/**
 * 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.iotdb.db.utils;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.apache.iotdb.db.auth.AuthException;
import org.apache.iotdb.db.auth.entity.PathPrivilege;
import org.apache.iotdb.db.auth.entity.PrivilegeType;
import org.apache.iotdb.db.conf.IoTDBConstant;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class AuthUtils {

  private static final Logger logger = LoggerFactory.getLogger(AuthUtils.class);

  private static final int MIN_PASSWORD_LENGTH = 4;
  private static final int MIN_USERNAME_LENGTH = 4;
  private static final int MIN_ROLENAME_LENGTH = 4;
  private static final String ROOT_PREFIX = IoTDBConstant.PATH_ROOT;
  private static final String ENCRYPT_ALGORITHM = "MD5";
  private static final String STRING_ENCODING = "utf-8";

  private AuthUtils() {

  }

  /**
   * validate password size.
   *
   * @param password user password
   * @throws AuthException Authenticate Exception
   */
  public static void validatePassword(String password) throws AuthException {
    if (password.length() < MIN_PASSWORD_LENGTH) {
      throw new AuthException(
          "Password's size must be greater than or equal to " + MIN_USERNAME_LENGTH);
    }
  }

  /**
   * validate username.
   *
   * @param username username
   * @throws AuthException Authenticate Exception
   */
  public static void validateUsername(String username) throws AuthException {
    if (username.length() < MIN_USERNAME_LENGTH) {
      throw new AuthException(
          "Username's size must be greater than or equal to " + MIN_USERNAME_LENGTH);
    }
  }

  /**
   * validate role name.
   *
   * @param rolename role name
   * @throws AuthException Authenticate Exception
   */
  public static void validateRolename(String rolename) throws AuthException {
    if (rolename.length() < MIN_ROLENAME_LENGTH) {
      throw new AuthException(
          "Role name's size must be greater than or equal to " + MIN_ROLENAME_LENGTH);
    }
  }

  /**
   * validate privilege.
   *
   * @param privilegeId privilege ID
   * @throws AuthException Authenticate Exception
   */
  public static void validatePrivilege(int privilegeId) throws AuthException {
    if (privilegeId < 0 || privilegeId >= PrivilegeType.values().length) {
      throw new AuthException(String.format("Invalid privilegeId %d", privilegeId));
    }
  }

  /**
   * validate series path.
   *
   * @param path series path
   * @throws AuthException Authenticate Exception
   */
  public static void validatePath(String path) throws AuthException {
    if (!path.startsWith(ROOT_PREFIX)) {
      throw new AuthException(
          String.format("Illegal seriesPath %s, seriesPath should start with \"%s\"", path,
              ROOT_PREFIX));
    }
  }

  /**
   * validate privilege on path.
   *
   * @param path series path
   * @param privilegeId privilege ID
   * @throws AuthException Authenticate Exception
   */
  public static void validatePrivilegeOnPath(String path, int privilegeId) throws AuthException {
    validatePrivilege(privilegeId);
    PrivilegeType type = PrivilegeType.values()[privilegeId];
    if (!path.equals(IoTDBConstant.PATH_ROOT)) {
      validatePath(path);
      switch (type) {
        case READ_TIMESERIES:
        case SET_STORAGE_GROUP:
        case CREATE_TIMESERIES:
        case DELETE_TIMESERIES:
        case INSERT_TIMESERIES:
        case UPDATE_TIMESERIES:
          return;
        default:
          throw new AuthException(
              String.format("Illegal privilege %s on seriesPath %s", type.toString(), path));
      }
    } else {
      switch (type) {
        case READ_TIMESERIES:
        case SET_STORAGE_GROUP:
        case CREATE_TIMESERIES:
        case DELETE_TIMESERIES:
        case INSERT_TIMESERIES:
        case UPDATE_TIMESERIES:
          validatePath(path);
          return;
        default:
          return;
      }
    }
  }

  /**
   * encrypt password.
   *
   * @param password password
   * @return encrypted password if success
   */
  public static String encryptPassword(String password) {
    try {
      MessageDigest messageDigest = MessageDigest.getInstance(ENCRYPT_ALGORITHM);
      messageDigest.update(password.getBytes(STRING_ENCODING));
      return new String(messageDigest.digest(), STRING_ENCODING);
    } catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
      logger.error("meet error while encrypting password.", e);
      return password;
    }
  }

