/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.hadoop.hbase.security.access;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;
import org.apache.commons.lang3.StringUtils;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.MasterNotRunningException;
import org.apache.hadoop.hbase.NamespaceDescriptor;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.client.Admin;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.client.security.SecurityCapability;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.yetus.audience.InterfaceAudience;

/**
 * Utility client for doing access control admin operations.
 */
@InterfaceAudience.Public
public class AccessControlClient {
  public static final TableName ACL_TABLE_NAME =
    TableName.valueOf(NamespaceDescriptor.SYSTEM_NAMESPACE_NAME_STR, "acl");

  /**
   * Return true if authorization is supported and enabled
   * @param connection The connection to use
   * @return true if authorization is supported and enabled, false otherwise
   */
  public static boolean isAuthorizationEnabled(Connection connection) throws IOException {
    return connection.getAdmin().getSecurityCapabilities()
      .contains(SecurityCapability.AUTHORIZATION);
  }

  /**
   * Return true if cell authorization is supported and enabled
   * @param connection The connection to use
   * @return true if cell authorization is supported and enabled, false otherwise
   */
  public static boolean isCellAuthorizationEnabled(Connection connection) throws IOException {
    return connection.getAdmin().getSecurityCapabilities()
      .contains(SecurityCapability.CELL_AUTHORIZATION);
  }

  /**
   * Grants permission on the specified table for the specified user
   * @param connection               The Connection instance to use
   * @param tableName                the table name
   * @param userName                 the user name
   * @param family                   the column family
   * @param qual                     the column qualifier
   * @param mergeExistingPermissions If set to false, later granted permissions will override
   *                                 previous granted permissions. otherwise, it'll merge with
   *                                 previous granted permissions.
   * @param actions                  the actions
   */
  private static void grant(Connection connection, final TableName tableName, final String userName,
    final byte[] family, final byte[] qual, boolean mergeExistingPermissions,
    final Permission.Action... actions) throws Throwable {
    connection.getAdmin().grant(new UserPermission(userName, Permission.newBuilder(tableName)
      .withFamily(family).withQualifier(qual).withActions(actions).build()),
      mergeExistingPermissions);
  }

  /**
   * Grants permission on the specified table for the specified user. If permissions for a specified
   * user exists, later granted permissions will override previous granted permissions.
   * @param connection The Connection instance to use
   * @param tableName  the table name
   * @param userName   the user name
   * @param family     the column family
   * @param qual       the column qualifier
   * @param actions    the actions
   */
  public static void grant(Connection connection, final TableName tableName, final String userName,
    final byte[] family, final byte[] qual, final Permission.Action... actions) throws Throwable {
    grant(connection, tableName, userName, family, qual, true, actions);
  }

  /**
   * Grants permission on the specified namespace for the specified user.
   * @param connection               The Connection instance to use
   * @param namespace                the namespace
   * @param userName                 the user name
   * @param mergeExistingPermissions If set to false, later granted permissions will override
   *                                 previous granted permissions. otherwise, it'll merge with
   *                                 previous granted permissions.
   * @param actions                  the actions
   */
  private static void grant(Connection connection, final String namespace, final String userName,
    boolean mergeExistingPermissions, final Permission.Action... actions) throws Throwable {
    connection.getAdmin().grant(
      new UserPermission(userName, Permission.newBuilder(namespace).withActions(actions).build()),
      mergeExistingPermissions);
  }

  /**
   * Grants permission on the specified namespace for the specified user. If permissions on the
   * specified namespace exists, later granted permissions will override previous granted
   * permissions.
   * @param connection The Connection instance to use
   * @param namespace  the namespace
   * @param userName   the user name
   * @param actions    the actions
   */
  public static void grant(Connection connection, final String namespace, final String userName,
    final Permission.Action... actions) throws Throwable {
    grant(connection, namespace, userName, true, actions);
  }

  /**
   * Grant global permissions for the specified user.
   * @param connection               The Connection instance to use
   * @param userName                 the user name
   * @param mergeExistingPermissions If set to false, later granted permissions will override
   *                                 previous granted permissions. otherwise, it'll merge with
   *                                 previous granted permissions.
   * @param actions                  the actions
   */
  private static void grant(Connection connection, final String userName,
    boolean mergeExistingPermissions, final Permission.Action... actions) throws Throwable {
    connection.getAdmin().grant(
      new UserPermission(userName, Permission.newBuilder().withActions(actions).build()),
      mergeExistingPermissions);
  }

