// Copyright 2006, 2007, 2008 The Apache Software Foundation
//
// 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.apache.tapestry5.ioc.internal;

import org.apache.tapestry5.ioc.Configuration;
import org.apache.tapestry5.ioc.internal.util.Defense;

/**
 * Performs some validation before delegating to another Configuration.
 */
public class ValidatingConfigurationWrapper<T> implements Configuration<T>
{
    private final String serviceId;

    private final Configuration<T> delegate;

    private final Class expectedType;

    // Need a strategy for determing the right order for this mass of parameters!

    public ValidatingConfigurationWrapper(String serviceId, Class expectedType, Configuration<T> delegate)
    {
        this.serviceId = serviceId;
        this.expectedType = expectedType;
        this.delegate = delegate;
    }

    public void add(T object)
    {
        if (object == null)
            throw new NullPointerException(IOCMessages.contributionWasNull(serviceId));

        // Sure, we say it is type T ... but is it really?

        if (!expectedType.isInstance(object))
            throw new IllegalArgumentException(IOCMessages.contributionWrongValueType(
                    serviceId,
                    object.getClass(),
                    expectedType));

        delegate.add(object);
    }

    public void addInstance(Class<? extends T> clazz)
    {
        Defense.notNull(clazz, "clazz");

        if (!expectedType.isAssignableFrom(clazz))
            throw new IllegalArgumentException(IOCMessages.wrongContributionClass(clazz, serviceId, expectedType));

        delegate.addInstance(clazz);
    }
}