/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch 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.elasticsearch.repositories.fs;

import org.elasticsearch.cluster.metadata.RepositoryMetaData;
import org.elasticsearch.common.blobstore.BlobPath;
import org.elasticsearch.common.blobstore.BlobStore;
import org.elasticsearch.common.blobstore.fs.FsBlobStore;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.common.xcontent.NamedXContentRegistry;
import org.elasticsearch.env.Environment;
import org.elasticsearch.repositories.RepositoryException;
import org.elasticsearch.repositories.blobstore.BlobStoreRepository;

import java.io.IOException;
import java.nio.file.Path;
import java.util.function.Function;

/**
 * Shared file system implementation of the BlobStoreRepository
 * <p>
 * Shared file system repository supports the following settings
 * <dl>
 * <dt>{@code location}</dt><dd>Path to the root of repository. This is mandatory parameter.</dd>
 * <dt>{@code concurrent_streams}</dt><dd>Number of concurrent read/write stream (per repository on each node). Defaults to 5.</dd>
 * <dt>{@code chunk_size}</dt><dd>Large file can be divided into chunks. This parameter specifies the chunk size. Defaults to not chucked.</dd>
 * <dt>{@code compress}</dt><dd>If set to true metadata files will be stored compressed. Defaults to false.</dd>
 * </dl>
 */
public class FsRepository extends BlobStoreRepository {

    public static final String TYPE = "fs";

    public static final Setting<String> LOCATION_SETTING =
        new Setting<>("location", "", Function.identity(), Property.NodeScope);
    public static final Setting<String> REPOSITORIES_LOCATION_SETTING =
        new Setting<>("repositories.fs.location", LOCATION_SETTING, Function.identity(), Property.NodeScope);
    public static final Setting<ByteSizeValue> CHUNK_SIZE_SETTING =
        Setting.byteSizeSetting("chunk_size", new ByteSizeValue(-1), Property.NodeScope);
    public static final Setting<ByteSizeValue> REPOSITORIES_CHUNK_SIZE_SETTING =
        Setting.byteSizeSetting("repositories.fs.chunk_size", new ByteSizeValue(-1), Property.NodeScope);
    public static final Setting<Boolean> COMPRESS_SETTING = Setting.boolSetting("compress", false, Property.NodeScope);
    public static final Setting<Boolean> REPOSITORIES_COMPRESS_SETTING =
        Setting.boolSetting("repositories.fs.compress", false, Property.NodeScope);

    private final FsBlobStore blobStore;

    private ByteSizeValue chunkSize;

    private final BlobPath basePath;

    private boolean compress;

    /**
     * Constructs a shared file system repository.
     */
    public FsRepository(RepositoryMetaData metadata, Environment environment,
                        NamedXContentRegistry namedXContentRegistry) throws IOException {
        super(metadata, environment.settings(), namedXContentRegistry);
        String location = REPOSITORIES_LOCATION_SETTING.get(metadata.settings());
        if (location.isEmpty()) {
            logger.warn("the repository location is missing, it should point to a shared file system location that is available on all master and data nodes");
            throw new RepositoryException(metadata.name(), "missing location");
        }
        Path locationFile = environment.resolveRepoFile(location);
        if (locationFile == null) {
            if (environment.repoFiles().length > 0) {
                logger.warn("The specified location [{}] doesn't start with any repository paths specified by the path.repo setting: [{}] ", location, environment.repoFiles());
                throw new RepositoryException(metadata.name(), "location [" + location + "] doesn't match any of the locations specified by path.repo");
            } else {
                logger.warn("The specified location [{}] should start with a repository path specified by the path.repo setting, but the path.repo setting was not set on this node", location);
                throw new RepositoryException(metadata.name(), "location [" + location + "] doesn't match any of the locations specified by path.repo because this setting is empty");
            }
        }

        blobStore = new FsBlobStore(settings, locationFile);
        if (CHUNK_SIZE_SETTING.exists(metadata.settings())) {
            this.chunkSize = CHUNK_SIZE_SETTING.get(metadata.settings());
        } else if (REPOSITORIES_CHUNK_SIZE_SETTING.exists(settings)) {
            this.chunkSize = REPOSITORIES_CHUNK_SIZE_SETTING.get(settings);
        } else {
            this.chunkSize = null;
        }
        this.compress = COMPRESS_SETTING.exists(metadata.settings()) ? COMPRESS_SETTING.get(metadata.settings()) : REPOSITORIES_COMPRESS_SETTING.get(settings);
        this.basePath = BlobPath.cleanPath();
    }

    @Override
    protected BlobStore blobStore() {
        return blobStore;
    }

    @Override
    protected boolean isCompress() {
        return compress;
    }

    @Override
    protected ByteSizeValue chunkSize() {
        return chunkSize;
    }

    @Override
    protected BlobPath basePath() {
        return basePath;
    }
}