/*
    * 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.Collection;
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.Map;
  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;
  
  /**
   * Implementation of composite lock when "composition" is needed for locks that are naturally mapped as 1:1 name
   * vs some backing implementation. Instances of these locks are "unique per call" and are not ref counted.
   *
   * @since 2.0.0
   */
  public final class CompositeNamedLock extends NamedLockSupport {
      private static final Logger LOGGER = LoggerFactory.getLogger(CompositeNamedLock.class);
  
      private final Map<NamedLockKey, NamedLock> locks;
  
      private final ArrayDeque<ArrayDeque<NamedLock>> steps = new ArrayDeque<>();
  
      public CompositeNamedLock(NamedLockKey key, NamedLockFactorySupport factory, Collection<NamedLock> namedLocks) {
          super(key, factory);
          LinkedHashMap<NamedLockKey, NamedLock> map = new LinkedHashMap<>();
          namedLocks.forEach(l -> map.put(l.key(), l));
          this.locks = Collections.unmodifiableMap(map);
      }
  
      @Override
      protected boolean doLockShared(long time, TimeUnit unit) throws InterruptedException {
          return lock(time, unit, true);
      }
  
      @Override
      protected boolean doLockExclusively(long time, TimeUnit unit) throws InterruptedException {
          return lock(time, unit, false);
      }
  
      private boolean lock(long time, TimeUnit timeUnit, boolean shared) throws InterruptedException {
          final ArrayDeque<NamedLock> step = new ArrayDeque<>(locks.size());
          final String timeStr = time + " " + timeUnit;
          final String lockKind = shared ? "shared" : "exclusive";
          LOGGER.trace(
                  "{}: Need {} {} lock(s) of {} in {}", key().name(), locks.size(), lockKind, key().resources(), timeStr);
          for (NamedLock namedLock : locks.values()) {
              LOGGER.trace("{}: Acquiring {} lock for '{}'", key().name(), lockKind, namedLock.key());
  
              boolean locked;
              if (shared) {
                  locked = namedLock.lockShared(time, timeUnit);
              } else {
                  locked = namedLock.lockExclusively(time, timeUnit);
              }
  
              if (!locked) {
                  LOGGER.trace(
                          "{}: Failed to acquire {} lock for '{}' in {}",
                          key().name(),
                          lockKind,
                          namedLock.key(),
                          timeStr);
  
                  unlockAll(step);
                  break;
              } else {
                  step.push(namedLock);
              }
          }
          if (step.size() == locks.size()) {
              steps.push(step);
              return true;
          }
          unlockAll(step);
          return false;
      }
 
     @Override
     protected void doUnlock() {
         unlockAll(steps.pop());
     }
 
     @Override
     protected void doClose() {
         locks.values().forEach(NamedLock::close);
     }
 
     private void unlockAll(final ArrayDeque<NamedLock> locks) {
         if (locks.isEmpty()) {
             return;
         }
 
         // Release locks in reverse locking order
         while (!locks.isEmpty()) {
             NamedLock namedLock = locks.pop();
             LOGGER.trace("{}: Releasing lock for '{}'", key().name(), namedLock.key());
             namedLock.unlock();
         }
     }
 }