/*
 * Licensed to CRATE.IO GmbH ("Crate") under one or more contributor
 * license agreements.  See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.  Crate 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.
 *
 * However, if you have executed another commercial license agreement
 * with Crate these terms will supersede the license and you may use the
 * software solely pursuant to the terms of the relevant commercial agreement.
 */

package io.crate.expression.reference.sys.snapshot;

import io.crate.common.annotations.VisibleForTesting;
import io.crate.common.collections.Lists2;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.Version;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.inject.Singleton;
import org.elasticsearch.repositories.RepositoriesService;
import org.elasticsearch.repositories.Repository;
import org.elasticsearch.snapshots.SnapshotException;
import org.elasticsearch.snapshots.SnapshotId;
import org.elasticsearch.snapshots.SnapshotInfo;
import org.elasticsearch.snapshots.SnapshotShardFailure;
import org.elasticsearch.snapshots.SnapshotState;

import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.function.Supplier;

@Singleton
public class SysSnapshots {

    private static final Logger LOGGER = LogManager.getLogger(SysSnapshots.class);
    private final Supplier<Collection<Repository>> getRepositories;

    @Inject
    public SysSnapshots(RepositoriesService repositoriesService) {
        this(repositoriesService::getRepositoriesList);
    }

    @VisibleForTesting
    SysSnapshots(Supplier<Collection<Repository>> getRepositories) {
        this.getRepositories = getRepositories;
    }

    public Iterable<SysSnapshot> currentSnapshots() {
        return () -> getRepositories.get().stream()
            .flatMap(repository -> repository.getRepositoryData().getSnapshotIds().stream()
                .map(snapshotId -> createSysSnapshot(repository, snapshotId))
            ).iterator();
    }

    private static SysSnapshot createSysSnapshot(Repository repository, SnapshotId snapshotId) {
        SnapshotInfo snapshotInfo;
        try {
            snapshotInfo = repository.getSnapshotInfo(snapshotId);
        } catch (SnapshotException e) {
            if (LOGGER.isDebugEnabled()) {
                LOGGER.debug("Couldn't retrieve snapshotId={} error={}", snapshotId, e);
            }
            return new SysSnapshot(
                snapshotId.getName(),
                repository.getMetadata().name(),
                Collections.emptyList(),
                null,
                null,
                null,
                SnapshotState.FAILED.name(),
                List.of()
            );
        }
        Version version = snapshotInfo.version();
        return new SysSnapshot(
            snapshotId.getName(),
            repository.getMetadata().name(),
            snapshotInfo.indices(),
            snapshotInfo.startTime(),
            snapshotInfo.endTime(),
            version == null ? null : version.toString(),
            snapshotInfo.state().name(),
            Lists2.map(snapshotInfo.shardFailures(), SnapshotShardFailure::toString)
        );
    }
}