/**
 * Copyright (C) 2006 Google Inc.
 *
 * 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.elasticsearch.common.inject.internal;

import org.elasticsearch.common.inject.Binding;
import org.elasticsearch.common.inject.Injector;
import org.elasticsearch.common.inject.Key;
import org.elasticsearch.common.inject.Provider;
import org.elasticsearch.common.inject.spi.BindingScopingVisitor;
import org.elasticsearch.common.inject.spi.ElementVisitor;
import org.elasticsearch.common.inject.spi.InstanceBinding;

/**
 * @author crazybob@google.com (Bob Lee)
 */
public abstract class BindingImpl<T> implements Binding<T> {

    private final Injector injector;
    private final Key<T> key;
    private final Object source;
    private final Scoping scoping;
    private final InternalFactory<? extends T> internalFactory;

    public BindingImpl(Injector injector, Key<T> key, Object source,
                       InternalFactory<? extends T> internalFactory, Scoping scoping) {
        this.injector = injector;
        this.key = key;
        this.source = source;
        this.internalFactory = internalFactory;
        this.scoping = scoping;
    }

    protected BindingImpl(Object source, Key<T> key, Scoping scoping) {
        this.internalFactory = null;
        this.injector = null;
        this.source = source;
        this.key = key;
        this.scoping = scoping;
    }

    public Key<T> getKey() {
        return key;
    }

    public Object getSource() {
        return source;
    }

    private volatile Provider<T> provider;

    public Provider<T> getProvider() {
        if (provider == null) {
            if (injector == null) {
                throw new UnsupportedOperationException("getProvider() not supported for module bindings");
            }

            provider = injector.getProvider(key);
        }
        return provider;
    }

    public InternalFactory<? extends T> getInternalFactory() {
        return internalFactory;
    }

    public Scoping getScoping() {
        return scoping;
    }

    /**
     * Is this a constant binding? This returns true for constant bindings as
     * well as toInstance() bindings.
     */
    public boolean isConstant() {
        return this instanceof InstanceBinding;
    }

    public <V> V acceptVisitor(ElementVisitor<V> visitor) {
        return visitor.visit(this);
    }

    public <V> V acceptScopingVisitor(BindingScopingVisitor<V> visitor) {
        return scoping.acceptVisitor(visitor);
    }

    protected BindingImpl<T> withScoping(Scoping scoping) {
        throw new AssertionError();
    }

    protected BindingImpl<T> withKey(Key<T> key) {
        throw new AssertionError();
    }

    @Override
    public String toString() {
        return new ToStringBuilder(Binding.class)
                .add("key", key)
                .add("scope", scoping)
                .add("source", source)
                .toString();
    }

    public Injector getInjector() {
        return injector;
    }
}