// Copyright (C) 2013 The Android Open Source Project
//
// Licensed 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 com.googlesource.gerrit.plugins.replication;

import com.google.common.collect.Multimap;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.common.FileUtil;
import com.google.gerrit.extensions.annotations.PluginData;
import com.google.gerrit.reviewdb.client.Project;
import com.google.gerrit.server.config.SitePaths;
import com.google.gerrit.server.git.WorkQueue;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import java.io.IOException;
import java.nio.file.Path;
import java.util.List;
import java.util.Optional;
import org.eclipse.jgit.errors.ConfigInvalidException;
import org.eclipse.jgit.transport.URIish;

@Singleton
public class AutoReloadConfigDecorator implements ReplicationConfig {
  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private ReplicationFileBasedConfig currentConfig;
  private long currentConfigTs;
  private long lastFailedConfigTs;

  private final SitePaths site;
  private final Destination.Factory destinationFactory;
  private final Path pluginDataDir;
  // Use Provider<> instead of injecting the ReplicationQueue because of circular dependency with
  // ReplicationConfig
  private final Provider<ReplicationQueue> replicationQueue;

  @Inject
  public AutoReloadConfigDecorator(
      SitePaths site,
      Destination.Factory destinationFactory,
      Provider<ReplicationQueue> replicationQueue,
      @PluginData Path pluginDataDir)
      throws ConfigInvalidException, IOException {
    this.site = site;
    this.destinationFactory = destinationFactory;
    this.pluginDataDir = pluginDataDir;
    this.currentConfig = loadConfig();
    this.currentConfigTs = getLastModified(currentConfig);
    this.replicationQueue = replicationQueue;
  }

  private static long getLastModified(ReplicationFileBasedConfig cfg) {
    return FileUtil.lastModified(cfg.getCfgPath());
  }

  private ReplicationFileBasedConfig loadConfig() throws ConfigInvalidException, IOException {
    return new ReplicationFileBasedConfig(site, destinationFactory, pluginDataDir);
  }

  private synchronized boolean isAutoReload() {
    return currentConfig.getConfig().getBoolean("gerrit", "autoReload", false);
  }

  @Override
  public synchronized List<Destination> getDestinations(FilterType filterType) {
    reloadIfNeeded();
    return currentConfig.getDestinations(filterType);
  }

  @Override
  public synchronized Multimap<Destination, URIish> getURIs(
      Optional<String> remoteName, Project.NameKey projectName, FilterType filterType) {
    reloadIfNeeded();
    return currentConfig.getURIs(remoteName, projectName, filterType);
  }

  private void reloadIfNeeded() {
    if (isAutoReload()) {
      ReplicationQueue queue = replicationQueue.get();
      long lastModified = getLastModified(currentConfig);
      try {
        if (lastModified > currentConfigTs && lastModified > lastFailedConfigTs) {
          queue.stop();
          currentConfig = loadConfig();
          currentConfigTs = lastModified;
          lastFailedConfigTs = 0;
          logger.atInfo().log(
              "Configuration reloaded: %d destinations",
              currentConfig.getDestinations(FilterType.ALL).size());
        }
      } catch (Exception e) {
        logger.atSevere().withCause(e).log(
            "Cannot reload replication configuration: keeping existing settings");
        lastFailedConfigTs = lastModified;
        return;
      } finally {
        queue.start();
      }
    }
  }

  @Override
  public synchronized boolean isReplicateAllOnPluginStart() {
    return currentConfig.isReplicateAllOnPluginStart();
  }

  @Override
  public synchronized boolean isDefaultForceUpdate() {
    return currentConfig.isDefaultForceUpdate();
  }

  @Override
  public synchronized int getMaxRefsToLog() {
    return currentConfig.getMaxRefsToLog();
  }

  @Override
  public synchronized boolean isEmpty() {
    return currentConfig.isEmpty();
  }

  @Override
  public Path getEventsDirectory() {
    return currentConfig.getEventsDirectory();
  }

  @Override
  public synchronized int shutdown() {
    return currentConfig.shutdown();
  }

  @Override
  public synchronized void startup(WorkQueue workQueue) {
    currentConfig.startup(workQueue);
  }
}

@@ -847,16 +847,76 @@
 inData;%0A
+import com.google.gerrit.extensions.annotations.PluginName;%0A
 import c
@@ -953,24 +953,24 @@
 nt.Project;%0A
-
 import com.g
@@ -1263,16 +1263,108 @@
 tional;%0A
+import java.util.concurrent.ScheduledExecutorService;%0Aimport java.util.concurrent.TimeUnit;%0A
 import o
@@ -1612,16 +1612,114 @@
 Class();
+%0A  private static final long RELOAD_DELAY = 120;%0A  private static final long RELOAD_INTERVAL = 60;
 %0A%0A  priv
@@ -2137,16 +2137,77 @@
 onQueue;
+%0A  private final ScheduledExecutorService autoReloadExecutor;
 %0A%0A  @Inj
@@ -2401,16 +2401,80 @@
 nDataDir
+,%0A      @PluginName String pluginName,%0A      WorkQueue workQueue
 )%0A      
@@ -2774,16 +2774,108 @@
 nQueue;%0A
+    this.autoReloadExecutor = workQueue.createQueue(1, pluginName + %22_auto-reload-config%22);%0A
   %7D%0A%0A  p
@@ -3410,38 +3410,16 @@
 Type) %7B%0A
-    reloadIfNeeded();%0A
     retu
@@ -3635,30 +3635,8 @@
 ) %7B%0A
-    reloadIfNeeded();%0A
     
@@ -3717,16 +3717,29 @@
 private 
+synchronized 
 void rel
@@ -5289,24 +5289,24 @@
 orkQueue) %7B%0A
-
     currentC
@@ -5327,18 +5327,142 @@
 workQueue);%0A
+    autoReloadExecutor.scheduleAtFixedRate(%0A        this::reloadIfNeeded, RELOAD_DELAY, RELOAD_INTERVAL, TimeUnit.SECONDS);%0A
   %7D%0A%7D%0A

Add auto-reload as background task