content: package act.internal.util;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * 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.
   * #L%
   */
  
  import act.Act;
  import act.crypto.AppCrypto;
  import act.util.LogSupportedDestroyableBase;
  import org.osgl.$;
  import org.osgl.util.E;
  import org.osgl.util.S;
  
  import java.io.InputStream;
  import java.util.HashMap;
  import java.util.Map;
  import javax.inject.Inject;
  import javax.inject.Singleton;
  
  @Singleton
  public class ResourceChecksumManager extends LogSupportedDestroyableBase {
  
      @Inject
      private AppCrypto crypto;
  
      // map path to checksum
      private Map<String, $.Val<String>> checksums = new HashMap<>();
  
      @Override
      protected void releaseResources() {
          checksums.clear();
          crypto = null;
      }
  
      public String checksumOf(String path) {
          E.illegalArgumentIf((path.startsWith("http:") || path.startsWith("//")));
          if (path.startsWith("/")) {
              path = path.substring(1);
          }
          if (path.contains("?")) {
              path = S.beforeFirst(path, "?");
          }
          $.Val<String> bag = checksums.get(path);
          if (null == bag) {
              InputStream is = Act.app().classLoader().getResourceAsStream(path);
              String checksum = null == is ? null : crypto.checksum(is);
              bag = $.val(checksum);
              checksums.put(path, bag);
          }
          return bag.get();
      }
  
  }
  