  /**
   * Grant global permissions for the specified user. If permissions for the specified user exists,
   * later granted permissions will override previous granted permissions.
   */
  public static void grant(Connection connection, final String userName,
    final Permission.Action... actions) throws Throwable {
    grant(connection, userName, true, actions);
  }

  public static boolean isAccessControllerRunning(Connection connection)
    throws MasterNotRunningException, ZooKeeperConnectionException, IOException {
    try (Admin admin = connection.getAdmin()) {
      return admin.isTableAvailable(ACL_TABLE_NAME);
    }
  }

  /**
   * Revokes the permission on the table
   * @param connection The Connection instance to use
   */
  public static void revoke(Connection connection, final TableName tableName, final String username,
    final byte[] family, final byte[] qualifier, final Permission.Action... actions)
    throws Throwable {
    connection.getAdmin().revoke(new UserPermission(username, Permission.newBuilder(tableName)
      .withFamily(family).withQualifier(qualifier).withActions(actions).build()));
  }

  /**
   * Revokes the permission on the namespace for the specified user.
   * @param connection The Connection instance to use
   */
  public static void revoke(Connection connection, final String namespace, final String userName,
    final Permission.Action... actions) throws Throwable {
    connection.getAdmin().revoke(
      new UserPermission(userName, Permission.newBuilder(namespace).withActions(actions).build()));
  }

  /**
   * Revoke global permissions for the specified user.
   * @param connection The Connection instance to use
   */
  public static void revoke(Connection connection, final String userName,
    final Permission.Action... actions) throws Throwable {
    connection.getAdmin()
      .revoke(new UserPermission(userName, Permission.newBuilder().withActions(actions).build()));
  }

  /**
   * List all the userPermissions matching the given pattern. If pattern is null, the behavior is
   * dependent on whether user has global admin privileges or not. If yes, the global permissions
   * along with the list of superusers would be returned. Else, no rows get returned.
   * @param connection The Connection instance to use
   * @param tableRegex The regular expression string to match against
   * @return List of UserPermissions
   */
  public static List<UserPermission> getUserPermissions(Connection connection, String tableRegex)
    throws Throwable {
    return getUserPermissions(connection, tableRegex, HConstants.EMPTY_STRING);
  }

  /**
   * List all the userPermissions matching the given table pattern and user name.
   * @param connection Connection
   * @param tableRegex The regular expression string to match against
   * @param userName   User name, if empty then all user permissions will be retrieved.
   * @return List of UserPermissions
   * @throws Throwable on failure
   */
  public static List<UserPermission> getUserPermissions(Connection connection, String tableRegex,
    String userName) throws Throwable {
    List<UserPermission> permList = new ArrayList<>();
    try (Admin admin = connection.getAdmin()) {
      if (tableRegex == null || tableRegex.isEmpty()) {
        permList = admin.getUserPermissions(
          GetUserPermissionsRequest.newBuilder().withUserName(userName).build());
      } else if (tableRegex.charAt(0) == '@') { // Namespaces
        String namespaceRegex = tableRegex.substring(1);
        for (NamespaceDescriptor nsds : admin.listNamespaceDescriptors()) { // Read out all
                                                                            // namespaces
          String namespace = nsds.getName();
          if (namespace.matches(namespaceRegex)) { // Match the given namespace regex?
            permList.addAll(admin.getUserPermissions(
              GetUserPermissionsRequest.newBuilder(namespace).withUserName(userName).build()));
          }
        }
      } else { // Tables
        List<TableDescriptor> htds = admin.listTableDescriptors(Pattern.compile(tableRegex), true);
        for (TableDescriptor htd : htds) {
          permList.addAll(admin.getUserPermissions(GetUserPermissionsRequest
            .newBuilder(htd.getTableName()).withUserName(userName).build()));
        }
      }
    }
    return permList;
  }

  /**
   * List all the userPermissions matching the given table pattern and column family.
   * @param connection   Connection
   * @param tableRegex   The regular expression string to match against. It shouldn't be null, empty
   *                     or a namespace regular expression.
   * @param columnFamily Column family
   * @return List of UserPermissions
   * @throws Throwable on failure
   */
  public static List<UserPermission> getUserPermissions(Connection connection, String tableRegex,
    byte[] columnFamily) throws Throwable {
    return getUserPermissions(connection, tableRegex, columnFamily, null, HConstants.EMPTY_STRING);
  }

  /**
   * List all the userPermissions matching the given table pattern, column family and user name.
   * @param connection   Connection
   * @param tableRegex   The regular expression string to match against. It shouldn't be null, empty
   *                     or a namespace regular expression.
   * @param columnFamily Column family
   * @param userName     User name, if empty then all user permissions will be retrieved.
   * @return List of UserPermissions
   * @throws Throwable on failure
   */
  public static List<UserPermission> getUserPermissions(Connection connection, String tableRegex,
    byte[] columnFamily, String userName) throws Throwable {
    return getUserPermissions(connection, tableRegex, columnFamily, null, userName);
  }

