--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/org/tmatesoft/hg/core/HgCheckoutCommand.java	Fri Jan 11 18:12:39 2013 +0100
@@ -0,0 +1,153 @@
+/*
+ * Copyright (c) 2012-2013 TMate Software Ltd
+ *  
+ * 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; version 2 of the License.
+ *
+ * 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.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@hg4j.com
+ */
+package org.tmatesoft.hg.core;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.nio.channels.FileChannel;
+
+import org.tmatesoft.hg.internal.DirstateBuilder;
+import org.tmatesoft.hg.internal.Experimental;
+import org.tmatesoft.hg.internal.Internals;
+import org.tmatesoft.hg.internal.WorkingDirFileWriter;
+import org.tmatesoft.hg.repo.HgDataFile;
+import org.tmatesoft.hg.repo.HgInvalidRevisionException;
+import org.tmatesoft.hg.repo.HgInvalidStateException;
+import org.tmatesoft.hg.repo.HgManifest;
+import org.tmatesoft.hg.repo.HgRepository;
+import org.tmatesoft.hg.repo.HgRuntimeException;
+import org.tmatesoft.hg.repo.HgManifest.Flags;
+import org.tmatesoft.hg.util.CancelledException;
+import org.tmatesoft.hg.util.Path;
+
+/**
+ * WORK IN PROGRESS.
+ * 
+ * Update working directory to specific state, 'hg checkout' counterpart.
+ * For the time being, only 'clean' checkout is supported ('hg co --clean')
+ * 
+ * @since 1.1
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+@Experimental(reason="Work in progress")
+public class HgCheckoutCommand extends HgAbstractCommand<HgCheckoutCommand>{
+
+	private final HgRepository repo;
+	private int revisionToCheckout = HgRepository.BAD_REVISION;
+
+	public HgCheckoutCommand(HgRepository hgRepo) {
+		repo = hgRepo;
+	}
+	
+	/**
+	 * Select revision to check out
+	 * 
+	 * @param nodeid revision
+	 * @return <code>this</code> for convenience
+	 * @throws HgBadArgumentException if failed to find supplied changeset 
+	 */
+	public HgCheckoutCommand changeset(Nodeid nodeid) throws HgBadArgumentException {
+		try {
+			return changeset(repo.getChangelog().getRevisionIndex(nodeid));
+		} catch (HgInvalidRevisionException ex) {
+			throw new HgBadArgumentException("Can't find revision", ex).setRevision(nodeid);
+		}
+	}
+
+	/**
+	 * Select revision to check out using local revision index
+	 * 
+	 * @param changesetIndex local revision index
+	 * @return <code>this</code> for convenience
+	 * @throws HgBadArgumentException if failed to find supplied changeset 
+	 */
+	public HgCheckoutCommand changeset(int changesetIndex) throws HgBadArgumentException {
+		int lastCsetIndex = repo.getChangelog().getLastRevision();
+		if (changesetIndex < 0 || changesetIndex > lastCsetIndex) {
+			throw new HgBadArgumentException(String.format("Bad revision index %d, value from [0..%d] expected", changesetIndex, lastCsetIndex), null).setRevisionIndex(changesetIndex);
+		}
+		revisionToCheckout = changesetIndex;
+		return this;
+	}
+
+	/**
+	 * 
+	 * @throws HgIOException to indicate troubles updating files in working copy
+	 * @throws HgException
+	 * @throws CancelledException
+	 */
+	public void execute() throws HgException, CancelledException {
+		Internals internalRepo = Internals.getInstance(repo);
+		// remove tracked files from wd (perhaps, just forget 'Added'?)
+		// TODO
+		final DirstateBuilder dirstateBuilder = new DirstateBuilder(internalRepo.buildFileNameEncodingHelper());
+		final Exception[] failure = new Exception[1];
+		HgManifest.Inspector worker = new HgManifest.Inspector() {
+			
+			public boolean next(Nodeid nid, Path fname, Flags flags) {
+				try {
+					HgDataFile df = repo.getFileNode(fname);
+					int fileRevIndex = df.getRevisionIndex(nid);
+					// check out files based on manifest
+					// FIXME links!
+					WorkingDirFileWriter workingDirWriter = new WorkingDirFileWriter(repo);
+					workingDirWriter.processFile(df, fileRevIndex);
+					// new dirstate based on manifest
+					dirstateBuilder.recordNormal(fname, flags, workingDirWriter.bytesWritten());
+					return true;
+				} catch (IOException ex) {
+					failure[0] = ex;
+				} catch (HgRuntimeException ex) {
+					failure[0] = ex;
+				}
+				return false;
+			}
+			
+			public boolean end(int manifestRevision) {
+				return false;
+			}
+			
+			public boolean begin(int mainfestRevision, Nodeid nid, int changelogRevision) {
+				return true;
+			}
+		};
+		dirstateBuilder.parents(repo.getChangelog().getRevision(revisionToCheckout), null);
+		repo.getManifest().walk(revisionToCheckout, revisionToCheckout, worker);
+		if (failure[0] != null) {
+			if (failure[0] instanceof IOException) {
+				throw new HgIOException("Failed to write down file revision", failure[0], /*FIXME file*/null);
+			}
+			if (failure[0] instanceof HgRuntimeException) {
+				throw new HgLibraryFailureException((HgRuntimeException) failure[0]);
+			}
+			HgInvalidStateException e = new HgInvalidStateException("Unexpected exception");
+			e.initCause(failure[0]);
+			throw e;
+		}
+		File dirstateFile = internalRepo.getFileFromRepoDir("dirstate");
+		try {
+			FileChannel dirstate = new FileOutputStream(dirstateFile).getChannel();
+			dirstateBuilder.serialize(dirstate);
+			dirstate.close();
+		} catch (IOException ex) {
+			throw new HgIOException("Can't write down new directory state", ex, dirstateFile);
+		}
+		// FIXME write down branch file
+	}
+}