// Copyright 2017 The Nomulus 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.rdap;

import static com.google.common.collect.ImmutableList.toImmutableList;
import static google.registry.model.ofy.ObjectifyService.ofy;
import static google.registry.rdap.RdapUtils.getRegistrarByIanaIdentifier;
import static google.registry.request.Action.Method.GET;
import static google.registry.request.Action.Method.HEAD;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Streams;
import com.google.common.primitives.Booleans;
import com.google.common.primitives.Longs;
import com.googlecode.objectify.cmd.Query;
import google.registry.model.contact.ContactResource;
import google.registry.model.registrar.Registrar;
import google.registry.rdap.RdapJsonFormatter.BoilerplateType;
import google.registry.rdap.RdapJsonFormatter.OutputDataType;
import google.registry.rdap.RdapMetrics.EndpointType;
import google.registry.rdap.RdapMetrics.SearchType;
import google.registry.rdap.RdapSearchResults.IncompletenessWarningType;
import google.registry.request.Action;
import google.registry.request.HttpException.BadRequestException;
import google.registry.request.HttpException.NotFoundException;
import google.registry.request.HttpException.UnprocessableEntityException;
import google.registry.request.Parameter;
import google.registry.request.auth.Auth;
import google.registry.util.Clock;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Optional;
import javax.inject.Inject;
import org.joda.time.DateTime;

/**
 * RDAP (new WHOIS) action for entity (contact and registrar) search requests.
 *
 * <p>All commands and responses conform to the RDAP spec as defined in RFCs 7480 through 7485.
 *
 * <p>The RDAP specification lumps contacts and registrars together and calls them "entities", which
 * is confusing for us, because "entity" means something else in Objectify. But here, when we use
 * the term, it means either a contact or registrar. When searching for entities, we always start by
 * returning all matching contacts, and after that all matching registrars.
 *
 * <p>There are two ways to search for entities: by full name (for contacts, the search name, for
 * registrars, the registrar name) or by handle (for contacts, the ROID, for registrars, the IANA
 * number). The ICANN operational profile document specifies this meaning for handle searches.
 *
 * <p>Cursors are complicated by the fact that we are essentially doing two independent searches:
 * one for contacts, and one for registrars. To accommodate this, the cursor has a prefix indicating
 * the type of the last returned item. If the last item was a contact, we return c:{value}, where
 * the value is either the search name or the ROID. If the last item was a registrar, we return
 * r:{value}, where the value is either the registrar name or the IANA number. If we get a c:
 * cursor, we use it to weed out contacts, and fetch all registrars. If we get an r: cursor, we know
 * that we can skip the contact search altogether (because we returned a registrar, and all
 * registrars come after all contacts).
 *
 * @see <a href="http://tools.ietf.org/html/rfc7482">RFC 7482: Registration Data Access Protocol
 *     (RDAP) Query Format</a>
 * @see <a href="http://tools.ietf.org/html/rfc7483">RFC 7483: JSON Responses for the Registration
 *     Data Access Protocol (RDAP)</a>
 */
@Action(
  path = RdapEntitySearchAction.PATH,
  method = {GET, HEAD},
  auth = Auth.AUTH_PUBLIC
)
public class RdapEntitySearchAction extends RdapSearchActionBase {

  public static final String PATH = "/rdap/entities";

  @Inject Clock clock;
  @Inject @Parameter("fn") Optional<String> fnParam;
  @Inject @Parameter("handle") Optional<String> handleParam;
  @Inject @Parameter("subtype") Optional<String> subtypeParam;
  @Inject RdapEntitySearchAction() {}

  private enum QueryType {
    FULL_NAME,
    HANDLE
  }

  private enum Subtype {
    ALL,
    CONTACTS,
    REGISTRARS
  }

  private enum CursorType {
    NONE,
    CONTACT,
    REGISTRAR
  }

  private static final String CONTACT_CURSOR_PREFIX = "c:";
  private static final String REGISTRAR_CURSOR_PREFIX = "r:";

  @Override
  public String getHumanReadableObjectTypeName() {
    return "entity search";
  }

  @Override
  public EndpointType getEndpointType() {
    return EndpointType.ENTITIES;
  }

