/*
    * 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.internal.impl.synccontext.named;
  
  import java.util.ArrayDeque;
  import java.util.Collection;
  import java.util.Deque;
  import java.util.Objects;
  import java.util.concurrent.TimeUnit;
  
  import org.eclipse.aether.RepositorySystemSession;
  import org.eclipse.aether.SyncContext;
  import org.eclipse.aether.artifact.Artifact;
  import org.eclipse.aether.metadata.Metadata;
  import org.eclipse.aether.named.NamedLock;
  import org.eclipse.aether.named.NamedLockFactory;
  import org.eclipse.aether.named.providers.FileLockNamedLockFactory;
  import org.eclipse.aether.util.ConfigUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Adapter to adapt {@link NamedLockFactory} and {@link NamedLock} to {@link SyncContext}.
   */
  public final class NamedLockFactoryAdapter {
      public static final String TIME_KEY = "aether.syncContext.named.time";
  
      public static final long DEFAULT_TIME = 30L;
  
      public static final String TIME_UNIT_KEY = "aether.syncContext.named.time.unit";
  
      public static final TimeUnit DEFAULT_TIME_UNIT = TimeUnit.SECONDS;
  
      private final NameMapper nameMapper;
  
      private final NamedLockFactory namedLockFactory;
  
      public NamedLockFactoryAdapter(final NameMapper nameMapper, final NamedLockFactory namedLockFactory) {
          this.nameMapper = Objects.requireNonNull(nameMapper);
          this.namedLockFactory = Objects.requireNonNull(namedLockFactory);
          // TODO: this is ad-hoc "validation", experimental and likely to change
          if (this.namedLockFactory instanceof FileLockNamedLockFactory && !this.nameMapper.isFileSystemFriendly()) {
              throw new IllegalArgumentException(
                      "Misconfiguration: FileLockNamedLockFactory lock factory requires FS friendly NameMapper");
          }
      }
  
      public SyncContext newInstance(final RepositorySystemSession session, final boolean shared) {
          return new AdaptedLockSyncContext(session, shared, nameMapper, namedLockFactory);
      }
  
      /**
       * @since 1.9.1
       */
      public NameMapper getNameMapper() {
          return nameMapper;
      }
  
      /**
       * @since 1.9.1
       */
      public NamedLockFactory getNamedLockFactory() {
          return namedLockFactory;
      }
  
      public String toString() {
          return getClass().getSimpleName()
                  + "(nameMapper=" + nameMapper
                  + ", namedLockFactory=" + namedLockFactory
                  + ")";
      }
  
      private static class AdaptedLockSyncContext implements SyncContext {
          private static final Logger LOGGER = LoggerFactory.getLogger(AdaptedLockSyncContext.class);
  
          private final RepositorySystemSession session;
  
          private final boolean shared;
  
          private final NameMapper lockNaming;
  
          private final NamedLockFactory namedLockFactory;
  
         private final long time;
 
         private final TimeUnit timeUnit;
 
         private final Deque<NamedLock> locks;
 
         private AdaptedLockSyncContext(
                 final RepositorySystemSession session,
                 final boolean shared,
                 final NameMapper lockNaming,
                 final NamedLockFactory namedLockFactory) {
             this.session = session;
             this.shared = shared;
             this.lockNaming = lockNaming;
             this.namedLockFactory = namedLockFactory;
             this.time = getTime(session);
             this.timeUnit = getTimeUnit(session);
             this.locks = new ArrayDeque<>();
 
             if (time < 0L) {
                 throw new IllegalArgumentException("time cannot be negative");
             }
         }
 
         private long getTime(final RepositorySystemSession session) {
             return ConfigUtils.getLong(session, DEFAULT_TIME, TIME_KEY);
         }
 
         private TimeUnit getTimeUnit(final RepositorySystemSession session) {
             return TimeUnit.valueOf(ConfigUtils.getString(session, DEFAULT_TIME_UNIT.name(), TIME_UNIT_KEY));
         }
 
         @Override
         public void acquire(Collection<? extends Artifact> artifacts, Collection<? extends Metadata> metadatas) {
             Collection<String> keys = lockNaming.nameLocks(session, artifacts, metadatas);
             if (keys.isEmpty()) {
                 return;
             }
 
             LOGGER.trace("Need {} {} lock(s) for {}", keys.size(), shared ? "read" : "write", keys);
             int acquiredLockCount = 0;
             for (String key : keys) {
                 NamedLock namedLock = namedLockFactory.getLock(key);
                 try {
                     LOGGER.trace("Acquiring {} lock for '{}'", shared ? "read" : "write", 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 '{}'", shared ? "read" : "write", key);
 
                         namedLock.close();
                         throw new IllegalStateException("Could not acquire " + (shared ? "read" : "write")
                                 + " lock for '" + namedLock.name() + "'");
                     }
 
                     locks.push(namedLock);
                     acquiredLockCount++;
                 } catch (InterruptedException e) {
                     Thread.currentThread().interrupt();
                     throw new RuntimeException(e);
                 }
             }
             LOGGER.trace("Total locks acquired: {}", acquiredLockCount);
         }
 
         @Override
         public void close() {
             if (locks.isEmpty()) {
                 return;
             }
 
             // Release locks in reverse insertion order
             int released = 0;
             while (!locks.isEmpty()) {
                 try (NamedLock namedLock = locks.pop()) {
                     LOGGER.trace("Releasing {} lock for '{}'", shared ? "read" : "write", namedLock.name());
                     namedLock.unlock();
                     released++;
                 }
             }
             LOGGER.trace("Total locks released: {}", released);
         }
     }
 }