package org.apache.maven.archetype.generator;

/*
 * 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 groovy.lang.Binding;
import groovy.lang.GroovyShell;
import org.apache.maven.archetype.ArchetypeGenerationRequest;
import org.apache.maven.archetype.common.ArchetypeArtifactManager;
import org.apache.maven.archetype.common.ArchetypeFilesResolver;
import org.apache.maven.archetype.common.Constants;
import org.apache.maven.archetype.common.PomManager;
import org.apache.maven.archetype.exception.ArchetypeGenerationFailure;
import org.apache.maven.archetype.exception.ArchetypeNotConfigured;
import org.apache.maven.archetype.exception.InvalidPackaging;
import org.apache.maven.archetype.exception.OutputFileExists;
import org.apache.maven.archetype.exception.PomFileExists;
import org.apache.maven.archetype.exception.ProjectDirectoryExists;
import org.apache.maven.archetype.exception.UnknownArchetype;
import org.apache.maven.archetype.metadata.AbstractArchetypeDescriptor;
import org.apache.maven.archetype.metadata.ArchetypeDescriptor;
import org.apache.maven.archetype.metadata.FileSet;
import org.apache.maven.archetype.metadata.ModuleDescriptor;
import org.apache.maven.archetype.metadata.RequiredProperty;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.context.Context;
import org.codehaus.plexus.component.annotations.Component;
import org.codehaus.plexus.component.annotations.Requirement;
import org.codehaus.plexus.logging.AbstractLogEnabled;
import org.codehaus.plexus.util.FileUtils;
import org.codehaus.plexus.util.IOUtil;
import org.codehaus.plexus.util.StringUtils;
import org.codehaus.plexus.util.xml.pull.XmlPullParserException;
import org.codehaus.plexus.velocity.VelocityComponent;
import org.xml.sax.SAXException;

import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.TransformerException;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.StringWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;

@Component( role = FilesetArchetypeGenerator.class )
public class DefaultFilesetArchetypeGenerator
    extends AbstractLogEnabled
    implements FilesetArchetypeGenerator
{
    @Requirement
    private ArchetypeArtifactManager archetypeArtifactManager;

    @Requirement
    private ArchetypeFilesResolver archetypeFilesResolver;

    @Requirement
    private PomManager pomManager;

    @Requirement
    private VelocityComponent velocity;

    /**
     * Pattern used to detect tokens in a string. Tokens are any text surrounded
     * by the delimiter <code>__</code>.
     */
    private static final Pattern TOKEN_PATTERN = Pattern.compile( "__((?:[^_]+_)*[^_]+)__" );

    @Override
    public void generateArchetype( ArchetypeGenerationRequest request, File archetypeFile )
            throws UnknownArchetype, ArchetypeNotConfigured, ProjectDirectoryExists, PomFileExists, OutputFileExists,
            ArchetypeGenerationFailure, InvalidPackaging
    {
        ClassLoader old = Thread.currentThread().getContextClassLoader();

        try
        {
            ArchetypeDescriptor archetypeDescriptor =
                archetypeArtifactManager.getFileSetArchetypeDescriptor( archetypeFile );

            if ( !isArchetypeConfigured( archetypeDescriptor, request ) )
            {
                if ( request.isInteractiveMode() )
                {
                    throw new ArchetypeNotConfigured( "No archetype was chosen.", null );
                }

                StringBuilder exceptionMessage = new StringBuilder(
                    "Archetype " + request.getArchetypeGroupId() + ":" + request.getArchetypeArtifactId() + ":"
                        + request.getArchetypeVersion() + " is not configured" );

                List<String> missingProperties = new ArrayList<>( 0 );
                for ( RequiredProperty requiredProperty : archetypeDescriptor.getRequiredProperties() )
                {
                    if ( StringUtils.isEmpty( request.getProperties().getProperty( requiredProperty.getKey() ) ) )
                    {
                        exceptionMessage.append( "\n\tProperty " + requiredProperty.getKey() + " is missing." );

                        missingProperties.add( requiredProperty.getKey() );
                    }
                }

                throw new ArchetypeNotConfigured( exceptionMessage.toString(), missingProperties );
            }

