/*
    * Copyright (C) 2008-2012, Google Inc.
    * 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.lib;
  
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.NOT_ATTEMPTED;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_OTHER_REASON;
  import static java.util.stream.Collectors.toCollection;
  
  import java.io.IOException;
  import java.text.MessageFormat;
  import java.time.Duration;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashSet;
  import java.util.List;
  import java.util.concurrent.TimeoutException;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.RefUpdate.Result;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.transport.PushCertificate;
  import org.eclipse.jgit.transport.ReceiveCommand;
  import org.eclipse.jgit.util.time.ProposedTimestamp;
  
  /**
   * Batch of reference updates to be applied to a repository.
   * <p>
   * The batch update is primarily useful in the transport code, where a client or
   * server is making changes to more than one reference at a time.
   */
  public class BatchRefUpdate {
  	/**
  	 * Maximum delay the calling thread will tolerate while waiting for a
  	 * {@code MonotonicClock} to resolve associated {@link ProposedTimestamp}s.
  	 * <p>
  	 * A default of 5 seconds was chosen by guessing. A common assumption is
  	 * clock skew between machines on the same LAN using an NTP server also on
  	 * the same LAN should be under 5 seconds. 5 seconds is also not that long
  	 * for a large `git push` operation to complete.
  	 *
  	 * @since 4.9
  	 */
  	protected static final Duration MAX_WAIT = Duration.ofSeconds(5);
  
  	private final RefDatabase refdb;
  
  	/** Commands to apply during this batch. */
  	private final List<ReceiveCommand> commands;
  
  	/** Does the caller permit a forced update on a reference? */
  	private boolean allowNonFastForwards;
  
  	/** Identity to record action as within the reflog. */
  	private PersonIdent refLogIdent;
  
  	/** Message the caller wants included in the reflog. */
  	private String refLogMessage;
  
  	/** Should the result value be appended to {@link #refLogMessage}. */
  	private boolean refLogIncludeResult;
  
  	/**
  	 * Should reflogs be written even if the configured default for this ref is
  	 * not to write it.
  	 */
  	private boolean forceRefLog;
  
  	/** Push certificate associated with this update. */
  	private PushCertificate pushCert;
  
  	/** Whether updates should be atomic. */
  	private boolean atomic;
  
  	/** Push options associated with this update. */
  	private List<String> pushOptions;
  
  	/** Associated timestamps that should be blocked on before update. */
  	private List<ProposedTimestamp> timestamps;
  
  	/**
  	 * Initialize a new batch update.
  	 *
  	 * @param refdb
  	 *            the reference database of the repository to be updated.
  	 */
  	protected BatchRefUpdate(RefDatabase refdb) {
 		this.refdb = refdb;
 		this.commands = new ArrayList<>();
 		this.atomic = refdb.performsAtomicTransactions();
 	}
 
 	/**
 	 * Whether the batch update will permit a non-fast-forward update to an
 	 * existing reference.
 	 *
 	 * @return true if the batch update will permit a non-fast-forward update to
 	 *         an existing reference.
 	 */
 	public boolean isAllowNonFastForwards() {
 		return allowNonFastForwards;
 	}
 
 	/**
 	 * Set if this update wants to permit a forced update.
 	 *
 	 * @param allow
 	 *            true if this update batch should ignore merge tests.
 	 * @return {@code this}.
 	 */
 	public BatchRefUpdate setAllowNonFastForwards(boolean allow) {
 		allowNonFastForwards = allow;
 		return this;
 	}
 
 	/**
 	 * Get identity of the user making the change in the reflog.
 	 *
 	 * @return identity of the user making the change in the reflog.
 	 */
 	public PersonIdent getRefLogIdent() {
 		return refLogIdent;
 	}
 
 	/**
 	 * Set the identity of the user appearing in the reflog.
 	 * <p>
 	 * The timestamp portion of the identity is ignored. A new identity with the
 	 * current timestamp will be created automatically when the update occurs
 	 * and the log record is written.
 	 *
 	 * @param pi
 	 *            identity of the user. If null the identity will be
 	 *            automatically determined based on the repository
 	 *            configuration.
 	 * @return {@code this}.
 	 */
 	public BatchRefUpdate setRefLogIdent(PersonIdent pi) {
 		refLogIdent = pi;
 		return this;
 	}
 
