Document StatusValue better and add per-resource restrictions

This generalizes the "LINKED can't be anywhere" idea into more
targeted restrictions.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=146158204

java/google/registry/model/eppcommon/StatusValue.java

@@ -18,6 +18,12 @@ import static com.google.common.base.CaseFormat.LOWER_CAMEL;
 import static com.google.common.base.CaseFormat.UPPER_UNDERSCORE;
 import static com.google.common.base.Strings.nullToEmpty;
 
+import com.google.common.collect.ImmutableSet;
+import google.registry.model.EppResource;
+import google.registry.model.contact.ContactResource;
+import google.registry.model.domain.DomainApplication;
+import google.registry.model.domain.DomainResource;
+import google.registry.model.host.HostResource;
 import google.registry.model.translators.EnumToAttributeAdapter.EppEnum;
 import google.registry.model.translators.StatusValueAdapter;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
@@ -43,22 +49,69 @@ public enum StatusValue implements EppEnum {
   CLIENT_RENEW_PROHIBITED,
   CLIENT_TRANSFER_PROHIBITED,
   CLIENT_UPDATE_PROHIBITED,
-  INACTIVE,
 
   /**
-   * A status that means a resource has an incoming reference from an active domain.
+   * A status for a domain with no nameservers that has all the other requirements for {@link #OK}.
+   *
+   * <p>Only domains can have this status, and it supersedes OK.
+   */
+  INACTIVE(ContactResource.class, HostResource.class, DomainApplication.class),
+
+  /**
+   * A status for a resource has an incoming reference from an active domain.
    *
    * <p>LINKED is a "virtual" status value that should never be persisted to Datastore on any
    * resource. It must be computed on the fly when we need it, as the set of domains using a
    * resource can change at any time.
    */
-  LINKED,
+  LINKED(ContactResource.class, DomainApplication.class, DomainResource.class, HostResource.class),
 
+  /**
+   * A status for a resource that has no other statuses.
+   *
+   * <p>Domains that have no other statuses but also have no nameservers get {@link #INACTIVE}
+   * instead. The spec also allows a resource to have {@link #LINKED} along with OK, but we
+   * implement LINKED as a virtual status that gets appended to outputs (such as info commands) on
+   * the fly, so we can ignore LINKED when dealing with persisted resources.
+   */
   OK,
-  PENDING_CREATE,
-  PENDING_DELETE,
-  PENDING_TRANSFER,
-  PENDING_UPDATE,
+
+  /**
+   * A status for a resource undergoing asynchronous creation.
+   *
+   * <p>We only use this for unallocated applications.
+   */
+  PENDING_CREATE(ContactResource.class, DomainResource.class, HostResource.class),
+
+  /**
+   * A status for a resource undergoing asynchronous deletion or for a recently deleted domain.
+   *
+   * <p>Contacts and hosts are deleted asynchronously because we need to check their incoming
+   * references with strong consistency, requiring a mapreduce.
+   *
+   * <p>Domains that are deleted after the add grace period ends go into a redemption grace period,
+   * and when that ends they go into pending delete for 5 days.
+   *
+   * <p>Applications are deleted synchronously and can never have this status.
+   */
+  PENDING_DELETE(DomainApplication.class),
+
+  /**
+   * A status for a resource with an unresolved transfer request.
+   *
+   * <p>Applications can't be transferred. Hosts transfer indirectly via superordinate domain.
+   */
+  // TODO(b/34844887): Remove PENDING_TRANSFER from all host resources and forbid it here.
+  PENDING_TRANSFER(DomainApplication.class),
+
+  /**
+   * A status for a resource undergoing an asynchronous update.
+   *
+   * <p>This status is here for completeness, but it is not used by our system.
+   */
+  PENDING_UPDATE(
+      ContactResource.class, DomainApplication.class, DomainResource.class, HostResource.class),
+
   SERVER_DELETE_PROHIBITED,
   SERVER_HOLD,
   SERVER_RENEW_PROHIBITED,
@@ -66,6 +119,12 @@ public enum StatusValue implements EppEnum {
   SERVER_UPDATE_PROHIBITED;
 
   private final String xmlName = UPPER_UNDERSCORE.to(LOWER_CAMEL, name());
+  private final ImmutableSet<Class<? extends EppResource>> forbiddenOn;
+
+  @SafeVarargs
+  private StatusValue(Class<? extends EppResource>... forbiddenOn) {
+    this.forbiddenOn = ImmutableSet.copyOf(forbiddenOn);
+  }
 
   @Override
   public String getXmlName() {
@@ -81,6 +140,10 @@ public enum StatusValue implements EppEnum {
     return xmlName.startsWith("server") && xmlName.endsWith("Prohibited");
   }
 
+  public boolean isForbiddenOn(Class<? extends EppResource> resource) {
+    return forbiddenOn.contains(resource);
+  }
+
   public static StatusValue fromXmlName(String xmlName) {
     return StatusValue.valueOf(LOWER_CAMEL.to(UPPER_UNDERSCORE, nullToEmpty(xmlName)));
   }