// Copyright 2016 The Domain Registry Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package google.registry.whois;

import static com.google.common.base.Preconditions.checkNotNull;
import static google.registry.model.EppResourceUtils.loadByUniqueId;
import static google.registry.model.registry.Registries.findTldForName;
import static google.registry.model.registry.Registries.getTlds;
import static javax.servlet.http.HttpServletResponse.SC_NOT_FOUND;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Optional;
import com.google.common.net.InternetDomainName;

import google.registry.model.EppResource;
import google.registry.util.TypeUtils.TypeInstantiator;

import org.joda.time.DateTime;

import javax.annotation.Nullable;

/** Represents a WHOIS lookup on a domain name (i.e. SLD) or a nameserver. */
abstract class DomainOrHostLookupCommand<T extends EppResource> implements WhoisCommand {

  @VisibleForTesting
  final InternetDomainName domainOrHostName;

  private final String errorPrefix;

  private Optional<InternetDomainName> tld;

  DomainOrHostLookupCommand(
      InternetDomainName domainName, @Nullable InternetDomainName tld, String errorPrefix) {
    this.errorPrefix = errorPrefix;
    this.domainOrHostName = checkNotNull(domainName, "domainOrHostName");
    this.tld = Optional.fromNullable(tld);
  }

  @Override
  public final WhoisResponse executeQuery(final DateTime now) throws WhoisException {
    if (!tld.isPresent()) {
      tld = findTldForName(domainOrHostName);
    }
    // Google Policy: Do not return records under TLDs for which we're not authoritative.
    if (tld.isPresent() && getTlds().contains(tld.get().toString())) {
      T domainOrHost = loadByUniqueId(
          new TypeInstantiator<T>(getClass()){}.getExactType(),
          domainOrHostName.toString(),
          now);
      if (domainOrHost != null) {
        return getSuccessResponse(domainOrHost, now);
      }
    }
    throw new WhoisException(now, SC_NOT_FOUND, errorPrefix + " not found.");
  }

  /** Renders a response record, provided its successfully retrieved datastore entity. */
  abstract WhoisResponse getSuccessResponse(T domainOrHost, DateTime now);
}