Use mojang's api for username fetching

core/src/main/java/tc/oc/pgm/PGMPlugin.java

@@ -81,8 +81,8 @@
 import tc.oc.pgm.util.tablist.TablistResizer;
 import tc.oc.pgm.util.text.TextException;
 import tc.oc.pgm.util.text.TextTranslations;
-import tc.oc.pgm.util.usernames.ApiUsernameResolver;
 import tc.oc.pgm.util.usernames.BukkitUsernameResolver;
+import tc.oc.pgm.util.usernames.MojangUsernameResolver;
 import tc.oc.pgm.util.usernames.UsernameResolvers;
 import tc.oc.pgm.util.xml.InvalidXMLException;
 
@@ -171,7 +171,7 @@ public void onEnable() {
     UsernameResolvers.setResolvers(
         new BukkitUsernameResolver(),
         new SqlUsernameResolver((SQLDatastore) datastore),
-        new ApiUsernameResolver());
+        new MojangUsernameResolver());
 
     datastore = new CacheDatastore(datastore);
 

util/src/main/java/tc/oc/pgm/util/usernames/MojangUsernameResolver.java

@@ -0,0 +1,116 @@
+package tc.oc.pgm.util.usernames;
+
+import static tc.oc.pgm.util.Assert.assertNotNull;
+
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.net.HttpURLConnection;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.logging.Level;
+import org.bukkit.Bukkit;
+import org.bukkit.plugin.Plugin;
+import tc.oc.pgm.util.bukkit.BukkitUtils;
+
+public class MojangUsernameResolver implements UsernameResolver {
+  private static final Gson GSON = new Gson();
+  private static final long WAIT_TIME = 6; // Mojang api allows 10 requests a minute
+  private static String userAgent = "PGM";
+  private static Instant nextExecution = Instant.now();
+  private static ExecutorService executor = Executors.newSingleThreadExecutor();
+  private static long currentWaitTime = 6;
+  protected final Map<UUID, CompletableFuture<UsernameResponse>> futures =
+      new ConcurrentHashMap<>();
+
+  static {
+    try {
+      final Plugin plugin = BukkitUtils.getPlugin();
+      if (plugin != null) {
+        userAgent = plugin.getDescription().getFullName() + Bukkit.getName();
+      }
+    } catch (Throwable t) {
+      // No-op, just to be safe in-case agent cannot be found
+    }
+  }
+
+  private CompletableFuture<UsernameResponse> resolveInternal(UUID uuid) {
+    CompletableFuture<UsernameResponse> completableFuture = new CompletableFuture<>();
+    completableFuture.whenComplete((o, t) -> futures.remove(uuid));
+    executor.submit(() -> {
+      Instant now = Instant.now();
+
+      if (now.isBefore(nextExecution)) {
+        try {
+          Thread.sleep(Duration.between(now, nextExecution));
+        } catch (InterruptedException e) {
+          // Ignore
+        }
+      }
+
+      String name = resolveSync(uuid);
+      if (name != null) {
+        currentWaitTime = WAIT_TIME;
+      }
+      nextExecution = Instant.now().plus(Duration.ofSeconds(currentWaitTime));
+
+      Bukkit.getLogger().log(Level.FINE, "Resolved " + uuid + " as " + name);
+
+      completableFuture.complete(UsernameResponse.of(name, MojangUsernameResolver.class));
+    });
+    return completableFuture;
+  }
+
+  @Override
+  public CompletableFuture<UsernameResponse> resolve(UUID uuid) {
+    return futures.computeIfAbsent(uuid, this::resolveInternal);
+  }
+
+  private static String resolveSync(UUID uuid) {
+    try {
+      final HttpURLConnection url = (HttpURLConnection) new URL(
+              "https://api.minecraftservices.com/minecraft/profile/lookup/" + assertNotNull(uuid))
+          .openConnection();
+      url.setRequestMethod("GET");
+      url.setRequestProperty("User-Agent", userAgent);
+      url.setRequestProperty("Accept", "application/json");
+      url.setInstanceFollowRedirects(true);
+      url.setConnectTimeout(10000);
+      url.setReadTimeout(10000);
+
+      try (final BufferedReader br =
+          new BufferedReader(new InputStreamReader(url.getInputStream(), StandardCharsets.UTF_8))) {
+        return GSON.fromJson(br, JsonObject.class).get("name").getAsString();
+      }
+    } catch (Throwable t) {
+      currentWaitTime *= 2;
+      Bukkit.getLogger()
+          .log(
+              Level.WARNING,
+              "Could not resolve username for " + uuid + " retrying in " + currentWaitTime
+                  + " seconds!",
+              t);
+    }
+    return null;
+  }
+
+  @Override
+  public void startBatch() {
+    // TODO: Refactor
+  }
+
+  @Override
+  public CompletableFuture<Void> endBatch() {
+    // TODO: Refactor
+    return new CompletableFuture<>();
+  }
+}

util/src/main/java/tc/oc/pgm/util/usernames/UsernameResolvers.java

@@ -8,7 +8,7 @@
 public interface UsernameResolvers {
 
   AtomicReference<UsernameResolver> INSTANCE =
-      new AtomicReference<>(of(new BukkitUsernameResolver(), new ApiUsernameResolver()));
+      new AtomicReference<>(of(new BukkitUsernameResolver(), new MojangUsernameResolver()));
 
   static UsernameResolver get() {
     return INSTANCE.get();