            Context context = prepareVelocityContext( request );

            String packageName = request.getPackage();
            String artifactId = request.getArtifactId();
            File outputDirectoryFile = new File( request.getOutputDirectory(), artifactId );
            File basedirPom = new File( request.getOutputDirectory(), Constants.ARCHETYPE_POM );
            File pom = new File( outputDirectoryFile, Constants.ARCHETYPE_POM );

            List<String> archetypeResources = archetypeArtifactManager.getFilesetArchetypeResources( archetypeFile );

            ZipFile archetypeZipFile = archetypeArtifactManager.getArchetypeZipFile( archetypeFile );

            ClassLoader archetypeJarLoader = archetypeArtifactManager.getArchetypeJarLoader( archetypeFile );

            Thread.currentThread().setContextClassLoader( archetypeJarLoader );

            if ( archetypeDescriptor.isPartial() )
            {
                getLogger().debug( "Processing partial archetype " + archetypeDescriptor.getName() );
                if ( outputDirectoryFile.exists() )
                {
                    if ( !pom.exists() )
                    {
                        throw new PomFileExists( "This is a partial archetype and the pom.xml file doesn't exist." );
                    }

                    processPomWithMerge( context, pom, "" );

                    processArchetypeTemplatesWithWarning( archetypeDescriptor, archetypeResources, archetypeZipFile, "",
                                                          context, packageName, outputDirectoryFile );
                }
                else
                {
                    if ( basedirPom.exists() )
                    {
                        processPomWithMerge( context, basedirPom, "" );

                        processArchetypeTemplatesWithWarning( archetypeDescriptor, archetypeResources, archetypeZipFile,
                                                              "", context, packageName,
                                                              new File( request.getOutputDirectory() ) );
                    }
                    else
                    {
                        processPom( context, pom, "" );

                        processArchetypeTemplates( archetypeDescriptor, archetypeResources, archetypeZipFile, "",
                                                   context, packageName, outputDirectoryFile );
                    }
                }

                if ( archetypeDescriptor.getModules().size() > 0 )
                {
                    getLogger().info( "Modules ignored in partial mode" );
                }
            }
            else
            {
                getLogger().debug( "Processing complete archetype " + archetypeDescriptor.getName() );
                if ( outputDirectoryFile.exists() && pom.exists() )
                {
                    throw new ProjectDirectoryExists(
                        "A Maven 2 project already exists in the directory " + outputDirectoryFile.getPath() );
                }

                if ( outputDirectoryFile.exists() )
                {
                    getLogger().warn( "The directory " + outputDirectoryFile.getPath() + " already exists." );
                }

                context.put( "rootArtifactId", artifactId );

                processFilesetModule( artifactId, artifactId, archetypeResources, pom, archetypeZipFile, "", basedirPom,
                                      outputDirectoryFile, packageName, archetypeDescriptor, context );
            }

            String postGenerationScript = archetypeArtifactManager.getPostGenerationScript( archetypeFile );
            if ( postGenerationScript != null )
            {
                getLogger().info( "Executing " + Constants.ARCHETYPE_POST_GENERATION_SCRIPT
                    + " post-generation script" );

                Binding binding = new Binding();

                final Properties archetypeGeneratorProperties = new Properties();
                archetypeGeneratorProperties.putAll( System.getProperties() );

                if ( request.getProperties() != null )
                {
                    archetypeGeneratorProperties.putAll( request.getProperties() );
                }

                for ( Map.Entry<Object, Object> entry : archetypeGeneratorProperties.entrySet() )
                {
                    binding.setVariable( entry.getKey().toString(), entry.getValue() );
                }

                binding.setVariable( "request", request );

                GroovyShell shell = new GroovyShell( binding );
                shell.evaluate( postGenerationScript );
            }

