// Copyright (c) 2009 The Chromium Authors. All rights reserved.

// Use of this source code is governed by a BSD-style license that can be

// found in the LICENSE file.

package org.chromium.sdk.internal;

import java.util.LinkedHashMap;

import java.util.Map;

import java.util.concurrent.ConcurrentHashMap;

/**

 * Utility class that behaves similarly to ConcurrentHashMap, but also

 * provides {@link #close} operation that stops all new registrations.

 */

public class CloseableMap<K, V> {

  public static <K, V> CloseableMap<K, V> newMap() {

    return new CloseableMap<K, V>(new ConcurrentHashMap<K, V>());

  }

  public static <K, V> CloseableMap<K, V> newLinkedMap() {

    // Creates linked hash map and makes "get" synchronized.

    return new CloseableMap<K, V>(new LinkedHashMap<K, V>()) {

      @Override

      public synchronized V get(K key) {

        // Base "get" is not synchronized, because we rely on ConcurrentHashMap.

        return super.get(key);

      }

    };

  }

  private final Map<K, V> map;

  private boolean mutationClosed = false;

  protected CloseableMap(Map<K, V> map) {

    this.map = map;

  }

  public V get(K key) {

    return map.get(key);

  }

  public synchronized Map<K, V> close() {

    if (mutationClosed) {

      throw new IllegalStateException();

    }

    mutationClosed = true;

    return map;

  }

  public synchronized V remove(K key) {

    if (mutationClosed) {

      // We probably can safely ignore this.

      return null;

    }

    V result = map.remove(key);

    if (result == null) {

      throw new IllegalArgumentException("This key is not registered");

    }

    return result;

  }

  public synchronized V removeIfContains(K key) {

    if (mutationClosed) {

      // We probably can safely ignore this.

      return null;

    }

    return map.remove(key);

  }

  public synchronized void put(K key, V value) {

    if (mutationClosed) {

      throw new IllegalStateException();

    }

    if (map.containsKey(key)) {

      throw new IllegalStateException("Such key is already registered");

    }

    map.put(key, value);

  }

}