/*
    * 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.revwalk;
  
  import java.io.IOException;
  
  import org.eclipse.jgit.errors.IncorrectObjectTypeException;
  import org.eclipse.jgit.errors.MissingObjectException;
  import org.eclipse.jgit.revwalk.filter.RevFilter;
  
  /**
   * An ordered list of {@link org.eclipse.jgit.revwalk.RevCommit} subclasses.
   *
   * @param <E>
   *            type of subclass of RevCommit the list is storing.
   */
  public class RevCommitList<E extends RevCommit> extends RevObjectList<E> {
  	private RevWalk walker;
  
  	/** {@inheritDoc} */
  	@Override
  	public void clear() {
  		super.clear();
  		walker = null;
  	}
  
  	/**
  	 * Apply a flag to all commits matching the specified filter.
  	 * <p>
  	 * Same as <code>applyFlag(matching, flag, 0, size())</code>, but without
  	 * the incremental behavior.
  	 *
  	 * @param matching
  	 *            the filter to test commits with. If the filter includes a
  	 *            commit it will have the flag set; if the filter does not
  	 *            include the commit the flag will be unset.
  	 * @param flag
  	 *            the flag to apply (or remove). Applications are responsible
  	 *            for allocating this flag from the source RevWalk.
  	 * @throws java.io.IOException
  	 *             revision filter needed to read additional objects, but an
  	 *             error occurred while reading the pack files or loose objects
  	 *             of the repository.
  	 * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
  	 *             revision filter needed to read additional objects, but an
  	 *             object was not of the correct type. Repository corruption may
  	 *             have occurred.
  	 * @throws org.eclipse.jgit.errors.MissingObjectException
  	 *             revision filter needed to read additional objects, but an
  	 *             object that should be present was not found. Repository
  	 *             corruption may have occurred.
  	 */
  	public void applyFlag(RevFilter matching, RevFlag flag)
  			throws MissingObjectException, IncorrectObjectTypeException,
  			IOException {
  		applyFlag(matching, flag, 0, size());
  	}
  
  	/**
  	 * Apply a flag to all commits matching the specified filter.
  	 * <p>
  	 * This version allows incremental testing and application, such as from a
  	 * background thread that needs to periodically halt processing and send
  	 * updates to the UI.
  	 *
  	 * @param matching
  	 *            the filter to test commits with. If the filter includes a
  	 *            commit it will have the flag set; if the filter does not
  	 *            include the commit the flag will be unset.
  	 * @param flag
  	 *            the flag to apply (or remove). Applications are responsible
  	 *            for allocating this flag from the source RevWalk.
  	 * @param rangeBegin
  	 *            first commit within the list to begin testing at, inclusive.
  	 *            Must not be negative, but may be beyond the end of the list.
  	 * @param rangeEnd
  	 *            last commit within the list to end testing at, exclusive. If
  	 *            smaller than or equal to <code>rangeBegin</code> then no
  	 *            commits will be tested.
  	 * @throws java.io.IOException
  	 *             revision filter needed to read additional objects, but an
  	 *             error occurred while reading the pack files or loose objects
  	 *             of the repository.
  	 * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
  	 *             revision filter needed to read additional objects, but an
  	 *             object was not of the correct type. Repository corruption may
  	 *             have occurred.
  	 * @throws org.eclipse.jgit.errors.MissingObjectException
  	 *             revision filter needed to read additional objects, but an
  	 *             object that should be present was not found. Repository
  	 *             corruption may have occurred.
 	 */
 	public void applyFlag(final RevFilter matching, final RevFlag flag,
 			int rangeBegin, int rangeEnd) throws MissingObjectException,
 			IncorrectObjectTypeException, IOException {
 		final RevWalk w = flag.getRevWalk();
 		rangeEnd = Math.min(rangeEnd, size());
 		while (rangeBegin < rangeEnd) {
 			int index = rangeBegin;
 			Block s = contents;
 			while (s.shift > 0) {
 				final int i = index >> s.shift;
 				index -= i << s.shift;
 				s = (Block) s.contents[i];
 			}
 
 			while (rangeBegin++ < rangeEnd && index < BLOCK_SIZE) {
 				final RevCommit c = (RevCommit) s.contents[index++];
 				if (matching.include(w, c))
 					c.add(flag);
 				else
 					c.remove(flag);
 			}
 		}
 	}
 
 	/**
 	 * Remove the given flag from all commits.
 	 * <p>
 	 * Same as <code>clearFlag(flag, 0, size())</code>, but without the
 	 * incremental behavior.
 	 *
 	 * @param flag
 	 *            the flag to remove. Applications are responsible for
 	 *            allocating this flag from the source RevWalk.
 	 */
 	public void clearFlag(RevFlag flag) {
 		clearFlag(flag, 0, size());
 	}
 