  /**
   * check if pathA belongs to pathB.
   *
   * @param pathA sub-path
   * @param pathB path
   * @return True if pathA == pathB, or pathA is an extension of pathB, e.g. pathA = "root.a.b.c"
   * and pathB = "root.a"
   */
  public static boolean pathBelongsTo(String pathA, String pathB) {
    return pathA.equals(pathB)
        || (pathA.startsWith(pathB)
        && pathA.charAt(pathB.length()) == IoTDBConstant.PATH_SEPARATOR);
  }

  /**
   * check privilege.
   *
   * @param path series path
   * @param privilegeId privilege ID
   * @param privilegeList privileges in List structure
   * @return True if privilege-check passed
   */
  public static boolean checkPrivilege(String path, int privilegeId,
      List<PathPrivilege> privilegeList) {
    if (privilegeList == null) {
      return false;
    }
    for (PathPrivilege pathPrivilege : privilegeList) {
      if (path != null) {
        if (pathPrivilege.getPath() != null &&
                AuthUtils.pathBelongsTo(path, pathPrivilege.getPath()) &&
                pathPrivilege.getPrivileges().contains(privilegeId)) {
          return true;
        }
      } else {
        if (pathPrivilege.getPath() == null && pathPrivilege.getPrivileges().contains(privilegeId)) {
          return true;
        }
      }
    }
    return false;
  }

  /**
   * get privileges.
   *
   * @param path The seriesPath on which the privileges take effect. If seriesPath-free privileges
   * are desired, this should be null.
   * @return The privileges granted to the role.
   */
  public static Set<Integer> getPrivileges(String path, List<PathPrivilege> privilegeList) {
    if (privilegeList == null) {
      return new HashSet<>();
    }
    Set<Integer> privileges = new HashSet<>();
    for (PathPrivilege pathPrivilege : privilegeList) {
      if (path != null) {
        if (pathPrivilege.getPath() != null && AuthUtils.pathBelongsTo(path, pathPrivilege.getPath())) {
          privileges.addAll(pathPrivilege.getPrivileges());
        }
      } else {
        if (pathPrivilege.getPath() == null) {
          privileges.addAll(pathPrivilege.getPrivileges());
        }
      }
    }
    return privileges;
  }

  /**
   * check if series path has this privilege.
   *
   * @param path series path
   * @param privilegeId privilege Id
   * @param privilegeList privileges in List structure
   * @return True if series path has this privilege
   */
  public static boolean hasPrivilege(String path, int privilegeId,
      List<PathPrivilege> privilegeList) {
    for (PathPrivilege pathPrivilege : privilegeList) {
      if (pathPrivilege.getPath().equals(path) && pathPrivilege.getPrivileges().contains(privilegeId)) {
        pathPrivilege.getReferenceCnt().incrementAndGet();
        return true;
      }
    }
    return false;
  }

  /**
   * add privilege.
   *
   * @param path series path
   * @param privilgeId privilege Id
   * @param privilegeList privileges in List structure
   */
  public static void addPrivilege(String path, int privilgeId, List<PathPrivilege> privilegeList) {
    for (PathPrivilege pathPrivilege : privilegeList) {
      if (pathPrivilege.getPath().equals(path)) {
        if (privilgeId != PrivilegeType.ALL.ordinal()) {
          pathPrivilege.getPrivileges().add(privilgeId);
        } else {
          for (PrivilegeType privilegeType : PrivilegeType.values()) {
            pathPrivilege.getPrivileges().add(privilegeType.ordinal());
          }
        }
        return;
      }
    }
    PathPrivilege pathPrivilege = new PathPrivilege(path);
    if (privilgeId != PrivilegeType.ALL.ordinal()) {
      pathPrivilege.getPrivileges().add(privilgeId);
    } else {
      for (PrivilegeType privilegeType : PrivilegeType.values()) {
        pathPrivilege.getPrivileges().add(privilegeType.ordinal());
      }
    }
    privilegeList.add(pathPrivilege);
  }

  /**
   * remove privilege.
   *
   * @param path series path
   * @param privilgeId privilege Id
   * @param privilegeList privileges in List structure
   */
  public static void removePrivilege(String path, int privilgeId,
      List<PathPrivilege> privilegeList) {
    PathPrivilege emptyPrivilege = null;
    for (PathPrivilege pathPrivilege : privilegeList) {
      if (pathPrivilege.getPath().equals(path)) {
        if (privilgeId != PrivilegeType.ALL.ordinal()) {
          pathPrivilege.getPrivileges().remove(privilgeId);
        } else {
          privilegeList.remove(pathPrivilege);
          return;
        }
        if (pathPrivilege.getPrivileges().isEmpty()) {
          emptyPrivilege = pathPrivilege;
        }
        break;
      }
    }
    if (emptyPrivilege != null) {
      privilegeList.remove(emptyPrivilege);
    }
  }

}
