/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */
package org.elasticsearch.index.shard;

import org.apache.lucene.index.CheckIndex;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.Lock;
import org.elasticsearch.ElasticsearchException;
import org.elasticsearch.cli.Terminal;
import org.elasticsearch.common.collect.Tuple;

import java.io.IOException;
import java.io.PrintStream;

/**
 * Removes corrupted Lucene index segments
 */
public class RemoveCorruptedLuceneSegmentsAction {

    public Tuple<RemoveCorruptedShardDataCommand.CleanStatus, String> getCleanStatus(Directory indexDirectory,
                                                                                     Lock writeLock,
                                                                                     PrintStream printStream,
                                                                                     boolean verbose) throws IOException {
        boolean markedCorrupted = RemoveCorruptedShardDataCommand.isCorruptMarkerFileIsPresent(indexDirectory);

        final CheckIndex.Status status;
        try (CheckIndex checker = new CheckIndex(indexDirectory, writeLock)) {
            checker.setChecksumsOnly(true);
            checker.setInfoStream(printStream, verbose);

            status = checker.checkIndex(null);

            if (status.missingSegments) {
                return Tuple.tuple(RemoveCorruptedShardDataCommand.CleanStatus.UNRECOVERABLE,
                    "Index is unrecoverable - there are missing segments");
            }

            return status.clean
                ? Tuple.tuple(markedCorrupted
                    ? RemoveCorruptedShardDataCommand.CleanStatus.CLEAN_WITH_CORRUPTED_MARKER
                    : RemoveCorruptedShardDataCommand.CleanStatus.CLEAN, null)
                : Tuple.tuple(RemoveCorruptedShardDataCommand.CleanStatus.CORRUPTED,
                    "Corrupted Lucene index segments found - " + status.totLoseDocCount + " documents will be lost.");
        }
    }

    public void execute(Terminal terminal,
                        Directory indexDirectory,
                        Lock writeLock,
                        PrintStream printStream,
                        boolean verbose) throws IOException {
        final CheckIndex.Status status;
        try (CheckIndex checker = new CheckIndex(indexDirectory, writeLock)) {

            checker.setChecksumsOnly(true);
            checker.setInfoStream(printStream, verbose);

            status = checker.checkIndex(null);

            if (status.missingSegments == false) {
                if (status.clean == false) {
                    terminal.println("Writing...");
                    checker.exorciseIndex(status);

                    terminal.println("OK");
                    terminal.println("Wrote new segments file \"" + status.segmentsFileName + "\"");
                }
            } else {
                throw new ElasticsearchException("Index is unrecoverable - there are missing segments");
            }
        }
    }
}
