Add logic to pull release information from GitHub API for download links

WasabiFan · WasabiFan · commit cbf7f3e39c6e · 2016-06-10T11:23:47.000-07:00
diff --git a/_includes/head.html b/_includes/head.html
@@ -37,6 +37,8 @@
 
     <!-- Loads user-cards from GH API -->
     <script src="/javascripts/cards.js"></script>
+    <!-- Configures special anchors to link to the most recent ev3dev release -->
+    <script src="/javascripts/releases.js"></script>
     <!-- Responds to queries typed into the "Quick nav" box -->
     <script src="/javascripts/search.js"></script>
     <!-- Converts static descriptors of tab target content into live text and links -->
diff --git a/docs/getting-started.md b/docs/getting-started.md
@@ -40,15 +40,15 @@ please [open an issue on GitHub](/support){: .alert-link}.
 
 ## Step 1: Download the latest ev3dev image file
 
-Releases are posted [on GitHub][releases]. Follow the link and download the latest
-**Test Release** image file for your hardware. Releases for LEGO MINDSTORMS EV3
-start with `ev3-`, Raspberry Pi starts with `rpi-` and Raspberry Pi 2 starts
-with `rpi2-`.
-
-For most users, downloading the `.xz` file will be the best option, but the `.zip`
-will work as well. If you are planning to image your card manually instead of
-following the recommended steps, you will need to choose based on your OS and
-imaging program.
+To get started, you will need to download the release corresponding to the platform
+you are using. If you are looking for older releases or other file types, you can
+check out the [GitHub releases page][releases].
+
+Download for:
+<a data-release-link-platform="ev3" class="btn btn-sm btn-primary">LEGO EV3 brick</a>
+<a data-release-link-platform="rpi" class="btn btn-sm btn-primary">Raspberry Pi 1</a>
+<a data-release-link-platform="rpi2" class="btn btn-sm btn-primary">Raspberry Pi 2</a>
+<a data-release-link-platform="evb" class="btn btn-sm btn-primary">Fatcat Lab EVB</a>
 
 ## Step 2: Copy the image on to the SD card
 
diff --git a/javascripts/releases.js b/javascripts/releases.js
@@ -0,0 +1,78 @@
+var ev3devRepoReleaseCacheKey = 'ev3dev-repo-release-cache';
+var releaseCacheTimeMillis = 1 * 24 * 60 * 60 * 1000;
+
+var releasePlatformRegexes = {
+    ev3: "ev3-[\\w\\d-]*\\.img\\.xz",
+    rpi: "rpi-[\\w\\d-]*\\.img\\.xz",
+    rpi2: "rpi2-[\\w\\d-]*\\.img\\.xz",
+    evb: "evb-[\\w\\d-]*\\.img\\.xz",
+}
+
+function supportsHtml5Storage() {
+    try {
+        return 'localStorage' in window && window['localStorage'] !== null;
+    } catch (e) {
+        return false;
+    }
+}
+
+$(document).ready(function () {
+    if ($('a[data-release-link-platform]').length > 0) {
+        function initReleaseLinks(releases) {
+            releases.sort(function (a, b) {
+                if (Date.parse(a['created_at']) < Date.parse(b['created_at']))
+                    return 1;
+                if (Date.parse(a['created_at']) > Date.parse(b['created_at']))
+                    return -1;
+
+                return 0;
+            });
+
+            $('a[data-release-link-platform]').each(function (i, element) {
+                var $linkElem = $(element);
+                var targetReleasePlatform = $linkElem.data('release-link-platform');
+                if(!releasePlatformRegexes[targetReleasePlatform]) {
+                    console.error('"' + targetReleasePlatform + '" is an invalid release target.');
+                    return true;
+                }
+                
+                var platformRegex = new RegExp(releasePlatformRegexes[targetReleasePlatform]);
+
+                for(var releaseIndex in releases) {
+                    var releaseAssets = releases[releaseIndex].assets;
+                    for(var assetIndex in releaseAssets) {
+                        if(platformRegex.test(releaseAssets[assetIndex].name)) {
+                            $linkElem.attr('href', releaseAssets[assetIndex]['browser_download_url']);
+                            return true;
+                        }
+                    }
+                }
+            });
+        }
+
+        var cacheData;
+        try {
+            cacheData = supportsHtml5Storage() ? JSON.parse(localStorage.getItem(ev3devRepoReleaseCacheKey)) : null;
+        }
+        catch(e) {
+            // Ignore the error; if the saved JSON is invalid, we'll just request it from the server.
+        }
+        
+        if (cacheData && Date.now() - cacheData.dateRetrieved < releaseCacheTimeMillis) {
+            initReleaseLinks(cacheData.releaseData);
+        }
+        else {
+            console.log("No cached copy of releases found. Downloading from GitHub.");
+            $.ajax('https://api.github.com/repos/ev3dev/ev3dev/releases').done(function (releases) {
+                if (supportsHtml5Storage())
+                    localStorage.setItem(ev3devRepoReleaseCacheKey, JSON.stringify({
+                        dateRetrieved: Date.now(),
+                        releaseData: releases
+                    }));
+                initReleaseLinks(releases);
+            }).fail(function (error) {
+                console.error("Error getting release info: " + error);
+            });
+        }
+    }
+});
