Torrent.java

package net.filebot.torrent;

import static java.nio.charset.StandardCharsets.*;
import static java.util.Collections.*;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import net.filebot.vfs.FileInfo;
import net.filebot.vfs.SimpleFileInfo;

public class Torrent {

	private String name;
	private String encoding;
	private String createdBy;
	private String announce;
	private String comment;
	private Long creationDate;
	private Long pieceLength;

	private List<FileInfo> files;
	private boolean singleFileTorrent;

	protected Torrent() {
		// used by serializer
	}

	public Torrent(File torrent) throws IOException {
		this(decodeTorrent(torrent));
	}

	public Torrent(Map<?, ?> torrentMap) {
		Charset charset = UTF_8;
		encoding = decodeString(torrentMap.get("encoding"), charset);

		try {
			charset = Charset.forName(encoding);
		} catch (IllegalArgumentException e) {
			// invalid encoding, just keep using UTF-8
		}

		createdBy = decodeString(torrentMap.get("created by"), charset);
		announce = decodeString(torrentMap.get("announce"), charset);
		comment = decodeString(torrentMap.get("comment"), charset);
		creationDate = decodeLong(torrentMap.get("creation date"));

		Map<?, ?> infoMap = (Map<?, ?>) torrentMap.get("info");

		name = decodeString(infoMap.get("name"), charset);
		pieceLength = (Long) infoMap.get("piece length");

		if (infoMap.containsKey("files")) {
			// torrent contains multiple entries
			singleFileTorrent = false;

			List<FileInfo> entries = new ArrayList<FileInfo>();

			for (Object fileMapObject : (List<?>) infoMap.get("files")) {
				Map<?, ?> fileMap = (Map<?, ?>) fileMapObject;
				List<?> pathList = (List<?>) fileMap.get("path");

				StringBuilder path = new StringBuilder(80);

				Iterator<?> iterator = pathList.iterator();

				while (iterator.hasNext()) {
					// append path element
					path.append(decodeString(iterator.next(), charset));

					// append separator
					if (iterator.hasNext()) {
						path.append("/");
					}
				}

				Long length = decodeLong(fileMap.get("length"));

				entries.add(new SimpleFileInfo(path.toString(), length));
			}

			files = unmodifiableList(entries);
		} else {
			// single file torrent
			singleFileTorrent = true;

			Long length = decodeLong(infoMap.get("length"));

			files = singletonList(new SimpleFileInfo(name, length));
		}
	}

	private static Map<?, ?> decodeTorrent(File torrent) throws IOException {
		InputStream in = new BufferedInputStream(new FileInputStream(torrent));

		try {
			return BDecoder.decode(in);
		} finally {
			in.close();
		}
	}

	private String decodeString(Object byteArray, Charset charset) {
		if (byteArray == null)
			return null;

		return new String((byte[]) byteArray, charset);
	}

	private Long decodeLong(Object number) {
		if (number == null)
			return null;

		return (Long) number;
	}

	public String getAnnounce() {
		return announce;
	}

	public String getComment() {
		return comment;
	}

	public String getCreatedBy() {
		return createdBy;
	}

	public Long getCreationDate() {
		return creationDate;
	}

	public String getEncoding() {
		return encoding;
	}

	public List<FileInfo> getFiles() {
		return files;
	}

	public String getName() {
		return name;
	}

	public Long getPieceLength() {
		return pieceLength;
	}

	public boolean isSingleFileTorrent() {
		return singleFileTorrent;
	}

}