/*
 * 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.cassandra.db.compaction.writers;

import java.util.Collection;
import java.util.Set;

import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.DecoratedKey;
import org.apache.cassandra.db.Directories;
import org.apache.cassandra.db.rows.UnfilteredRowIterator;
import org.apache.cassandra.db.compaction.CompactionTask;
import org.apache.cassandra.db.lifecycle.LifecycleTransaction;
import org.apache.cassandra.io.sstable.SSTableRewriter;
import org.apache.cassandra.io.sstable.format.SSTableReader;
import org.apache.cassandra.utils.concurrent.Transactional;


/**
 * Class that abstracts away the actual writing of files to make it possible to use CompactionTask for more
 * use cases.
 */
public abstract class CompactionAwareWriter extends Transactional.AbstractTransactional implements Transactional
{
    protected final ColumnFamilyStore cfs;
    protected final Directories directories;
    protected final Set<SSTableReader> nonExpiredSSTables;
    protected final long estimatedTotalKeys;
    protected final long maxAge;
    protected final long minRepairedAt;

    protected final LifecycleTransaction txn;
    protected final SSTableRewriter sstableWriter;
    private boolean isInitialized = false;

    public CompactionAwareWriter(ColumnFamilyStore cfs,
                                 Directories directories,
                                 LifecycleTransaction txn,
                                 Set<SSTableReader> nonExpiredSSTables,
                                 boolean offline,
                                 boolean keepOriginals)
    {
        this.cfs = cfs;
        this.directories = directories;
        this.nonExpiredSSTables = nonExpiredSSTables;
        this.estimatedTotalKeys = SSTableReader.getApproximateKeyCount(nonExpiredSSTables);
        this.maxAge = CompactionTask.getMaxDataAge(nonExpiredSSTables);
        this.minRepairedAt = CompactionTask.getMinRepairedAt(nonExpiredSSTables);
        this.txn = txn;
        this.sstableWriter = SSTableRewriter.construct(cfs, txn, keepOriginals, maxAge, offline);
    }

    @Override
    protected Throwable doAbort(Throwable accumulate)
    {
        return sstableWriter.abort(accumulate);
    }

    @Override
    protected Throwable doCommit(Throwable accumulate)
    {
        return sstableWriter.commit(accumulate);
    }

    @Override
    protected void doPrepare()
    {
        sstableWriter.prepareToCommit();
    }

    /**
     * we are done, return the finished sstables so that the caller can mark the old ones as compacted
     * @return all the written sstables sstables
     */
    @Override
    public Collection<SSTableReader> finish()
    {
        super.finish();
        return sstableWriter.finished();
    }

    /**
     * estimated number of keys we should write
     */
    public long estimatedKeys()
    {
        return estimatedTotalKeys;
    }

    public final boolean append(UnfilteredRowIterator partition)
    {
        maybeSwitchWriter(partition.partitionKey());
        return realAppend(partition);
    }

    @Override
    protected Throwable doPostCleanup(Throwable accumulate)
    {
        sstableWriter.close();
        return super.doPostCleanup(accumulate);
    }

    protected abstract boolean realAppend(UnfilteredRowIterator partition);

    /**
     * Guaranteed to be called before the first call to realAppend.
     * @param key
     */
    protected void maybeSwitchWriter(DecoratedKey key)
    {
        if (!isInitialized)
            switchCompactionLocation(getDirectories().getWriteableLocation(cfs.getExpectedCompactedFileSize(nonExpiredSSTables, txn.opType())));
        isInitialized = true;
    }

    /**
     * Implementations of this method should finish the current sstable writer and start writing to this directory.
     *
     * Called once before starting to append and then whenever we see a need to start writing to another directory.
     * @param directory
     */
    protected abstract void switchCompactionLocation(Directories.DataDirectory directory);

    /**
     * The directories we can write to
     */
    public Directories getDirectories()
    {
        return directories;
    }

    /**
     * Return a directory where we can expect expectedWriteSize to fit.
     */
    public Directories.DataDirectory getWriteDirectory(long expectedWriteSize)
    {
        Directories.DataDirectory directory = getDirectories().getWriteableLocation(expectedWriteSize);
        if (directory == null)
            throw new RuntimeException("Insufficient disk space to write " + expectedWriteSize + " bytes");

        return directory;
    }
}