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/*
 * tksCommons
 * 
 * Author : Thomas Kuhlmann (ThK-Systems, http://www.thk-systems.de) License : LGPL (https://www.gnu.org/licenses/lgpl.html)
 */
package de.thksystems.util.reflection;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * Reflection-Helper.
 */
public final class ReflectionUtils {

	private ReflectionUtils() {
	}

	/**
	 * Gets all fields from a class including the fields from all its super-classes.
	 */
	public static List getAllFields(Class type) {
		List fieldList = new ArrayList<>();
		getAllFields(fieldList, type);
		return fieldList;
	}

	private static List getAllFields(List fields, Class type) {
		for (Field field : type.getDeclaredFields()) {
			fields.add(field);
		}
		if (type.getSuperclass() != null) {
			fields = getAllFields(fields, type.getSuperclass());
		}
		return fields;
	}

	/**
	 * Get non-null field values of the given objects filtered by field type.
	 * 
	 * @param deepIntoCollectionAndArrays
	 *            Add field values from collections and arrays (1-dim), if matching given field type.
	 * @param excludeTransient
	 *            Exclude transients fields
	 */
	public static  Set getFieldValuesOfType(Object object, Class expectedFieldType, boolean deepIntoCollectionAndArrays, boolean excludeTransient)
			throws IllegalArgumentException, IllegalAccessException {
		Set valueSet = new HashSet<>();
		Field[] declaredFields = object.getClass().getDeclaredFields();
		for (Field declaredField : declaredFields) {
			// Exclude transient fields, if set
			if (excludeTransient && Modifier.isTransient(declaredField.getModifiers())) {
				continue;
			}
			// Set and remember field accessibility
			boolean declaredFieldAccessibility = declaredField.isAccessible();
			declaredField.setAccessible(true);
			// Check for field type
			Class declaredFieldType = declaredField.getDeclaringClass();
			// ... field is of expected type
			if (expectedFieldType.isAssignableFrom(declaredFieldType)) {
				@SuppressWarnings("unchecked")
				T declaredFieldValue = (T) declaredField.get(object);
				if (declaredFieldValue != null) {
					valueSet.add(declaredFieldValue);
				}
			}
			// ... field is of collection type
			if (deepIntoCollectionAndArrays && Collection.class.isAssignableFrom(declaredFieldType)) {
				@SuppressWarnings("rawtypes")
				Collection col = (Collection) declaredField.get(object);
				for (Object colEntry : col) {
					if (colEntry != null && expectedFieldType.isAssignableFrom(colEntry.getClass())) {
						@SuppressWarnings("unchecked")
						T value = (T) colEntry;
						valueSet.add(value);
					}
				}
			}
			// ... field is array
			if (deepIntoCollectionAndArrays && declaredFieldType.isArray()) {
				Object[] array = (Object[]) declaredField.get(object);
				for (Object arrayEntry : array) {
					if (arrayEntry != null && expectedFieldType.isAssignableFrom(arrayEntry.getClass())) {
						@SuppressWarnings("unchecked")
						T value = (T) arrayEntry;
						valueSet.add(value);
					}
				}
			}
			// Reset field accessibility
			declaredField.setAccessible(declaredFieldAccessibility);
		}
		return valueSet;
	}

	/**
	 * Returns the field value, even of a private field.
	 */
	public static Object getFieldValue(Object myObject, Field field) throws IllegalArgumentException, IllegalAccessException {
		boolean oldAccessibility = field.isAccessible();
		field.setAccessible(true);
		Object fieldValue = field.get(myObject);
		field.setAccessible(oldAccessibility);
		return fieldValue;
	}

}