  @Override
  public String getActionPath() {
    return PATH;
  }

  /** Parses the parameters and calls the appropriate search function. */
  @Override
  public ImmutableMap<String, Object> getJsonObjectForResource(
      String pathSearchString, boolean isHeadRequest) {
    DateTime now = clock.nowUtc();

    // RDAP syntax example: /rdap/entities?fn=Bobby%20Joe*.
    // The pathSearchString is not used by search commands.
    if (pathSearchString.length() > 0) {
      throw new BadRequestException("Unexpected path");
    }
    if (Booleans.countTrue(fnParam.isPresent(), handleParam.isPresent()) != 1) {
      throw new BadRequestException("You must specify either fn=XXXX or handle=YYYY");
    }

    // Check the subtype.
    Subtype subtype;
    if (!subtypeParam.isPresent() || subtypeParam.get().equalsIgnoreCase("all")) {
      subtype = Subtype.ALL;
    } else if (subtypeParam.get().equalsIgnoreCase("contacts")) {
      subtype = Subtype.CONTACTS;
    } else if (subtypeParam.get().equalsIgnoreCase("registrars")) {
      subtype = Subtype.REGISTRARS;
    } else {
      throw new BadRequestException("Subtype parameter must specify contacts, registrars or all");
    }

    // Decode the cursor token and extract the prefix and string portions.
    decodeCursorToken();
    CursorType cursorType;
    Optional<String> cursorQueryString;
    if (!cursorString.isPresent()) {
      cursorType = CursorType.NONE;
      cursorQueryString = Optional.empty();
    } else {
      if (cursorString.get().startsWith(CONTACT_CURSOR_PREFIX)) {
        cursorType = CursorType.CONTACT;
        cursorQueryString =
            Optional.of(cursorString.get().substring(CONTACT_CURSOR_PREFIX.length()));
      } else if (cursorString.get().startsWith(REGISTRAR_CURSOR_PREFIX)) {
        cursorType = CursorType.REGISTRAR;
        cursorQueryString =
            Optional.of(cursorString.get().substring(REGISTRAR_CURSOR_PREFIX.length()));
      } else {
        throw new BadRequestException(String.format("invalid cursor: %s", cursorTokenParam));
      }
    }

    // Search by name.
    RdapSearchResults results;
    if (fnParam.isPresent()) {
      metricInformationBuilder.setSearchType(SearchType.BY_FULL_NAME);
      // syntax: /rdap/entities?fn=Bobby%20Joe*
      // The name is the contact name or registrar name (not registrar contact name).
      results =
          searchByName(
              recordWildcardType(RdapSearchPattern.create(fnParam.get(), false)),
              cursorType,
              cursorQueryString,
              subtype,
              now);

    // Search by handle.
    } else {
      metricInformationBuilder.setSearchType(SearchType.BY_HANDLE);
      // syntax: /rdap/entities?handle=12345-*
      // The handle is either the contact roid or the registrar clientId.
      results =
          searchByHandle(
              recordWildcardType(RdapSearchPattern.create(handleParam.get(), false)),
              cursorType,
              cursorQueryString,
              subtype,
              now);
    }

    // Build the result object and return it.
    if (results.jsonList().isEmpty()) {
      throw new NotFoundException("No entities found");
    }
    ImmutableMap.Builder<String, Object> jsonBuilder = new ImmutableMap.Builder<>();
    jsonBuilder.put("entitySearchResults", results.jsonList());
    rdapJsonFormatter.addTopLevelEntries(
        jsonBuilder,
        BoilerplateType.ENTITY,
        getNotices(results),
        ImmutableList.of(),
        fullServletPath);
    return jsonBuilder.build();
  }