            // ----------------------------------------------------------------------
            // Log message on OldArchetype creation
            // ----------------------------------------------------------------------
            if ( getLogger().isInfoEnabled() )
            {
                getLogger().info( "Project created from Archetype in dir: " + outputDirectoryFile.getAbsolutePath() );
            }
        }
        catch ( IOException | XmlPullParserException | ParserConfigurationException | TransformerException
                | SAXException e )
        {
            throw new ArchetypeGenerationFailure( e );
        }
        finally
        {
            Thread.currentThread().setContextClassLoader( old );
        }
    }

    public String getPackageAsDirectory( String packageName )
    {
        return StringUtils.replace( packageName, ".", "/" );
    }

    private boolean copyFile( final File outFile, final String template, final boolean failIfExists,
                              final ZipFile archetypeZipFile )
        throws OutputFileExists, IOException
    {
        getLogger().debug( "Copying file " + template );

        if ( failIfExists && outFile.exists() )
        {
            throw new OutputFileExists( "Don't rewrite file " + outFile.getName() );
        }
        else if ( outFile.exists() )
        {
            getLogger().warn( "CP Don't override file " + outFile );

            return false;
        }

        ZipEntry input = archetypeZipFile.getEntry( Constants.ARCHETYPE_RESOURCES + "/" + template );

        if ( input.isDirectory() )
        {
            outFile.mkdirs();
        }
        else
        {
            outFile.getParentFile().mkdirs();
            if ( !outFile.exists() && !outFile.createNewFile() )
            {
                getLogger().warn( "Could not create new file \"" + outFile.getPath()
                        + "\" or the file already exists." );
            }

            try ( InputStream inputStream = archetypeZipFile.getInputStream( input );
                  OutputStream out = new FileOutputStream( outFile ) )
            {
                IOUtil.copy( inputStream, out );
            }
        }

        return true;
    }

    private int copyFiles( String directory, List<String> fileSetResources, boolean packaged, String packageName,
                           File outputDirectoryFile, ZipFile archetypeZipFile, String moduleOffset,
                           boolean failIfExists, Context context )
        throws OutputFileExists, FileNotFoundException, IOException
    {
        int count = 0;

        for ( String template : fileSetResources )
        {
            File outputFile =
                getOutputFile( template, directory, outputDirectoryFile, packaged, packageName, moduleOffset, context );

            if ( copyFile( outputFile, template, failIfExists, archetypeZipFile ) )
            {
                count++;
            }
        }

        return count;
    }

    private String getEncoding( String archetypeEncoding )
    {
        return StringUtils.isEmpty( archetypeEncoding ) ? "UTF-8" : archetypeEncoding;
    }

    private String getOffsetSeparator( String moduleOffset )
    {
        return StringUtils.isEmpty( moduleOffset ) ? "/" : ( "/" + moduleOffset + "/" );
    }

    private File getOutputFile( String template, String directory, File outputDirectoryFile, boolean packaged,
                                String packageName, String moduleOffset, Context context )
    {
        String templateName = StringUtils.replaceOnce( template, directory, "" );

        String outputFileName =
            directory + "/" + ( packaged ? getPackageAsDirectory( packageName ) : "" ) + "/" + templateName.substring(
                moduleOffset.length() );

        outputFileName = replaceFilenameTokens( outputFileName, context );

        return new File( outputDirectoryFile, outputFileName );
    }

    /**
     * Replaces all tokens (text matching {@link #TOKEN_PATTERN}) within
     * the given string, using properties contained within the context. If a
     * property does not exist in the context, the token is left unmodified
     * and a warning is logged.
     *
     * @param filePath the file name and path to be interpolated
     * @param context  contains the available properties
     */
    private String replaceFilenameTokens( final String filePath, final Context context )
    {
        StringBuffer interpolatedResult = new StringBuffer();
        Matcher matcher = TOKEN_PATTERN.matcher( filePath );

        while ( matcher.find() )
        {
            String propertyToken = matcher.group( 1 );
            String contextPropertyValue = (String) context.get( propertyToken );
            if ( contextPropertyValue != null && contextPropertyValue.trim().length() > 0 )
            {
                if ( getLogger().isDebugEnabled() )
                {
                    getLogger().debug( "Replacing property '" + propertyToken + "' in file path '" + filePath
                        + "' with value '" + contextPropertyValue + "'." );
                }
                matcher.appendReplacement( interpolatedResult, contextPropertyValue );
            }
            else
            {
                // Need to skip the undefined property
                getLogger().warn( "Property '" + propertyToken + "' was not specified, so the token in '" + filePath
                    + "' is not being replaced." );
            }
        }

