/**
 * Copyright (C) 2010 hprange <hprange@gmail.com>
 * 
 * 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 com.woinject;

import static com.webobjects.foundation.NSKeyValueCoding.NullValue;

import com.google.inject.Key;
import com.google.inject.OutOfScopeException;
import com.google.inject.Provider;
import com.google.inject.Scope;
import com.webobjects.appserver.WORequest;

import er.extensions.appserver.ERXWOContext;

/**
 * WORequest scope.
 * 
 * @author <a href="mailto:hprange@gmail.com">Henrique Prange</a>
 * @author Sébastien Letélie
 * @since 1.0
 */
class WORequestScope implements Scope {
    WORequestScope() {
    }

    WORequest request() {
        return ERXWOContext.currentContext().request();
    }

    /*
     * (non-Javadoc)
     * 
     * @see com.google.inject.Scope#scope(com.google.inject.Key,
     * com.google.inject.Provider)
     */
    public <T> Provider<T> scope(final Key<T> key, final Provider<T> creator) {
        final String name = key.toString();

        return new Provider<T>() {
            public T get() {
                WORequest request = request();

                if (request == null) {
                    throw new OutOfScopeException("Cannot access scoped object. Either the request has not been dispatched yet, or its cycle has ended.");
                }

                synchronized (request) {
                    Object object = request.userInfoForKey(name);

                    if (object == NullValue) {
                        return null;
                    }

                    @SuppressWarnings("unchecked")
                    T t = (T) object;

                    if (t == null) {
                        t = creator.get();

                        request.setUserInfoForKey(t == null ? NullValue : t, name);
                    }

                    return t;
                }
            }
        };
    }
}