/*
    * 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.shardingsphere.infra.url.core.arg;
  
  import com.google.common.base.Strings;
  import lombok.AccessLevel;
  import lombok.RequiredArgsConstructor;
  
  import java.util.Optional;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  /**
   * URL argument line.
   */
  @RequiredArgsConstructor(access = AccessLevel.PRIVATE)
  public final class URLArgumentLine {
      
      private static final Pattern PLACEHOLDER_PATTERN = Pattern.compile("\\$\\$\\{(.*?)::(.*?)}");
      
      private final Matcher placeholderMatcher;
      
      /**
       * Parse URL argument line.
       *
       * @param line line
       * @return parsed URL argument line
       */
      public static Optional<URLArgumentLine> parse(final String line) {
          Matcher matcher = PLACEHOLDER_PATTERN.matcher(line);
          if (!matcher.find()) {
              return Optional.empty();
          }
          return Optional.of(new URLArgumentLine(matcher));
      }
      
      /**
       * Replace argument.
       *
       * @param type placeholder type
       * @return replaced argument
       */
      public String replaceArgument(final URLArgumentPlaceholderType type) {
          placeholderMatcher.reset();
          StringBuffer result = new StringBuffer();
          while (placeholderMatcher.find()) {
              String variableName = placeholderMatcher.group(1);
              String defaultValue = placeholderMatcher.group(2);
              String argumentValue = getArgumentValue(variableName, type);
              if (Strings.isNullOrEmpty(argumentValue)) {
                  argumentValue = defaultValue;
              }
              placeholderMatcher.appendReplacement(result, argumentValue);
          }
          placeholderMatcher.appendTail(result);
          return rightTrim(result);
      }
      
      private String rightTrim(final StringBuffer buffer) {
          while (buffer.length() > 0 && Character.isWhitespace(buffer.charAt(buffer.length() - 1))) {
              buffer.deleteCharAt(buffer.length() - 1);
          }
          return buffer.toString();
      }
      
      private String getArgumentValue(final String argName, final URLArgumentPlaceholderType type) {
          if (URLArgumentPlaceholderType.ENVIRONMENT == type) {
              return System.getenv(argName);
          }
          if (URLArgumentPlaceholderType.SYSTEM_PROPS == type) {
              return System.getProperty(argName);
          }
          return null;
      }
  }