package us.codecraft.webmagic.selector;
   
   
   import java.util.ArrayList;
   import java.util.List;
   import java.util.Map;
   import com.alibaba.fastjson.JSON;
   import com.jayway.jsonpath.JsonPath;
   
  /**
   * JsonPath selector.<br>
   * Used to extract content from JSON.<br>
   *
   * @author code4crafter@gmail.com <br>
   * @since 0.2.1
   */
  public class JsonPathSelector implements Selector {
  
      private final String jsonPathStr;
  
      private final JsonPath jsonPath;
  
      public JsonPathSelector(String jsonPathStr) {
          this.jsonPathStr = jsonPathStr;
          this.jsonPath = JsonPath.compile(this.jsonPathStr);
      }
  
      @SuppressWarnings("unused")
      public String getJsonPathStr() {
          return jsonPathStr;
      }
  
      @Override
      public String select(String text) {
          Object object = jsonPath.read(text);
          if (object == null) {
              return null;
          }
          if (object instanceof List) {
              List<?> list = (List<?>) object;
              if (list.size() > 0) {
                  return toString(list.iterator().next());
              }
          }
          return object.toString();
      }
  
      private String toString(Object object) {
          if (object instanceof Map) {
              return JSON.toJSONString(object);
          } else {
              return String.valueOf(object);
          }
      }
  
      @Override
      @SuppressWarnings("unchecked")
      public List<String> selectList(String text) {
          List<String> list = new ArrayList<>();
          Object object = jsonPath.read(text);
          if (object == null) {
              return list;
          }
          if (object instanceof List) {
              List<Object> items = (List<Object>) object;
              for (Object item : items) {
                  list.add(toString(item));
              }
          } else {
              list.add(toString(object));
          }
          return list;
      }
  }