        matcher.appendTail( interpolatedResult );

        if ( getLogger().isDebugEnabled() )
        {
            getLogger().debug( "Final interpolated file path: '" + interpolatedResult + "'" );
        }

        return interpolatedResult.toString();
    }

    private String getPackageInPathFormat( String aPackage )
    {
        return StringUtils.replace( aPackage, ".", "/" );
    }

    private boolean isArchetypeConfigured( ArchetypeDescriptor archetypeDescriptor, ArchetypeGenerationRequest request )
    {
        for ( RequiredProperty requiredProperty : archetypeDescriptor.getRequiredProperties() )
        {
            if ( StringUtils.isEmpty( request.getProperties().getProperty( requiredProperty.getKey() ) ) )
            {
                return false;
            }
        }

        return true;
    }

    private void setParentArtifactId( Context context, String artifactId )
    {
        context.put( Constants.PARENT_ARTIFACT_ID, artifactId );
    }

    private Context prepareVelocityContext( ArchetypeGenerationRequest request )
    {
        Context context = new VelocityContext();
        context.put( Constants.GROUP_ID, request.getGroupId() );
        context.put( Constants.ARTIFACT_ID, request.getArtifactId() );
        context.put( Constants.VERSION, request.getVersion() );
        context.put( Constants.PACKAGE, request.getPackage() );
        final String packageInPathFormat = getPackageInPathFormat( request.getPackage() );
        context.put( Constants.PACKAGE_IN_PATH_FORMAT, packageInPathFormat );

        if ( getLogger().isInfoEnabled() )
        {
            getLogger().info( "----------------------------------------------------------------------------" );

            getLogger().info(
                "Using following parameters for creating project from Archetype: " + request.getArchetypeArtifactId()
                    + ":" + request.getArchetypeVersion() );

            getLogger().info( "----------------------------------------------------------------------------" );
            getLogger().info( "Parameter: " + Constants.GROUP_ID + ", Value: " + request.getGroupId() );
            getLogger().info( "Parameter: " + Constants.ARTIFACT_ID + ", Value: " + request.getArtifactId() );
            getLogger().info( "Parameter: " + Constants.VERSION + ", Value: " + request.getVersion() );
            getLogger().info( "Parameter: " + Constants.PACKAGE + ", Value: " + request.getPackage() );
            getLogger().info( "Parameter: " + Constants.PACKAGE_IN_PATH_FORMAT + ", Value: " + packageInPathFormat );
        }

        for ( Iterator<?> iterator = request.getProperties().keySet().iterator(); iterator.hasNext(); )
        {
            String key = (String) iterator.next();

            String value = request.getProperties().getProperty( key );

            if ( maybeVelocityExpression( value ) )
            {
                value = evaluateExpression( context, key, value );
            }

            context.put( key, value );

            if ( getLogger().isInfoEnabled() )
            {
                getLogger().info( "Parameter: " + key + ", Value: " + value );
            }
        }
        return context;
    }

    private boolean maybeVelocityExpression( String value )
    {
        return value != null && value.contains( "${" );
    }

    private String evaluateExpression( Context context, String key, String value )
    {
        try ( StringWriter stringWriter = new StringWriter() )
        {
            Velocity.evaluate( context, stringWriter, key, value );
            return stringWriter.toString();
        }
        catch ( Exception ex )
        {
            return value;
        }
    }

    private void processArchetypeTemplates( AbstractArchetypeDescriptor archetypeDescriptor,
                                            List<String> archetypeResources, ZipFile archetypeZipFile,
                                            String moduleOffset, Context context, String packageName,
                                            File outputDirectoryFile )
        throws OutputFileExists, ArchetypeGenerationFailure, FileNotFoundException, IOException
    {
        processTemplates( packageName, outputDirectoryFile, context, archetypeDescriptor, archetypeResources,
                          archetypeZipFile, moduleOffset, false );
    }

