/*
    * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  
  package org.eclipse.jgit.transport;
  
  import static org.eclipse.jgit.transport.WalkRemoteObjectDatabase.ROOT_DIR;
  
  import java.io.BufferedOutputStream;
  import java.io.File;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.LinkedHashMap;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.TreeMap;
  
  import org.eclipse.jgit.errors.TransportException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.internal.storage.file.PackFile;
  import org.eclipse.jgit.internal.storage.pack.PackExt;
  import org.eclipse.jgit.internal.storage.pack.PackWriter;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectIdRef;
  import org.eclipse.jgit.lib.ProgressMonitor;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.Ref.Storage;
  import org.eclipse.jgit.lib.RefWriter;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.transport.RemoteRefUpdate.Status;
  
  /**
   * Generic push support for dumb transport protocols.
   * <p>
   * Since there are no Git-specific smarts on the remote side of the connection
   * the client side must handle everything on its own. The generic push support
   * requires being able to delete, create and overwrite files on the remote side,
   * as well as create any missing directories (if necessary). Typically this can
   * be handled through an FTP style protocol.
   * <p>
   * Objects not on the remote side are uploaded as pack files, using one pack
   * file per invocation. This simplifies the implementation as only two data
   * files need to be written to the remote repository.
   * <p>
   * Push support supplied by this class is not multiuser safe. Concurrent pushes
   * to the same repository may yield an inconsistent reference database which may
   * confuse fetch clients.
   * <p>
   * A single push is concurrently safe with multiple fetch requests, due to the
   * careful order of operations used to update the repository. Clients fetching
   * may receive transient failures due to short reads on certain files if the
   * protocol does not support atomic file replacement.
   *
   * @see WalkRemoteObjectDatabase
   */
  class WalkPushConnection extends BaseConnection implements PushConnection {
  	/** The repository this transport pushes out of. */
  	private final Repository local;
  
  	/** Location of the remote repository we are writing to. */
  	private final URIish uri;
  
  	/** Database connection to the remote repository. */
  	final WalkRemoteObjectDatabase dest;
  
  	/** The configured transport we were constructed by. */
  	private final Transport transport;
  
  	/**
  	 * Packs already known to reside in the remote repository.
  	 * <p>
  	 * This is a LinkedHashMap to maintain the original order.
  	 */
  	private LinkedHashMap<String, String> packNames;
  
  	/** Complete listing of refs the remote will have after our push. */
  	private Map<String, Ref> newRefs;
  
  	/**
  	 * Updates which require altering the packed-refs file to complete.
  	 * <p>
  	 * If this collection is non-empty then any refs listed in {@link #newRefs}
  	 * with a storage class of {@link Storage#PACKED} will be written.
  	 */
  	private Collection<RemoteRefUpdate> packedRefUpdates;
  
  	WalkPushConnection(final WalkTransport walkTransport,
 			final WalkRemoteObjectDatabase w) {
 		transport = (Transport) walkTransport;
 		local = transport.local;
 		uri = transport.getURI();
 		dest = w;
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void push(final ProgressMonitor monitor,
 			final Map<String, RemoteRefUpdate> refUpdates)
 			throws TransportException {
 		push(monitor, refUpdates, null);
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void push(final ProgressMonitor monitor,
 			final Map<String, RemoteRefUpdate> refUpdates, OutputStream out)
 			throws TransportException {
 		markStartedOperation();
 		packNames = null;
 		newRefs = new TreeMap<>(getRefsMap());
 		packedRefUpdates = new ArrayList<>(refUpdates.size());
 
 		// Filter the commands and issue all deletes first. This way we
 		// can correctly handle a directory being cleared out and a new
 		// ref using the directory name being created.
 		//
 		final List<RemoteRefUpdate> updates = new ArrayList<>();
 		for (RemoteRefUpdate u : refUpdates.values()) {
 			final String n = u.getRemoteName();
 			if (!n.startsWith("refs/") || !Repository.isValidRefName(n)) { //$NON-NLS-1$
 				u.setStatus(Status.REJECTED_OTHER_REASON);
 				u.setMessage(JGitText.get().funnyRefname);
 				continue;
 			}
 
 			if (AnyObjectId.isEqual(ObjectId.zeroId(), u.getNewObjectId()))
 				deleteCommand(u);
 			else
 				updates.add(u);
 		}
 