  /**
   * Searches for entities by name, returning a JSON array of entity info maps.
   *
   * <p>As per Gustavo Lozano of ICANN, registrar name search should be by registrar name only, not
   * by registrar contact name:
   *
   * <p>The search is by registrar name only. The profile is supporting the functionality defined in
   * the Base Registry Agreement.
   *
   * <p>According to RFC 7482 section 6.1, punycode is only used for domain name labels, so we can
   * assume that entity names are regular unicode.
   *
   * <p>The includeDeleted flag is ignored when searching for contacts, because contact names are
   * set to null when the contact is deleted, so a deleted contact can never have a name.
   *
   * <p>Since we are restricting access to contact names, we don't want name searches to return
   * contacts whose names are not visible. That would allow unscrupulous users to query by name and
   * infer that all returned contacts contain that name string. So we check the authorization level
   * to determine what to do.
   *
   * @see <a
   *     href="https://newgtlds.icann.org/sites/default/files/agreements/agreement-approved-09jan14-en.htm">1.6
   *     of Section 4 of the Base Registry Agreement</a>
   */
  private RdapSearchResults searchByName(
      final RdapSearchPattern partialStringQuery,
      CursorType cursorType,
      Optional<String> cursorQueryString,
      Subtype subtype,
      DateTime now) {
    // Don't allow wildcard suffixes when searching for entities.
    if (partialStringQuery.getHasWildcard() && (partialStringQuery.getSuffix() != null)) {
      throw new UnprocessableEntityException(
          partialStringQuery.getHasWildcard()
              ? "Suffixes not allowed in wildcard entity name searches"
              : "Suffixes not allowed when searching for deleted entities");
    }
    // For wildcards, make sure the initial string is long enough, except in the special case of
    // searching for all registrars, where we aren't worried about inefficient searches.
    if (partialStringQuery.getHasWildcard()
        && (subtype != Subtype.REGISTRARS)
        && (partialStringQuery.getInitialString().length()
            < RdapSearchPattern.MIN_INITIAL_STRING_LENGTH)) {
      throw new UnprocessableEntityException(
          partialStringQuery.getHasWildcard()
              ? "Initial search string required in wildcard entity name searches"
              : "Initial search string required when searching for deleted entities");
    }
    // Get the registrar matches. If we have a registrar cursor, weed out registrars up to and
    // including the one we ended with last time. We can skip registrars if subtype is CONTACTS.
    ImmutableList<Registrar> registrars;
    if (subtype == Subtype.CONTACTS) {
      registrars = ImmutableList.of();
    } else {
      registrars =
          Streams.stream(Registrar.loadAllCached())
              .sorted(
                  Comparator.comparing(Registrar::getRegistrarName, String.CASE_INSENSITIVE_ORDER))
              .filter(
                  registrar ->
                      partialStringQuery.matches(registrar.getRegistrarName())
                          && ((cursorType != CursorType.REGISTRAR)
                              || (registrar.getRegistrarName().compareTo(cursorQueryString.get())
                                  > 0))
                          && shouldBeVisible(registrar))
              .limit(rdapResultSetMaxSize + 1)
              .collect(toImmutableList());
    }
    // Get the contact matches and return the results, fetching an additional contact to detect
    // truncation. Don't bother searching for contacts by name if the request would not be able to
    // see any names anyway. Also, if a registrar cursor is present, we have already moved past the
    // contacts, and don't need to fetch them this time. We can skip contacts if subtype is
    // REGISTRARS.
    RdapResultSet<ContactResource> resultSet;
    if (subtype == Subtype.REGISTRARS) {
      resultSet = RdapResultSet.create(ImmutableList.of());
    } else {
      RdapAuthorization authorization = getAuthorization();
      if ((authorization.role() == RdapAuthorization.Role.PUBLIC)
          || (cursorType == CursorType.REGISTRAR)) {
        resultSet = RdapResultSet.create(ImmutableList.of());
      } else {
        Query<ContactResource> query =
            queryItems(
                ContactResource.class,
                "searchName",
                partialStringQuery,
                cursorQueryString, // if we get this far, and there's a cursor, it must be a contact
                DeletedItemHandling.EXCLUDE,
                rdapResultSetMaxSize + 1);
        if (authorization.role() != RdapAuthorization.Role.ADMINISTRATOR) {
          query = query.filter("currentSponsorClientId in", authorization.clientIds());
        }
        resultSet = getMatchingResources(query, false, now, rdapResultSetMaxSize + 1);
      }
    }
    return makeSearchResults(resultSet, registrars, QueryType.FULL_NAME, now);
  }