 	/**
 	 * Get the message to include in the reflog.
 	 *
 	 * @return message the caller wants to include in the reflog; null if the
 	 *         update should not be logged.
 	 */
 	@Nullable
 	public String getRefLogMessage() {
 		return refLogMessage;
 	}
 
 	/**
 	 * Check whether the reflog message should include the result of the update,
 	 * such as fast-forward or force-update.
 	 * <p>
 	 * Describes the default for commands in this batch that do not override it
 	 * with
 	 * {@link org.eclipse.jgit.transport.ReceiveCommand#setRefLogMessage(String, boolean)}.
 	 *
 	 * @return true if the message should include the result.
 	 */
 	public boolean isRefLogIncludingResult() {
 		return refLogIncludeResult;
 	}
 
 	/**
 	 * Set the message to include in the reflog.
 	 * <p>
 	 * Repository implementations may limit which reflogs are written by
 	 * default, based on the project configuration. If a repo is not configured
 	 * to write logs for this ref by default, setting the message alone may have
 	 * no effect. To indicate that the repo should write logs for this update in
 	 * spite of configured defaults, use {@link #setForceRefLog(boolean)}.
 	 * <p>
 	 * Describes the default for commands in this batch that do not override it
 	 * with
 	 * {@link org.eclipse.jgit.transport.ReceiveCommand#setRefLogMessage(String, boolean)}.
 	 *
 	 * @param msg
 	 *            the message to describe this change. If null and appendStatus
 	 *            is false, the reflog will not be updated.
 	 * @param appendStatus
 	 *            true if the status of the ref change (fast-forward or
 	 *            forced-update) should be appended to the user supplied
 	 *            message.
 	 * @return {@code this}.
 	 */
 	public BatchRefUpdate setRefLogMessage(String msg, boolean appendStatus) {
 		if (msg == null && !appendStatus)
 			disableRefLog();
 		else if (msg == null && appendStatus) {
 			refLogMessage = ""; //$NON-NLS-1$
 			refLogIncludeResult = true;
 		} else {
 			refLogMessage = msg;
 			refLogIncludeResult = appendStatus;
 		}
 		return this;
 	}
 
 	/**
 	 * Don't record this update in the ref's associated reflog.
 	 * <p>
 	 * Equivalent to {@code setRefLogMessage(null, false)}.
 	 *
 	 * @return {@code this}.
 	 */
 	public BatchRefUpdate disableRefLog() {
 		refLogMessage = null;
 		refLogIncludeResult = false;
 		return this;
 	}
 
 	/**
 	 * Force writing a reflog for the updated ref.
 	 *
 	 * @param force whether to force.
 	 * @return {@code this}
 	 * @since 4.9
 	 */
 	public BatchRefUpdate setForceRefLog(boolean force) {
 		forceRefLog = force;
 		return this;
 	}
 
 	/**
 	 * Check whether log has been disabled by {@link #disableRefLog()}.
 	 *
 	 * @return true if disabled.
 	 */
 	public boolean isRefLogDisabled() {
 		return refLogMessage == null;
 	}
 
 	/**
 	 * Check whether the reflog should be written regardless of repo defaults.
 	 *
 	 * @return whether force writing is enabled.
 	 * @since 4.9
 	 */
 	protected boolean isForceRefLog() {
 		return forceRefLog;
 	}
 
 	/**
 	 * Request that all updates in this batch be performed atomically.
 	 * <p>
 	 * When atomic updates are used, either all commands apply successfully, or
 	 * none do. Commands that might have otherwise succeeded are rejected with
 	 * {@code REJECTED_OTHER_REASON}.
 	 * <p>
 	 * This method only works if the underlying ref database supports atomic
 	 * transactions, i.e.
 	 * {@link org.eclipse.jgit.lib.RefDatabase#performsAtomicTransactions()}
 	 * returns true. Calling this method with true if the underlying ref
 	 * database does not support atomic transactions will cause all commands to
 	 * fail with {@code
 	 * REJECTED_OTHER_REASON}.
 	 *
 	 * @param atomic
 	 *            whether updates should be atomic.
 	 * @return {@code this}
 	 * @since 4.4
 	 */
 	public BatchRefUpdate setAtomic(boolean atomic) {
 		this.atomic = atomic;
 		return this;
 	}
 