 		// If we have any updates we need to upload the objects first, to
 		// prevent creating refs pointing at non-existent data. Then we
 		// can update the refs, and the info-refs file for dumb transports.
 		//
 		if (!updates.isEmpty())
 			sendpack(updates, monitor);
 		for (RemoteRefUpdate u : updates)
 			updateCommand(u);
 
 		// Is this a new repository? If so we should create additional
 		// metadata files so it is properly initialized during the push.
 		//
 		if (!updates.isEmpty() && isNewRepository())
 			createNewRepository(updates);
 
 		RefWriter refWriter = new RefWriter(newRefs.values()) {
 			@Override
 			protected void writeFile(String file, byte[] content)
 					throws IOException {
 				dest.writeFile(ROOT_DIR + file, content);
 			}
 		};
 		if (!packedRefUpdates.isEmpty()) {
 			try {
 				refWriter.writePackedRefs();
 				for (RemoteRefUpdate u : packedRefUpdates)
 					u.setStatus(Status.OK);
 			} catch (IOException err) {
 				for (RemoteRefUpdate u : packedRefUpdates) {
 					u.setStatus(Status.REJECTED_OTHER_REASON);
 					u.setMessage(err.getMessage());
 				}
 				throw new TransportException(uri, JGitText.get().failedUpdatingRefs, err);
 			}
 		}
 
 		try {
 			refWriter.writeInfoRefs();
 		} catch (IOException err) {
 			throw new TransportException(uri, JGitText.get().failedUpdatingRefs, err);
 		}
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public void close() {
 		dest.close();
 	}
 
 	private void sendpack(final List<RemoteRefUpdate> updates,
 			final ProgressMonitor monitor) throws TransportException {
 		PackFile pack = null;
 		PackFile idx = null;
 		try (PackWriter writer = new PackWriter(transport.getPackConfig(),
 				local.newObjectReader())) {
 
 			final Set<ObjectId> need = new HashSet<>();
 			final Set<ObjectId> have = new HashSet<>();
 			for (RemoteRefUpdate r : updates)
 				need.add(r.getNewObjectId());
 			for (Ref r : getRefs()) {
 				have.add(r.getObjectId());
 				if (r.getPeeledObjectId() != null)
 					have.add(r.getPeeledObjectId());
 			}
 			writer.preparePack(monitor, need, have);
 
 			// We don't have to continue further if the pack will
 			// be an empty pack, as the remote has all objects it
 			// needs to complete this change.
 			//
 			if (writer.getObjectCount() == 0)
 				return;
 
 			packNames = new LinkedHashMap<>();
 			for (String n : dest.getPackNames())
 				packNames.put(n, n);
 
 			File packDir = new File("pack"); //$NON-NLS-1$
 			pack = new PackFile(packDir, writer.computeName(),
 					PackExt.PACK);
 			idx = pack.create(PackExt.INDEX);
 
 			if (packNames.remove(pack.getName()) != null) {
 				// The remote already contains this pack. We should
 				// remove the index before overwriting to prevent bad
 				// offsets from appearing to clients.
 				//
 				dest.writeInfoPacks(packNames.keySet());
 				dest.deleteFile(idx.getPath());
 			}
 
 			// Write the pack file, then the index, as readers look the
 			// other direction (index, then pack file).
 			//
 			String wt = "Put " + pack.getName().substring(0, 12); //$NON-NLS-1$
 			try (OutputStream os = new BufferedOutputStream(
 					dest.writeFile(pack.getPath(), monitor,
 							wt + "." + pack.getPackExt().getExtension()))) { //$NON-NLS-1$
 				writer.writePack(monitor, monitor, os);
 			}
 
 			try (OutputStream os = new BufferedOutputStream(
 					dest.writeFile(idx.getPath(), monitor,
 							wt + "." + idx.getPackExt().getExtension()))) { //$NON-NLS-1$
 				writer.writeIndex(os);
 			}
 
