/*

 * Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.beans.IntrospectionException;

import java.beans.Introspector;

import java.beans.PropertyDescriptor;

import java.lang.reflect.Array;

import java.lang.reflect.Field;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.util.ArrayList;

import java.util.Collection;

import java.util.IdentityHashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import java.util.Queue;

import java.util.SortedMap;

import java.util.SortedSet;

final class BeanValidator {

    private final Map<Object, Object> cache = new IdentityHashMap<Object, Object>();

    public void validate(Object object1, Object object2) {

        // compare references

        if (object1 == object2) {

            return;

        }

        // check for null

        if ((object1 == null) || (object2 == null)) {

            throw new IllegalStateException("could not compare object with null");

        }

        // resolve self references

        if (isCyclic(object1, object2)) {

            return;

        }

        // resolve cross references

        if (isCyclic(object2, object1)) {

            return;

        }

        Class type = object1.getClass();

        if (!type.equals(object2.getClass())) {

            // resolve different implementations of the Map.Entry interface

            if ((object1 instanceof Map.Entry) && (object2 instanceof Map.Entry)) {

                log("!!! special case", "Map.Entry");

                Map.Entry entry1 = (Map.Entry) object1;

                Map.Entry entry2 = (Map.Entry) object2;

                validate(entry1.getKey(), entry2.getKey());

                validate(entry1.getValue(), entry2.getValue());

                return;

            }

            throw new IllegalStateException("could not compare objects with different types");

        }

        // validate elements of arrays

        if (type.isArray()) {

            int length = Array.getLength(object1);

            if (length != Array.getLength(object2)) {

                throw new IllegalStateException("could not compare arrays with different lengths");

            }

            try {

                this.cache.put(object1, object2);

                for (int i = 0; i < length; i++) {

                    log("validate array element", Integer.valueOf(i));

                    validate(Array.get(object1, i), Array.get(object2, i));

                }

            } finally {

                this.cache.remove(object1);

            }

            return;

        }

        // special case for collections: do not use equals

        boolean ignore = Collection.class.isAssignableFrom(type)

                || Map.Entry.class.isAssignableFrom(type)

                || Map.class.isAssignableFrom(type);

        // validate objects using equals()

        // we assume that the method equals(Object) can be called,

        // if the class declares such method

        if (!ignore && isDefined(type, "equals", Object.class)) {

            if (object1.equals(object2)) {

                return;

            }

            throw new IllegalStateException("the first object is not equal to the second one");

        }

        // validate comparable objects using compareTo()

        // we assume that the method compareTo(Object) can be called,

        // if the class declares such method and implements interface Comparable

        if (Comparable.class.isAssignableFrom(type) && isDefined(type, "compareTo", Object.class)) {

            Comparable cmp = (Comparable) object1;

            if (0 == cmp.compareTo(object2)) {

                return;

            }

            throw new IllegalStateException("the first comparable object is not equal to the second one");

        }

        try {

            this.cache.put(object1, object2);

            // validate values of public fields

            for (Field field : getFields(type)) {

                int mod = field.getModifiers();

                if (!Modifier.isStatic(mod)) {

                    log("validate field", field.getName());

                    validate(object1, object2, field);

                }

            }

            // validate values of properties

            for (PropertyDescriptor pd : getDescriptors(type)) {

                Method method = pd.getReadMethod();

                if (method != null) {

                    log("validate property", pd.getName());

                    validate(object1, object2, method);

                }

            }

            // validate contents of maps

            if (SortedMap.class.isAssignableFrom(type)) {

                validate((Map) object1, (Map) object2, true);

            } else if (Map.class.isAssignableFrom(type)) {

                validate((Map) object1, (Map) object2, false);

            }

            // validate contents of collections

            if (SortedSet.class.isAssignableFrom(type)) {

                validate((Collection) object1, (Collection) object2, true);

            } else if (List.class.isAssignableFrom(type)) {

                validate((Collection) object1, (Collection) object2, true);

            } else if (Queue.class.isAssignableFrom(type)) {

                validate((Collection) object1, (Collection) object2, true);