 	/**
 	 * Whether updates should be atomic.
 	 *
 	 * @return atomic whether updates should be atomic.
 	 * @since 4.4
 	 */
 	public boolean isAtomic() {
 		return atomic;
 	}
 
 	/**
 	 * Set a push certificate associated with this update.
 	 * <p>
 	 * This usually includes commands to update the refs in this batch, but is not
 	 * required to.
 	 *
 	 * @param cert
 	 *            push certificate, may be null.
 	 * @since 4.1
 	 */
 	public void setPushCertificate(PushCertificate cert) {
 		pushCert = cert;
 	}
 
 	/**
 	 * Set the push certificate associated with this update.
 	 * <p>
 	 * This usually includes commands to update the refs in this batch, but is not
 	 * required to.
 	 *
 	 * @return push certificate, may be null.
 	 * @since 4.1
 	 */
 	protected PushCertificate getPushCertificate() {
 		return pushCert;
 	}
 
 	/**
 	 * Get commands this update will process.
 	 *
 	 * @return commands this update will process.
 	 */
 	public List<ReceiveCommand> getCommands() {
 		return Collections.unmodifiableList(commands);
 	}
 
 	/**
 	 * Add a single command to this batch update.
 	 *
 	 * @param cmd
 	 *            the command to add, must not be null.
 	 * @return {@code this}.
 	 */
 	public BatchRefUpdate addCommand(ReceiveCommand cmd) {
 		commands.add(cmd);
 		return this;
 	}
 
 	/**
 	 * Add commands to this batch update.
 	 *
 	 * @param cmd
 	 *            the commands to add, must not be null.
 	 * @return {@code this}.
 	 */
 	public BatchRefUpdate addCommand(ReceiveCommand... cmd) {
 		return addCommand(Arrays.asList(cmd));
 	}
 
 	/**
 	 * Add commands to this batch update.
 	 *
 	 * @param cmd
 	 *            the commands to add, must not be null.
 	 * @return {@code this}.
 	 */
 	public BatchRefUpdate addCommand(Collection<ReceiveCommand> cmd) {
 		commands.addAll(cmd);
 		return this;
 	}
 
 	/**
 	 * Gets the list of option strings associated with this update.
 	 *
 	 * @return push options that were passed to {@link #execute}; prior to calling
 	 *         {@link #execute}, always returns null.
 	 * @since 4.5
 	 */
 	@Nullable
 	public List<String> getPushOptions() {
 		return pushOptions;
 	}
 
 	/**
 	 * Set push options associated with this update.
 	 * <p>
 	 * Implementations must call this at the top of {@link #execute(RevWalk,
 	 * ProgressMonitor, List)}.
 	 *
 	 * @param options options passed to {@code execute}.
 	 * @since 4.9
 	 */
 	protected void setPushOptions(List<String> options) {
 		pushOptions = options;
 	}
 
 	/**
 	 * Get list of timestamps the batch must wait for.
 	 *
 	 * @return list of timestamps the batch must wait for.
 	 * @since 4.6
 	 */
 	public List<ProposedTimestamp> getProposedTimestamps() {
 		if (timestamps != null) {
 			return Collections.unmodifiableList(timestamps);
 		}
 		return Collections.emptyList();
 	}
 
 	/**
 	 * Request the batch to wait for the affected timestamps to resolve.
 	 *
 	 * @param ts
 	 *            a {@link org.eclipse.jgit.util.time.ProposedTimestamp} object.
 	 * @return {@code this}.
 	 * @since 4.6
 	 */
 	public BatchRefUpdate addProposedTimestamp(ProposedTimestamp ts) {
 		if (timestamps == null) {
 			timestamps = new ArrayList<>(4);
 		}
 		timestamps.add(ts);
 		return this;
 	}
 
