// Copyright (C) 2016 The Android Open Source Project
//
// 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 com.google.gerrit.server.query.account;

import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toSet;

import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.Multimap;
import com.google.gerrit.index.FieldDef;
import com.google.gerrit.index.IndexConfig;
import com.google.gerrit.index.Schema;
import com.google.gerrit.index.query.InternalQuery;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.server.account.AccountState;
import com.google.gerrit.server.account.externalids.ExternalId;
import com.google.gerrit.server.index.account.AccountField;
import com.google.gerrit.server.index.account.AccountIndexCollection;
import com.google.inject.Inject;
import java.util.List;
import java.util.Set;

/**
 * Query wrapper for the account index.
 *
 * <p>Instances are one-time-use. Other singleton classes should inject a Provider rather than
 * holding on to a single instance.
 */
public class InternalAccountQuery extends InternalQuery<AccountState, InternalAccountQuery> {
  @Inject
  InternalAccountQuery(
      AccountQueryProcessor queryProcessor,
      AccountIndexCollection indexes,
      IndexConfig indexConfig) {
    super(queryProcessor, indexes, indexConfig);
  }

  public List<AccountState> byDefault(String query) {
    return query(AccountPredicates.defaultPredicate(schema(), true, query));
  }

  public List<AccountState> byExternalId(String scheme, String id) {
    return byExternalId(ExternalId.Key.create(scheme, id));
  }

  public List<AccountState> byExternalId(ExternalId.Key externalId) {
    return query(AccountPredicates.externalIdIncludingSecondaryEmails(externalId.toString()));
  }

  public List<AccountState> byFullName(String fullName) {
    return query(AccountPredicates.fullName(fullName));
  }

  /**
   * Queries for accounts that have a preferred email that exactly matches the given email.
   *
   * @param email preferred email by which accounts should be found
   * @return list of accounts that have a preferred email that exactly matches the given email
   */
  public List<AccountState> byPreferredEmail(String email) {
    if (hasPreferredEmailExact()) {
      return query(AccountPredicates.preferredEmailExact(email));
    }

    if (!hasPreferredEmail()) {
      return ImmutableList.of();
    }

    return query(AccountPredicates.preferredEmail(email)).stream()
        .filter(a -> a.getAccount().preferredEmail().equals(email))
        .collect(toList());
  }

  /**
   * Makes multiple queries for accounts by preferred email (exact match).
   *
   * @param emails preferred emails by which accounts should be found
   * @return multimap of the given emails to accounts that have a preferred email that exactly
   *     matches this email
   */
  public Multimap<String, AccountState> byPreferredEmail(List<String> emails) {
    if (hasPreferredEmailExact()) {
      List<List<AccountState>> r =
          query(emails.stream().map(AccountPredicates::preferredEmailExact).collect(toList()));
      Multimap<String, AccountState> accountsByEmail = ArrayListMultimap.create();
      for (int i = 0; i < emails.size(); i++) {
        accountsByEmail.putAll(emails.get(i), r.get(i));
      }
      return accountsByEmail;
    }

    if (!hasPreferredEmail()) {
      return ImmutableListMultimap.of();
    }

    List<List<AccountState>> r =
        query(emails.stream().map(AccountPredicates::preferredEmail).collect(toList()));
    Multimap<String, AccountState> accountsByEmail = ArrayListMultimap.create();
    for (int i = 0; i < emails.size(); i++) {
      String email = emails.get(i);
      Set<AccountState> matchingAccounts =
          r.get(i).stream()
              .filter(a -> a.getAccount().preferredEmail().equals(email))
              .collect(toSet());
      accountsByEmail.putAll(email, matchingAccounts);
    }
    return accountsByEmail;
  }

  public List<AccountState> byWatchedProject(Project.NameKey project) {
    return query(AccountPredicates.watchedProject(project));
  }

  private boolean hasField(FieldDef<AccountState, ?> field) {
    Schema<AccountState> s = schema();
    return (s != null && s.hasField(field));
  }

  private boolean hasPreferredEmail() {
    return hasField(AccountField.PREFERRED_EMAIL);
  }

  private boolean hasPreferredEmailExact() {
    return hasField(AccountField.PREFERRED_EMAIL_EXACT);
  }
}