/*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF 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
    *
   *   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 org.eclipse.aether.named.support;
  
  import java.util.ArrayDeque;
  import java.util.Collections;
  import java.util.Deque;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.TimeUnit;
  
  import org.eclipse.aether.named.NamedLock;
  import org.eclipse.aether.named.NamedLockKey;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Support class for {@link NamedLock} implementations providing reference counting.
   */
  public abstract class NamedLockSupport implements NamedLock {
      protected final Logger logger = LoggerFactory.getLogger(getClass());
  
      private final NamedLockKey key;
  
      private final NamedLockFactorySupport factory;
  
      private final ConcurrentHashMap<Thread, Deque<String>> diagnosticState; // non-null only if diag enabled
  
      public NamedLockSupport(final NamedLockKey key, final NamedLockFactorySupport factory) {
          this.key = key;
          this.factory = factory;
          this.diagnosticState = factory.isDiagnosticEnabled() ? new ConcurrentHashMap<>() : null;
      }
  
      @Override
      public NamedLockKey key() {
          return key;
      }
  
      @Override
      public boolean lockShared(long time, TimeUnit unit) throws InterruptedException {
          Deque<String> steps = null;
          if (diagnosticState != null) {
              steps = diagnosticState.computeIfAbsent(Thread.currentThread(), k -> new ArrayDeque<>());
          }
          if (steps != null) {
              steps.push("wait-shared");
          }
          boolean result = doLockShared(time, unit);
          if (steps != null) {
              steps.pop();
              if (result) {
                  steps.push("shared");
              }
          }
          return result;
      }
  
      protected abstract boolean doLockShared(long time, TimeUnit unit) throws InterruptedException;
  
      @Override
      public boolean lockExclusively(long time, TimeUnit unit) throws InterruptedException {
          Deque<String> steps = null;
          if (diagnosticState != null) {
              steps = diagnosticState.computeIfAbsent(Thread.currentThread(), k -> new ArrayDeque<>());
          }
          if (steps != null) {
              steps.push("wait-exclusive");
          }
          boolean result = doLockExclusively(time, unit);
          if (steps != null) {
              steps.pop();
              if (result) {
                  steps.push("exclusive");
              }
          }
          return result;
      }
  
      protected abstract boolean doLockExclusively(long time, TimeUnit unit) throws InterruptedException;
  
      @Override
      public void unlock() {
         doUnlock();
         if (diagnosticState != null) {
             diagnosticState
                     .computeIfAbsent(Thread.currentThread(), k -> new ArrayDeque<>())
                     .pop();
         }
     }
 
     protected abstract void doUnlock();
 
     @Override
     public final void close() {
         doClose();
     }
 
     protected void doClose() {
         factory.closeLock(key);
     }
 
     /**
      * Returns the diagnostic state (if collected) or empty map, never {@code null}.
      *
      * @since 1.9.11
      */
     public Map<Thread, Deque<String>> diagnosticState() {
         if (diagnosticState != null) {
             return diagnosticState;
         } else {
             return Collections.emptyMap();
         }
     }
 
     @Override
     public String toString() {
         return getClass().getSimpleName() + "{" + "key='" + key + '\'' + '}';
     }
 }