content: /*
   * 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.kafka.streams.state.internals;
  
  import org.apache.kafka.streams.errors.InvalidStateStoreException;
  import org.apache.kafka.streams.kstream.Windowed;
  import org.apache.kafka.streams.state.KeyValueIterator;
  import org.apache.kafka.streams.state.QueryableStoreType;
  import org.apache.kafka.streams.state.ReadOnlyWindowStore;
  import org.apache.kafka.streams.state.WindowStoreIterator;
  
  import java.time.Instant;
  import java.util.List;
  import java.util.Objects;
  
  /**
   * Wrapper over the underlying {@link ReadOnlyWindowStore}s found in a {@link
   * org.apache.kafka.streams.processor.internals.ProcessorTopology}
   */
  public class CompositeReadOnlyWindowStore<K, V> implements ReadOnlyWindowStore<K, V> {
  
      private final QueryableStoreType<ReadOnlyWindowStore<K, V>> windowStoreType;
      private final String storeName;
      private final StateStoreProvider provider;
  
      public CompositeReadOnlyWindowStore(final StateStoreProvider provider,
                                          final QueryableStoreType<ReadOnlyWindowStore<K, V>> windowStoreType,
                                          final String storeName) {
          this.provider = provider;
          this.windowStoreType = windowStoreType;
          this.storeName = storeName;
      }
  
      @Override
      public V fetch(final K key, final long time) {
          Objects.requireNonNull(key, "key can't be null");
          final List<ReadOnlyWindowStore<K, V>> stores = provider.stores(storeName, windowStoreType);
          for (final ReadOnlyWindowStore<K, V> windowStore : stores) {
              try {
                  final V result = windowStore.fetch(key, time);
                  if (result != null) {
                      return result;
                  }
              } catch (final InvalidStateStoreException e) {
                  throw new InvalidStateStoreException(
                      "State store is not available anymore and may have been migrated to another instance; " +
                          "please re-discover its location from the state metadata.");
              }
          }
          return null;
      }
  
      @Override
      public WindowStoreIterator<V> fetch(final K key,
                                          final Instant timeFrom,
                                          final Instant timeTo) {
          Objects.requireNonNull(key, "key can't be null");
          final List<ReadOnlyWindowStore<K, V>> stores = provider.stores(storeName, windowStoreType);
          for (final ReadOnlyWindowStore<K, V> windowStore : stores) {
              try {
                  final WindowStoreIterator<V> result = windowStore.fetch(key, timeFrom, timeTo);
                  if (!result.hasNext()) {
                      result.close();
                  } else {
                      return result;
                  }
              } catch (final InvalidStateStoreException e) {
                  throw new InvalidStateStoreException(
                      "State store is not available anymore and may have been migrated to another instance; " +
                          "please re-discover its location from the state metadata.");
              }
          }
          return KeyValueIterators.emptyWindowStoreIterator();
      }
  
      @Override
      public WindowStoreIterator<V> backwardFetch(final K key,
                                                  final Instant timeFrom,
                                                  final Instant timeTo) throws IllegalArgumentException {
          Objects.requireNonNull(key, "key can't be null");
          final List<ReadOnlyWindowStore<K, V>> stores = provider.stores(storeName, windowStoreType);
          for (final ReadOnlyWindowStore<K, V> windowStore : stores) {
              try {
                  final WindowStoreIterator<V> result = windowStore.backwardFetch(key, timeFrom, timeTo);
                  if (!result.hasNext()) {
                      result.close();
                  } else {
                      return result;
                  }
              } catch (final InvalidStateStoreException e) {
                  throw new InvalidStateStoreException(
                      "State store is not available anymore and may have been migrated to another instance; " +
                          "please re-discover its location from the state metadata.");
              }
          }
          return KeyValueIterators.emptyWindowStoreIterator();
      }
  
      @Override
      public KeyValueIterator<Windowed<K>, V> fetch(final K keyFrom,
                                                    final K keyTo,
                                                    final Instant timeFrom,
                                                    final Instant timeTo) {
          final NextIteratorFunction<Windowed<K>, V, ReadOnlyWindowStore<K, V>> nextIteratorFunction =
              store -> store.fetch(keyFrom, keyTo, timeFrom, timeTo);
          return new DelegatingPeekingKeyValueIterator<>(
              storeName,
              new CompositeKeyValueIterator<>(
                  provider.stores(storeName, windowStoreType).iterator(),
                  nextIteratorFunction));
      }
  
      @Override
      public KeyValueIterator<Windowed<K>, V> backwardFetch(final K keyFrom,
                                                            final K keyTo,
                                                            final Instant timeFrom,
                                                            final Instant timeTo) throws IllegalArgumentException {
          final NextIteratorFunction<Windowed<K>, V, ReadOnlyWindowStore<K, V>> nextIteratorFunction =
              store -> store.backwardFetch(keyFrom, keyTo, timeFrom, timeTo);
          return new DelegatingPeekingKeyValueIterator<>(
              storeName,
              new CompositeKeyValueIterator<>(
                  provider.stores(storeName, windowStoreType).iterator(),
                  nextIteratorFunction));
      }
  
      @Override
      public KeyValueIterator<Windowed<K>, V> all() {
          final NextIteratorFunction<Windowed<K>, V, ReadOnlyWindowStore<K, V>> nextIteratorFunction =
              ReadOnlyWindowStore::all;
          return new DelegatingPeekingKeyValueIterator<>(
              storeName,
              new CompositeKeyValueIterator<>(
                  provider.stores(storeName, windowStoreType).iterator(),
                  nextIteratorFunction));
      }
  
      @Override
      public KeyValueIterator<Windowed<K>, V> backwardAll() {
          final NextIteratorFunction<Windowed<K>, V, ReadOnlyWindowStore<K, V>> nextIteratorFunction =
              ReadOnlyWindowStore::backwardAll;
          return new DelegatingPeekingKeyValueIterator<>(
              storeName,
              new CompositeKeyValueIterator<>(
                  provider.stores(storeName, windowStoreType).iterator(),
                  nextIteratorFunction));
      }
  
      @Override
      public KeyValueIterator<Windowed<K>, V> fetchAll(final Instant timeFrom,
                                                       final Instant timeTo) {
          final NextIteratorFunction<Windowed<K>, V, ReadOnlyWindowStore<K, V>> nextIteratorFunction =
              store -> store.fetchAll(timeFrom, timeTo);
          return new DelegatingPeekingKeyValueIterator<>(
              storeName,
              new CompositeKeyValueIterator<>(
                  provider.stores(storeName, windowStoreType).iterator(),
                  nextIteratorFunction));
      }
  
      @Override
      public KeyValueIterator<Windowed<K>, V> backwardFetchAll(final Instant timeFrom,
                                                               final Instant timeTo) throws IllegalArgumentException {
          final NextIteratorFunction<Windowed<K>, V, ReadOnlyWindowStore<K, V>> nextIteratorFunction =
              store -> store.backwardFetchAll(timeFrom, timeTo);
          return new DelegatingPeekingKeyValueIterator<>(
              storeName,
              new CompositeKeyValueIterator<>(
                  provider.stores(storeName, windowStoreType).iterator(),
                  nextIteratorFunction));
      }
  }
  