Add branch selector

index.html

@@ -9,7 +9,11 @@
 <p>
     <input type="button" value="Test Requests" onclick="test_request()" />
 </p>
-<h1>Render a Rule</h1>
+<h3><label for="branch-name-selector">Repository branch</label></h3>
+<select id="branch-name-selector" onchange="onChangeBranch(this.value)">
+    <!-- dynamically filled by initBranchNameSelector() -->
+</select>
+<h3>Render a Rule</h3>
 <select onchange="renderRule(this.value)">
     <option value="">--Please choose a rule--</option>
     <option value="S3457/c-family">S3457/c-family</option>
@@ -21,6 +25,35 @@
 </body>
 <script src="asciidoctor/asciidoctor.js"></script>
 <script>
+    function init() {
+      initBranchNameSelector();
+    }
+
+    function initBranchNameSelector() {
+      let selectElement = document.getElementById("branch-name-selector");
+      httpGetGithubApi("/repos/SonarSource/rspec/branches", function(body) {
+        let branchList = JSON.parse(body);
+        for (let i = 0; i < branchList.length; i++) {
+          let branchName = branchList[i].name;
+          addSelectOption(selectElement, branchName, branchName);
+          if (branchName === "master") {
+            selectElement.selectedIndex = i;
+          }
+        }
+      });
+    }
+
+    function addSelectOption(/*object*/selectElement, /*string*/value, /*string*/text) {
+      const opt = document.createElement('option');
+      opt.appendChild(document.createTextNode(text));
+      opt.value = value;
+      selectElement.appendChild(opt);
+    }
+
+    function onChangeBranch(/*string*/branchName) {
+
+    }
+
     function renderRule(/*string*/ruleId) {
       if (ruleId === "") {
         document.getElementById("div-result").innerHTML = "";
@@ -36,10 +69,13 @@
       });
     }
 
-    function httpGet(/*string*/url, /*function*/bodyConsumer) /*void*/ {
+    function httpGet(/*string*/url, /*function*/bodyConsumer, /*string?*/accept) /*void*/ {
+      if (typeof accept === "undefined") {
+        accept = "*";
+      }
       const xhr = new XMLHttpRequest();
       xhr.open('GET', url, true);
-      xhr.setRequestHeader("Accept", "*");
+      xhr.setRequestHeader("Accept", accept);
       xhr.onreadystatechange = function() {
         if(xhr.readyState === 4) {
           if (xhr.status === 0 /*local files*/ || xhr.status === 200) {
@@ -52,8 +88,9 @@
       xhr.send();
     }
 
-    function init() {
+    function httpGetGithubApi(/*string*/relativeUrl, /*function*/bodyConsumer) {
-
+      const url = "https://api.github.com" + relativeUrl;
+      httpGet(url, bodyConsumer, "application/vnd.github.v3.html");
     }
 
     function test_request() {