// Copyright (C) 2024 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.pull;

import static com.googlesource.gerrit.plugins.replication.pull.SourceConfiguration.DEFAULT_PERIODIC_FETCH_DISABLED;
import static java.util.stream.Collectors.toList;

import com.google.common.base.Suppliers;
import com.google.common.flogger.FluentLogger;
import com.google.gerrit.server.git.WorkQueue;
import com.google.inject.Inject;
import com.google.inject.Provider;
import com.google.inject.Singleton;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.function.Supplier;

@Singleton
class SourcesFetchPeriodically {
  private static final FluentLogger logger = FluentLogger.forEnclosingClass();

  private final WorkQueue workQueue;
  private final Provider<SourcesCollection> sources;
  private final Provider<SourceFetchPeriodically.Factory> fetchAllCreator;
  private final List<ScheduledFuture<?>> scheduled;

  @Inject
  SourcesFetchPeriodically(
      WorkQueue workQueue,
      Provider<SourcesCollection> sources,
      Provider<SourceFetchPeriodically.Factory> fetchAllCreator) {
    this.workQueue = workQueue;
    this.sources = sources;
    this.fetchAllCreator = fetchAllCreator;
    this.scheduled = new ArrayList<>();
  }

  void start() {
    scheduled.addAll(scheduleFetchAll(workQueue, sources.get(), fetchAllCreator.get()));
  }

  private List<ScheduledFuture<?>> scheduleFetchAll(
      WorkQueue workQueue,
      SourcesCollection sources,
      SourceFetchPeriodically.Factory fetchAllCreator) {
    Supplier<ScheduledExecutorService> queue =
        Suppliers.memoize(() -> workQueue.createQueue(1, "PeriodicallyFetchFromSources"));
    return sources.getAll().stream()
        .filter(source -> source.fetchEvery() > DEFAULT_PERIODIC_FETCH_DISABLED)
        .map(
            source -> {
              logger.atInfo().log(
                  "Enabling periodic (every %ds) fetch of all refs for [%s] remote",
                  source.fetchEvery(), source.getRemoteConfigName());
              return fetchAllCreator.create(source).start(queue.get());
            })
        .collect(toList());
  }

  void stop() {
    scheduled.forEach(schedule -> schedule.cancel(true));
  }
}