check-equal? (get-attribute 'href (bits->attributes
+                                      ((query-selector
+                                        (λ (t a c) (dict-has-key? a 'data-test-wikilink))
+                                        transformed))))
+                "/test/wiki/Another_Page")
+  ; check that a.image has noreferrer
+  (check-equal? (get-attribute 'rel (bits->attributes
+                                     ((query-selector
+                                       (λ (t a c) (and (eq? t 'a)
+                                                       (has-class? "image" a)))
+                                       transformed))))
+                " noreferrer")
+  ; check that article collapse sections become uncollapsed
+  (check-equal? (get-attribute 'class (bits->attributes
+                                       ((query-selector
+                                         (λ (t a c) (dict-has-key? a 'data-test-collapsesection))
+                                         transformed))))
+                "collapsible collapsetoggle-inline")
+  ; check that iframes are gone
+  (check-false ((query-selector (λ (t a c) (eq? t 'iframe)) transformed)))
+  (check-equal? (let* ([alternative ((query-selector (λ (t a c) (has-class? "iframe-alternative" a)) transformed))]
+                       [link ((query-selector (λ (t a c) (eq? t 'a)) alternative))])
+                  (get-attribute 'href (bits->attributes link)))
+                "https://example.com/iframe-src")
+  ; check that images are proxied
+  (check-equal? (get-attribute 'src (bits->attributes
+                                     ((query-selector
+                                       (λ (t a c) (eq? t 'img))
+                                       transformed))))
+                "/proxy?dest=https%3A%2F%2Fstatic.wikia.nocookie.net%2Fnice-image-thumbnail.png")
+  ; check that links to images are proxied
+  (check-equal? (get-attribute 'href (bits->attributes
+                                      ((query-selector
+                                        (λ (t a c) (and (eq? t 'a) (has-class? "image-thumbnail" a)))
+                                        transformed))))
+                "/proxy?dest=https%3A%2F%2Fstatic.wikia.nocookie.net%2Fnice-image.png")
+  (check-equal? (get-attribute 'href (bits->attributes
+                                      ((query-selector
+                                        (λ (t a c) (member '(data-test-figure-a) a))
+                                        transformed))))
+                "/proxy?dest=https%3A%2F%2Fstatic.wikia.nocookie.net%2Fnice-image.png")
+  ; check that noscript images are removed
+  (check-equal? ((query-selector (λ (t a c) (eq? t 'noscript)) transformed)) #f)
+  ; benchmark
+  (when (file-exists? "Frog.html2")
+    (with-input-from-file "Frog.html2"
+      (λ ()
+        (define tree (html->xexp (current-input-port)))
+        (time (length (update-tree-wiki tree "minecraft")))))))