/*
    * Copyright (C) 2010, 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.lib;
  
  import static org.eclipse.jgit.lib.Constants.OBJECT_ID_LENGTH;
  import static org.eclipse.jgit.lib.Constants.OBJ_TREE;
  import static org.eclipse.jgit.lib.Constants.encode;
  import static org.eclipse.jgit.lib.FileMode.GITLINK;
  import static org.eclipse.jgit.lib.FileMode.REGULAR_FILE;
  import static org.eclipse.jgit.lib.FileMode.TREE;
  
  import java.io.IOException;
  
  import org.eclipse.jgit.errors.CorruptObjectException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.revwalk.RevBlob;
  import org.eclipse.jgit.revwalk.RevCommit;
  import org.eclipse.jgit.revwalk.RevTree;
  import org.eclipse.jgit.treewalk.CanonicalTreeParser;
  import org.eclipse.jgit.util.TemporaryBuffer;
  
  /**
   * Mutable formatter to construct a single tree object.
   *
   * This formatter does not process subtrees. Callers must handle creating each
   * subtree on their own.
   *
   * To maintain good performance for bulk operations, this formatter does not
   * validate its input. Callers are responsible for ensuring the resulting tree
   * object is correctly well formed by writing entries in the correct order.
   */
  public class TreeFormatter {
  	/**
  	 * Compute the size of a tree entry record.
  	 *
  	 * This method can be used to estimate the correct size of a tree prior to
  	 * allocating a formatter. Getting the size correct at allocation time
  	 * ensures the internal buffer is sized correctly, reducing copying.
  	 *
  	 * @param mode
  	 *            the mode the entry will have.
  	 * @param nameLen
  	 *            the length of the name, in bytes.
  	 * @return the length of the record.
  	 */
  	public static int entrySize(FileMode mode, int nameLen) {
  		return mode.copyToLength() + nameLen + OBJECT_ID_LENGTH + 2;
  	}
  
  	private byte[] buf;
  
  	private int ptr;
  
  	private TemporaryBuffer.Heap overflowBuffer;
  
  	/**
  	 * Create an empty formatter with a default buffer size.
  	 */
  	public TreeFormatter() {
  		this(8192);
  	}
  
  	/**
  	 * Create an empty formatter with the specified buffer size.
  	 *
  	 * @param size
  	 *            estimated size of the tree, in bytes. Callers can use
  	 *            {@link #entrySize(FileMode, int)} to estimate the size of each
  	 *            entry in advance of allocating the formatter.
  	 */
  	public TreeFormatter(int size) {
  		buf = new byte[size];
  	}
  
  	/**
  	 * Add a link to a submodule commit, mode is {@link org.eclipse.jgit.lib.FileMode#GITLINK}.
  	 *
  	 * @param name
  	 *            name of the entry.
  	 * @param commit
  	 *            the ObjectId to store in this entry.
  	 */
  	public void append(String name, RevCommit commit) {
  		append(name, GITLINK, commit);
  	}
  
  	/**
  	 * Add a subtree, mode is {@link org.eclipse.jgit.lib.FileMode#TREE}.
  	 *
  	 * @param name
  	 *            name of the entry.
 	 * @param tree
 	 *            the ObjectId to store in this entry.
 	 */
 	public void append(String name, RevTree tree) {
 		append(name, TREE, tree);
 	}
 
 	/**
 	 * Add a regular file, mode is {@link org.eclipse.jgit.lib.FileMode#REGULAR_FILE}.
 	 *
 	 * @param name
 	 *            name of the entry.
 	 * @param blob
 	 *            the ObjectId to store in this entry.
 	 */
 	public void append(String name, RevBlob blob) {
 		append(name, REGULAR_FILE, blob);
 	}
 
 	/**
 	 * Append any entry to the tree.
 	 *
 	 * @param name
 	 *            name of the entry.
 	 * @param mode
 	 *            mode describing the treatment of {@code id}.
 	 * @param id
 	 *            the ObjectId to store in this entry.
 	 */
 	public void append(String name, FileMode mode, AnyObjectId id) {
 		append(encode(name), mode, id);
 	}
 
