You can now fetch xuid by gamertag and gamertag by xuid

api/src/main/java/org/geysermc/floodgate/api/FloodgateApi.java

@@ -27,6 +27,7 @@ package org.geysermc.floodgate.api;
 
 import java.util.Collection;
 import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
 import org.geysermc.cumulus.Form;
 import org.geysermc.cumulus.util.FormBuilder;
 import org.geysermc.floodgate.api.link.PlayerLink;
@@ -94,6 +95,42 @@ public interface FloodgateApi {
 
     boolean sendForm(UUID uuid, FormBuilder<?, ?> formBuilder);
 
+    /**
+     * Get the xuid of the user that has the given gamertag.
+     *
+     * @param gamertag the gamertag of the player
+     * @return the xuid of the player with the given gamertag, or null when there is no player with
+     * the given gamertag
+     */
+    CompletableFuture<Long> getXuidFor(String gamertag);
+
+    /**
+     * Get the xuid of the player that has the given gamertag. It does the same thing as {@link
+     * #getXuidFor(String)} except that this method will return the xuid in Floodgate uuid format
+     * instead of just a long
+     *
+     * @param gamertag the gamertag of the player
+     * @return the xuid of the player with the given gamertag, or null when there is no player with
+     * the given gamertag
+     */
+    default CompletableFuture<UUID> getUuidFor(String gamertag) {
+        return getXuidFor(gamertag).thenApply(xuid -> {
+            if (xuid == null) {
+                return null;
+            }
+            return createJavaPlayerId(xuid);
+        });
+    }
+
+    /**
+     * Get the gamertag of the user that has the given xuid.
+     *
+     * @param xuid the gamertag of the player
+     * @return the gamertag of the player with the given xuid, or null when there is not player with
+     * the given xuid
+     */
+    CompletableFuture<String> getGamertagFor(long xuid);
+
     /**
      * Returns the instance that manages all the linking.
      */

common/src/main/java/org/geysermc/floodgate/api/SimpleFloodgateApi.java

@@ -26,10 +26,12 @@
 package org.geysermc.floodgate.api;
 
 import com.google.common.collect.ImmutableSet;
+import com.google.gson.JsonObject;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.UUID;
+import java.util.concurrent.CompletableFuture;
 import javax.annotation.Nullable;
 import lombok.RequiredArgsConstructor;
 import org.geysermc.cumulus.Form;
@@ -39,6 +41,8 @@ import org.geysermc.floodgate.config.FloodgateConfigHolder;
 import org.geysermc.floodgate.player.FloodgatePlayerImpl;
 import org.geysermc.floodgate.pluginmessage.PluginMessageManager;
 import org.geysermc.floodgate.pluginmessage.channel.FormChannel;
+import org.geysermc.floodgate.util.Constants;
+import org.geysermc.floodgate.util.HttpUtils;
 import org.geysermc.floodgate.util.Utils;
 
 @RequiredArgsConstructor
@@ -105,6 +109,50 @@ public class SimpleFloodgateApi implements FloodgateApi {
         return sendForm(uuid, formBuilder.build());
     }
 
+    @Override
+    public CompletableFuture<Long> getXuidFor(String gamertag) {
+        if (gamertag == null || gamertag.isEmpty() || gamertag.length() > 16) {
+            return Utils.failedFuture(new IllegalStateException("Received an invalid gamertag"));
+        }
+
+        return HttpUtils.asyncGet(Constants.GET_XUID_URL + gamertag)
+                .thenApply(result -> {
+                    JsonObject response = result.getResponse();
+                    boolean success = response.get("success").getAsBoolean();
+
+                    if (!success) {
+                        throw new IllegalStateException(response.get("message").getAsString());
+                    }
+
+                    JsonObject data = response.getAsJsonObject("data");
+                    if (data.size() == 0) {
+                        return null;
+                    }
+
+                    return data.get("xuid").getAsLong();
+                });
+    }
+
+    @Override
+    public CompletableFuture<String> getGamertagFor(long xuid) {
+        return HttpUtils.asyncGet(Constants.GET_GAMERTAG_URL + xuid)
+                .thenApply(result -> {
+                    JsonObject response = result.getResponse();
+                    boolean success = response.get("success").getAsBoolean();
+
+                    if (!success) {
+                        throw new IllegalStateException(response.get("message").getAsString());
+                    }
+
+                    JsonObject data = response.getAsJsonObject("data");
+                    if (data.size() == 0) {
+                        return null;
+                    }
+
+                    return data.get("gamertag").getAsString();
+                });
+    }
+
     public FloodgatePlayer addPlayer(UUID uuid, FloodgatePlayer player) {
         return players.put(uuid, player);
     }

common/src/main/java/org/geysermc/floodgate/util/Constants.java

@@ -32,6 +32,7 @@ public final class Constants {
     private static final String API_BASE_URL = "s://api.geysermc.org";
     public static final String WEBSOCKET_URL = "ws" + API_BASE_URL + "/ws";
     public static final String GET_XUID_URL = "http" + API_BASE_URL + "/v1/xbox/xuid/";
+    public static final String GET_GAMERTAG_URL = "http" + API_BASE_URL + "/v1/xbox/gamertag/";
 
     public static final String LINK_INFO_URL = "https://link.geysermc.org/";