 			// Record the pack at the start of the pack info list. This
 			// way clients are likely to consult the newest pack first,
 			// and discover the most recent objects there.
 			//
 			final ArrayList<String> infoPacks = new ArrayList<>();
 			infoPacks.add(pack.getName());
 			infoPacks.addAll(packNames.keySet());
 			dest.writeInfoPacks(infoPacks);
 
 		} catch (IOException err) {
 			safeDelete(idx);
 			safeDelete(pack);
 
 			throw new TransportException(uri, JGitText.get().cannotStoreObjects, err);
 		}
 	}
 
 	private void safeDelete(File path) {
 		if (path != null) {
 			try {
 				dest.deleteFile(path.getPath());
 			} catch (IOException cleanupFailure) {
 				// Ignore the deletion failure. We probably are
 				// already failing and were just trying to pick
 				// up after ourselves.
 			}
 		}
 	}
 
 	private void deleteCommand(RemoteRefUpdate u) {
 		final Ref r = newRefs.remove(u.getRemoteName());
 		if (r == null) {
 			// Already gone.
 			//
 			u.setStatus(Status.OK);
 			return;
 		}
 
 		if (r.getStorage().isPacked())
 			packedRefUpdates.add(u);
 
 		if (r.getStorage().isLoose()) {
 			try {
 				dest.deleteRef(u.getRemoteName());
 				u.setStatus(Status.OK);
 			} catch (IOException e) {
 				u.setStatus(Status.REJECTED_OTHER_REASON);
 				u.setMessage(e.getMessage());
 			}
 		}
 
 		try {
 			dest.deleteRefLog(u.getRemoteName());
 		} catch (IOException e) {
 			u.setStatus(Status.REJECTED_OTHER_REASON);
 			u.setMessage(e.getMessage());
 		}
 	}
 
 	private void updateCommand(RemoteRefUpdate u) {
 		try {
 			dest.writeRef(u.getRemoteName(), u.getNewObjectId());
 			newRefs.put(u.getRemoteName(), new ObjectIdRef.Unpeeled(
 					Storage.LOOSE, u.getRemoteName(), u.getNewObjectId()));
 			u.setStatus(Status.OK);
 		} catch (IOException e) {
 			u.setStatus(Status.REJECTED_OTHER_REASON);
 			u.setMessage(e.getMessage());
 		}
 	}
 
 	private boolean isNewRepository() {
 		return getRefsMap().isEmpty() && packNames != null
 				&& packNames.isEmpty();
 	}
 
 	private void createNewRepository(List<RemoteRefUpdate> updates)
 			throws TransportException {
 		try {
 			final String ref = "ref: " + pickHEAD(updates) + "\n"; //$NON-NLS-1$ //$NON-NLS-2$
 			final byte[] bytes = Constants.encode(ref);
 			dest.writeFile(ROOT_DIR + Constants.HEAD, bytes);
 		} catch (IOException e) {
 			throw new TransportException(uri, JGitText.get().cannotCreateHEAD, e);
 		}
 
 		try {
 			final String config = "[core]\n" //$NON-NLS-1$
 					+ "\trepositoryformatversion = 0\n"; //$NON-NLS-1$
 			final byte[] bytes = Constants.encode(config);
 			dest.writeFile(ROOT_DIR + Constants.CONFIG, bytes);
 		} catch (IOException e) {
 			throw new TransportException(uri, JGitText.get().cannotCreateConfig, e);
 		}
 	}
 
 	private static String pickHEAD(List<RemoteRefUpdate> updates) {
 		// Try to use master if the user is pushing that, it is the
 		// default branch and is likely what they want to remain as
 		// the default on the new remote.
 		//
 		for (RemoteRefUpdate u : updates) {
 			final String n = u.getRemoteName();
 			if (n.equals(Constants.R_HEADS + Constants.MASTER))
 				return n;
 		}
 
 		// Pick any branch, under the assumption the user pushed only
 		// one to the remote side.
 		//
 		for (RemoteRefUpdate u : updates) {
 			final String n = u.getRemoteName();
 			if (n.startsWith(Constants.R_HEADS))
 				return n;
 		}
 		return updates.get(0).getRemoteName();
 	}
 }