    private void processArchetypeTemplatesWithWarning( ArchetypeDescriptor archetypeDescriptor,
                                                       List<String> archetypeResources, ZipFile archetypeZipFile,
                                                       String moduleOffset, Context context, String packageName,
                                                       File outputDirectoryFile )
        throws OutputFileExists, ArchetypeGenerationFailure, FileNotFoundException, IOException
    {
        processTemplates( packageName, outputDirectoryFile, context, archetypeDescriptor, archetypeResources,
                          archetypeZipFile, moduleOffset, true );
    }

    private int processFileSet( String directory, List<String> fileSetResources, boolean packaged, String packageName,
                                Context context, File outputDirectoryFile, String moduleOffset,
                                String archetypeEncoding, boolean failIfExists )
        throws IOException, OutputFileExists, ArchetypeGenerationFailure
    {
        int count = 0;

        for ( String template : fileSetResources )
        {
            File outputFile =
                getOutputFile( template, directory, outputDirectoryFile, packaged, packageName, moduleOffset, context );

            if ( processTemplate( outputFile, context, Constants.ARCHETYPE_RESOURCES + "/" + template,
                                  archetypeEncoding, failIfExists ) )
            {
                count++;
            }
        }

        return count;
    }

    private void processFilesetModule( final String rootArtifactId, final String artifactId,
                                       final List<String> archetypeResources, File pom, final ZipFile archetypeZipFile,
                                       String moduleOffset, File basedirPom, File outputDirectoryFile,
                                       final String packageName, final AbstractArchetypeDescriptor archetypeDescriptor,
                                       final Context context ) throws XmlPullParserException, IOException,
            ParserConfigurationException, SAXException, TransformerException,
            OutputFileExists, ArchetypeGenerationFailure, InvalidPackaging
    {
        outputDirectoryFile.mkdirs();
        getLogger().debug( "Processing module " + artifactId );
        getLogger().debug( "Processing module rootArtifactId " + rootArtifactId );
        getLogger().debug( "Processing module pom " + pom );
        getLogger().debug( "Processing module moduleOffset " + moduleOffset );
        getLogger().debug( "Processing module outputDirectoryFile " + outputDirectoryFile );

        processFilesetProject( archetypeDescriptor,
                               StringUtils.replace( artifactId, "${rootArtifactId}", rootArtifactId ),
                               archetypeResources, pom, archetypeZipFile, moduleOffset, context, packageName,
                               outputDirectoryFile, basedirPom );

        String parentArtifactId = (String) context.get( Constants.PARENT_ARTIFACT_ID );

        Iterator<ModuleDescriptor> subprojects = archetypeDescriptor.getModules().iterator();

        if ( subprojects.hasNext() )
        {
            getLogger().debug( artifactId + " has modules (" + archetypeDescriptor.getModules() + ")" );

            setParentArtifactId( context, StringUtils.replace( artifactId, "${rootArtifactId}", rootArtifactId ) );
        }

        while ( subprojects.hasNext() )
        {
            ModuleDescriptor project = subprojects.next();

            String modulePath = StringUtils.replace( project.getDir(), "__rootArtifactId__", rootArtifactId );
            modulePath = replaceFilenameTokens( modulePath, context );
            
            File moduleOutputDirectoryFile = new File( outputDirectoryFile, modulePath );

            context.put( Constants.ARTIFACT_ID,
                         StringUtils.replace( project.getId(), "${rootArtifactId}", rootArtifactId ) );
            
            String moduleArtifactId = StringUtils.replace( project.getDir(), "__rootArtifactId__", rootArtifactId );
            moduleArtifactId = replaceFilenameTokens( moduleArtifactId, context );
            
            processFilesetModule( rootArtifactId, moduleArtifactId,
                                  archetypeResources, new File( moduleOutputDirectoryFile, Constants.ARCHETYPE_POM ),
                                  archetypeZipFile,
                                  ( StringUtils.isEmpty( moduleOffset ) ? "" : ( moduleOffset + "/" ) )
                                      + StringUtils.replace( project.getDir(), "${rootArtifactId}", rootArtifactId ),
                                  pom, moduleOutputDirectoryFile, packageName, project, context );
        }

