/*
    * Copyright (C) 2008, Google Inc.
    * 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
    *
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   * without modification, are permitted provided that the following
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  package org.eclipse.jgit.transport;
  
  import java.io.IOException;
  import java.text.MessageFormat;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.AnyObjectId;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.RefUpdate;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.revwalk.RevObject;
  import org.eclipse.jgit.revwalk.RevWalk;
  
  /**
   * A command being processed by {@link BaseReceivePack}.
   * <p>
   * This command instance roughly translates to the server side representation of
   * the {@link RemoteRefUpdate} created by the client.
   */
  public class ReceiveCommand {
  	/** Type of operation requested. */
  	public static enum Type {
  		/** Create a new ref; the ref must not already exist. */
  		CREATE,
  
  		/**
  		 * Update an existing ref with a fast-forward update.
  		 * <p>
  		 * During a fast-forward update no changes will be lost; only new
  		 * commits are inserted into the ref.
  		 */
  		UPDATE,
  
  		/**
  		 * Update an existing ref by potentially discarding objects.
  		 * <p>
  		 * The current value of the ref is not fully reachable from the new
  		 * value of the ref, so a successful command may result in one or more
  		 * objects becoming unreachable.
  		 */
  		UPDATE_NONFASTFORWARD,
  
  		/** Delete an existing ref; the ref should already exist. */
  		DELETE;
  	}
  
  	/** Result of the update command. */
  	public static enum Result {
  		/** The command has not yet been attempted by the server. */
  		NOT_ATTEMPTED,
  
  		/** The server is configured to deny creation of this ref. */
  		REJECTED_NOCREATE,
 
 		/** The server is configured to deny deletion of this ref. */
 		REJECTED_NODELETE,
 
 		/** The update is a non-fast-forward update and isn't permitted. */
 		REJECTED_NONFASTFORWARD,
 
 		/** The update affects <code>HEAD</code> and cannot be permitted. */
 		REJECTED_CURRENT_BRANCH,
 
 		/**
 		 * One or more objects aren't in the repository.
 		 * <p>
 		 * This is severe indication of either repository corruption on the
 		 * server side, or a bug in the client wherein the client did not supply
 		 * all required objects during the pack transfer.
 		 */
 		REJECTED_MISSING_OBJECT,
 
 		/** Other failure; see {@link ReceiveCommand#getMessage()}. */
 		REJECTED_OTHER_REASON,
 
 		/** The ref could not be locked and updated atomically; try again. */
 		LOCK_FAILURE,
 
 		/** The change was completed successfully. */
 		OK;
 	}
 
 	/**
 	 * Filter a list of commands according to result.
 	 *
 	 * @param commands
 	 *            commands to filter.
 	 * @param want
 	 *            desired status to filter by.
 	 * @return a copy of the command list containing only those commands with
 	 *         the desired status.
 	 * @since 2.0
 	 */
 	public static List<ReceiveCommand> filter(List<ReceiveCommand> commands,
 			final Result want) {
 		List<ReceiveCommand> r = new ArrayList<ReceiveCommand>(commands.size());
 		for (final ReceiveCommand cmd : commands) {
 			if (cmd.getResult() == want)
 				r.add(cmd);
 		}
 		return r;
 	}
 
 	private final ObjectId oldId;
 
 	private final ObjectId newId;
 
 	private final String name;
 
 	private Type type;
 
 	private Ref ref;
 
 	private Result status = Result.NOT_ATTEMPTED;
 
 	private String message;
 
 	private boolean typeIsCorrect;
 
 	/**
 	 * Create a new command for {@link BaseReceivePack}.
 	 *
 	 * @param oldId
 	 *            the old object id; must not be null. Use
 	 *            {@link ObjectId#zeroId()} to indicate a ref creation.
 	 * @param newId
 	 *            the new object id; must not be null. Use
 	 *            {@link ObjectId#zeroId()} to indicate a ref deletion.
 	 * @param name
 	 *            name of the ref being affected.
 	 */
 	public ReceiveCommand(final ObjectId oldId, final ObjectId newId,
 			final String name) {
 		this.oldId = oldId;
 		this.newId = newId;
 		this.name = name;
 
 		type = Type.UPDATE;
 		if (ObjectId.zeroId().equals(oldId))
 			type = Type.CREATE;
 		if (ObjectId.zeroId().equals(newId))
 			type = Type.DELETE;
 	}
 
 	/**
 	 * Create a new command for {@link BaseReceivePack}.
 	 *
 	 * @param oldId
 	 *            the old object id; must not be null. Use
 	 *            {@link ObjectId#zeroId()} to indicate a ref creation.
 	 * @param newId
 	 *            the new object id; must not be null. Use
 	 *            {@link ObjectId#zeroId()} to indicate a ref deletion.
 	 * @param name
 	 *            name of the ref being affected.
 	 * @param type
 	 *            type of the command.
 	 * @since 2.0
 	 */
 	public ReceiveCommand(final ObjectId oldId, final ObjectId newId,
 			final String name, final Type type) {
 		this.oldId = oldId;
 		this.newId = newId;
 		this.name = name;
 		this.type = type;
 	}
 
 	/** @return the old value the client thinks the ref has. */
 	public ObjectId getOldId() {
 		return oldId;
 	}
 
 	/** @return the requested new value for this ref. */
 	public ObjectId getNewId() {
 		return newId;
 	}
 
