/*
    * Copyright (C) 2008-2012, Google Inc.
    * Copyright (C) 2008, Shawn O. Pearce <spearce@spearce.org>
    * and other copyright owners as documented in the project's IP log.
    *
    * This program and the accompanying materials are made available
    * under the terms of the Eclipse Distribution License v1.0 which
    * accompanies this distribution, is reproduced below, and is
    * available at http://www.eclipse.org/org/documents/edl-v10.php
   *
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or
   * without modification, are permitted provided that the following
   * conditions are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   *
   * - Redistributions in binary form must reproduce the above
   *   copyright notice, this list of conditions and the following
   *   disclaimer in the documentation and/or other materials provided
   *   with the distribution.
   *
   * - Neither the name of the Eclipse Foundation, Inc. nor the
   *   names of its contributors may be used to endorse or promote
   *   products derived from this software without specific prior
   *   written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
   * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
   * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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  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 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.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.
  	 */
  	private 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;
 
 	/** 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();
 	}
 
 	/**
 	 * @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;
 	}
 
 	/** @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(final 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.
 	 */
 	public String getRefLogMessage() {
 		return refLogMessage;
 	}
 
 	/** @return {@code true} if the ref log message should show the result. */
 	public boolean isRefLogIncludingResult() {
 		return refLogIncludeResult;
 	}
 
 	/**
 	 * Set the message to include in the reflog.
 	 *
 	 * @param msg
 	 *            the message to describe this change. It may be null if
 	 *            appendStatus is null in order not to append to the reflog
 	 * @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.
 	 *
 	 * @return {@code this}.
 	 */
 	public BatchRefUpdate disableRefLog() {
 		refLogMessage = null;
 		refLogIncludeResult = false;
 		return this;
 	}
 
 	/** @return true if log has been disabled by {@link #disableRefLog()}. */
 	public boolean isRefLogDisabled() {
 		return refLogMessage == null;
 	}
 
 	/**
 	 * 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 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;
 	}
 
 	/**
 	 * @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;
 	}
 
 	/** @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 pushOptions
 	 * @since 4.5
 	 */
 	public List<String> getPushOptions() {
 		return pushOptions;
 	}
 
 	/**
 	 * @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
 	 * @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 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 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) {
 			pushOptions = 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) {
 					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 = new HashSet<>(refdb.getRefs(
 					RefDatabase.ALL).keySet());
 			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);
 							addRefToPrefixes(takenPrefixes, 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();
 	}
 
 	/**
 	 * 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 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(
 			final Collection<String> names) {
 		Collection<String> ref = new HashSet<>();
 		for (String name : names)
 			ref.addAll(getPrefixes(name));
 		return ref;
 	}
 
 	private static void addRefToPrefixes(Collection<String> prefixes,
 			String name) {
 		for (String prefix : getPrefixes(name)) {
 			prefixes.add(prefix);
 		}
 	}
 
 	static Collection<String> getPrefixes(String s) {
 		Collection<String> ret = new HashSet<>();
 		int p1 = s.indexOf('/');
 		while (p1 > 0) {
 			ret.add(s.substring(0, p1));
 			p1 = s.indexOf('/', p1 + 1);
 		}
 		return ret;
 	}
 
 	/**
 	 * 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 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())
 			ru.disableRefLog();
 		else {
 			ru.setRefLogIdent(refLogIdent);
 			ru.setRefLogMessage(refLogMessage, refLogIncludeResult);
 		}
 		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;
 		}
 	}
 
 	@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();
 	}
 }