Add reader mode handler

Fixes: https://gitlab.gnome.org/GNOME/epiphany/-/issues/50

3 files changed, 112 insertions, 2 deletions

diff --git a/third-party/readability/README.epiphany b/third-party/readability/README.epiphany
index 731426a81..1273a0529 100644
--- a/third-party/readability/README.epiphany
+++ b/third-party/readability/README.epiphany
@@ -5,14 +5,20 @@ This directory contains an official readability.js release version, distributed
 ## Update process
 
 $ wget https://raw.githubusercontent.com/mozilla/readability/master/Readability.js
+$ wget https://raw.githubusercontent.com/mozilla/readability/master/Readability-readerable.js
 
-Copy Readability.js to <epiphany-source>/third-party/readability/
+Copy Readability.js and Readability-readerable.js to <epiphany-source>/third-party/readability/
 
-# Added the following to the bottom of the js file:
+# Added the following to the bottom of the Readability.js file:
 
 // Added for Epiphany
 var documentClone = document.cloneNode(true);
 reader = new Readability(documentClone);
 reader.parse();
 
+# Added the following to the bottom of the Readability-readerable.js file:
+
+// Added for Epiphany
+isProbablyReaderable(document, false);
+
 # Documentation created by Jan-Michael Brummer <jan.brummer@tabos.org>
\ No newline at end of file
diff --git a/third-party/readability/Readability-readerable.js b/third-party/readability/Readability-readerable.js
new file mode 100644
index 000000000..4d4001c6e
--- /dev/null
+++ b/third-party/readability/Readability-readerable.js
@@ -0,0 +1,103 @@
+/* eslint-env es6:false */
+/* globals exports */
+/*
+ * Copyright (c) 2010 Arc90 Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * This code is heavily based on Arc90's readability.js (1.7.1) script
+ * available at: http://code.google.com/p/arc90labs-readability
+ */
+
+var REGEXPS = {
+  // NOTE: These two regular expressions are duplicated in
+  // Readability.js. Please keep both copies in sync.
+  unlikelyCandidates: /-ad-|ai2html|banner|breadcrumbs|combx|comment|community|cover-wrap|disqus|extra|footer|gdpr|header|legends|menu|related|remark|replies|rss|shoutbox|sidebar|skyscraper|social|sponsor|supplemental|ad-break|agegate|pagination|pager|popup|yom-remote/i,
+  okMaybeItsACandidate: /and|article|body|column|content|main|shadow/i,
+};
+
+function isNodeVisible(node) {
+  // Have to null-check node.style and node.className.indexOf to deal with SVG and MathML nodes.
+  return (!node.style || node.style.display != "none")
+    && !node.hasAttribute("hidden")
+    //check for "fallback-image" so that wikimedia math images are displayed
+    && (!node.hasAttribute("aria-hidden") || node.getAttribute("aria-hidden") != "true" || (node.className && node.className.indexOf && node.className.indexOf("fallback-image") !== -1));
+}
+
+/**
+ * Decides whether or not the document is reader-able without parsing the whole thing.
+ *
+ * @return boolean Whether or not we suspect Readability.parse() will suceeed at returning an article object.
+ */
+function isProbablyReaderable(doc, isVisible) {
+  if (!isVisible) {
+    isVisible = isNodeVisible;
+  }
+
+  var nodes = doc.querySelectorAll("p, pre");
+
+  // Get <div> nodes which have <br> node(s) and append them into the `nodes` variable.
+  // Some articles' DOM structures might look like
+  // <div>
+  //   Sentences<br>
+  //   <br>
+  //   Sentences<br>
+  // </div>
+  var brNodes = doc.querySelectorAll("div > br");
+  if (brNodes.length) {
+    var set = new Set(nodes);
+    [].forEach.call(brNodes, function(node) {
+      set.add(node.parentNode);
+    });
+    nodes = Array.from(set);
+  }
+
+  var score = 0;
+  // This is a little cheeky, we use the accumulator 'score' to decide what to return from
+  // this callback:
+  return [].some.call(nodes, function(node) {
+    if (!isVisible(node))
+      return false;
+
+    var matchString = node.className + " " + node.id;
+    if (REGEXPS.unlikelyCandidates.test(matchString) &&
+        !REGEXPS.okMaybeItsACandidate.test(matchString)) {
+      return false;
+    }
+
+    if (node.matches("li p")) {
+      return false;
+    }
+
+    var textContentLength = node.textContent.trim().length;
+    if (textContentLength < 140) {
+      return false;
+    }
+
+    score += Math.sqrt(textContentLength - 140);
+
+    if (score > 20) {
+      return true;
+    }
+    return false;
+  });
+}
+
+if (typeof exports === "object") {
+  exports.isProbablyReaderable = isProbablyReaderable;
+}
+
+// Added for Epiphany
+isProbablyReaderable(document, false);
diff --git a/third-party/readability/readability.gresource.xml b/third-party/readability/readability.gresource.xml
index b3216fd5f..ff4dc2b2d 100644
--- a/third-party/readability/readability.gresource.xml
+++ b/third-party/readability/readability.gresource.xml
@@ -2,6 +2,7 @@
 <gresources>
   <gresource prefix="/org/gnome/epiphany/readability">
     <file compressed="true">Readability.js</file>
+    <file compressed="true">Readability-readerable.js</file>
     <file compressed="true">reader.css</file>
   </gresource>
 </gresources>