/*
    * dpkg - Debian Package library and the Debian Package Maven plugin
    * (c) Copyright 2016 Gerrit Hohl
    *
    * This program 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 2
    * 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, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
   */
  package net.sourceforge.javadpkg.impl;
  
  import java.io.BufferedWriter;
  import java.io.IOException;
  import java.io.OutputStreamWriter;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.List;
  
  import net.sourceforge.javadpkg.BuildException;
  import net.sourceforge.javadpkg.GlobalConstants;
  import net.sourceforge.javadpkg.MD5SumsBuilder;
  import net.sourceforge.javadpkg.io.DataTarget;
  import net.sourceforge.javadpkg.store.DataStore;
  import net.sourceforge.javadpkg.store.FileHash;
  
  
  /**
   * <p>
   * A {@link MD5SumsBuilder} implementation.
   * </p>
   *
   * @author Gerrit Hohl (gerrit-hohl@users.sourceforge.net)
   * @version <b>1.0</b>, 26.04.2016 by Gerrit Hohl
   * @version <b>1.1</b>, 23.01.2018 by Gerrit Hohl
   */
  public class MD5SumsBuilderImpl implements MD5SumsBuilder, GlobalConstants {
  	
  	
  	/**
  	 * <p>
  	 * Creates a builder.
  	 * </p>
  	 */
  	public MD5SumsBuilderImpl() {
  		super();
  	}
  	
  	
  	@Override
  	public void buildMD5Sums(DataStore store, DataTarget target) throws IOException, BuildException {
  		MessageDigest digest;
  		List<FileHash> fileHashes;
  		String path;
  
  
  		if (store == null)
  			throw new IllegalArgumentException("Argument store is null.");
  		if (target == null)
  			throw new IllegalArgumentException("Argument target is null.");
  
  		// --- Create the digest ---
  		try {
  			digest = MessageDigest.getInstance("MD5");
  		} catch (NoSuchAlgorithmException e) {
  			throw new BuildException("Couldn't build MD5 sums: MD5 is not supported: " + e.getMessage(), e);
  		}
  
  		// --- Create hashes ---
  		try {
  			fileHashes = store.createFileHashes(digest);
  		} catch (IOException e) {
  			throw new IOException("Couldn't build MD5 sums: Couldn't create hashes: " + e.getMessage(), e);
  		}
  
  		// --- Write hashes ---
  		try {
  			try (BufferedWriter out = new BufferedWriter(new OutputStreamWriter(target.getOutputStream(), UTF_8_CHARSET))) {
  				for (FileHash fileHash : fileHashes) {
  					out.write(fileHash.getHashAsHex());
  					out.write(" ");
  
  					path = fileHash.getPath();
  					if (path.startsWith("/")) {
  						path = path.substring(1);
  					}
  					out.write(path);
  					out.write("\n");
  				}
  			}
  		} catch (IOException e) {
 			throw new IOException("Couldn't build MD5 sums: Couldn't write MD5 sums: " + e.getMessage(), e);
 		}
 	}
 
 
 }