        restoreParentArtifactId( context, parentArtifactId );

        getLogger().debug( "Processed " + artifactId );
    }

    private void processFilesetProject( final AbstractArchetypeDescriptor archetypeDescriptor, final String moduleId,
                                        final List<String> archetypeResources, final File pom,
                                        final ZipFile archetypeZipFile, String moduleOffset, final Context context,
                                        final String packageName, final File outputDirectoryFile,
                                        final File basedirPom )
            throws XmlPullParserException, IOException, ParserConfigurationException, SAXException,
            TransformerException, OutputFileExists, ArchetypeGenerationFailure, InvalidPackaging
    {
        getLogger().debug( "Processing fileset project moduleId " + moduleId );
        getLogger().debug( "Processing fileset project pom " + pom );
        getLogger().debug( "Processing fileset project moduleOffset " + moduleOffset );
        getLogger().debug( "Processing fileset project outputDirectoryFile " + outputDirectoryFile );
        getLogger().debug( "Processing fileset project basedirPom " + basedirPom );

        if ( basedirPom.exists() )
        {
            processPomWithParent( context, pom, moduleOffset, basedirPom, moduleId );
        }
        else
        {
            processPom( context, pom, moduleOffset );
        }

        processArchetypeTemplates( archetypeDescriptor, archetypeResources, archetypeZipFile, moduleOffset, context,
                                   packageName, outputDirectoryFile );
    }

    private void processPom( Context context, File pom, String moduleOffset )
        throws IOException, OutputFileExists, ArchetypeGenerationFailure
    {
        getLogger().debug( "Processing pom " + pom );

        processTemplate( pom, context,
                         Constants.ARCHETYPE_RESOURCES + getOffsetSeparator( moduleOffset ) + Constants.ARCHETYPE_POM,
                         getEncoding( null ), true );
    }

    private void processPomWithMerge( Context context, File pom, String moduleOffset )
        throws OutputFileExists, IOException, XmlPullParserException, ArchetypeGenerationFailure
    {
        getLogger().debug( "Processing pom " + pom + " with merge" );

        File temporaryPom = getTemporaryFile( pom );

        processTemplate( temporaryPom, context,
                         Constants.ARCHETYPE_RESOURCES + getOffsetSeparator( moduleOffset ) + Constants.ARCHETYPE_POM,
                         getEncoding( null ), true );

        pomManager.mergePoms( pom, temporaryPom );

        // getTemporaryFile sets deleteOnExit. Lets try to delete and then make sure deleteOnExit is
        // still set. Windows has issues deleting files with certain JDKs.
        try
        {
            FileUtils.forceDelete( temporaryPom );
        }
        catch ( IOException e )
        {
            temporaryPom.deleteOnExit();
        }
    }

    private void processPomWithParent( Context context, File pom, String moduleOffset, File basedirPom,
                                       String moduleId )
            throws XmlPullParserException, IOException, ParserConfigurationException, SAXException,
            TransformerException, OutputFileExists, ArchetypeGenerationFailure, InvalidPackaging
    {
        getLogger().debug( "Processing pom " + pom + " with parent " + basedirPom );

        processTemplate( pom, context,
                         Constants.ARCHETYPE_RESOURCES + getOffsetSeparator( moduleOffset ) + Constants.ARCHETYPE_POM,
                         getEncoding( null ), true );

        getLogger().debug( "Adding module " + moduleId );

        pomManager.addModule( basedirPom, moduleId );

        pomManager.addParent( pom, basedirPom );
    }

    @SuppressWarnings( "deprecation" )
    private boolean processTemplate( File outFile, Context context, String templateFileName, String encoding,
                                     boolean failIfExists )
        throws IOException, OutputFileExists, ArchetypeGenerationFailure
    {
        templateFileName = templateFileName.replace( File.separatorChar, '/' );