 	/**
 	 * Append any entry to the tree.
 	 *
 	 * @param name
 	 *            name of the entry. The name should be UTF-8 encoded, but file
 	 *            name encoding is not a well defined concept in Git.
 	 * @param mode
 	 *            mode describing the treatment of {@code id}.
 	 * @param id
 	 *            the ObjectId to store in this entry.
 	 */
 	public void append(byte[] name, FileMode mode, AnyObjectId id) {
 		append(name, 0, name.length, mode, id);
 	}
 
 	/**
 	 * Append any entry to the tree.
 	 *
 	 * @param nameBuf
 	 *            buffer holding the name of the entry. The name should be UTF-8
 	 *            encoded, but file name encoding is not a well defined concept
 	 *            in Git.
 	 * @param namePos
 	 *            first position within {@code nameBuf} of the name data.
 	 * @param nameLen
 	 *            number of bytes from {@code nameBuf} to use as the name.
 	 * @param mode
 	 *            mode describing the treatment of {@code id}.
 	 * @param id
 	 *            the ObjectId to store in this entry.
 	 */
 	public void append(byte[] nameBuf, int namePos, int nameLen, FileMode mode,
 			AnyObjectId id) {
 		append(nameBuf, namePos, nameLen, mode, id, false);
 	}
 
 	/**
 	 * Append any entry to the tree.
 	 *
 	 * @param nameBuf
 	 *            buffer holding the name of the entry. The name should be UTF-8
 	 *            encoded, but file name encoding is not a well defined concept
 	 *            in Git.
 	 * @param namePos
 	 *            first position within {@code nameBuf} of the name data.
 	 * @param nameLen
 	 *            number of bytes from {@code nameBuf} to use as the name.
 	 * @param mode
 	 *            mode describing the treatment of {@code id}.
 	 * @param id
 	 *            the ObjectId to store in this entry.
 	 * @param allowEmptyName
 	 *            allow an empty filename (creating a corrupt tree)
 	 * @since 4.6
 	 */
 	public void append(byte[] nameBuf, int namePos, int nameLen, FileMode mode,
 			AnyObjectId id, boolean allowEmptyName) {
 		if (nameLen == 0 && !allowEmptyName) {
 			throw new IllegalArgumentException(
 					JGitText.get().invalidTreeZeroLengthName);
 		}
 		if (fmtBuf(nameBuf, namePos, nameLen, mode)) {
 			id.copyRawTo(buf, ptr);
 			ptr += OBJECT_ID_LENGTH;
 
 		} else {
 			try {
 				fmtOverflowBuffer(nameBuf, namePos, nameLen, mode);
 				id.copyRawTo(overflowBuffer);
 			} catch (IOException badBuffer) {
 				// This should never occur.
 				throw new RuntimeException(badBuffer);
 			}
 		}
 	}
 
 	/**
 	 * Append any entry to the tree.
 	 *
 	 * @param nameBuf
 	 *            buffer holding the name of the entry. The name should be UTF-8
 	 *            encoded, but file name encoding is not a well defined concept
 	 *            in Git.
 	 * @param namePos
 	 *            first position within {@code nameBuf} of the name data.
 	 * @param nameLen
 	 *            number of bytes from {@code nameBuf} to use as the name.
 	 * @param mode
 	 *            mode describing the treatment of {@code id}.
 	 * @param idBuf
 	 *            buffer holding the raw ObjectId of the entry.
 	 * @param idPos
 	 *            first position within {@code idBuf} to copy the id from.
 	 */
 	public void append(byte[] nameBuf, int namePos, int nameLen, FileMode mode,
 			byte[] idBuf, int idPos) {
 		if (fmtBuf(nameBuf, namePos, nameLen, mode)) {
 			System.arraycopy(idBuf, idPos, buf, ptr, OBJECT_ID_LENGTH);
 			ptr += OBJECT_ID_LENGTH;
 
 		} else {
 			try {
 				fmtOverflowBuffer(nameBuf, namePos, nameLen, mode);
 				overflowBuffer.write(idBuf, idPos, OBJECT_ID_LENGTH);
 			} catch (IOException badBuffer) {
 				// This should never occur.
 				throw new RuntimeException(badBuffer);
 			}
 		}
 	}
 
 	private boolean fmtBuf(byte[] nameBuf, int namePos, int nameLen,
 			FileMode mode) {
 		if (buf == null || buf.length < ptr + entrySize(mode, nameLen))
 			return false;
 
 		mode.copyTo(buf, ptr);
 		ptr += mode.copyToLength();
 		buf[ptr++] = ' ';
 
