/*
 * 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.flink.streaming.api.operators.sorted.state;

import org.apache.flink.api.common.state.ListState;
import org.apache.flink.api.common.state.State;
import org.apache.flink.api.common.state.StateDescriptor;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.runtime.state.internal.InternalListState;

import java.util.ArrayList;
import java.util.List;

import static org.apache.flink.util.Preconditions.checkNotNull;

/** A {@link ListState} which keeps value for a single key at a time. */
class BatchExecutionKeyListState<K, N, T>
        extends MergingAbstractBatchExecutionKeyState<K, N, List<T>, T, Iterable<T>>
        implements InternalListState<K, N, T> {

    protected BatchExecutionKeyListState(
            List<T> defaultValue,
            TypeSerializer<K> keySerializer,
            TypeSerializer<N> namespaceSerializer,
            TypeSerializer<List<T>> stateTypeSerializer) {
        super(defaultValue, keySerializer, namespaceSerializer, stateTypeSerializer);
    }

    @Override
    public void update(List<T> values) {
        checkNotNull(values);
        clear();
        for (T value : values) {
            add(value);
        }
    }

    @Override
    public void addAll(List<T> values) {
        if (checkNotNull(values).isEmpty()) {
            return;
        }
        for (T value : values) {
            add(value);
        }
    }

    @Override
    public void add(T value) {
        checkNotNull(value);
        initIfNull();
        getCurrentNamespaceValue().add(value);
    }

    private void initIfNull() {
        if (getCurrentNamespaceValue() == null) {
            setCurrentNamespaceValue(new ArrayList<>());
        }
    }

    @Override
    public Iterable<T> get() throws Exception {
        return getCurrentNamespaceValue();
    }

    @SuppressWarnings("unchecked")
    static <T, K, N, SV, S extends State, IS extends S> IS create(
            TypeSerializer<K> keySerializer,
            TypeSerializer<N> namespaceSerializer,
            StateDescriptor<S, SV> stateDesc) {
        return (IS)
                new BatchExecutionKeyListState<>(
                        (List<T>) stateDesc.getDefaultValue(),
                        keySerializer,
                        namespaceSerializer,
                        (TypeSerializer<List<T>>) stateDesc.getSerializer());
    }

    @Override
    protected List<T> merge(List<T> target, List<T> source) {
        target.addAll(source);
        return target;
    }
}
