/*
 * 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.lifecycle;

import java.io.File;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.io.IOException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.cassandra.io.FSError;
import org.apache.cassandra.io.FSReadError;
import org.apache.cassandra.io.util.FileUtils;
import org.apache.cassandra.utils.NativeLibrary;

Because a column family may have sstables on different disks and disks can
be removed, we duplicate log files into many replicas so as to have a file
in each directory where sstables exist.
Each replica contains the exact same content but we do allow for final
partial records in case we crashed after writing to one replica but
before compliting the write to another replica.
See Also:
LogFile/**
 * Because a column family may have sstables on different disks and disks can
 * be removed, we duplicate log files into many replicas so as to have a file
 * in each directory where sstables exist.
 *
 * Each replica contains the exact same content but we do allow for final
 * partial records in case we crashed after writing to one replica but
 * before compliting the write to another replica.
 *
 * @see LogFile
 */
final class LogReplica implements AutoCloseable
{
    private static final Logger logger = LoggerFactory.getLogger(LogReplica.class);

    private final File file;
    private int directoryDescriptor;
    private final Map<String, String> errors = new HashMap<>();

    static LogReplica create(File directory, String fileName)
    {
        int folderFD = NativeLibrary.tryOpenDirectory(directory.getPath());
        if (folderFD == -1)
            throw new FSReadError(new IOException(String.format("Invalid folder descriptor trying to create log replica %s", directory.getPath())), directory.getPath());

        return new LogReplica(new File(fileName), folderFD);
    }

    static LogReplica open(File file)
    {
        int folderFD = NativeLibrary.tryOpenDirectory(file.getParentFile().getPath());
        if (folderFD == -1)
            throw new FSReadError(new IOException(String.format("Invalid folder descriptor trying to create log replica %s", file.getParentFile().getPath())), file.getParentFile().getPath());

        return new LogReplica(file, folderFD);
    }

    LogReplica(File file, int directoryDescriptor)
    {
        this.file = file;
        this.directoryDescriptor = directoryDescriptor;
    }

    File file()
    {
        return file;
    }

    List<String> readLines()
    {
        return FileUtils.readLines(file);
    }

    String getFileName()
    {
        return file.getName();
    }

    String getDirectory()
    {
        return file.getParent();
    }

    void append(LogRecord record)
    {
        boolean existed = exists();
        try
        {
            FileUtils.appendAndSync(file, record.toString());
        }
        catch (FSError e)
        {
            logger.error("Failed to sync file {}", file, e);
            FileUtils.handleFSErrorAndPropagate(e);
        }

        // If the file did not exist before appending the first
        // line, then sync the directory as well since now it must exist
        if (!existed)
            syncDirectory();
    }

    void syncDirectory()
    {
        try
        {
            if (directoryDescriptor >= 0)
                NativeLibrary.trySync(directoryDescriptor);
        }
        catch (FSError e)
        {
            logger.error("Failed to sync directory descriptor {}", directoryDescriptor, e);
            FileUtils.handleFSErrorAndPropagate(e);
        }
    }

    void delete()
    {
        LogTransaction.delete(file);
        syncDirectory();
    }

    boolean exists()
    {
        return file.exists();
    }

    public void close()
    {
        if (directoryDescriptor >= 0)
        {
            NativeLibrary.tryCloseFD(directoryDescriptor);
            directoryDescriptor = -1;
        }
    }

    @Override
    public String toString()
    {
        return String.format("[%s] ", file);
    }

    void setError(String line, String error)
    {
        errors.put(line, error);
    }

    void printContentsWithAnyErrors(StringBuilder str)
    {
        str.append(file.getPath());
        str.append(System.lineSeparator());
        FileUtils.readLines(file).forEach(line -> printLineWithAnyError(str, line));
    }

    private void printLineWithAnyError(StringBuilder str, String line)
    {
        str.append('\t');
        str.append(line);
        str.append(System.lineSeparator());

        String error = errors.get(line);
        if (error != null)
        {
            str.append("\t\t***");
            str.append(error);
            str.append(System.lineSeparator());
        }
    }
}