From 21175a8267aae9d88652fac832a90266d5484cd5 Mon Sep 17 00:00:00 2001
From: hackademix <giorgio@maone.net>
Date: Tue, 30 Apr 2019 13:31:49 +0200
Subject: Display NOSCRIPT elements when scripts are blocked or the
 data-librejs-display attribute is present.

---
 main_background.js       | 64 +++++++++++++++++++++++++++++++++++++++---------
 test/spec/LibreJSSpec.js | 24 ++++++++++++++++++
 2 files changed, 77 insertions(+), 11 deletions(-)

diff --git a/main_background.js b/main_background.js
index f9e7521..0a1a2e9 100644
--- a/main_background.js
+++ b/main_background.js
@@ -938,16 +938,55 @@ function doc2HTML(doc) {
 }
 
 /**
-*	Removes noscript tags with name "librejs-path" leaving the inner content to load.
+* Shortcut to create a correctly namespaced DOM HTML elements
 */
-function remove_noscripts(html_doc){
-	for(var i = 0; i < html_doc.getElementsByName("librejs-path").length; i++){
-		if(html_doc.getElementsByName("librejs-path")[i].tagName == "NOSCRIPT"){
-			html_doc.getElementsByName("librejs-path")[i].outerHTML = html_doc.getElementsByName("librejs-path")[i].innerHTML;
-		}
-	}
+function createHTMLElement(doc, name) {
+  return doc.createElementNS("http://www.w3.org/1999/xhtml", name);
+}
 
-	return doc2HTML(html_doc);
+/**
+* Replace any element with a span having the same content (useful to force
+* NOSCRIPT elements to visible the same way as NoScript and uBlock do)
+*/
+function forceElement(doc, element) {
+	let replacement = createHTMLElement(doc, "span");
+	replacement.innerHTML = element.innerHTML;
+	element.replaceWith(replacement);
+	return replacement;
+}
+
+/**
+*	Forces displaying any element having the "data-librejs-display" attribute and
+* <noscript> elements on pages where LibreJS disabled inline scripts (unless
+* they have the "data-librejs-nodisplay" attribute).
+*/
+function forceNoscriptElements(doc) {
+	let shown = 0;
+	// inspired by NoScript's onScriptDisabled.js
+	for (let noscript of doc.querySelectorAll("noscript:not([data-librejs-nodisplay])")) {
+    let replacement = forceElement(doc, noscript);
+    // emulate meta-refresh
+    let meta = replacement.querySelector('meta[http-equiv="refresh"]');
+    if (meta) {
+      refresh = true;
+      doc.head.appendChild(meta);
+    }
+		shown++;
+  }
+	return shown;
+}
+/**
+*	Forces displaying any element having the "data-librejs-display" attribute and
+* <noscript> elements on pages where LibreJS disabled inline scripts (unless
+* they have the "data-librejs-nodisplay" attribute).
+*/
+function showConditionalElements(doc) {
+	let shown = 0;
+	for (let element of document.querySelectorAll("[data-librejs-display]")) {
+		forceElement(doc, element);
+		shown++;
+	}
+	return shown;
 }
 
 /**
@@ -1113,10 +1152,13 @@ async function editHtml(html, documentUrl, tabId, frameId, whitelisted){
 				}
 			}
 		}
+
+		modified = showConditionalElements(html_doc) > 0 || modified;
 		if (modified) {
-			return modifiedInline
-				? await remove_noscripts(html_doc)
-				: doc2HTML(html_doc);
+			if (modifiedInline) {
+				forceNoscriptElements(html_doc);
+			}
+			return doc2HTML(html_doc);
 		}
 	}
 	return null;
diff --git a/test/spec/LibreJSSpec.js b/test/spec/LibreJSSpec.js
index 43f37a7..8d4aebe 100644
--- a/test/spec/LibreJSSpec.js
+++ b/test/spec/LibreJSSpec.js
@@ -222,6 +222,30 @@ describe("LibreJS' components", () => {
       expect(processed).toContain(trivialAsUrl);
       expect(processed).not.toContain(nontrivialAsUrl);
     });
+
+    it("should force displaying NOSCRIPT elements (except those with @data-librejs-nodisplay) where scripts have been blocked", async () => {
+      let noscriptContent = "I'm NOSCRIPT content";
+      let asNoscript = `<noscript>${noscriptContent}</noscript>`;
+      let asNodisplay = `<noscript data-librejs-nodisplay>${noscriptContent}</noscript>`;
+      let asSpan = `<span>${noscriptContent}</span>`;
+      let page = addToBody(addToBody(nontrivialInHtml, asNoscript), asNodisplay);
+      let processed = await processHtml(page);
+      expect(processed).not.toContain(asNoscript);
+      expect(processed).toContain(asSpan);
+      expect(processed).not.toContain(asNodisplay);
+    });
+
+    it("should always force displaying @data-librejs-display elements", async () => {
+      let content = "I'm FORCED content";
+      let asDisplay = `<span data-librejs-display>${content}</span>`;
+      let asSpan = `<span>${content}</span>`;
+      for (let page of [nontrivialInHtml, "<body></body>"]) {
+        page = addToBody(page, asDisplay);
+        let processed = await processHtml(page);
+        expect(processed).not.toContain(asDisplay);
+        expect(processed).not.toContain(asSpan);
+      }
+    });
   });
 
   describe("The external (Web Labels) license checker", () => {
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