 		System.arraycopy(nameBuf, namePos, buf, ptr, nameLen);
 		ptr += nameLen;
 		buf[ptr++] = 0;
 		return true;
 	}
 
 	private void fmtOverflowBuffer(byte[] nameBuf, int namePos, int nameLen,
 			FileMode mode) throws IOException {
 		if (buf != null) {
 			overflowBuffer = new TemporaryBuffer.Heap(Integer.MAX_VALUE);
 			overflowBuffer.write(buf, 0, ptr);
 			buf = null;
 		}
 
 		mode.copyTo(overflowBuffer);
 		overflowBuffer.write((byte) ' ');
 		overflowBuffer.write(nameBuf, namePos, nameLen);
 		overflowBuffer.write((byte) 0);
 	}
 
 	/**
 	 * Insert this tree and obtain its ObjectId.
 	 *
 	 * @param ins
 	 *            the inserter to store the tree.
 	 * @return computed ObjectId of the tree
 	 * @throws java.io.IOException
 	 *             the tree could not be stored.
 	 */
 	public ObjectId insertTo(ObjectInserter ins) throws IOException {
 		if (buf != null)
 			return ins.insert(OBJ_TREE, buf, 0, ptr);
 
 		final long len = overflowBuffer.length();
 		return ins.insert(OBJ_TREE, len, overflowBuffer.openInputStream());
 	}
 
 	/**
 	 * Compute the ObjectId for this tree
 	 *
 	 * @param ins a {@link org.eclipse.jgit.lib.ObjectInserter} object.
 	 * @return ObjectId for this tree
 	 */
 	public ObjectId computeId(ObjectInserter ins) {
 		if (buf != null)
 			return ins.idFor(OBJ_TREE, buf, 0, ptr);
 
 		final long len = overflowBuffer.length();
 		try {
 			return ins.idFor(OBJ_TREE, len, overflowBuffer.openInputStream());
 		} catch (IOException e) {
 			// this should never happen
 			throw new RuntimeException(e);
 		}
 	}
 
 	/**
 	 * Copy this formatter's buffer into a byte array.
 	 *
 	 * This method is not efficient, as it needs to create a copy of the
 	 * internal buffer in order to supply an array of the correct size to the
 	 * caller. If the buffer is just to pass to an ObjectInserter, consider
 	 * using {@link org.eclipse.jgit.lib.ObjectInserter#insert(TreeFormatter)}
 	 * instead.
 	 *
 	 * @return a copy of this formatter's buffer.
 	 */
 	public byte[] toByteArray() {
 		if (buf != null) {
 			byte[] r = new byte[ptr];
 			System.arraycopy(buf, 0, r, 0, ptr);
 			return r;
 		}
 
 		try {
 			return overflowBuffer.toByteArray();
 		} catch (IOException err) {
 			// This should never happen, its read failure on a byte array.
 			throw new RuntimeException(err);
 		}
 	}
 
 	/** {@inheritDoc} */
 	@SuppressWarnings("nls")
 	@Override
 	public String toString() {
 		byte[] raw = toByteArray();
 
 		CanonicalTreeParser p = new CanonicalTreeParser();
 		p.reset(raw);
 
 		StringBuilder r = new StringBuilder();
 		r.append("Tree={");
 		if (!p.eof()) {
 			r.append('\n');
 			try {
 				new ObjectChecker().checkTree(raw);
 			} catch (CorruptObjectException error) {
 				r.append("*** ERROR: ").append(error.getMessage()).append("\n");
 				r.append('\n');
 			}
 		}
 		while (!p.eof()) {
 			final FileMode mode = p.getEntryFileMode();
 			r.append(mode);
 			r.append(' ');
 			r.append(Constants.typeString(mode.getObjectType()));
 			r.append(' ');
 			r.append(p.getEntryObjectId().name());
 			r.append(' ');
 			r.append(p.getEntryPathString());
 			r.append('\n');
 			p.next();
 		}
 		r.append("}");
 		return r.toString();
 	}
 }