3.6-beta

add force rankup and prestige
add update notification on join
more reliable legacy server version check

added permissions: rankup.admin (grants rankup.checkversion, rankup.reload, rankup.force, and rankup.notify), rankup.notify (receive update notiifications on login), rankup.force (force a player to rankup or prestige)

src/main/java/sh/okx/rankup/util/ItemUtil.java

@@ -0,0 +1,31 @@
+package sh.okx.rankup.util;
+
+import com.google.common.base.Suppliers;
+import java.util.function.Supplier;
+import org.bukkit.Material;
+
+public class ItemUtil {
+  private static Supplier<Boolean> flattenedSupplier = Suppliers.memoize(ItemUtil::isServerFlattenedPrivate);
+
+  private static boolean isServerFlattenedPrivate() {
+    try {
+      Material.valueOf("BLACK_STAINED_GLASS_PANE");
+      return true;
+    } catch (IllegalArgumentException e) {
+      return false;
+    }
+  }
+
+  /**
+   * Determines if a server is post-flattening or pre-flattening.
+   * The flattening is the name for a process where, instead of using durability to represent
+   * similar items, Mojang decided to use distinct item types for each item.
+   * This caused many {@link Material} names to change, making some things incompatible.
+   * The flattening happened in 1.13.
+   *
+   * @return true if the server is post-flattening (server versions 1.13, 1.14, 1.15) or false if it is pre-flattening (1.12, 1.11, 1.10 etc)
+   */
+  public static boolean isServerFlattened() {
+    return flattenedSupplier.get();
+  }
+}

src/main/java/sh/okx/rankup/util/UpdateNotifier.java

@@ -0,0 +1,56 @@
+package sh.okx.rankup.util;
+
+import org.bukkit.ChatColor;
+import org.bukkit.command.CommandSender;
+import sh.okx.rankup.util.VersionChecker.VersionCheckerCallback;
+
+public class UpdateNotifier {
+  private static final String PREFIX = ChatColor.GREEN + "" + ChatColor.BOLD + "Rankup " + ChatColor.RESET;
+
+  private final VersionChecker checker;
+
+  public UpdateNotifier(VersionChecker checker) {
+    this.checker = checker;
+  }
+
+  public void notify(CommandSender sender, boolean join) {
+    if (!checker.hasChecked() && !join) {
+      send(sender, false, ChatColor.YELLOW + "Checking version...");
+    }
+    checker.checkVersion(new VersionCheckerCallback() {
+      @Override
+      public void onLatestVersion(String version) {
+        if (!join) {
+          send(sender, false, ChatColor.GREEN + "You are on the latest version.");
+        }
+      }
+
+      @Override
+      public void onOutdatedVersion(String currentVersion, String latestVersion) {
+        send(sender, join, ChatColor.YELLOW + "A new version is available: " + ChatColor.GOLD + latestVersion
+            + ChatColor.YELLOW + ". You are on: " + ChatColor.GOLD + currentVersion
+            + ChatColor.GOLD + "\nhttps://www.spigotmc.org/resources/rankup.17933/");
+      }
+
+      @Override
+      public void onPreReleaseVersion(String version) {
+        send(sender, join, ChatColor.RED + "You are on a pre-release version.");
+      }
+
+      @Override
+      public void onFailure() {
+        if (!join) {
+          send(sender, join, ChatColor.RED + "Error while checking version.");
+        }
+      }
+    });
+  }
+
+  private void send(CommandSender sender, boolean prefix, String message) {
+    if (prefix) {
+      sender.sendMessage(PREFIX + message);
+    } else {
+      sender.sendMessage(message);
+    }
+  }
+}

