404 Page handling w/ issue form (#362)

.github/ISSUE_TEMPLATE/form404.yml

@@ -0,0 +1,32 @@
+name: Broken Link Report
+description: File a broken link report
+title: "Broken Link:"
+labels: ["bug"]
+projects: ["ros-infrastructure/rosindex"]
+body:
+
+  - type: input
+    id: 404page
+    attributes:
+      label: 404 Page URL
+      description: Enter the url of the page that doesn't exist
+      placeholder: Failed to automatically detect 404 page. Please enter url here.
+    validations:
+      required: true
+
+  - type: input
+    id: referer
+    attributes:
+      label: Referrer URL
+      description: Enter the URL of the referring page which has the wrong link.
+      placeholder: Automatic detection of the referrer page failed, please enter it here.
+    validations:
+      required: true
+
+  - type: textarea
+    id: description
+    attributes:
+      label: Description
+      placeholder: Please describe where the link is that you followed if it might not be obvious on the referring page. If any additional information is needed, please provide it here too.
+    validations:
+      required: false

404.html

@@ -30,7 +30,7 @@ <h2>Move along.</h2>
         </div>
         <div class="row">
           <div class="col-xs-offset-3 col-xs-6 text-center">
-            <a target="_blank" href="https://github.com/ros-infrastructure/rosindex/issues/new?title=Broken%20Link:%20" class="btn btn-sm btn-default btn-block">Report Broken Link</a>
+            <a id="github_issue_link" target="_blank" href="" class="btn btn-sm btn-default btn-block">Report Broken Link</a>
           </div>
         </div>
         <div class="row">
@@ -42,7 +42,41 @@ <h2>Move along.</h2>
 </div>
 
 <script>
-$(function () {
-    // TODO add url to the report button
-  };)
+  $(function () {
+    function updateGitHref() {
+      let githubLink = "https://github.com/ros-infrastructure/rosindex/issues/new?labels=bug&template=form404.yml";
+
+      // Get current url
+      var currentUrl = window.location.href;
+      if (!currentUrl) {
+        currentUrl = "";
+      }
+
+      // Get the url that brought us here
+      var referrerUrl = document.referrer;
+      if (!referrerUrl) {
+        referrerUrl = "";
+      }
+
+      // Encode the urls
+      var title = "title=Broken+Link:" + encodeURIComponent(currentUrl);
+      var currentUrl_encoded = "404page=" + encodeURIComponent(currentUrl);
+      var referrerUrl_encoded = "referer=" + encodeURIComponent(referrerUrl);
+
+      // Update the href
+      githubLink += "&" + title + "&" + currentUrl_encoded + "&" + referrerUrl_encoded;
+
+      // Set the href
+      var githubIssueLink = $("#github_issue_link");
+      if (!githubIssueLink.length) {
+        console.error("Github issue link element is not available");
+        return;
+      }
+      githubIssueLink.attr("href", githubLink);
+    }
+
+    // Update the href
+    updateGitHref();
+
+  });
 </script>