/**
 * 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.helix.util;

/**
 * Path related utilities
 */
public class PathUtils {

  /**
   * validate the provided znode path string
   * @param path znode path string
   * @param isSequential if the path is being created
   *          with a sequential flag
   * @throws IllegalArgumentException if the path is invalid
   */
  public static void validatePath(String path, boolean isSequential)
      throws IllegalArgumentException {
    validatePath(isSequential ? path + "1" : path);
  }

  /**
   * Validate the provided znode path string
   * @param path znode path string
   * @throws IllegalArgumentException if the path is invalid
   */
  public static void validatePath(String path) throws IllegalArgumentException {
    if (path == null) {
      throw new IllegalArgumentException("Path cannot be null");
    }
    if (path.length() == 0) {
      throw new IllegalArgumentException("Path length must be > 0");
    }
    if (path.charAt(0) != '/') {
      throw new IllegalArgumentException("Path must start with / character");
    }
    if (path.length() == 1) { // done checking - it's the root
      return;
    }
    if (path.charAt(path.length() - 1) == '/') {
      throw new IllegalArgumentException("Path must not end with / character");
    }

    String reason = null;
    char lastc = '/';
    char chars[] = path.toCharArray();
    char c;
    for (int i = 1; i < chars.length; lastc = chars[i], i++) {
      c = chars[i];

      if (c == 0) {
        reason = "null character not allowed @" + i;
        break;
      } else if (c == '/' && lastc == '/') {
        reason = "empty node name specified @" + i;
        break;
      } else if (c == '.' && lastc == '.') {
        if (chars[i - 2] == '/' && ((i + 1 == chars.length) || chars[i + 1] == '/')) {
          reason = "relative paths not allowed @" + i;
          break;
        }
      } else if (c == '.') {
        if (chars[i - 1] == '/' && ((i + 1 == chars.length) || chars[i + 1] == '/')) {
          reason = "relative paths not allowed @" + i;
          break;
        }
      } else if (c > '\u0000' && c <= '\u001f' || c >= '\u007f' && c <= '\u009F' || c >= '\ud800'
          && c <= '\uf8ff' || c >= '\ufff0' && c <= '\uffff') {
        reason = "invalid charater @" + i;
        break;
      }
    }

    if (reason != null) {
      throw new IllegalArgumentException("Invalid path string \"" + path + "\" caused by " + reason);
    }
  }
}