src/main/java/sh/okx/rankup/util/VersionChecker.java

@@ -0,0 +1,144 @@
+package sh.okx.rankup.util;
+
+import com.google.common.base.Charsets;
+import com.google.common.io.CharStreams;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.URL;
+import org.bukkit.Bukkit;
+import org.bukkit.plugin.Plugin;
+
+public class VersionChecker {
+
+  private static final int RESOURCE_ID = 17933;
+
+  private final Plugin plugin; // used exclusively for scheduling
+  private final String currentVersion;
+  private String latestVersion;
+  private boolean checked = false;
+
+  public VersionChecker(Plugin plugin) {
+    this.currentVersion = plugin.getDescription().getVersion();
+    this.plugin = plugin;
+  }
+
+  /**
+   * Checks if the version checker has already made an asynchronous call to the web server to check
+   * the version, so future checks will run instantly.
+   * @return true if the version checker already knows the latest version, false otherwise
+   */
+  public boolean hasChecked() {
+    return checked;
+  }
+
+  public void checkVersion(VersionCheckerCallback callback) {
+    if (latestVersion != null) {
+      if (currentVersion.equals(latestVersion)) {
+        callback.onLatestVersion(currentVersion);
+      } else {
+        callback.onOutdatedVersion(currentVersion, latestVersion);
+      }
+    } else {
+      Bukkit.getScheduler().runTaskAsynchronously(plugin,
+          () -> checkVersionSync(new SyncVersionCheckerCallback(plugin, callback)));
+    }
+  }
+
+  private void checkVersionSync(VersionCheckerCallback callback) {
+    if (currentVersion.contains("alpha")
+        || currentVersion.contains("beta")
+        || currentVersion.contains("rc")) {
+      checked = true;
+      callback.onPreReleaseVersion(currentVersion);
+      return;
+    }
+
+    try {
+      latestVersion = getLatestVersion();
+      checked = true;
+      if (currentVersion.equals(latestVersion)) {
+        callback.onLatestVersion(currentVersion);
+      } else {
+        callback.onOutdatedVersion(currentVersion, latestVersion);
+      }
+
+    } catch (IOException e) {
+      callback.onFailure();
+    }
+  }
+
+  private String getLatestVersion() throws IOException {
+    URL url = new URL("https://api.spigotmc.org/legacy/update.php?resource=" + RESOURCE_ID);
+    return CharStreams.toString(new InputStreamReader(url.openStream(), Charsets.UTF_8));
+  }
+
+  /**
+   * A callback used when a version check runs
+   */
+  public interface VersionCheckerCallback {
+
+    /**
+     * Called when the plugin is already on the latest version
+     *
+     * @param version the current, and latest, version of the plugin
+     */
+    void onLatestVersion(String version);
+
+    /**
+     * Called when the plugin is on a version other than the latest on the SpigotMC plugin page.
+     *
+     * @param currentVersion the current version of the plugin specified in plugin.yml
+     * @param latestVersion the latest version of the plugin specified on SpigotMC.
+     */
+    void onOutdatedVersion(String currentVersion, String latestVersion);
+
+    /**
+     * Called when the plugin is on a pre-release version and is exempt to the usual update system.
+     * @param version the current version of the plugin
+     */
+    void onPreReleaseVersion(String version);
+
+    /**
+     * Called when the version checker was unable to retrieve the latest version
+     */
+    void onFailure();
+  }
+
+  /**
+   * An implementation of {@link VersionCheckerCallback} that is called asynchronously, and then
+   * forwards the calls an underlying VersionCheckerCallback synchronously on the main Bukkit thread.
+   */
+  class SyncVersionCheckerCallback implements VersionCheckerCallback {
+    private final Plugin plugin;
+    private final VersionCheckerCallback callback;
+
+    SyncVersionCheckerCallback(Plugin plugin, VersionCheckerCallback callback) {
+      this.plugin = plugin;
+      this.callback = callback;
+    }
+
+    @Override
+    public void onLatestVersion(String version) {
+      doSync(() -> callback.onLatestVersion(version));
+    }
+
+    @Override
+    public void onOutdatedVersion(String currentVersion, String latestVersion) {
+      doSync(() -> callback.onOutdatedVersion(currentVersion, latestVersion));
+    }
+
+    @Override
+    public void onPreReleaseVersion(String version) {
+      doSync(() -> callback.onPreReleaseVersion(version));
+    }
+
+    @Override
+    public void onFailure() {
+      doSync(callback::onFailure);
+    }
+
+    private void doSync(Runnable r) {
+      Bukkit.getScheduler().scheduleSyncDelayedTask(plugin, r);
+    }
+  }
+}