 	/** @return the name of the ref being updated. */
 	public String getRefName() {
 		return name;
 	}
 
 	/** @return the type of this command; see {@link Type}. */
 	public Type getType() {
 		return type;
 	}
 
 	/** @return the ref, if this was advertised by the connection. */
 	public Ref getRef() {
 		return ref;
 	}
 
 	/** @return the current status code of this command. */
 	public Result getResult() {
 		return status;
 	}
 
 	/** @return the message associated with a failure status. */
 	public String getMessage() {
 		return message;
 	}
 
 	/**
 	 * Set the status of this command.
 	 *
 	 * @param s
 	 *            the new status code for this command.
 	 */
 	public void setResult(final Result s) {
 		setResult(s, null);
 	}
 
 	/**
 	 * Set the status of this command.
 	 *
 	 * @param s
 	 *            new status code for this command.
 	 * @param m
 	 *            optional message explaining the new status.
 	 */
 	public void setResult(final Result s, final String m) {
 		status = s;
 		message = m;
 	}
 
 	/**
 	 * Update the type of this command by checking for fast-forward.
 	 * <p>
 	 * If the command's current type is UPDATE, a merge test will be performed
 	 * using the supplied RevWalk to determine if {@link #getOldId()} is fully
 	 * merged into {@link #getNewId()}. If some commits are not merged the
 	 * update type is changed to {@link Type#UPDATE_NONFASTFORWARD}.
 	 *
 	 * @param walk
 	 *            an instance to perform the merge test with. The caller must
 	 *            allocate and release this object.
 	 * @throws IOException
 	 *             either oldId or newId is not accessible in the repository
 	 *             used by the RevWalk. This usually indicates data corruption,
 	 *             and the command cannot be processed.
 	 */
 	public void updateType(RevWalk walk) throws IOException {
 		if (typeIsCorrect)
 			return;
 		if (type == Type.UPDATE && !AnyObjectId.equals(oldId, newId)) {
 			RevObject o = walk.parseAny(oldId);
 			RevObject n = walk.parseAny(newId);
 			if (!(o instanceof RevCommit)
 					|| !(n instanceof RevCommit)
 					|| !walk.isMergedInto((RevCommit) o, (RevCommit) n))
 				setType(Type.UPDATE_NONFASTFORWARD);
 		}
 		typeIsCorrect = true;
 	}
 
 	/**
 	 * Execute this command during a receive-pack session.
 	 * <p>
 	 * Sets the status of the command as a side effect.
 	 *
 	 * @param rp
 	 *            receive-pack session.
 	 * @since 2.0
 	 */
 	public void execute(final BaseReceivePack rp) {
 		try {
 			final RefUpdate ru = rp.getRepository().updateRef(getRefName());
 			ru.setRefLogIdent(rp.getRefLogIdent());
 			switch (getType()) {
 			case DELETE:
 				if (!ObjectId.zeroId().equals(getOldId())) {
 					// We can only do a CAS style delete if the client
 					// didn't bork its delete request by sending the
 					// wrong zero id rather than the advertised one.
 					//
 					ru.setExpectedOldObjectId(getOldId());
 				}
 				ru.setForceUpdate(true);
 				setResult(ru.delete(rp.getRevWalk()));
 				break;
 
 			case CREATE:
 			case UPDATE:
 			case UPDATE_NONFASTFORWARD:
 				ru.setForceUpdate(rp.isAllowNonFastForwards());
 				ru.setExpectedOldObjectId(getOldId());
 				ru.setNewObjectId(getNewId());
 				ru.setRefLogMessage("push", true); //$NON-NLS-1$
 				setResult(ru.update(rp.getRevWalk()));
 				break;
 			}
 		} catch (IOException err) {
 			reject(err);
 		}
 	}
 
 	void setRef(final Ref r) {
 		ref = r;
 	}
 
 	void setType(final Type t) {
 		type = t;
 	}
 
 	void setTypeFastForwardUpdate() {
 		type = Type.UPDATE;
 		typeIsCorrect = true;
 	}
 
 	/**
 	 * Set the result of this command.
 	 *
 	 * @param r
 	 *            the new result code for this command.
 	 */
 	public void setResult(RefUpdate.Result r) {
 		switch (r) {
 		case NOT_ATTEMPTED:
 			setResult(Result.NOT_ATTEMPTED);
 			break;
 
 		case LOCK_FAILURE:
 		case IO_FAILURE:
 			setResult(Result.LOCK_FAILURE);
 			break;
 
 		case NO_CHANGE:
 		case NEW:
 		case FORCED:
 		case FAST_FORWARD:
 			setResult(Result.OK);
 			break;
 
 		case REJECTED:
 			setResult(Result.REJECTED_NONFASTFORWARD);
 			break;
 
 		case REJECTED_CURRENT_BRANCH:
 			setResult(Result.REJECTED_CURRENT_BRANCH);
 			break;
 
 		default:
 			setResult(Result.REJECTED_OTHER_REASON, r.name());
 			break;
 		}
 	}
 
 	void reject(IOException err) {
 		setResult(Result.REJECTED_OTHER_REASON, MessageFormat.format(
 				JGitText.get().lockError, err.getMessage()));
 	}
 
 	@SuppressWarnings("nls")
 	@Override
 	public String toString() {
 		return getType().name() + ": " + getOldId().name() + " "
 				+ getNewId().name() + " " + getRefName();
 	}
 }