content: /*
   * 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.camel.jsonpath.easypredicate;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import static org.apache.camel.jsonpath.easypredicate.EasyPredicateOperators.hasOperator;
  import static org.apache.camel.jsonpath.easypredicate.EasyPredicateOperators.isOperator;
  
  /**
   * To allow defining very easy jsonpath predicates using the syntax: left OP right
   * <p/>
   * The easy parser is only in use if the predicate do not start with the <tt>$</tt> sign which is used by jsonpath. The
   * parser is intended for predicates only.
   */
  public class EasyPredicateParser {
  
      /**
       * Parses the predicate
       *
       * @param  predicate the predicate
       * @return           the parsed predicate or the original predicate if easy parser did not kick-in
       */
      public String parse(String predicate) {
  
          if (predicate.startsWith("$")) {
              // regular json path so skip
              return predicate;
          }
  
          // must have an operator
          if (!hasOperator(predicate)) {
              return predicate;
          }
  
          StringBuilder sb = new StringBuilder();
  
          // grab before operator
          String[] parts = tokens(predicate);
  
          // only support one operator currently
          if (parts.length == 3) {
              String prev = parts[0];
              String op = parts[1];
              String next = parts[2];
              if (isOperator(op)) {
                  String before;
                  String after;
                  int pos = prev.lastIndexOf('.');
                  if (pos == -1) {
                      before = "..*";
                      after = prev;
                  } else {
                      before = prev.substring(0, pos);
                      after = prev.substring(pos + 1);
                  }
                  sb.append("$");
                  if (!before.startsWith(".")) {
                      sb.append(".");
                  }
                  sb.append(before);
                  sb.append("[?(@.");
                  sb.append(after);
                  sb.append(" ");
                  sb.append(op);
                  sb.append(" ");
                  sb.append(next);
                  sb.append(")]");
              }
              return sb.toString();
          }
  
          // not able to parse so return as-is
          return predicate;
      }
  
      /**
       * Splits the predicate into: left OP right
       *
       * @param  predicate the predicate
       * @return           the splitted parts
       */
      private static String[] tokens(String predicate) {
          List<String> list = new ArrayList<>();
  
          StringBuilder part = new StringBuilder();
          for (int i = 0; i < predicate.length(); i++) {
  
              // is there a new operator
              String s = predicate.substring(i);
              String op = EasyPredicateOperators.getOperatorAtStart(s);
              if (op != null) {
                  if (part.length() > 0) {
                      list.add(part.toString());
                      part.setLength(0);
                  }
                  list.add(op.trim());
                  // move i ahead
                  i = i + op.length() + 1;
              } else {
                  char ch = predicate.charAt(i);
                  part.append(ch);
              }
          }
  
          // ant leftovers
          if (part.length() > 0) {
              list.add(part.toString());
          }
  
          return list.toArray(new String[0]);
      }
  
  }
  