Create a transitional recaptcha client for upgrading

service/src/main/java/org/whispersystems/textsecuregcm/recaptcha/TransitionalRecaptchaClient.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.recaptcha;
+
+import java.util.Objects;
+import javax.annotation.Nonnull;
+
+public class TransitionalRecaptchaClient implements RecaptchaClient {
+
+  private static final String PREFIX = "signal-v2:";
+
+  private final LegacyRecaptchaClient legacyRecaptchaClient;
+  private final EnterpriseRecaptchaClient enterpriseRecaptchaClient;
+
+  public TransitionalRecaptchaClient(
+      @Nonnull final LegacyRecaptchaClient legacyRecaptchaClient,
+      @Nonnull final EnterpriseRecaptchaClient enterpriseRecaptchaClient) {
+    this.legacyRecaptchaClient = Objects.requireNonNull(legacyRecaptchaClient);
+    this.enterpriseRecaptchaClient = Objects.requireNonNull(enterpriseRecaptchaClient);
+  }
+
+  @Override
+  public boolean verify(@Nonnull final String token, @Nonnull final String ip) {
+    if (token.startsWith(PREFIX)) {
+      return enterpriseRecaptchaClient.verify(token.substring(PREFIX.length()), ip);
+    } else {
+      return legacyRecaptchaClient.verify(token, ip);
+    }
+  }
+}