/*
 * 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 com.google.inject.jndi;

import com.google.inject.Inject;
import com.google.inject.Provider;
import javax.naming.Context;
import javax.naming.NamingException;

/**
 * Integrates Guice with JNDI. Requires a binding to {@link javax.naming.Context}.
 *
 * @author crazybob@google.com (Bob Lee)
 */
public class JndiIntegration {

  private JndiIntegration() {}

  /**
   * Creates a provider which looks up objects in JNDI using the given name. Example usage:
   *
   * <pre>
   * bind(DataSource.class).toProvider(fromJndi(DataSource.class, "java:..."));
   * </pre>
   */
  public static <T> Provider<T> fromJndi(Class<T> type, String name) {
    return new JndiProvider<T>(type, name);
  }

  static class JndiProvider<T> implements Provider<T> {

    @Inject Context context;
    final Class<T> type;
    final String name;

    public JndiProvider(Class<T> type, String name) {
      this.type = type;
      this.name = name;
    }

    @Override
    public T get() {
      try {
        return type.cast(context.lookup(name));
      } catch (NamingException e) {
        throw new RuntimeException(e);
      }
    }
  }
}
