Add Jenkins test build notifier

This will only send a notification into the log once for each new build
 and can be disabled in the config or the new jenkinsBuildNotifier.yml

src/main/java/com/Acrobot/ChestShop/ChestShop.java

@@ -38,6 +38,7 @@ import com.Acrobot.ChestShop.Logging.FileFormatter;
 import com.Acrobot.ChestShop.Metadata.ItemDatabase;
 import com.Acrobot.ChestShop.Signs.RestrictedSign;
 import com.Acrobot.ChestShop.UUIDs.NameManager;
+import com.Acrobot.ChestShop.Updater.JenkinsBuildsNotifier;
 import com.Acrobot.ChestShop.Updater.Updater;
 
 import com.google.common.io.ByteArrayDataOutput;
@@ -142,6 +143,7 @@ public class ChestShop extends JavaPlugin {
         }
 
         startStatistics();
+        startBuildNotificatier();
         startUpdater();
     }
 
@@ -414,6 +416,16 @@ public class ChestShop extends JavaPlugin {
         new Updater(this, PROJECT_BUKKITDEV_ID, this.getFile(), Updater.UpdateType.DEFAULT, true);
     }
 
+    private static final String PROJECT_JENKINS_JOB_URL = "https://ci.minebench.de/job/ChestShop-3/";
+
+    private void startBuildNotificatier() {
+        if (Properties.TURN_OFF_DEV_UPDATE_NOTIFIER) {
+            return;
+        }
+
+        new JenkinsBuildsNotifier(this, PROJECT_JENKINS_JOB_URL);
+    }
+
     ///////////////////////////////////////////////////////////////////////////////
 
     public static ItemDatabase getItemDatabase() {

src/main/java/com/Acrobot/ChestShop/Configuration/Properties.java

@@ -102,6 +102,9 @@ public class Properties {
     @ConfigurationComment("Do you want to turn off the automatic updates of ChestShop?")
     public static boolean TURN_OFF_UPDATES = true;
 
+    @ConfigurationComment("Do you want to turn off the automatic notifications for new development builds?")
+    public static boolean TURN_OFF_DEV_UPDATE_NOTIFIER = false;
+
     @PrecededBySpace
     @ConfigurationComment("How large should the internal caches be?")
     public static int CACHE_SIZE = 1000;

src/main/java/com/Acrobot/ChestShop/Updater/JenkinsBuildsNotifier.java

@@ -0,0 +1,123 @@
+package com.Acrobot.ChestShop.Updater;
+
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
+import org.bukkit.configuration.file.FileConfiguration;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.bukkit.plugin.Plugin;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.logging.Level;
+
+public class JenkinsBuildsNotifier implements Runnable {
+    private final Plugin plugin;
+
+    private final File configFile;
+    private final FileConfiguration config;
+
+    private int build;
+    private URL apiUrl;
+
+    public JenkinsBuildsNotifier(Plugin plugin, String jenkinsJobUrl) {
+        this.plugin = plugin;
+
+        configFile = new File(plugin.getDataFolder(), "jenkinsBuildsNotifier.yml");
+        if (configFile.exists()) {
+            config = YamlConfiguration.loadConfiguration(configFile);
+        } else {
+            config = new YamlConfiguration();
+            config.addDefault("disabled", false);
+            config.addDefault("jenkins-job-url-override", "");
+            config.options().copyDefaults(true);
+            saveConfig();
+        }
+
+        if (config.getBoolean("disabled")) {
+            return;
+        }
+
+        build = getBuildNumber();
+        if (build < 1) {
+            plugin.getLogger().log(Level.WARNING, "Unable to parse plugin build from version string! (" + plugin.getDescription().getVersion() + ")");
+            return;
+        }
+
+        String jenkinsJobUrlOverride = config.getString("jenkins-job-url-override");
+        if (jenkinsJobUrlOverride != null && !jenkinsJobUrlOverride.isEmpty()) {
+            jenkinsJobUrl = jenkinsJobUrlOverride;
+        }
+
+        try {
+            apiUrl = new URL(jenkinsJobUrl + "api/json");
+            plugin.getServer().getScheduler().runTaskAsynchronously(plugin, this);
+        } catch (MalformedURLException e) {
+            plugin.getLogger().log(Level.WARNING, "Can not check for new dev builds as " + jenkinsJobUrl + "api/json is not a valid url!", e);
+        }
+    }
+
+    private void saveConfig() {
+        try {
+            config.save(configFile);
+        } catch (IOException e) {
+            plugin.getLogger().log(Level.WARNING, "Error while saving " + configFile.getName() + "! " + e.getMessage());
+        }
+    }
+
+    private int getBuildNumber() {
+        String tag = "(build ";
+        String versionStr = plugin.getDescription().getVersion();
+        int start = versionStr.indexOf(tag);
+        int end = versionStr.indexOf(')', start);
+        if (start > 0 && end > start) {
+            try {
+                return Integer.parseInt(versionStr.substring(start + tag.length(), end));
+            } catch (NumberFormatException ignored) {}
+        }
+        return -1;
+    }
+
+    @Override
+    public void run() {
+        try {
+            JsonObject responseJson = queryJson();
+            if (responseJson.has("lastStableBuild") && responseJson.get("lastStableBuild").isJsonObject()) {
+                JsonObject lastStable = responseJson.getAsJsonObject("lastStableBuild");
+                int lastStableBuild = lastStable.get("number").getAsInt();
+                if (lastStableBuild > build && config.getInt("last-announced-build", 0) < lastStableBuild) {
+                    String url = lastStable.get("url").getAsString();
+                    plugin.getLogger().log(Level.INFO, "A new development build is available for testing: " + url);
+
+                    config.set("last-announced-build", lastStableBuild);
+                    saveConfig();
+                }
+            }
+
+        } catch (Exception e) {
+            plugin.getLogger().log(Level.WARNING, "Error while trying to query Jenkins API", e);
+        }
+    }
+
+    private JsonObject queryJson() throws IOException {
+        HttpURLConnection con = (HttpURLConnection) apiUrl.openConnection();
+        con.setRequestProperty("User-Agent", plugin.getName() + " " + plugin.getDescription().getVersion() + " Jenkins Builds Notifier");
+        con.setRequestMethod("GET");
+        StringBuilder msg = new StringBuilder();
+        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
+        String line;
+        while((line = in.readLine()) != null) {
+            if(msg.length() != 0) {
+                msg.append("\n");
+            }
+            msg.append(line);
+        }
+        in.close();
+
+        return new JsonParser().parse(msg.toString()).getAsJsonObject();
+    }
+}