        String localTemplateFileName = templateFileName.replace( '/', File.separatorChar );
        if ( !templateFileName.equals( localTemplateFileName ) && !velocity.getEngine().templateExists(
            templateFileName ) && velocity.getEngine().templateExists( localTemplateFileName ) )
        {
            templateFileName = localTemplateFileName;
        }

        getLogger().debug( "Processing template " + templateFileName );

        if ( outFile.exists() )
        {
            if ( failIfExists )
            {
                throw new OutputFileExists( "Don't override file " + outFile.getAbsolutePath() );
            }

            getLogger().warn( "Don't override file " + outFile );

            return false;
        }

        if ( templateFileName.endsWith( "/" ) )
        {
            getLogger().debug( "Creating directory " + outFile );

            outFile.mkdirs();

            return true;
        }

        if ( !outFile.getParentFile().exists() )
        {
            outFile.getParentFile().mkdirs();
        }

        if ( !outFile.exists() && !outFile.createNewFile() )
        {
            getLogger().warn( "Could not create new file \"" + outFile.getPath() + "\" or the file already exists." );
        }

        getLogger().debug( "Merging into " + outFile );

        try ( Writer writer = new OutputStreamWriter( new FileOutputStream( outFile ), encoding ) )
        {
            StringWriter stringWriter = new StringWriter();

            velocity.getEngine().mergeTemplate( templateFileName, encoding, context, stringWriter );

            writer.write( StringUtils.unifyLineSeparators( stringWriter.toString() ) );
        }
        catch ( Exception e )
        {
            throw new ArchetypeGenerationFailure( "Error merging velocity templates: " + e.getMessage(), e );
        }

        return true;
    }

    private void processTemplates( String packageName, File outputDirectoryFile, Context context,
                                   AbstractArchetypeDescriptor archetypeDescriptor, List<String> archetypeResources,
                                   ZipFile archetypeZipFile, String moduleOffset, boolean failIfExists )
        throws OutputFileExists, ArchetypeGenerationFailure, IOException
    {
        Iterator<FileSet> iterator = archetypeDescriptor.getFileSets().iterator();
        if ( iterator.hasNext() )
        {
            getLogger().debug( "Processing filesets" + "\n  " + archetypeResources );
        }

        int count = 0;
        while ( iterator.hasNext() )
        {
            FileSet fileSet = iterator.next();
            count++;

            List<String> fileSetResources =
                archetypeFilesResolver.filterFiles( moduleOffset, fileSet, archetypeResources );

            // This creates an empty directory, even if there is no file to process
            // Fix for ARCHETYPE-57
            getOutputFile( moduleOffset, fileSet.getDirectory(), outputDirectoryFile, fileSet.isPackaged(), packageName,
                           moduleOffset, context ).mkdirs();

            if ( fileSet.isFiltered() )
            {
                getLogger().debug( "    Processing fileset " + fileSet + " -> " + fileSetResources.size() + ":\n      "
                                       + fileSetResources );

                int processed =
                    processFileSet( fileSet.getDirectory(), fileSetResources, fileSet.isPackaged(), packageName,
                                    context, outputDirectoryFile, moduleOffset, getEncoding( fileSet.getEncoding() ),
                                    failIfExists );

                getLogger().debug( "    Processed " + processed + " files." );
            }
            else
            {
                getLogger().debug( "    Copying fileset " + fileSet + " -> " + fileSetResources.size() + ":\n      "
                                       + fileSetResources );

                int copied = copyFiles( fileSet.getDirectory(), fileSetResources, fileSet.isPackaged(), packageName,
                                        outputDirectoryFile, archetypeZipFile, moduleOffset, failIfExists, context );

                getLogger().debug( "    Copied " + copied + " files." );
            }
        }

        getLogger().debug( "Processed " + count + " filesets" );
    }

    private void restoreParentArtifactId( Context context, String parentArtifactId )
    {
        if ( StringUtils.isEmpty( parentArtifactId ) )
        {
            context.remove( Constants.PARENT_ARTIFACT_ID );
        }
        else
        {
            context.put( Constants.PARENT_ARTIFACT_ID, parentArtifactId );
        }
    }

    private File getTemporaryFile( File file )
    {
        File tmp = FileUtils.createTempFile( file.getName(), Constants.TMP, file.getParentFile() );

        tmp.deleteOnExit();

        return tmp;
    }
}