/**
 * Copyright 2010 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.wave.api.data.converter;

import com.google.wave.api.ProtocolVersion;

import java.util.Map.Entry;
import java.util.NavigableMap;

/**
 * A simple utility class that manages the {@link EventDataConverter} for
 * various protocol versions.
 *
 */
public class EventDataConverterManager {

  /** A map of protocol version to {@link EventDataConverter}. */
  private final NavigableMap<ProtocolVersion, EventDataConverter> eventDataConverters;

  /**
   * Constructor.
   *
   * @param eventDataConverters a map of {@link EventDataConverter}.
   */
  public EventDataConverterManager(
      NavigableMap<ProtocolVersion, EventDataConverter> eventDataConverters) {
    this.eventDataConverters = eventDataConverters;
  }

  /**
   * Returns an instance of an {@link EventDataConverter} for the given
   * protocol version.
   *
   * @param protocolVersion the protocol version.
   * @return an instance of an {@link EventDataConverter}, or {@code null} if
   *     there is no converter for the given version.
   */
  public EventDataConverter getEventDataConverter(ProtocolVersion protocolVersion) {
    // Get the latest instance of {@link EventDataConverter} for a protocol
    // version that is less than or equal to the given version, as not every
    // protocol version will have a versioned {@link EventDataConverter}.
    Entry<ProtocolVersion, EventDataConverter> entry = eventDataConverters.floorEntry(
        protocolVersion);
    if (entry == null) {
      return null;
    }
    return entry.getValue();
  }
}