/*
    * Copyright (C) 2016, Google Inc. 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.internal.storage.reftree;
  
  import static org.eclipse.jgit.lib.Constants.OBJ_TREE;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.NOT_ATTEMPTED;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.OK;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_NONFASTFORWARD;
  import static org.eclipse.jgit.transport.ReceiveCommand.Result.REJECTED_OTHER_REASON;
  import static org.eclipse.jgit.transport.ReceiveCommand.Type.UPDATE;
  import static org.eclipse.jgit.transport.ReceiveCommand.Type.UPDATE_NONFASTFORWARD;
  
  import java.io.IOException;
  import java.text.MessageFormat;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.eclipse.jgit.annotations.Nullable;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.BatchRefUpdate;
  import org.eclipse.jgit.lib.CommitBuilder;
  import org.eclipse.jgit.lib.NullProgressMonitor;
  import org.eclipse.jgit.lib.ObjectId;
  import org.eclipse.jgit.lib.ObjectInserter;
  import org.eclipse.jgit.lib.ObjectReader;
  import org.eclipse.jgit.lib.PersonIdent;
  import org.eclipse.jgit.lib.ProgressMonitor;
  import org.eclipse.jgit.lib.Ref;
  import org.eclipse.jgit.lib.Repository;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.revwalk.RevWalk;
  import org.eclipse.jgit.transport.ReceiveCommand;
  
  /** Batch update a {@link RefTreeDatabase}. */
  class RefTreeBatch extends BatchRefUpdate {
  	private final RefTreeDatabase refdb;
  	private Ref src;
  	private ObjectId parentCommitId;
  	private ObjectId parentTreeId;
  	private RefTree tree;
  	private PersonIdent author;
  	private ObjectId newCommitId;
  
  	RefTreeBatch(RefTreeDatabase refdb) {
  		super(refdb);
  		this.refdb = refdb;
  	}
  
  	/** {@inheritDoc} */
  	@Override
  	public void execute(RevWalk rw, ProgressMonitor monitor)
  			throws IOException {
  		List<Command> todo = new ArrayList<>(getCommands().size());
  		for (ReceiveCommand c : getCommands()) {
  			if (!isAllowNonFastForwards()) {
  				if (c.getType() == UPDATE) {
  					c.updateType(rw);
  				}
  				if (c.getType() == UPDATE_NONFASTFORWARD) {
  					c.setResult(REJECTED_NONFASTFORWARD);
  					if (isAtomic()) {
  						ReceiveCommand.abort(getCommands());
  						return;
  					}
  					continue;
  				}
  			}
  			todo.add(new Command(rw, c));
  		}
  		init(rw);
  		execute(rw, todo);
  	}
  
  	void init(RevWalk rw) throws IOException {
  		src = refdb.getBootstrap().exactRef(refdb.getTxnCommitted());
  		if (src != null && src.getObjectId() != null) {
  			RevCommit c = rw.parseCommit(src.getObjectId());
  			parentCommitId = c;
  			parentTreeId = c.getTree();
  			tree = RefTree.read(rw.getObjectReader(), c.getTree());
  		} else {
  			parentCommitId = ObjectId.zeroId();
  			try (ObjectInserter.Formatter fmt = new ObjectInserter.Formatter()) {
  				parentTreeId = fmt.idFor(OBJ_TREE, new byte[] {});
  			}
  			tree = RefTree.newEmptyTree();
  		}
  	}
  
  	@Nullable
  	Ref exactRef(ObjectReader reader, String name) throws IOException {
 		return tree.exactRef(reader, name);
 	}
 
 	/**
 	 * Execute an update from {@link RefTreeUpdate} or {@link RefTreeRename}.
 	 *
 	 * @param rw
 	 *            current RevWalk handling the update or rename.
 	 * @param todo
 	 *            commands to execute. Must never be a bootstrap reference name.
 	 * @throws IOException
 	 *             the storage system is unable to read or write data.
 	 */
 	void execute(RevWalk rw, List<Command> todo) throws IOException {
 		for (Command c : todo) {
 			if (c.getResult() != NOT_ATTEMPTED) {
 				Command.abort(todo, null);
 				return;
 			}
 			if (refdb.conflictsWithBootstrap(c.getRefName())) {
 				c.setResult(REJECTED_OTHER_REASON, MessageFormat
 						.format(JGitText.get().invalidRefName, c.getRefName()));
 				Command.abort(todo, null);
 				return;
 			}
 		}
 
 		if (apply(todo) && newCommitId != null) {
 			commit(rw, todo);
 		}
 	}
 
 	private boolean apply(List<Command> todo) throws IOException {
 		if (!tree.apply(todo)) {
 			// apply set rejection information on commands.
 			return false;
 		}
 
 		Repository repo = refdb.getRepository();
 		try (ObjectInserter ins = repo.newObjectInserter()) {
 			CommitBuilder b = new CommitBuilder();
 			b.setTreeId(tree.writeTree(ins));
 			if (parentTreeId.equals(b.getTreeId())) {
 				for (Command c : todo) {
 					c.setResult(OK);
 				}
 				return true;
 			}
 			if (!parentCommitId.equals(ObjectId.zeroId())) {
 				b.setParentId(parentCommitId);
 			}
 
 			author = getRefLogIdent();
 			if (author == null) {
 				author = new PersonIdent(repo);
 			}
 			b.setAuthor(author);
 			b.setCommitter(author);
 			b.setMessage(getRefLogMessage());
 			newCommitId = ins.insert(b);
 			ins.flush();
 		}
 		return true;
 	}
 
 	private void commit(RevWalk rw, List<Command> todo) throws IOException {
 		ReceiveCommand commit = new ReceiveCommand(
 				parentCommitId, newCommitId,
 				refdb.getTxnCommitted());
 		updateBootstrap(rw, commit);
 
 		if (commit.getResult() == OK) {
 			for (Command c : todo) {
 				c.setResult(OK);
 			}
 		} else {
 			Command.abort(todo, commit.getResult().name());
 		}
 	}
 
 	private void updateBootstrap(RevWalk rw, ReceiveCommand commit)
 			throws IOException {
 		BatchRefUpdate u = refdb.getBootstrap().newBatchUpdate();
 		u.setAllowNonFastForwards(true);
 		u.setPushCertificate(getPushCertificate());
 		if (isRefLogDisabled()) {
 			u.disableRefLog();
 		} else {
 			u.setRefLogIdent(author);
 			u.setRefLogMessage(getRefLogMessage(), false);
 		}
 		u.addCommand(commit);
 		u.execute(rw, NullProgressMonitor.INSTANCE);
 	}
 }