Add escrow file import validation logic

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=129116064

java/google/registry/rde/RdeImportUtils.java

@@ -14,17 +14,30 @@
 
 package google.registry.rde;
 
+import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkState;
 
+import com.google.appengine.tools.cloudstorage.GcsFilename;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.Work;
+import google.registry.config.ConfigModule.Config;
+import google.registry.gcs.GcsUtils;
 import google.registry.model.contact.ContactResource;
 import google.registry.model.index.EppResourceIndex;
 import google.registry.model.index.ForeignKeyIndex;
 import google.registry.model.ofy.Ofy;
+import google.registry.model.registrar.Registrar;
+import google.registry.model.registry.Registry;
+import google.registry.model.registry.Registry.RegistryNotFoundException;
+import google.registry.model.registry.Registry.TldState;
 import google.registry.util.Clock;
 import google.registry.util.FormattingLogger;
+import google.registry.xjc.rderegistrar.XjcRdeRegistrar;
+import java.io.IOException;
+import java.io.InputStream;
 import javax.inject.Inject;
+import javax.xml.stream.XMLStreamException;
+import org.joda.time.DateTime;
 
 /** Utility functions for escrow file import. */
 public final class RdeImportUtils {
@@ -33,11 +46,16 @@ public final class RdeImportUtils {
 
   private final Ofy ofy;
   private final Clock clock;
+  private final String escrowBucketName;
+  private final GcsUtils gcsUtils;
 
   @Inject
-  public RdeImportUtils(Ofy ofy, Clock clock) {
+  public RdeImportUtils(
+      Ofy ofy, Clock clock, @Config("rdeImportBucket") String escrowBucketName, GcsUtils gcsUtils) {
     this.ofy = ofy;
     this.clock = clock;
+    this.gcsUtils = gcsUtils;
+    this.escrowBucketName = escrowBucketName;
   }
 
   /**
@@ -84,4 +102,55 @@ public final class RdeImportUtils {
           }
         });
   }
+
+  /**
+   * Validates an escrow file for import.
+   *
+   * <p>Before an escrow file is imported into the registry, the following conditions must be met:
+   *
+   * <ul>
+   * <li>The TLD must already exist in the registry
+   * <li>The TLD must be in the PREDELEGATION state
+   * <li>Each registrar must already exist in the registry
+   * <li>Each IDN table referenced must already exist in the registry
+   * </ul>
+   *
+   * <p>If any of the above conditions is not true, an {@link IllegalStateException} will be thrown.
+   *
+   * @param escrowFilePath Path to the escrow file to validate
+   * @throws IOException If the escrow file cannot be read
+   * @throws IllegalArgumentException if the escrow file cannot be imported
+   */
+  public void validateEscrowFileForImport(String escrowFilePath) throws IOException {
+    // TODO (wolfgang): Add validation method for IDN tables
+    try (InputStream input =
+        gcsUtils.openInputStream(new GcsFilename(escrowBucketName, escrowFilePath))) {
+      try {
+        RdeParser parser = new RdeParser(input);
+        // validate that tld exists and is in PREDELEGATION state
+        String tld = parser.getHeader().getTld();
+        try {
+          Registry registry = Registry.get(tld);
+          TldState currentState = registry.getTldState(DateTime.now());
+          checkArgument(
+              currentState == TldState.PREDELEGATION,
+              String.format("Tld '%s' is in state %s and cannot be imported", tld, currentState));
+        } catch (RegistryNotFoundException e) {
+          throw new IllegalArgumentException(
+              String.format("Tld '%s' not found in the registry", tld));
+        }
+        // validate that all registrars exist
+        while (parser.nextRegistrar()) {
+          XjcRdeRegistrar registrar = parser.getRegistrar();
+          if (Registrar.loadByClientId(registrar.getId()) == null) {
+            throw new IllegalArgumentException(
+                String.format("Registrar '%s' not found in the registry", registrar.getId()));
+          }
+        }
+      } catch (XMLStreamException e) {
+        throw new IllegalArgumentException(
+            String.format("Invalid XML file: '%s'", escrowFilePath), e);
+      }
+    }
+  }
 }