  /**
   * List all the userPermissions matching the given table pattern, column family and column
   * qualifier.
   * @param connection      Connection
   * @param tableRegex      The regular expression string to match against. It shouldn't be null,
   *                        empty or a namespace regular expression.
   * @param columnFamily    Column family
   * @param columnQualifier Column qualifier
   * @return List of UserPermissions
   * @throws Throwable on failure
   */
  public static List<UserPermission> getUserPermissions(Connection connection, String tableRegex,
    byte[] columnFamily, byte[] columnQualifier) throws Throwable {
    return getUserPermissions(connection, tableRegex, columnFamily, columnQualifier,
      HConstants.EMPTY_STRING);
  }

  /**
   * List all the userPermissions matching the given table pattern, column family and column
   * qualifier.
   * @param connection      Connection
   * @param tableRegex      The regular expression string to match against. It shouldn't be null,
   *                        empty or a namespace regular expression.
   * @param columnFamily    Column family
   * @param columnQualifier Column qualifier
   * @param userName        User name, if empty then all user permissions will be retrieved.
   * @return List of UserPermissions
   * @throws Throwable on failure
   */
  public static List<UserPermission> getUserPermissions(Connection connection, String tableRegex,
    byte[] columnFamily, byte[] columnQualifier, String userName) throws Throwable {
    if (tableRegex == null || tableRegex.isEmpty() || tableRegex.charAt(0) == '@') {
      throw new IllegalArgumentException("Table name can't be null or empty or a namespace.");
    }
    List<UserPermission> permList = new ArrayList<UserPermission>();
    try (Admin admin = connection.getAdmin()) {
      List<TableDescriptor> htds = admin.listTableDescriptors(Pattern.compile(tableRegex), true);
      // Retrieve table permissions
      for (TableDescriptor htd : htds) {
        permList.addAll(admin.getUserPermissions(
          GetUserPermissionsRequest.newBuilder(htd.getTableName()).withFamily(columnFamily)
            .withQualifier(columnQualifier).withUserName(userName).build()));
      }
    }
    return permList;
  }

  /**
   * Validates whether specified user has permission to perform actions on the mentioned table,
   * column family or column qualifier.
   * @param connection      Connection
   * @param tableName       Table name, it shouldn't be null or empty.
   * @param columnFamily    The column family. Optional argument, can be empty. If empty then
   *                        validation will happen at table level.
   * @param columnQualifier The column qualifier. Optional argument, can be empty. If empty then
   *                        validation will happen at table and column family level. columnQualifier
   *                        will not be considered if columnFamily is passed as null or empty.
   * @param userName        User name, it shouldn't be null or empty.
   * @param actions         Actions
   * @return true if access allowed to the specified user, otherwise false.
   * @throws Throwable on failure
   */
  public static boolean hasPermission(Connection connection, String tableName, String columnFamily,
    String columnQualifier, String userName, Permission.Action... actions) throws Throwable {
    return hasPermission(connection, tableName, Bytes.toBytes(columnFamily),
      Bytes.toBytes(columnQualifier), userName, actions);
  }

  /**
   * Validates whether specified user has permission to perform actions on the mentioned table,
   * column family or column qualifier.
   * @param connection      Connection
   * @param tableName       Table name, it shouldn't be null or empty.
   * @param columnFamily    The column family. Optional argument, can be empty. If empty then
   *                        validation will happen at table level.
   * @param columnQualifier The column qualifier. Optional argument, can be empty. If empty then
   *                        validation will happen at table and column family level. columnQualifier
   *                        will not be considered if columnFamily is passed as null or empty.
   * @param userName        User name, it shouldn't be null or empty.
   * @param actions         Actions
   * @return true if access allowed to the specified user, otherwise false.
   * @throws Throwable on failure
   */
  public static boolean hasPermission(Connection connection, String tableName, byte[] columnFamily,
    byte[] columnQualifier, String userName, Permission.Action... actions) throws Throwable {
    if (StringUtils.isEmpty(tableName) || StringUtils.isEmpty(userName)) {
      throw new IllegalArgumentException("Table and user name can't be null or empty.");
    }
    List<Permission> permissions = new ArrayList<>(1);
    permissions.add(Permission.newBuilder(TableName.valueOf(tableName)).withFamily(columnFamily)
      .withQualifier(columnQualifier).withActions(actions).build());
    return connection.getAdmin().hasUserPermissions(userName, permissions).get(0);
  }
}