  /**
   * Searches for entities by handle, returning a JSON array of entity info maps.
   *
   * <p>Searches for deleted entities are treated like wildcard searches.
   *
   * <p>We don't allow suffixes after a wildcard in entity searches. Suffixes are used in domain
   * searches to specify a TLD, and in nameserver searches to specify a locally managed domain name.
   * In both cases, the suffix can be turned into an additional query filter field. For contacts,
   * there is no equivalent string suffix that can be used as a query filter, so we disallow use.
   */
  private RdapSearchResults searchByHandle(
      final RdapSearchPattern partialStringQuery,
      CursorType cursorType,
      Optional<String> cursorQueryString,
      Subtype subtype,
      DateTime now) {
    if (partialStringQuery.getSuffix() != null) {
      throw new UnprocessableEntityException("Suffixes not allowed in entity handle searches");
    }
    // Handle queries without a wildcard (and not including deleted) -- load by ID.
    if (!partialStringQuery.getHasWildcard() && !shouldIncludeDeleted()) {
      ImmutableList<ContactResource> contactResourceList;
      if (subtype == Subtype.REGISTRARS) {
        contactResourceList = ImmutableList.of();
      } else {
        ContactResource contactResource =
            ofy()
                .load()
                .type(ContactResource.class)
                .id(partialStringQuery.getInitialString())
                .now();
        contactResourceList =
            ((contactResource != null) && shouldBeVisible(contactResource, now))
                ? ImmutableList.of(contactResource)
                : ImmutableList.of();
      }
      ImmutableList<Registrar> registrarList;
      if (subtype == Subtype.CONTACTS) {
        registrarList = ImmutableList.of();
      } else {
        registrarList = getMatchingRegistrars(partialStringQuery.getInitialString());
      }
      return makeSearchResults(
          contactResourceList,
          IncompletenessWarningType.COMPLETE,
          contactResourceList.size(),
          registrarList,
          QueryType.HANDLE,
          now);
    // Handle queries with a wildcard (or including deleted), but no suffix. Because the handle
    // for registrars is the IANA identifier number, don't allow wildcard searches for registrars,
    // by simply not searching for registrars if a wildcard is present (unless the request is for
    // all registrars, in which case we know what to do). Fetch an extra contact to detect result
    // set truncation.
    } else {
      ImmutableList<Registrar> registrars;
      if ((subtype == Subtype.REGISTRARS)
          && partialStringQuery.getHasWildcard()
          && partialStringQuery.getInitialString().isEmpty()) {
        // Even though we are searching by IANA identifier, we should still sort by name, because
        // the IANA identifier can by missing, and sorting on that would screw up our cursors.
        registrars =
            Streams.stream(Registrar.loadAllCached())
                .sorted(
                    Comparator.comparing(
                        Registrar::getRegistrarName, String.CASE_INSENSITIVE_ORDER))
                .filter(
                    registrar ->
                        ((cursorType != CursorType.REGISTRAR)
                                || (registrar.getRegistrarName().compareTo(cursorQueryString.get())
                                    > 0))
                            && shouldBeVisible(registrar))
                .limit(rdapResultSetMaxSize + 1)
                .collect(toImmutableList());
      } else if ((subtype == Subtype.CONTACTS) || partialStringQuery.getHasWildcard()) {
        registrars = ImmutableList.of();
      } else {
        registrars = getMatchingRegistrars(partialStringQuery.getInitialString());
      }
      // Get the contact matches and return the results, fetching an additional contact to detect
      // truncation. If we are including deleted entries, we must fetch more entries, in case some
      // get excluded due to permissioning. Any cursor present must be a contact cursor, because we
      // would never return a registrar for this search.
      int querySizeLimit = getStandardQuerySizeLimit();
      RdapResultSet<ContactResource> contactResultSet;
      if (subtype == Subtype.REGISTRARS) {
        contactResultSet = RdapResultSet.create(ImmutableList.of());
      } else {
        contactResultSet =
            getMatchingResources(
                queryItemsByKey(
                    ContactResource.class,
                    partialStringQuery,
                    cursorQueryString,
                    getDeletedItemHandling(),
                    querySizeLimit),
                shouldIncludeDeleted(),
                now,
                querySizeLimit);
      }
      return makeSearchResults(
          contactResultSet,
          registrars,
          QueryType.HANDLE,
          now);
    }
  }

  /** Looks up registrars by handle (i.e. IANA identifier). */
  private ImmutableList<Registrar> getMatchingRegistrars(final String ianaIdentifierString) {
    Long ianaIdentifier = Longs.tryParse(ianaIdentifierString);
    if (ianaIdentifier == null) {
      return ImmutableList.of();
    }
    Optional<Registrar> registrar = getRegistrarByIanaIdentifier(ianaIdentifier);
    return (registrar.isPresent() && shouldBeVisible(registrar.get()))
        ? ImmutableList.of(registrar.get())
        : ImmutableList.of();
  }

