indexer-reader/src/main/java/org/apache/maven/index/reader/Utils.java

package org.apache.maven.index.reader;

/*
 * 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.
 */

import org.apache.maven.index.reader.Record.EntryKey;
import org.apache.maven.index.reader.Record.Type;
import org.apache.maven.index.reader.ResourceHandler.Resource;
import org.apache.maven.index.reader.WritableResourceHandler.WritableResource;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.HashMap;
import java.util.Properties;
import java.util.TimeZone;
import java.util.regex.Pattern;

/**
 * Reusable code snippets and constants.
 *
 * @since 5.1.2
 */
public final class Utils
{
    private Utils()
    {
        // nothing
    }

    public static final String INDEX_FILE_PREFIX = "nexus-maven-repository-index";

    public static final DateFormat INDEX_DATE_FORMAT;

    static
    {
        INDEX_DATE_FORMAT = new SimpleDateFormat( "yyyyMMddHHmmss.SSS Z" );
        INDEX_DATE_FORMAT.setTimeZone( TimeZone.getTimeZone( "GMT" ) );
    }

    public static final String FIELD_SEPARATOR = "|";

    public static final String NOT_AVAILABLE = "NA";

    public static final String UINFO = "u";

    public static final String INFO = "i";

    public static final Pattern FS_PATTERN = Pattern.compile( Pattern.quote( FIELD_SEPARATOR ) );

    /**
     * Creates and loads {@link Properties} from provided {@link InputStream} and closes the stream.
     */
    public static Properties loadProperties( final InputStream inputStream )
        throws IOException
    {
        try
        {
            final Properties properties = new Properties();
            properties.load( inputStream );
            return properties;
        }
        finally
        {
            inputStream.close();
        }
    }

    /**
     * Creates and loads {@link Properties} from provided {@link Resource} if exists, and closes the resource. If not
     * exists, returns {@code null}.
     */
    public static Properties loadProperties( final Resource resource )
        throws IOException
    {
        final InputStream inputStream = resource.read();
        if ( inputStream == null )
        {
            return null;
        }
        return loadProperties( inputStream );
    }

    /**
     * Saves {@link Properties} to provided {@link OutputStream} and closes the stream.
     */
    public static void storeProperties( final OutputStream outputStream, final Properties properties )
        throws IOException
    {
        try
        {
            properties.store( outputStream, "Maven Indexer Writer" );
        }
        finally
        {
            outputStream.close();
        }
    }


    /**
     * Saves {@link Properties} to provided {@link WritableResource} and closes the resource.
     */
    public static void storeProperties( final WritableResource writableResource, final Properties properties )
        throws IOException
    {
        try
        {
            storeProperties( writableResource.write(), properties );
        }
        finally
        {
            writableResource.close();
        }
    }

    /**
     * Creates a record of type {@link Type#DESCRIPTOR}.
     */
    public static Record descriptor( final String repoId )
    {
        HashMap<EntryKey, Object> entries = new HashMap<EntryKey, Object>();
        entries.put( Record.REPOSITORY_ID, repoId );
        return new Record( Type.DESCRIPTOR, entries );
    }

    /**
     * Creates a record of type {@link Type#ALL_GROUPS}.
     */
    public static Record allGroups( final Collection<String> allGroups )
    {
        HashMap<EntryKey, Object> entries = new HashMap<EntryKey, Object>();
        entries.put( Record.ALL_GROUPS, allGroups.toArray( new String[allGroups.size()] ) );
        return new Record( Type.ALL_GROUPS, entries );
    }

    /**
     * Creates a record of type {@link Type#ROOT_GROUPS}.
     */
    public static Record rootGroups( final Collection<String> rootGroups )
    {
        HashMap<EntryKey, Object> entries = new HashMap<EntryKey, Object>();
        entries.put( Record.ROOT_GROUPS, rootGroups.toArray( new String[rootGroups.size()] ) );
        return new Record( Type.ROOT_GROUPS, entries );
    }

    /**
     * Helper to translate the "NA" (not available) input into {@code null} value.
     */
    public static String renvl( final String v )
    {
        return NOT_AVAILABLE.equals( v ) ? null : v;
    }

    /**
     * Helper to translate {@code null} into "NA" (not available) value.
     */
    public static String nvl( final String v )
    {
        return v == null ? NOT_AVAILABLE : v;
    }

    /**
     * Returns the "root group" of given groupId.
     */
    public static String rootGroup( final String groupId )
    {
        int n = groupId.indexOf( '.' );
        if ( n > -1 )
        {
            return groupId.substring( 0, n );
        }
        return groupId;
    }
}