/*
 * Copyright (C) 2008-2009, 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.dircache;

import static org.eclipse.jgit.lib.FileMode.TYPE_MASK;
import static org.eclipse.jgit.lib.FileMode.TYPE_TREE;

import java.io.IOException;
import java.text.MessageFormat;
import java.util.Arrays;

import org.eclipse.jgit.internal.JGitText;
import org.eclipse.jgit.lib.AnyObjectId;
import org.eclipse.jgit.lib.ObjectReader;
import org.eclipse.jgit.treewalk.CanonicalTreeParser;

Updates a DirCache by adding individual DirCacheEntrys. 

A builder always starts from a clean slate and appends in every single
DirCacheEntry which the final updated index must have to reflect
its new content.
 For maximum performance applications should add entries in path name order. Adding entries out of order is permitted, however a final sorting pass will be implicitly performed during finish() to correct any out-of-order entries. Duplicate detection is also delayed until the sorting is complete. 
See Also:
DirCacheEditor/**
 * Updates a {@link org.eclipse.jgit.dircache.DirCache} by adding individual
 * {@link org.eclipse.jgit.dircache.DirCacheEntry}s.
 * <p>
 * A builder always starts from a clean slate and appends in every single
 * <code>DirCacheEntry</code> which the final updated index must have to reflect
 * its new content.
 * <p>
 * For maximum performance applications should add entries in path name order.
 * Adding entries out of order is permitted, however a final sorting pass will
 * be implicitly performed during {@link #finish()} to correct any out-of-order
 * entries. Duplicate detection is also delayed until the sorting is complete.
 *
 * @see DirCacheEditor
 */
public class DirCacheBuilder extends BaseDirCacheEditor {
	private boolean sorted;

	
Construct a new builder.
Params:
dc – 
           the cache this builder will eventually update.
ecnt – 
           estimated number of entries the builder will have upon
           completion. This sizes the initial entry table./**
	 * Construct a new builder.
	 *
	 * @param dc
	 *            the cache this builder will eventually update.
	 * @param ecnt
	 *            estimated number of entries the builder will have upon
	 *            completion. This sizes the initial entry table.
	 */
	protected DirCacheBuilder(DirCache dc, int ecnt) {
		super(dc, ecnt);
	}

	
Append one entry into the resulting entry list.
 The entry is placed at the end of the entry list. If the entry causes the list to now be incorrectly sorted a final sorting phase will be automatically enabled within finish(). 

The internal entry table is automatically expanded if there is
insufficient space for the new addition.
Params:
newEntry – 
           the new entry to add.
Throws:
IllegalArgumentException – 
            If the FileMode of the entry was not set by the caller./**
	 * Append one entry into the resulting entry list.
	 * <p>
	 * The entry is placed at the end of the entry list. If the entry causes the
	 * list to now be incorrectly sorted a final sorting phase will be
	 * automatically enabled within {@link #finish()}.
	 * <p>
	 * The internal entry table is automatically expanded if there is
	 * insufficient space for the new addition.
	 *
	 * @param newEntry
	 *            the new entry to add.
	 * @throws java.lang.IllegalArgumentException
	 *             If the FileMode of the entry was not set by the caller.
	 */
	public void add(DirCacheEntry newEntry) {
		if (newEntry.getRawMode() == 0)
			throw new IllegalArgumentException(MessageFormat.format(
					JGitText.get().fileModeNotSetForPath,
					newEntry.getPathString()));
		beforeAdd(newEntry);
		fastAdd(newEntry);
	}

	
Add a range of existing entries from the destination cache.
 The entries are placed at the end of the entry list. If any of the entries causes the list to now be incorrectly sorted a final sorting phase will be automatically enabled within finish(). 

This method copies from the destination cache, which has not yet been
updated with this editor's new table. So all offsets into the destination
cache are not affected by any updates that may be currently taking place
in this editor.

The internal entry table is automatically expanded if there is
insufficient space for the new additions.
Params:
pos – 
           first entry to copy from the destination cache.
cnt – 
           number of entries to copy./**
	 * Add a range of existing entries from the destination cache.
	 * <p>
	 * The entries are placed at the end of the entry list. If any of the
	 * entries causes the list to now be incorrectly sorted a final sorting
	 * phase will be automatically enabled within {@link #finish()}.
	 * <p>
	 * This method copies from the destination cache, which has not yet been
	 * updated with this editor's new table. So all offsets into the destination
	 * cache are not affected by any updates that may be currently taking place
	 * in this editor.
	 * <p>
	 * The internal entry table is automatically expanded if there is
	 * insufficient space for the new additions.
	 *
	 * @param pos
	 *            first entry to copy from the destination cache.
	 * @param cnt
	 *            number of entries to copy.
	 */
	public void keep(int pos, int cnt) {
		beforeAdd(cache.getEntry(pos));
		fastKeep(pos, cnt);
	}

	
Recursively add an entire tree into this builder.

If pathPrefix is "a/b" and the tree contains file "c" then the resulting
DirCacheEntry will have the path "a/b/c".

