/*
 * 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.streaming;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterators;
import org.apache.cassandra.db.TypeSizes;
import org.apache.cassandra.io.IVersionedSerializer;
import org.apache.cassandra.io.sstable.Component;
import org.apache.cassandra.io.sstable.Descriptor;
import org.apache.cassandra.io.util.DataInputPlus;
import org.apache.cassandra.io.util.DataOutputPlus;

import java.io.File;
import java.io.IOException;
import java.util.*;

/**
 * SSTable components and their sizes to be tranfered via entire-sstable-streaming
 */
public final class ComponentManifest implements Iterable<Component>
{
    private static final List<Component> STREAM_COMPONENTS = ImmutableList.of(Component.DATA, Component.PRIMARY_INDEX, Component.STATS,
                                                                             Component.COMPRESSION_INFO, Component.FILTER, Component.SUMMARY,
                                                                             Component.DIGEST, Component.CRC);

    private final LinkedHashMap<Component, Long> components;

    public ComponentManifest(Map<Component, Long> components)
    {
        this.components = new LinkedHashMap<>(components);
    }

    @VisibleForTesting
    public static ComponentManifest create(Descriptor descriptor)
    {
        LinkedHashMap<Component, Long> components = new LinkedHashMap<>(STREAM_COMPONENTS.size());

        for (Component component : STREAM_COMPONENTS)
        {
            File file = new File(descriptor.filenameFor(component));
            if (!file.exists())
                continue;

            components.put(component, file.length());
        }

        return new ComponentManifest(components);
    }

    public long sizeOf(Component component)
    {
        Long size = components.get(component);
        if (size == null)
            throw new IllegalArgumentException("Component " + component + " is not present in the manifest");
        return size;
    }

    public long totalSize()
    {
        long totalSize = 0;
        for (Long size : components.values())
            totalSize += size;
        return totalSize;
    }

    public List<Component> components()
    {
        return new ArrayList<>(components.keySet());
    }

    @Override
    public boolean equals(Object o)
    {
        if (this == o)
            return true;

        if (!(o instanceof ComponentManifest))
            return false;

        ComponentManifest that = (ComponentManifest) o;
        return components.equals(that.components);
    }

    @Override
    public int hashCode()
    {
        return components.hashCode();
    }

    public static final IVersionedSerializer<ComponentManifest> serializer = new IVersionedSerializer<ComponentManifest>()
    {
        public void serialize(ComponentManifest manifest, DataOutputPlus out, int version) throws IOException
        {
            out.writeUnsignedVInt(manifest.components.size());
            for (Map.Entry<Component, Long> entry : manifest.components.entrySet())
            {
                out.writeUTF(entry.getKey().name);
                out.writeUnsignedVInt(entry.getValue());
            }
        }

        public ComponentManifest deserialize(DataInputPlus in, int version) throws IOException
        {
            int size = (int) in.readUnsignedVInt();

            LinkedHashMap<Component, Long> components = new LinkedHashMap<>(size);

            for (int i = 0; i < size; i++)
            {
                Component component = Component.parse(in.readUTF());
                long length = in.readUnsignedVInt();
                components.put(component, length);
            }

            return new ComponentManifest(components);
        }

        public long serializedSize(ComponentManifest manifest, int version)
        {
            long size = TypeSizes.sizeofUnsignedVInt(manifest.components.size());
            for (Map.Entry<Component, Long> entry : manifest.components.entrySet())
            {
                size += TypeSizes.sizeof(entry.getKey().name);
                size += TypeSizes.sizeofUnsignedVInt(entry.getValue());
            }
            return size;
        }
    };

    @Override
    public Iterator<Component> iterator()
    {
        return Iterators.unmodifiableIterator(components.keySet().iterator());
    }
}
