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Neo4j property value system.
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/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.values.storable;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import static java.util.Collections.unmodifiableSet;

public class TimeZones
{
    /**
     * Prevent instance creation.
     */
    private TimeZones()
    {
    }

    private static final List TIME_ZONE_SHORT_TO_STRING = new ArrayList<>( 1024 );
    private static final Map TIME_ZONE_STRING_TO_SHORT = new HashMap<>( 1024 );

    private static final long MIN_ZONE_OFFSET_SECONDS = -18 * 3600;
    private static final long MAX_ZONE_OFFSET_SECONDS = 18 * 3600;

    public static boolean validZoneOffset( int zoneOffsetSeconds )
    {
        return zoneOffsetSeconds >= MIN_ZONE_OFFSET_SECONDS && zoneOffsetSeconds <= MAX_ZONE_OFFSET_SECONDS;
    }

    public static boolean validZoneId( short zoneId )
    {
        return zoneId >= 0 && zoneId < TIME_ZONE_SHORT_TO_STRING.size();
    }

    private static final String LATEST_SUPPORTED_IANA_VERSION;

    /**
     * @throws IllegalArgumentException if tzid is not in the file
     */
    public static short map( String tzid )
    {
        if ( !TIME_ZONE_STRING_TO_SHORT.containsKey( tzid ) )
        {
            throw new IllegalArgumentException( String.format( "unknown tzid '%s'", tzid ) );
        }
        return TIME_ZONE_STRING_TO_SHORT.get( tzid );
    }

    public static String map( short offset )
    {
        return TIME_ZONE_SHORT_TO_STRING.get( offset );
    }

    public static Set supportedTimeZones()
    {
        return unmodifiableSet( TIME_ZONE_STRING_TO_SHORT.keySet() );
    }

    static
    {
        String latestVersion = "";
        Pattern version = Pattern.compile( "# tzdata([0-9]{4}[a-z])" );
        Map oldToNewName = new HashMap<>( 1024 );

        try ( BufferedReader reader = new BufferedReader( new InputStreamReader( TimeZones.class.getResourceAsStream( "/TZIDS" ) ) ) )
        {
            for ( String line; (line = reader.readLine()) != null; )
            {
                if ( line.startsWith( "//" ) || line.isBlank() )
                {
                    continue;
                }
                else if ( line.startsWith( "#" ) )
                {
                    Matcher matcher = version.matcher( line );
                    if ( matcher.matches() )
                    {
                        latestVersion = matcher.group( 1 );
                    }
                    continue;
                }
                int sep = line.indexOf( ' ' );
                if ( sep != -1 )
                {
                    String oldName = line.substring( 0, sep );
                    String newName = line.substring( sep + 1 );
                    TIME_ZONE_SHORT_TO_STRING.add( newName );
                    oldToNewName.put( oldName, newName );
                }
                else
                {
                    TIME_ZONE_SHORT_TO_STRING.add( line );
                    TIME_ZONE_STRING_TO_SHORT.put( line, (short) (TIME_ZONE_SHORT_TO_STRING.size() - 1) );
                }
            }
            LATEST_SUPPORTED_IANA_VERSION = latestVersion;
        }
        catch ( IOException e )
        {
            throw new RuntimeException( "Failed to read time zone id file." );
        }

        for ( Map.Entry entry : oldToNewName.entrySet() )
        {
            String oldName = entry.getKey();
            String newName = entry.getValue();
            Short newNameId = TIME_ZONE_STRING_TO_SHORT.get( newName );
            TIME_ZONE_STRING_TO_SHORT.put( oldName, newNameId );
        }
    }
}