All entries are inserted at stage 0, therefore assuming that the
application will not insert any other paths with the same pathPrefix.
Params:
pathPrefix – 
           UTF-8 encoded prefix to mount the tree's entries at. If the
           path does not end with '/' one will be automatically inserted
           as necessary.
stage – 
           stage of the entries when adding them.
reader – 
           reader the tree(s) will be read from during recursive
           traversal. This must be the same repository that the resulting
           DirCache would be written out to (or used in) otherwise the
           caller is simply asking for deferred MissingObjectExceptions.
           Caller is responsible for releasing this reader when done.
tree – 
           the tree to recursively add. This tree's contents will appear
           under pathPrefix. The ObjectId must be that of a
           tree; the caller is responsible for dereferencing a tag or
           commit (if necessary).
Throws:
IOException – 
            a tree cannot be read to iterate through its entries./**
	 * Recursively add an entire tree into this builder.
	 * <p>
	 * If pathPrefix is "a/b" and the tree contains file "c" then the resulting
	 * DirCacheEntry will have the path "a/b/c".
	 * <p>
	 * All entries are inserted at stage 0, therefore assuming that the
	 * application will not insert any other paths with the same pathPrefix.
	 *
	 * @param pathPrefix
	 *            UTF-8 encoded prefix to mount the tree's entries at. If the
	 *            path does not end with '/' one will be automatically inserted
	 *            as necessary.
	 * @param stage
	 *            stage of the entries when adding them.
	 * @param reader
	 *            reader the tree(s) will be read from during recursive
	 *            traversal. This must be the same repository that the resulting
	 *            DirCache would be written out to (or used in) otherwise the
	 *            caller is simply asking for deferred MissingObjectExceptions.
	 *            Caller is responsible for releasing this reader when done.
	 * @param tree
	 *            the tree to recursively add. This tree's contents will appear
	 *            under <code>pathPrefix</code>. The ObjectId must be that of a
	 *            tree; the caller is responsible for dereferencing a tag or
	 *            commit (if necessary).
	 * @throws java.io.IOException
	 *             a tree cannot be read to iterate through its entries.
	 */
	public void addTree(byte[] pathPrefix, int stage, ObjectReader reader,
			AnyObjectId tree) throws IOException {
		CanonicalTreeParser p = createTreeParser(pathPrefix, reader, tree);
		while (!p.eof()) {
			if (isTree(p)) {
				p = enterTree(p, reader);
				continue;
			}

			DirCacheEntry first = toEntry(stage, p);
			beforeAdd(first);
			fastAdd(first);
			p = p.next();
			break;
		}

		// Rest of tree entries are correctly sorted; use fastAdd().
		while (!p.eof()) {
			if (isTree(p)) {
				p = enterTree(p, reader);
			} else {
				fastAdd(toEntry(stage, p));
				p = p.next();
			}
		}
	}

	private static CanonicalTreeParser createTreeParser(byte[] pathPrefix,
			ObjectReader reader, AnyObjectId tree) throws IOException {
		return new CanonicalTreeParser(pathPrefix, reader, tree);
	}

	private static boolean isTree(CanonicalTreeParser p) {
		return (p.getEntryRawMode() & TYPE_MASK) == TYPE_TREE;
	}

	private static CanonicalTreeParser enterTree(CanonicalTreeParser p,
			ObjectReader reader) throws IOException {
		p = p.createSubtreeIterator(reader);
		return p.eof() ? p.next() : p;
	}

	private static DirCacheEntry toEntry(int stage, CanonicalTreeParser i) {
		byte[] buf = i.getEntryPathBuffer();
		int len = i.getEntryPathLength();
		byte[] path = new byte[len];
		System.arraycopy(buf, 0, path, 0, len);

		DirCacheEntry e = new DirCacheEntry(path, stage);
		e.setFileMode(i.getEntryRawMode());
		e.setObjectIdFromRaw(i.idBuffer(), i.idOffset());
		return e;
	}

	
{@inheritDoc} /** {@inheritDoc} */
	@Override
	public void finish() {
		if (!sorted)
			resort();
		replace();
	}

	private void beforeAdd(DirCacheEntry newEntry) {
		if (sorted && entryCnt > 0) {
			final DirCacheEntry lastEntry = entries[entryCnt - 1];
			final int cr = DirCache.cmp(lastEntry, newEntry);
			if (cr > 0) {
				// The new entry sorts before the old entry; we are
				// no longer sorted correctly. We'll need to redo
				// the sorting before we can close out the build.
				//
				sorted = false;
			} else if (cr == 0) {
				// Same file path; we can only insert this if the
				// stages won't be violated.
				//
				final int peStage = lastEntry.getStage();
				final int dceStage = newEntry.getStage();
				if (peStage == dceStage)
					throw bad(newEntry, JGitText.get().duplicateStagesNotAllowed);
				if (peStage == 0 || dceStage == 0)
					throw bad(newEntry, JGitText.get().mixedStagesNotAllowed);
				if (peStage > dceStage)
					sorted = false;
			}
		}
	}

	private void resort() {
		Arrays.sort(entries, 0, entryCnt, DirCache.ENT_CMP);

		for (int entryIdx = 1; entryIdx < entryCnt; entryIdx++) {
			final DirCacheEntry pe = entries[entryIdx - 1];
			final DirCacheEntry ce = entries[entryIdx];
			final int cr = DirCache.cmp(pe, ce);
			if (cr == 0) {
				// Same file path; we can only allow this if the stages
				// are 1-3 and no 0 exists.
				//
				final int peStage = pe.getStage();
				final int ceStage = ce.getStage();
				if (peStage == ceStage)
					throw bad(ce, JGitText.get().duplicateStagesNotAllowed);
				if (peStage == 0 || ceStage == 0)
					throw bad(ce, JGitText.get().mixedStagesNotAllowed);
			}
		}

		sorted = true;
	}

	private static IllegalStateException bad(DirCacheEntry a, String msg) {
		return new IllegalStateException(String.format(
				"%s: %d %s", //$NON-NLS-1$
				msg, Integer.valueOf(a.getStage()), a.getPathString()));
	}
}