/*
    * Copyright 2021 LINE Corporation
    *
    * LINE Corporation 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:
    *
    *   https://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.linecorp.centraldogma.client;
  
  import java.util.concurrent.CompletableFuture;
  import java.util.concurrent.Executor;
  import java.util.concurrent.ScheduledExecutorService;
  import java.util.function.Function;
  
  import javax.annotation.Nullable;
  
  import com.linecorp.centraldogma.common.Entry;
  import com.linecorp.centraldogma.common.Query;
  import com.linecorp.centraldogma.common.Revision;
  
  final class FileWatcher<T> extends AbstractWatcher<T> {
  
      private final CentralDogma centralDogma;
      private final String projectName;
      private final String repositoryName;
      private final Query<T> query;
      private final long timeoutMillis;
      private final boolean errorOnEntryNotFound;
      @Nullable
      private final Function<Object, ? extends T> mapper;
      @Nullable
      private final Executor mapperExecutor;
  
      FileWatcher(CentralDogma centralDogma, ScheduledExecutorService watchScheduler,
                  String projectName, String repositoryName, Query<T> query,
                  long timeoutMillis, boolean errorOnEntryNotFound,
                  @Nullable Function<Object, ? extends T> mapper, Executor mapperExecutor,
                  long delayOnSuccessMillis, long initialDelayMillis, long maxDelayMillis,
                  double multiplier, double jitterRate) {
          super(watchScheduler, projectName, repositoryName, query.path(), errorOnEntryNotFound,
                delayOnSuccessMillis, initialDelayMillis, maxDelayMillis, multiplier, jitterRate);
          this.centralDogma = centralDogma;
          this.projectName = projectName;
          this.repositoryName = repositoryName;
          this.query = query;
          this.timeoutMillis = timeoutMillis;
          this.errorOnEntryNotFound = errorOnEntryNotFound;
          this.mapper = mapper;
          this.mapperExecutor = mapperExecutor;
      }
  
      @Override
      CompletableFuture<Latest<T>> doWatch(Revision lastKnownRevision) {
          final CompletableFuture<Entry<T>> future = centralDogma.watchFile(
                  projectName, repositoryName, lastKnownRevision, query, timeoutMillis, errorOnEntryNotFound);
          if (mapper == null) {
              return future.thenApply(entry -> {
                  if (entry == null) {
                      return null;
                  }
                  return new Latest<>(entry.revision(), entry.content());
              });
          }
          return future.thenApplyAsync(entry -> {
              if (entry == null) {
                  return null;
              }
              return new Latest<>(entry.revision(), mapper.apply(entry.content()));
          }, mapperExecutor);
      }
  }