CssMapper.java

package fr.lteconsulting.hexacssmaven;

import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.apache.maven.plugin.logging.Log;

/**
 * Loads a CSS file and a mapping file. Every selector in the css file are
 * changed to their mapped name. Selectors in the css file that are not used in
 * the mapping file can be pruned (optional).
 */
public class CssMapper
{
	/**
	 * Process an input file
	 * 
	 * @throws IOException In case there is a problem
	 * 
	 * @param input
	 *            The input file content
	 * @param mappingPath
	 *            The file containing mapping information (lines in the form of
	 *            newName=oldName)
	 * @param outputFile
	 *            Path to the output file
	 * @param doPrune
	 *            <code>true</code> if pruning unused CSS rules is needed
	 * @param log
	 *            Maven logger
	 */
	public static void processFile( String input, String mappingPath, String outputFile, boolean doPrune, Log log ) throws IOException
	{
		Set<String> usedClassNames = new HashSet<>();

		input = replaceClassNames( input, mappingPath, usedClassNames, log );

		log.debug( usedClassNames.size() + " used css classes in the mapping file" );
		log.debug( "used css classes : " + usedClassNames );

		CssRewriter cssRewriter = new CssRewriter( usedClassNames, doPrune, log );
		input = cssRewriter.process( input );

		input += "\r\n// generated by HexaCss maven plugin, see http://www.lteconsulting.fr/hexacss";

		writeFile( outputFile, input, log );
	}

	private static void writeFile( String path, String content, Log log ) throws IOException
	{
		Path outputPath = Paths.get( path );
		if( Files.exists( outputPath ) )
			Files.delete( outputPath );
		BufferedWriter writer = Files.newBufferedWriter( outputPath, StandardCharsets.UTF_8, StandardOpenOption.CREATE_NEW );
		writer.append( content );
		writer.close();

		log.info( "Wrote to file " + outputPath );
		log.debug( "Output content :" );
		log.debug( content );
	}

	private static String replaceClassNames( String input, String mappingPath, Set<String> usedClassNames, Log log ) throws IOException
	{
		List<String> lines = Files.readAllLines( Paths.get( mappingPath ), StandardCharsets.UTF_8 );

		Set<String> done = new HashSet<>();
		List<String[]> renames = new ArrayList<>();
		for( String line : lines )
		{
			String[] parts = line.split( "=" );
			if( done.contains( parts[0] ) )
				continue;
			else
				done.add( parts[0] );
			renames.add( parts );
		}

		Collections.sort( renames, new Comparator<String[]>()
		{
			@Override
			public int compare( String[] a, String[] b )
			{
				return ((Integer) b[1].length()).compareTo( a[1].length() );
			}
		} );

		for( String[] line : renames )
		{
			log.debug( line[1] + " => " + line[0] );
			if( !input.contains( "." + line[1] ) )
				log.warn( "not found ." + line[1] + " css rule in the source file, mapping to ." + line[0] );
			input = input.replaceAll( "\\." + line[1], "." + line[0] );
			usedClassNames.add( line[0] );
		}

		log.info( renames.size() + " CSS obfuscated rule(s)." );

		return input;
	}
}