 	/**
 	 * Execute this batch update.
 	 * <p>
 	 * The default implementation of this method performs a sequential reference
 	 * update over each reference.
 	 * <p>
 	 * Implementations must respect the atomicity requirements of the underlying
 	 * database as described in {@link #setAtomic(boolean)} and
 	 * {@link org.eclipse.jgit.lib.RefDatabase#performsAtomicTransactions()}.
 	 *
 	 * @param walk
 	 *            a RevWalk to parse tags in case the storage system wants to
 	 *            store them pre-peeled, a common performance optimization.
 	 * @param monitor
 	 *            progress monitor to receive update status on.
 	 * @param options
 	 *            a list of option strings; set null to execute without
 	 * @throws java.io.IOException
 	 *             the database is unable to accept the update. Individual
 	 *             command status must be tested to determine if there is a
 	 *             partial failure, or a total failure.
 	 * @since 4.5
 	 */
 	public void execute(RevWalk walk, ProgressMonitor monitor,
 			List<String> options) throws IOException {
 
 		if (atomic && !refdb.performsAtomicTransactions()) {
 			for (ReceiveCommand c : commands) {
 				if (c.getResult() == NOT_ATTEMPTED) {
 					c.setResult(REJECTED_OTHER_REASON,
 							JGitText.get().atomicRefUpdatesNotSupported);
 				}
 			}
 			return;
 		}
 		if (!blockUntilTimestamps(MAX_WAIT)) {
 			return;
 		}
 
 		if (options != null) {
 			setPushOptions(options);
 		}
 
 		monitor.beginTask(JGitText.get().updatingReferences, commands.size());
 		List<ReceiveCommand> commands2 = new ArrayList<>(
 				commands.size());
 		// First delete refs. This may free the name space for some of the
 		// updates.
 		for (ReceiveCommand cmd : commands) {
 			try {
 				if (cmd.getResult() == NOT_ATTEMPTED) {
 					if (isMissing(walk, cmd.getOldId())
 							|| isMissing(walk, cmd.getNewId())) {
 						cmd.setResult(ReceiveCommand.Result.REJECTED_MISSING_OBJECT);
 						continue;
 					}
 					cmd.updateType(walk);
 					switch (cmd.getType()) {
 					case CREATE:
 						commands2.add(cmd);
 						break;
 					case UPDATE:
 					case UPDATE_NONFASTFORWARD:
 						commands2.add(cmd);
 						break;
 					case DELETE:
 						RefUpdate rud = newUpdate(cmd);
 						monitor.update(1);
 						cmd.setResult(rud.delete(walk));
 					}
 				}
 			} catch (IOException err) {
 				cmd.setResult(
 						REJECTED_OTHER_REASON,
 						MessageFormat.format(JGitText.get().lockError,
 								err.getMessage()));
 			}
 		}
 		if (!commands2.isEmpty()) {
 			// What part of the name space is already taken
 			Collection<String> takenNames = refdb.getRefs().stream()
 					.map(Ref::getName)
 					.collect(toCollection(HashSet::new));
 			Collection<String> takenPrefixes = getTakenPrefixes(takenNames);
 
