/*
    * 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.redisson;
  
  import javax.inject.Named;
  import javax.inject.Singleton;
  
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.TimeUnit;
  
  import org.eclipse.aether.named.NamedLock;
  import org.eclipse.aether.named.NamedLockKey;
  import org.eclipse.aether.named.support.AdaptedSemaphoreNamedLock;
  import org.redisson.api.RSemaphore;
  
  /**
   * Provider of {@link RedissonSemaphoreNamedLockFactory} using Redisson and {@link org.redisson.api.RSemaphore}.
   */
  @Singleton
  @Named(RedissonSemaphoreNamedLockFactory.NAME)
  public class RedissonSemaphoreNamedLockFactory extends RedissonNamedLockFactorySupport {
      public static final String NAME = "semaphore-redisson";
  
      private static final String TYPED_NAME_PREFIX = NAME_PREFIX + NAME + ":";
  
      private final ConcurrentMap<NamedLockKey, RSemaphore> semaphores;
  
      public RedissonSemaphoreNamedLockFactory() {
          this.semaphores = new ConcurrentHashMap<>();
      }
  
      @Override
      protected AdaptedSemaphoreNamedLock createLock(final NamedLockKey key) {
          RSemaphore semaphore = semaphores.computeIfAbsent(key, k -> {
              RSemaphore result = redissonClient.getSemaphore(TYPED_NAME_PREFIX + k.name());
              if (!result.trySetPermits(Integer.MAX_VALUE)) {
                  logger.warn("Failed to set permits on semaphore '{}'; it may be in a stale state", k.name());
              }
              return result;
          });
          return new AdaptedSemaphoreNamedLock(key, this, new RedissonSemaphore(semaphore));
      }
  
      @Override
      protected void destroyLock(final NamedLock namedLock) {
          if (namedLock instanceof AdaptedSemaphoreNamedLock) {
              final NamedLockKey key = namedLock.key();
              RSemaphore semaphore = semaphores.remove(key);
              if (semaphore == null) {
                  throw new IllegalStateException("Semaphore expected, but does not exist: " + key);
              }
              /* There is no reasonable way to destroy the semaphore in Redis because we cannot know
               * when the last process has stopped using it.
               */
          }
      }
  
      private static final class RedissonSemaphore implements AdaptedSemaphoreNamedLock.AdaptedSemaphore {
          private final RSemaphore semaphore;
  
          private RedissonSemaphore(final RSemaphore semaphore) {
              this.semaphore = semaphore;
          }
  
          @Override
          public boolean tryAcquire(final int perms, final long time, final TimeUnit unit) throws InterruptedException {
              return semaphore.tryAcquire(perms, time, unit);
          }
  
          @Override
          public void release(final int perms) {
              semaphore.release(perms);
          }
      }
  }