/*
 * 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.connector.file.table.stream;

import org.apache.flink.annotation.Internal;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.core.fs.Path;
import org.apache.flink.runtime.state.StateInitializationContext;
import org.apache.flink.runtime.state.StateSnapshotContext;
import org.apache.flink.streaming.api.functions.sink.filesystem.StreamingFileSink;
import org.apache.flink.streaming.runtime.streamrecord.StreamRecord;

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NavigableMap;
import java.util.Set;
import java.util.TreeMap;

import static org.apache.flink.connector.file.table.FileSystemConnectorOptions.SINK_PARTITION_COMMIT_POLICY_KIND;
import static org.apache.flink.connector.file.table.stream.PartitionCommitPredicate.PredicateContext;

/** Writer for emitting {@link PartitionCommitInfo} to downstream. */
@Internal
public class StreamingFileWriter<IN> extends AbstractStreamingWriter<IN, PartitionCommitInfo> {

    private static final long serialVersionUID = 2L;

    private final List<String> partitionKeys;
    private final Configuration conf;

    private transient Set<String> currentNewPartitions;
    private transient TreeMap<Long, Set<String>> newPartitions;
    private transient Set<String> committablePartitions;
    private transient Map<String, Long> inProgressPartitions;

    private transient PartitionCommitPredicate partitionCommitPredicate;

    public StreamingFileWriter(
            long bucketCheckInterval,
            StreamingFileSink.BucketsBuilder<
                            IN, String, ? extends StreamingFileSink.BucketsBuilder<IN, String, ?>>
                    bucketsBuilder,
            List<String> partitionKeys,
            Configuration conf) {
        super(bucketCheckInterval, bucketsBuilder);
        this.partitionKeys = partitionKeys;
        this.conf = conf;
    }

    @Override
    public void initializeState(StateInitializationContext context) throws Exception {
        if (isPartitionCommitTriggerEnabled()) {
            partitionCommitPredicate =
                    PartitionCommitPredicate.create(conf, getUserCodeClassloader(), partitionKeys);
        }

        currentNewPartitions = new HashSet<>();
        newPartitions = new TreeMap<>();
        committablePartitions = new HashSet<>();
        inProgressPartitions = new HashMap<>();
        super.initializeState(context);
    }

    @Override
    protected void partitionCreated(String partition) {
        currentNewPartitions.add(partition);
        inProgressPartitions.putIfAbsent(
                partition, getProcessingTimeService().getCurrentProcessingTime());
    }

    @Override
    protected void partitionInactive(String partition) {
        committablePartitions.add(partition);
        inProgressPartitions.remove(partition);
    }

    @Override
    protected void onPartFileOpened(String s, Path newPath) {}

    @Override
    public void snapshotState(StateSnapshotContext context) throws Exception {
        closePartFileForPartitions();
        super.snapshotState(context);
        newPartitions.put(context.getCheckpointId(), new HashSet<>(currentNewPartitions));
        currentNewPartitions.clear();
    }

    private boolean isPartitionCommitTriggerEnabled() {
        // when partition keys and partition commit policy exist,
        // the partition commit trigger is enabled
        return partitionKeys.size() > 0 && conf.contains(SINK_PARTITION_COMMIT_POLICY_KIND);
    }

    /** Close in-progress part file when partition is committable. */
    private void closePartFileForPartitions() throws Exception {
        if (partitionCommitPredicate != null) {
            final Iterator<Map.Entry<String, Long>> iterator =
                    inProgressPartitions.entrySet().iterator();
            while (iterator.hasNext()) {
                Map.Entry<String, Long> entry = iterator.next();
                String partition = entry.getKey();
                Long creationTime = entry.getValue();
                PredicateContext predicateContext =
                        PartitionCommitPredicate.createPredicateContext(
                                partition,
                                creationTime,
                                processingTimeService.getCurrentProcessingTime(),
                                currentWatermark);
                if (partitionCommitPredicate.isPartitionCommittable(predicateContext)) {
                    // if partition is committable, close in-progress part file in this partition
                    buckets.closePartFileForBucket(partition);
                    iterator.remove();
                }
            }
        }
    }

    @Override
    protected void commitUpToCheckpoint(long checkpointId) throws Exception {
        super.commitUpToCheckpoint(checkpointId);

        NavigableMap<Long, Set<String>> headPartitions =
                this.newPartitions.headMap(checkpointId, true);
        Set<String> partitions = new HashSet<>(committablePartitions);
        committablePartitions.clear();
        headPartitions.values().forEach(partitions::addAll);
        headPartitions.clear();

        output.collect(
                new StreamRecord<>(
                        new PartitionCommitInfo(
                                checkpointId,
                                getRuntimeContext().getIndexOfThisSubtask(),
                                getRuntimeContext().getNumberOfParallelSubtasks(),
                                partitions.toArray(new String[0]))));
    }
}
