// 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.account.externalids;

import static com.google.common.collect.ImmutableSet.toImmutableSet;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.SetMultimap;
import com.google.gerrit.reviewdb.client.Account;
import com.google.inject.Inject;
import com.google.inject.Singleton;
import java.io.IOException;
import java.util.Optional;
import java.util.Set;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.lib.ObjectId;

/**
 * Class to access external IDs.
 *
 * <p>The external IDs are either read from NoteDb or retrieved from the cache.
 */
@Singleton
public class ExternalIds {
  private final ExternalIdReader externalIdReader;
  private final ExternalIdCache externalIdCache;

  @Inject
  public ExternalIds(ExternalIdReader externalIdReader, ExternalIdCache externalIdCache) {
    this.externalIdReader = externalIdReader;
    this.externalIdCache = externalIdCache;
  }

  /** Returns all external IDs. */
  public ImmutableSet<ExternalId> all() throws IOException, ConfigInvalidException {
    return externalIdReader.all();
  }

  /** Returns all external IDs from the specified revision of the refs/meta/external-ids branch. */
  public ImmutableSet<ExternalId> all(ObjectId rev) throws IOException, ConfigInvalidException {
    return externalIdReader.all(rev);
  }

  /** Returns the specified external ID. */
  public Optional<ExternalId> get(ExternalId.Key key) throws IOException, ConfigInvalidException {
    return externalIdReader.get(key);
  }

  /** Returns the specified external ID from the given revision. */
  public Optional<ExternalId> get(ExternalId.Key key, ObjectId rev)
      throws IOException, ConfigInvalidException {
    return externalIdReader.get(key, rev);
  }

  /** Returns the external IDs of the specified account. */
  public Set<ExternalId> byAccount(Account.Id accountId) throws IOException {
    return externalIdCache.byAccount(accountId);
  }

  /** Returns the external IDs of the specified account that have the given scheme. */
  public Set<ExternalId> byAccount(Account.Id accountId, String scheme) throws IOException {
    return byAccount(accountId).stream()
        .filter(e -> e.key().isScheme(scheme))
        .collect(toImmutableSet());
  }

  /** Returns the external IDs of the specified account. */
  public Set<ExternalId> byAccount(Account.Id accountId, ObjectId rev) throws IOException {
    return externalIdCache.byAccount(accountId, rev);
  }

  /** Returns the external IDs of the specified account that have the given scheme. */
  public Set<ExternalId> byAccount(Account.Id accountId, String scheme, ObjectId rev)
      throws IOException {
    return byAccount(accountId, rev).stream()
        .filter(e -> e.key().isScheme(scheme))
        .collect(toImmutableSet());
  }

  /** Returns all external IDs by account. */
  public SetMultimap<Account.Id, ExternalId> allByAccount() throws IOException {
    return externalIdCache.allByAccount();
  }

  /**
   * Returns the external ID with the given email.
   *
   * <p>Each email should belong to a single external ID only. This means if more than one external
   * ID is returned there is an inconsistency in the external IDs.
   *
   * <p>The external IDs are retrieved from the external ID cache. Each access to the external ID
   * cache requires reading the SHA1 of the refs/meta/external-ids branch. If external IDs for
   * multiple emails are needed it is more efficient to use {@link #byEmails(String...)} as this
   * method reads the SHA1 of the refs/meta/external-ids branch only once (and not once per email).
   *
   * @see #byEmails(String...)
   */
  public Set<ExternalId> byEmail(String email) throws IOException {
    return externalIdCache.byEmail(email);
  }

  /**
   * Returns the external IDs for the given emails.
   *
   * <p>Each email should belong to a single external ID only. This means if more than one external
   * ID for an email is returned there is an inconsistency in the external IDs.
   *
   * <p>The external IDs are retrieved from the external ID cache. Each access to the external ID
   * cache requires reading the SHA1 of the refs/meta/external-ids branch. If external IDs for
   * multiple emails are needed it is more efficient to use this method instead of {@link
   * #byEmail(String)} as this method reads the SHA1 of the refs/meta/external-ids branch only once
   * (and not once per email).
   *
   * @see #byEmail(String)
   */
  public SetMultimap<String, ExternalId> byEmails(String... emails) throws IOException {
    return externalIdCache.byEmails(emails);
  }

  /** Returns all external IDs by email. */
  public SetMultimap<String, ExternalId> allByEmail() throws IOException {
    return externalIdCache.allByEmail();
  }
}