/*
    * 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.apache.syncope.core.provisioning.java.pushpull;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.Optional;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.Future;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.function.Supplier;
  import org.apache.syncope.core.persistence.api.entity.task.ProvisioningTask;
  import org.apache.syncope.core.provisioning.api.pushpull.ProvisioningActions;
  import org.apache.syncope.core.provisioning.api.pushpull.ProvisioningProfile;
  import org.apache.syncope.core.provisioning.api.pushpull.SyncopeResultHandler;
  import org.apache.syncope.core.spring.security.AuthContextUtils;
  import org.apache.syncope.core.spring.security.SyncopeAuthenticationDetails;
  import org.apache.syncope.core.spring.security.SyncopeGrantedAuthority;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
  import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
  import org.springframework.security.core.context.SecurityContextHolder;
  import org.springframework.security.core.userdetails.User;
  
  public abstract class SyncopeResultHandlerDispatcher<
          T extends ProvisioningTask<?>, A extends ProvisioningActions, RA extends SyncopeResultHandler<T, A>> {
  
      protected static final Logger LOG = LoggerFactory.getLogger(SyncopeResultHandlerDispatcher.class);
  
      private static final String PLACEHOLDER_PWD = "PLACEHOLDER_PWD";
  
      protected final Optional<ThreadPoolTaskExecutor> tpte;
  
      protected final Map<String, Supplier<RA>> suppliers = new ConcurrentHashMap<>();
  
      protected final Map<String, RA> handlers = new ConcurrentHashMap<>();
  
      protected final List<Future<?>> futures = new ArrayList<>();
  
      protected SyncopeResultHandlerDispatcher(final ProvisioningProfile<T, A> profile) {
          if (profile.getTask().getConcurrentSettings() == null) {
              tpte = Optional.empty();
          } else {
              ThreadPoolTaskExecutor t = new ThreadPoolTaskExecutor();
              t.setCorePoolSize(profile.getTask().getConcurrentSettings().getCorePoolSize());
              t.setMaxPoolSize(profile.getTask().getConcurrentSettings().getMaxPoolSize());
              t.setQueueCapacity(profile.getTask().getConcurrentSettings().getQueueCapacity());
              t.setWaitForTasksToCompleteOnShutdown(true);
              t.setThreadNamePrefix("provisioningTask-" + profile.getTask().getKey() + "-");
              t.setRejectedExecutionHandler(new ThreadPoolExecutor.AbortPolicy());
  
              String domain = AuthContextUtils.getDomain();
              String delegatedBy = AuthContextUtils.getDelegatedBy().orElse(null);
              Set<SyncopeGrantedAuthority> authorities = AuthContextUtils.getAuthorities();
              t.setTaskDecorator(d -> () -> {
                  // set placeholder authentication object by creating fresh and copying data from caller's
                  UsernamePasswordAuthenticationToken placeHolderAuth = new UsernamePasswordAuthenticationToken(
                          new User(profile.getExecutor(), PLACEHOLDER_PWD, authorities), PLACEHOLDER_PWD, authorities);
                  placeHolderAuth.setDetails(new SyncopeAuthenticationDetails(domain, delegatedBy));
                  SecurityContextHolder.getContext().setAuthentication(placeHolderAuth);
  
                  d.run();
              });
  
              t.initialize();
  
              tpte = Optional.of(t);
          }
      }
  
      public void addHandlerSupplier(final String key, final Supplier<RA> supplier) {
          suppliers.put(key, supplier);
      }
  
      protected RA nonConcurrentHandler(final String key) {
          return Optional.ofNullable(handlers.get(key)).orElseGet(() -> {
              RA h = suppliers.get(key).get();
              handlers.put(key, h);
              return h;
         });
     }
 
     protected void submit(final Runnable runnable) {
         tpte.ifPresent(executor -> futures.add(executor.submit(runnable)));
     }
 
     protected void shutdown() {
         for (Future<?> f : this.futures) {
             try {
                 f.get();
             } catch (ExecutionException | InterruptedException e) {
                 LOG.error("Unexpected error when waiting for completion", e);
             }
         }
 
         tpte.ifPresent(ThreadPoolTaskExecutor::shutdown);
     }
 }