            } else if (Collection.class.isAssignableFrom(type)) {

                validate((Collection) object1, (Collection) object2, false);

            }

        } finally {

            this.cache.remove(object1);

        }

    }

    private void validate(Object object1, Object object2, Field field) {

        try {

            object1 = field.get(object1);

            object2 = field.get(object2);

            validate(object1, object2);

        }

        catch (IllegalAccessException exception) {

            log(exception);

        }

    }

    private void validate(Object object1, Object object2, Method method) {

        try {

            object1 = method.invoke(object1);

            object2 = method.invoke(object2);

            validate(object1, object2);

        }

        catch (IllegalAccessException exception) {

            log(exception);

        }

        catch (InvocationTargetException exception) {

            log(exception.getCause());

        }

    }

    private void validate(Collection c1, Collection c2, boolean sorted) {

        if (c1.size() != c2.size()) {

            throw new IllegalStateException("could not compare collections with different sizes");

        }

        if (sorted) {

            Iterator first = c1.iterator();

            Iterator second = c2.iterator();

            for (int i = 0; first.hasNext() && second.hasNext(); i++) {

                log("validate collection element", Integer.valueOf(i));

                validate(first.next(), second.next());

            }

            if (first.hasNext() || second.hasNext()) {

                throw new IllegalStateException("one collection contains more elements than another one");

            }

        } else {

            List list = new ArrayList(c2);

            Iterator first = c1.iterator();

            for (int i = 0; first.hasNext(); i++) {

                Object value = first.next();

                log("validate collection element", Integer.valueOf(i));

                Iterator second = list.iterator();

                for (int j = 0; second.hasNext(); j++) {

                    log("validate collection element against", Integer.valueOf(j));

                    try {

                        validate(value, second.next());

                        second.remove();

                        break;

                    } catch (IllegalStateException exception) {

                        if (!second.hasNext()) {

                            throw new IllegalStateException("one collection does not contain some elements from another one", exception);

                        }

                    }

                }

            }

        }

    }

    private void validate(Map map1, Map map2, boolean sorted) {

        validate(map1.entrySet(), map2.entrySet(), sorted);

    }

    private boolean isCyclic(Object object1, Object object2) {

        Object object = this.cache.get(object1);

        if (object == null) {

            return false;

        }

        if (object == object2) {

            return true;

        }

        throw new IllegalStateException("could not resolve cyclic reference");

    }

    private boolean isDefined(Class type, String name, Class... params) {

        try {

            return type.equals(type.getMethod(name, params).getDeclaringClass());

        }

        catch (NoSuchMethodException exception) {

            log(exception);

        }

        catch (SecurityException exception) {

            log(exception);

        }

        return false;

    }

    private static final Field[] FIELDS = {};

    private Field[] getFields(Class type) {

        try {

            return type.getFields();

        }

        catch (SecurityException exception) {

            log(exception);

        }

        return FIELDS;

    }

    private static final PropertyDescriptor[] DESCRIPTORS = {};

    private PropertyDescriptor[] getDescriptors(Class type) {

        try {

            return Introspector.getBeanInfo(type, Object.class).getPropertyDescriptors();

        }

        catch (IntrospectionException exception) {

            log(exception);

        }

        return DESCRIPTORS;

    }

    private final StringBuilder sb = new StringBuilder(1024);

    private void log(String message, Object value) {

        this.sb.setLength(0);

        int size = this.cache.size();

        while (0 < size--) {

            this.sb.append("  ");

        }

        this.sb.append(" - ");

        this.sb.append(message);

        if (value != null) {

            this.sb.append(": ");

            this.sb.append(value);

        }

        System.out.println(this.sb.toString());

    }

    private void log(Throwable throwable) {

        this.sb.setLength(0);

        int size = this.cache.size();

        while (0 < size--) {

            this.sb.append("  ");

        }

        this.sb.append(" ? ");

        this.sb.append(throwable);

        System.out.println(this.sb.toString());

    }

}