content: /*
   * Created on Oct 31, 2006
   * 
   * Licensed 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.
   * 
   * Copyright @2006-2013 the original author or authors.
   */
  package org.fest.reflect.field;
  
  import org.fest.reflect.exception.ReflectionError;
  
  import org.jetbrains.annotations.NotNull;
  import org.jetbrains.annotations.Nullable;
  import java.lang.reflect.Field;
  
  import static org.fest.reflect.util.Accessibles.*;
  import static org.fest.reflect.util.Types.castSafely;
  import static org.fest.util.Preconditions.checkNotNull;
  import static org.fest.util.Preconditions.checkNotNullOrEmpty;
  
  /**
   * Accesses a field via
   * <a href="http://docs.oracle.com/javase/tutorial/reflect/index.html" target="_blank">Java Reflection</a>.
   *
   * @param <T> the type of the field to access.
   * @author Alex Ruiz
   */
  public final class FieldAccessor<T> {
    private final Class<T> fieldType;
    private final Object target;
    private final Field field;
    private final boolean accessible;
  
    FieldAccessor(@NotNull String fieldName, @NotNull Class<T> fieldType, @NotNull Object target) {
      this.fieldType = checkNotNull(fieldType);
      this.target = checkNotNull(target);
      field = findFieldInClassHierarchy(checkNotNullOrEmpty(fieldName));
      accessible = field.isAccessible();
    }
  
    private @NotNull Field findFieldInClassHierarchy(@NotNull String fieldName) {
      Field field = null;
      Class<?> originalType = target instanceof Class<?> ? (Class<?>) target : target.getClass();
      Class<?> targetType = originalType;
      while (targetType != null) {
        try {
          field = targetType.getDeclaredField(fieldName);
        } catch (NoSuchFieldException e) {
          targetType = targetType.getSuperclass();
          continue;
        }
        break;
      }
      if (field != null) {
        boolean isAccessible = field.isAccessible();
        try {
          makeAccessible(field);
          Class<?> actualType = field.getType();
          if (!fieldType.isAssignableFrom(actualType)) {
            String format = "Expecting type of field '%s' in %s to be <%s> but was <%s>";
            String msg =
                String.format(format, fieldName, originalType.getName(), fieldType.getName(), actualType.getName());
            throw new ReflectionError(msg);
          }
        } finally {
          setAccessibleIgnoringExceptions(field, isAccessible);
        }
        return field;
      }
      String format = "Failed to find field '%s' in %s";
      String msg = String.format(format, fieldName, originalType.getName());
      throw new ReflectionError(msg);
    }
  
    /**
     * Sets a value in the field specified in this fluent interface.
     * <p/>
     * Examples:
     * <pre>
     * // import static {@link org.fest.reflect.core.Reflection#field(String) org.fest.reflect.core.Reflection.field};
     *
     * // Retrieves the value of the field "name"
     * String name = {@link org.fest.reflect.core.Reflection#field(String) field}("name").{@link FieldName#ofType(Class) ofType}(String.class).{@link FieldType#in(Object) in}(person).{@link FieldAccessor#get() get}();
     *
     * // Sets the value of the field "name" to "Yoda"
     * {@link org.fest.reflect.core.Reflection#field(String) field}("name").{@link FieldName#ofType(Class) ofType}(String.class).{@link FieldType#in(Object) in}(person).{@link FieldAccessor#set(Object) set}("Yoda");
     *
     * // Retrieves the value of the field "powers"
     * List&lt;String&gt; powers = {@link org.fest.reflect.core.Reflection#field(String) field}("powers").{@link FieldName#ofType(org.fest.reflect.reference.TypeRef) ofType}(new {@link org.fest.reflect.reference.TypeRef TypeRef}&lt;List&lt;String&gt;&gt;() {}).{@link FieldTypeRef#in(Object) in}(jedi).{@link FieldAccessor#get() get}();
     *
     * // Sets the value of the field "powers"
     * List&lt;String&gt; powers = new ArrayList&lt;String&gt;();
     * powers.add("heal");
     * {@link org.fest.reflect.core.Reflection#field(String) field}("powers").{@link FieldName#ofType(org.fest.reflect.reference.TypeRef) ofType}(new {@link org.fest.reflect.reference.TypeRef TypeRef}&lt;List&lt;String&gt;&gt;() {}).{@link FieldTypeRef#in(Object) in}(jedi).{@link FieldAccessor#set(Object) set}(powers);
     *
     * // Retrieves the value of the static field "count" in Person.class
     * int count = {@link org.fest.reflect.core.Reflection#field(String) field}("count").{@link org.fest.reflect.field.FieldName#ofType(Class) ofType}(int.class).{@link org.fest.reflect.field.FieldType#in(Object) in}(Person.class).{@link org.fest.reflect.field.FieldAccessor#get() get}();
     * </pre>
     *
     * @param value the value to set.
     * @throws ReflectionError if the given value cannot be set.
     */
    public void set(@Nullable T value) {
      Field f = checkNotNull(field);
      try {
        setAccessible(f, true);
        f.set(target, value);
      } catch (Throwable t) {
        String format = "Failed to set value %s in field '%s'";
        String msg = String.format(format, String.valueOf(value), f.getName());
        throw new ReflectionError(msg, t);
      } finally {
        setAccessibleIgnoringExceptions(f, accessible);
      }
    }
  
