/*
    * 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.ipc;
  
  import java.util.ArrayDeque;
  import java.util.Collection;
  import java.util.Objects;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.TimeoutException;
  
  import org.eclipse.aether.named.NamedLockKey;
  import org.eclipse.aether.named.support.LockUpgradeNotSupportedException;
  import org.eclipse.aether.named.support.NamedLockSupport;
  
  /**
   * IPC named locks.
   *
   * @since 2.0.1
   */
  class IpcNamedLock extends NamedLockSupport {
  
      final IpcClient client;
      final Collection<String> keys;
      final ThreadLocal<ArrayDeque<Ctx>> contexts;
  
      IpcNamedLock(NamedLockKey key, IpcNamedLockFactory factory, IpcClient client, Collection<String> keys) {
          super(key, factory);
          this.client = client;
          this.keys = keys;
          this.contexts = ThreadLocal.withInitial(ArrayDeque::new);
      }
  
      @Override
      public boolean doLockShared(long time, TimeUnit unit) {
          ArrayDeque<Ctx> contexts = this.contexts.get();
          if (!contexts.isEmpty()) {
              contexts.push(new Ctx(false, null, true));
              return true;
          }
          try {
              String contextId = client.newContext(true, time, unit);
              client.lock(Objects.requireNonNull(contextId), keys, time, unit);
              contexts.push(new Ctx(true, contextId, true));
              return true;
          } catch (TimeoutException e) {
              return false;
          }
      }
  
      @Override
      public boolean doLockExclusively(long time, TimeUnit unit) {
          ArrayDeque<Ctx> contexts = this.contexts.get();
          if (contexts.stream().anyMatch(c -> c.shared)) {
              throw new LockUpgradeNotSupportedException(this);
          }
          if (!contexts.isEmpty()) {
              contexts.push(new Ctx(false, null, false));
              return true;
          }
          try {
              String contextId = client.newContext(false, time, unit);
              client.lock(Objects.requireNonNull(contextId), keys, time, unit);
              contexts.push(new Ctx(true, contextId, false));
              return true;
          } catch (TimeoutException e) {
              return false;
          }
      }
  
      @Override
      public void doUnlock() {
          ArrayDeque<Ctx> contexts = this.contexts.get();
          if (contexts.isEmpty()) {
              throw new IllegalStateException("improper boxing");
          }
          Ctx ctx = contexts.pop();
          if (ctx.acted) {
              client.unlock(ctx.contextId);
          }
      }
  
      private static final class Ctx {
          private final boolean acted;
         private final String contextId;
         private final boolean shared;
 
         private Ctx(boolean acted, String contextId, boolean shared) {
             this.acted = acted;
             this.contextId = contextId;
             this.shared = shared;
         }
     }
 }