 			// Now to the update that may require more room in the name space
 			for (ReceiveCommand cmd : commands2) {
 				try {
 					if (cmd.getResult() == NOT_ATTEMPTED) {
 						cmd.updateType(walk);
 						RefUpdate ru = newUpdate(cmd);
 						SWITCH: switch (cmd.getType()) {
 						case DELETE:
 							// Performed in the first phase
 							break;
 						case UPDATE:
 						case UPDATE_NONFASTFORWARD:
 							RefUpdate ruu = newUpdate(cmd);
 							cmd.setResult(ruu.update(walk));
 							break;
 						case CREATE:
 							for (String prefix : getPrefixes(cmd.getRefName())) {
 								if (takenNames.contains(prefix)) {
 									cmd.setResult(Result.LOCK_FAILURE);
 									break SWITCH;
 								}
 							}
 							if (takenPrefixes.contains(cmd.getRefName())) {
 								cmd.setResult(Result.LOCK_FAILURE);
 								break SWITCH;
 							}
 							ru.setCheckConflicting(false);
 							takenPrefixes.addAll(getPrefixes(cmd.getRefName()));
 							takenNames.add(cmd.getRefName());
 							cmd.setResult(ru.update(walk));
 						}
 					}
 				} catch (IOException err) {
 					cmd.setResult(REJECTED_OTHER_REASON, MessageFormat.format(
 							JGitText.get().lockError, err.getMessage()));
 				} finally {
 					monitor.update(1);
 				}
 			}
 		}
 		monitor.endTask();
 	}
 
 	private static boolean isMissing(RevWalk walk, ObjectId id)
 			throws IOException {
 		if (id.equals(ObjectId.zeroId())) {
 			return false; // Explicit add or delete is not missing.
 		}
 		try {
 			walk.parseAny(id);
 			return false;
 		} catch (MissingObjectException e) {
 			return true;
 		}
 	}
 
 	/**
 	 * Wait for timestamps to be in the past, aborting commands on timeout.
 	 *
 	 * @param maxWait
 	 *            maximum amount of time to wait for timestamps to resolve.
 	 * @return true if timestamps were successfully waited for; false if
 	 *         commands were aborted.
 	 * @since 4.6
 	 */
 	protected boolean blockUntilTimestamps(Duration maxWait) {
 		if (timestamps == null) {
 			return true;
 		}
 		try {
 			ProposedTimestamp.blockUntil(timestamps, maxWait);
 			return true;
 		} catch (TimeoutException | InterruptedException e) {
 			String msg = JGitText.get().timeIsUncertain;
 			for (ReceiveCommand c : commands) {
 				if (c.getResult() == NOT_ATTEMPTED) {
 					c.setResult(REJECTED_OTHER_REASON, msg);
 				}
 			}
 			return false;
 		}
 	}
 
 	/**
 	 * Execute this batch update without option strings.
 	 *
 	 * @param walk
 	 *            a RevWalk to parse tags in case the storage system wants to
 	 *            store them pre-peeled, a common performance optimization.
 	 * @param monitor
 	 *            progress monitor to receive update status on.
 	 * @throws java.io.IOException
 	 *             the database is unable to accept the update. Individual
 	 *             command status must be tested to determine if there is a
 	 *             partial failure, or a total failure.
 	 */
 	public void execute(RevWalk walk, ProgressMonitor monitor)
 			throws IOException {
 		execute(walk, monitor, null);
 	}
 
 	private static Collection<String> getTakenPrefixes(Collection<String> names) {
 		Collection<String> ref = new HashSet<>();
 		for (String name : names) {
 			addPrefixesTo(name, ref);
 		}
 		return ref;
 	}
 
 	/**
 	 * Get all path prefixes of a ref name.
 	 *
 	 * @param name
 	 *            ref name.
 	 * @return path prefixes of the ref name. For {@code refs/heads/foo}, returns
 	 *         {@code refs} and {@code refs/heads}.
 	 * @since 4.9
 	 */
 	protected static Collection<String> getPrefixes(String name) {
 		Collection<String> ret = new HashSet<>();
 		addPrefixesTo(name, ret);
 		return ret;
 	}
 
 	/**
 	 * Add prefixes of a ref name to an existing collection.
 	 *
 	 * @param name
 	 *            ref name.
 	 * @param out
 	 *            path prefixes of the ref name. For {@code refs/heads/foo},
 	 *            returns {@code refs} and {@code refs/heads}.
 	 * @since 4.9
 	 */
 	protected static void addPrefixesTo(String name, Collection<String> out) {
 		int p1 = name.indexOf('/');
 		while (p1 > 0) {
 			out.add(name.substring(0, p1));
 			p1 = name.indexOf('/', p1 + 1);
 		}
 	}
 
