package com.atlassian.pageobjects.util;
   
   import java.lang.annotation.Annotation;
   import java.lang.reflect.Field;
   import java.util.Collection;
   import java.util.HashMap;
   import java.util.Map;
   
   /**
   * Utility methods for custom injections
   */
  public class InjectUtils
  {
      /**
       * A callback method for fields annotated with a certain annotation
       * @param <A> The annotation the field is decorated with
       */
      public static interface FieldVisitor<A extends Annotation>
      {
          void visit(Field field, A annotation);
      }
  
      /**
       * Executes the callback for each private field marked with the desired annotation
       *
       * @param instance The object to inspect
       * @param annotation The annotation to scan for
       * @param fieldVisitor The callback when a field is found
       * @param <A> The annotation type to scan for
       */
      public static <A extends Annotation> void forEachFieldWithAnnotation(Object instance, Class<A> annotation, FieldVisitor<A> fieldVisitor)
      {
          for (Field field : findAllFields(instance))
          {
              A ann = field.getAnnotation(annotation);
              if (ann != null)
              {
                  fieldVisitor.visit(field, ann);
              }
          }
      }
  
      private static Collection<Field> findAllFields(Object instance)
      {
          Map<String,Field> fields = new HashMap<String,Field>();
          Class<?> cls = instance.getClass();
          while (cls != Object.class)
          {
              for (Field field : cls.getDeclaredFields())
              {
                  if (!fields.containsKey(field.getName()))
                  {
                      fields.put(field.getName(), field);
                  }
              }
              cls = cls.getSuperclass();
          }
          return fields.values();
      }
  }