  /**
   * Builds a JSON array of entity info maps based on the specified contacts and registrars.
   *
   * <p>This is a convenience wrapper for the four-argument makeSearchResults; it unpacks the
   * properties of the {@link RdapResultSet} structure and passes them as separate arguments.
   */
  private RdapSearchResults makeSearchResults(
      RdapResultSet<ContactResource> resultSet,
      List<Registrar> registrars,
      QueryType queryType,
      DateTime now) {
    return makeSearchResults(
        resultSet.resources(),
        resultSet.incompletenessWarningType(),
        resultSet.numResourcesRetrieved(),
        registrars,
        queryType,
        now);
  }

  /**
   * Builds a JSON array of entity info maps based on the specified contacts and registrars.
   *
   * <p>The number of contacts retrieved is recorded for use by the metrics.
   *
   * @param contacts the list of contacts which can be returned
   * @param incompletenessWarningType MIGHT_BE_INCOMPLETE if the list of contacts might be
   *        incomplete; this only matters if the total count of contacts and registrars combined is
   *        less than a full result set's worth
   * @param numContactsRetrieved the number of contacts retrieved in the process of generating the
   *        results
   * @param registrars the list of registrars which can be returned
   * @param queryType whether the query was by full name or by handle
   * @param now the current date and time
   * @return an {@link RdapSearchResults} object
   */
  private RdapSearchResults makeSearchResults(
      List<ContactResource> contacts,
      IncompletenessWarningType incompletenessWarningType,
      int numContactsRetrieved,
      List<Registrar> registrars,
      QueryType queryType,
      DateTime now) {

    metricInformationBuilder.setNumContactsRetrieved(numContactsRetrieved);

    // Determine what output data type to use, depending on whether more than one entity will be
    // returned.
    OutputDataType outputDataType =
        (contacts.size() + registrars.size() > 1) ? OutputDataType.SUMMARY : OutputDataType.FULL;

    // There can be more results than our max size, partially because we have two pools to draw from
    // (contacts and registrars), and partially because we try to fetch one more than the max size,
    // so we can tell whether to display the truncation notification.
    RdapAuthorization authorization = getAuthorization();
    List<ImmutableMap<String, Object>> jsonOutputList = new ArrayList<>();
    // Each time we add a contact or registrar to the output data set, remember what the appropriate
    // cursor would be if it were the last item returned. When we stop adding items, the last cursor
    // value we remembered will be the right one to pass back.
    Optional<String> newCursor = Optional.empty();
    for (ContactResource contact : contacts) {
      if (jsonOutputList.size() >= rdapResultSetMaxSize) {
        return RdapSearchResults.create(
            ImmutableList.copyOf(jsonOutputList),
            IncompletenessWarningType.TRUNCATED,
            newCursor);
      }
      // As per Andy Newton on the regext mailing list, contacts by themselves have no role, since
      // they are global, and might have different roles for different domains.
      jsonOutputList.add(rdapJsonFormatter.makeRdapJsonForContact(
          contact,
          false,
          Optional.empty(),
          fullServletPath,
          rdapWhoisServer,
          now,
          outputDataType,
          authorization));
      newCursor =
          Optional.of(
              CONTACT_CURSOR_PREFIX
                  + ((queryType == QueryType.FULL_NAME)
                      ? contact.getSearchName()
                      : contact.getRepoId()));
    }
    for (Registrar registrar : registrars) {
      if (jsonOutputList.size() >= rdapResultSetMaxSize) {
        return RdapSearchResults.create(
            ImmutableList.copyOf(jsonOutputList),
            IncompletenessWarningType.TRUNCATED,
            newCursor);
      }
      jsonOutputList.add(rdapJsonFormatter.makeRdapJsonForRegistrar(
          registrar, false, fullServletPath, rdapWhoisServer, now, outputDataType));
      newCursor = Optional.of(REGISTRAR_CURSOR_PREFIX + registrar.getRegistrarName());
    }
    return RdapSearchResults.create(
        ImmutableList.copyOf(jsonOutputList),
        (jsonOutputList.size() < rdapResultSetMaxSize)
            ? incompletenessWarningType
            : IncompletenessWarningType.COMPLETE,
        Optional.empty());
  }
}