 	/**
 	 * Create a new RefUpdate copying the batch settings.
 	 *
 	 * @param cmd
 	 *            specific command the update should be created to copy.
 	 * @return a single reference update command.
 	 * @throws java.io.IOException
 	 *             the reference database cannot make a new update object for
 	 *             the given reference.
 	 */
 	protected RefUpdate newUpdate(ReceiveCommand cmd) throws IOException {
 		RefUpdate ru = refdb.newUpdate(cmd.getRefName(), false);
 		if (isRefLogDisabled(cmd)) {
 			ru.disableRefLog();
 		} else {
 			ru.setRefLogIdent(refLogIdent);
 			ru.setRefLogMessage(getRefLogMessage(cmd), isRefLogIncludingResult(cmd));
 			ru.setForceRefLog(isForceRefLog(cmd));
 		}
 		ru.setPushCertificate(pushCert);
 		switch (cmd.getType()) {
 		case DELETE:
 			if (!ObjectId.zeroId().equals(cmd.getOldId()))
 				ru.setExpectedOldObjectId(cmd.getOldId());
 			ru.setForceUpdate(true);
 			return ru;
 
 		case CREATE:
 		case UPDATE:
 		case UPDATE_NONFASTFORWARD:
 		default:
 			ru.setForceUpdate(isAllowNonFastForwards());
 			ru.setExpectedOldObjectId(cmd.getOldId());
 			ru.setNewObjectId(cmd.getNewId());
 			return ru;
 		}
 	}
 
 	/**
 	 * Check whether reflog is disabled for a command.
 	 *
 	 * @param cmd
 	 *            specific command.
 	 * @return whether the reflog is disabled, taking into account the state from
 	 *         this instance as well as overrides in the given command.
 	 * @since 4.9
 	 */
 	protected boolean isRefLogDisabled(ReceiveCommand cmd) {
 		return cmd.hasCustomRefLog() ? cmd.isRefLogDisabled() : isRefLogDisabled();
 	}
 
 	/**
 	 * Get reflog message for a command.
 	 *
 	 * @param cmd
 	 *            specific command.
 	 * @return reflog message, taking into account the state from this instance as
 	 *         well as overrides in the given command.
 	 * @since 4.9
 	 */
 	protected String getRefLogMessage(ReceiveCommand cmd) {
 		return cmd.hasCustomRefLog() ? cmd.getRefLogMessage() : getRefLogMessage();
 	}
 
 	/**
 	 * Check whether the reflog message for a command should include the result.
 	 *
 	 * @param cmd
 	 *            specific command.
 	 * @return whether the reflog message should show the result, taking into
 	 *         account the state from this instance as well as overrides in the
 	 *         given command.
 	 * @since 4.9
 	 */
 	protected boolean isRefLogIncludingResult(ReceiveCommand cmd) {
 		return cmd.hasCustomRefLog()
 				? cmd.isRefLogIncludingResult() : isRefLogIncludingResult();
 	}
 
 	/**
 	 * Check whether the reflog for a command should be written regardless of repo
 	 * defaults.
 	 *
 	 * @param cmd
 	 *            specific command.
 	 * @return whether force writing is enabled.
 	 * @since 4.9
 	 */
 	protected boolean isForceRefLog(ReceiveCommand cmd) {
 		Boolean isForceRefLog = cmd.isForceRefLog();
 		return isForceRefLog != null ? isForceRefLog.booleanValue()
 				: isForceRefLog();
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public String toString() {
 		StringBuilder r = new StringBuilder();
 		r.append(getClass().getSimpleName()).append('[');
 		if (commands.isEmpty())
 			return r.append(']').toString();
 
 		r.append('\n');
 		for (ReceiveCommand cmd : commands) {
 			r.append("  "); //$NON-NLS-1$
 			r.append(cmd);
 			r.append("  (").append(cmd.getResult()); //$NON-NLS-1$
 			if (cmd.getMessage() != null) {
 				r.append(": ").append(cmd.getMessage()); //$NON-NLS-1$
 			}
 			r.append(")\n"); //$NON-NLS-1$
 		}
 		return r.append(']').toString();
 	}
 }