/*
 * Copyright 2007 the original author or authors.
 *
 * 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.
 */
package org.wamblee.system.core;

import org.wamblee.reflection.ReflectionUtils;

import java.util.Arrays;


/**
 * DOCUMENT ME!
 *
 * @author $author$
 * @version $Revision$
 */
public class DefaultRequiredInterface implements RequiredInterface {
    /**
     * DOCUMENT ME!
     */
    private String name;

    /**
     * DOCUMENT ME!
     */
    private boolean optional;

    /**
     * DOCUMENT ME!
     */
    private Class[] required;

    /**
     * DOCUMENT ME!
     */
    private ProvidedInterface provider;

/**
     * Creates a new DefaultRequiredInterface object.
     *
     * @param aName DOCUMENT ME!
     * @param aInterface DOCUMENT ME!
     */
    public DefaultRequiredInterface(String aName, Class aInterface) {
        this(aName, new Class[] { aInterface });
    }

/**
     * Creates a new DefaultRequiredInterface object.
     *
     * @param aName DOCUMENT ME!
     * @param aInterfaces DOCUMENT ME!
     */
    public DefaultRequiredInterface(String aName, Class[] aInterfaces) {
        this(aName, aInterfaces, false);
    }

/**
     * Creates a new DefaultRequiredInterface object.
     *
     * @param aName DOCUMENT ME!
     * @param aInterface DOCUMENT ME!
     * @param aIsOptional DOCUMENT ME!
     */
    public DefaultRequiredInterface(String aName, Class aInterface,
        boolean aIsOptional) {
        this(aName, new Class[] { aInterface }, aIsOptional);
    }

/**
     * Creates a new DefaultRequiredInterface object.
     *
     * @param aName DOCUMENT ME!
     * @param aInterfaces DOCUMENT ME!
     * @param aIsOptional DOCUMENT ME!
     */
    public DefaultRequiredInterface(String aName, Class[] aInterfaces,
        boolean aIsOptional) {
        name         = aName;
        optional     = aIsOptional;
        required     = aInterfaces;
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    @Override
    public String getName() {
        return name;
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    @Override
    public boolean isOptional() {
        return optional;
    }

    /**
     * DOCUMENT ME!
     *
     * @param aDescriptor DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    @Override
    public boolean implementedBy(ProvidedInterface aDescriptor) {
        Class[] provided = aDescriptor.getInterfaceTypes();

        for (Class requiredIntf : required) {
            if (!serviceProvided(requiredIntf, provided)) {
                return false;
            }
        }

        // all required interfaces are provided.
        return true;
    }

    /**
     * Check if the required interface is implemented by one of the
     * provided interfaces.
     *
     * @param aRequired required interface
     * @param aProvided Provided interfaces.
     *
     * @return
     */
    private boolean serviceProvided(Class aRequired, Class[] aProvided) {
        for (Class provided : aProvided) {
            try {
                provided      = ReflectionUtils.wrapIfNeeded(provided);
                aRequired     = ReflectionUtils.wrapIfNeeded(aRequired);
                provided.asSubclass(aRequired);

                return true;
            } catch (ClassCastException e) {
                // No match, try the next one.
            }
        }

        return false;
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    @Override
    public ProvidedInterface getProvider() {
        return provider;
    }

    /**
     * DOCUMENT ME!
     *
     * @param aProvider DOCUMENT ME!
     */
    @Override
    public void setProvider(ProvidedInterface aProvider) {
        assert aProvider != null;
        assert implementedBy(aProvider);
        provider = aProvider;
    }

    /**
     * DOCUMENT ME!
     *
     * @param obj DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    @Override
    public boolean equals(Object obj) {
        return this == obj;
    }

    /**
     * DOCUMENT ME!
     *
     * @param obj DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    @Override
    public boolean covers(RequiredInterface obj) {
        // TODO do more than equals. 
        if (!(obj instanceof DefaultRequiredInterface)) {
            return false;
        }

        DefaultRequiredInterface descr = (DefaultRequiredInterface) obj;

        if (required.length != descr.required.length) {
            return false;
        }

        String[] interfaces1 = new String[required.length];
        String[] interfaces2 = new String[required.length];

        for (int i = 0; i < required.length; i++) {
            interfaces1[i]     = required[i].getName();
            interfaces2[i]     = descr.required[i].getName();
        }

        Arrays.sort(interfaces1);
        Arrays.sort(interfaces2);

        return Arrays.equals(interfaces1, interfaces2);
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    @Override
    public int hashCode() {
        return required.hashCode();
    }

    /**
     * DOCUMENT ME!
     *
     * @return DOCUMENT ME!
     */
    @Override
    public String toString() {
        StringBuffer buf = new StringBuffer();
        buf.append("." + getName() + ":");

        for (Class intf : required) {
            buf.append("." + intf.getName());
        }

        return buf.toString();
    }
}