    /**
     * Retrieves the value of the field specified in this fluent interface.
     * <p/>
     * Examples:
     * <pre>
     * // import static {@link org.fest.reflect.core.Reflection#field(String) org.fest.reflect.core.Reflection.field};
     *
     * // Retrieves the value of the field "name"
     * String name = {@link org.fest.reflect.core.Reflection#field(String) field}("name").{@link FieldName#ofType(Class) ofType}(String.class).{@link FieldType#in(Object) in}(person).{@link FieldAccessor#get() get}();
     *
     * // Sets the value of the field "name" to "Yoda"
     * {@link org.fest.reflect.core.Reflection#field(String) field}("name").{@link FieldName#ofType(Class) ofType}(String.class).{@link FieldType#in(Object) in}(person).{@link FieldAccessor#set(Object) set}("Yoda");
     *
     * // Retrieves the value of the field "powers"
     * List&lt;String&gt; powers = {@link org.fest.reflect.core.Reflection#field(String) field}("powers").{@link FieldName#ofType(org.fest.reflect.reference.TypeRef) ofType}(new {@link org.fest.reflect.reference.TypeRef TypeRef}&lt;List&lt;String&gt;&gt;() {}).{@link FieldTypeRef#in(Object) in}(jedi).{@link FieldAccessor#get() get}();
     *
     * // Sets the value of the field "powers"
     * List&lt;String&gt; powers = new ArrayList&lt;String&gt;();
     * powers.add("heal");
     * {@link org.fest.reflect.core.Reflection#field(String) field}("powers").{@link FieldName#ofType(org.fest.reflect.reference.TypeRef) ofType}(new {@link org.fest.reflect.reference.TypeRef TypeRef}&lt;List&lt;String&gt;&gt;() {}).{@link FieldTypeRef#in(Object) in}(jedi).{@link FieldAccessor#set(Object) set}(powers);
     *
     * // Retrieves the value of the static field "count" in Person.class
     * int count = {@link org.fest.reflect.core.Reflection#field(String) field}("count").{@link org.fest.reflect.field.FieldName#ofType(Class) ofType}(int.class).{@link org.fest.reflect.field.FieldType#in(Object) in}(Person.class).{@link org.fest.reflect.field.FieldAccessor#get() get}();
     * </pre>
     *
     * @return the value of the field in this fluent interface.
     * @throws ReflectionError if the value of the field cannot be retrieved.
     */
    public @Nullable T get() {
      Field f = checkNotNull(field);
      try {
        setAccessible(f, true);
        Object value = f.get(target);
        return castSafely(value, checkNotNull(fieldType));
      } catch (Throwable t) {
        String msg = String.format("Failed to get the value of field '%s'", f.getName());
        throw new ReflectionError(msg, t);
      } finally {
        setAccessibleIgnoringExceptions(f, accessible);
      }
    }
  
    /**
     * @return the underlying field to access.
     */
    public @NotNull Field target() {
      return field;
    }
  }
  