/*
    * Copyright 2021 The Netty Project
    *
    * The Netty Project licenses this file to you 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:
    *
    *   https://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 io.netty5.buffer.api;
  
  import io.netty5.util.internal.logging.InternalLogger;
  import io.netty5.util.internal.logging.InternalLoggerFactory;
  
  import java.util.function.Consumer;
  
  /**
   * The {@link LoggingLeakCallback} can be {@linkplain MemoryManager#onLeakDetected(Consumer) installed} to enable
   * logging output when a leak is detected.
   * <p>
   * The logging output will be done with the {@code ERROR} level.
   * <p>
   * Note that asynchronous and fast logging should be preferred, since the callback may run inside a cleaner-thread.
   */
  public final class LoggingLeakCallback implements Consumer<LeakInfo> {
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(LoggingLeakCallback.class);
      private static final LoggingLeakCallback instance = new LoggingLeakCallback();
  
      /**
       * Get an instance of the {@link LoggingLeakCallback}.
       *
       * @return An instance of the {@link LoggingLeakCallback} class.
       */
      public static LoggingLeakCallback getInstance() {
          return instance;
      }
  
      private LoggingLeakCallback() {
      }
  
      @Override
      public void accept(LeakInfo leakInfo) {
          if (logger.isErrorEnabled()) {
              String message = "LEAK: Object \"" + leakInfo.objectDescription() + "\" was not property closed before " +
                               "it was garbage collected. " +
                               "A life-cycle back-trace (if any) is attached as suppressed exceptions. " +
                               "See https://netty.io/wiki/reference-counted-objects.html for more information.";
              logger.error(message, LeakReport.reportFor(leakInfo));
          }
      }
  
      private static final class LeakReport extends Throwable {
          private static final long serialVersionUID = -1894217374238341652L;
  
          static LeakReport reportFor(LeakInfo info) {
              LeakReport report = new LeakReport();
              info.forEach(tracePoint -> report.addSuppressed(tracePoint.traceback()));
              return report;
          }
  
          private LeakReport() {
              super("Object life-cycle trace:", null, true, false);
          }
      }
  }