 	/**
 	 * Remove the given flag from all commits.
 	 * <p>
 	 * This method is actually implemented in terms of:
 	 * <code>applyFlag(RevFilter.NONE, flag, rangeBegin, rangeEnd)</code>.
 	 *
 	 * @param flag
 	 *            the flag to remove. Applications are responsible for
 	 *            allocating this flag from the source RevWalk.
 	 * @param rangeBegin
 	 *            first commit within the list to begin testing at, inclusive.
 	 *            Must not be negative, but may be beyond the end of the list.
 	 * @param rangeEnd
 	 *            last commit within the list to end testing at, exclusive. If
 	 *            smaller than or equal to <code>rangeBegin</code> then no
 	 *            commits will be tested.
 	 */
 	public void clearFlag(final RevFlag flag, final int rangeBegin,
 			final int rangeEnd) {
 		try {
 			applyFlag(RevFilter.NONE, flag, rangeBegin, rangeEnd);
 		} catch (IOException e) {
 			// Never happen. The filter we use does not throw any
 			// exceptions, for any reason.
 		}
 	}
 
 	/**
 	 * Find the next commit that has the given flag set.
 	 *
 	 * @param flag
 	 *            the flag to test commits against.
 	 * @param begin
 	 *            first commit index to test at. Applications may wish to begin
 	 *            at 0, to test the first commit in the list.
 	 * @return index of the first commit at or after index <code>begin</code>
 	 *         that has the specified flag set on it; -1 if no match is found.
 	 */
 	public int indexOf(RevFlag flag, int begin) {
 		while (begin < size()) {
 			int index = begin;
 			Block s = contents;
 			while (s.shift > 0) {
 				final int i = index >> s.shift;
 				index -= i << s.shift;
 				s = (Block) s.contents[i];
 			}
 
 			while (begin++ < size() && index < BLOCK_SIZE) {
 				final RevCommit c = (RevCommit) s.contents[index++];
 				if (c.has(flag))
 					return begin;
 			}
 		}
 		return -1;
 	}
 
 	/**
 	 * Find the next commit that has the given flag set.
 	 *
 	 * @param flag
 	 *            the flag to test commits against.
 	 * @param begin
 	 *            first commit index to test at. Applications may wish to begin
 	 *            at <code>size()-1</code>, to test the last commit in the
 	 *            list.
 	 * @return index of the first commit at or before index <code>begin</code>
 	 *         that has the specified flag set on it; -1 if no match is found.
 	 */
 	public int lastIndexOf(RevFlag flag, int begin) {
 		begin = Math.min(begin, size() - 1);
 		while (begin >= 0) {
 			int index = begin;
 			Block s = contents;
 			while (s.shift > 0) {
 				final int i = index >> s.shift;
 				index -= i << s.shift;
 				s = (Block) s.contents[i];
 			}
 
 			while (begin-- >= 0 && index >= 0) {
 				final RevCommit c = (RevCommit) s.contents[index--];
 				if (c.has(flag))
 					return begin;
 			}
 		}
 		return -1;
 	}
 
 	/**
 	 * Set the revision walker this list populates itself from.
 	 *
 	 * @param w
 	 *            the walker to populate from.
 	 * @see #fillTo(int)
 	 */
 	public void source(RevWalk w) {
 		walker = w;
 	}
 
 	/**
 	 * Is this list still pending more items?
 	 *
 	 * @return true if {@link #fillTo(int)} might be able to extend the list
 	 *         size when called.
 	 */
 	public boolean isPending() {
 		return walker != null;
 	}
 
 	/**
 	 * Ensure this list contains at least a specified number of commits.
 	 * <p>
 	 * The revision walker specified by {@link #source(RevWalk)} is pumped until
 	 * the given number of commits are contained in this list. If there are
 	 * fewer total commits available from the walk then the method will return
 	 * early. Callers can test the final size of the list by {@link #size()} to
 	 * determine if the high water mark specified was met.
 	 *
 	 * @param highMark
 	 *            number of commits the caller wants this list to contain when
 	 *            the fill operation is complete.
 	 * @throws java.io.IOException
 	 *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
 	 * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
 	 *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
 	 * @throws org.eclipse.jgit.errors.MissingObjectException
 	 *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
 	 */
 	@SuppressWarnings("unchecked")
 	public void fillTo(int highMark) throws MissingObjectException,
 			IncorrectObjectTypeException, IOException {
 		if (walker == null || size > highMark)
 			return;
 
 		RevCommit c = walker.next();
 		if (c == null) {
 			walker = null;
 			return;
 		}
 		enter(size, (E) c);
 		add((E) c);
 
 		while (size <= highMark) {
 			int index = size;
 			Block s = contents;
 			while (index >> s.shift >= BLOCK_SIZE) {
 				s = new Block(s.shift + BLOCK_SHIFT);
 				s.contents[0] = contents;
 				contents = s;
 			}
 			while (s.shift > 0) {
 				final int i = index >> s.shift;
 				index -= i << s.shift;
 				if (s.contents[i] == null)
 					s.contents[i] = new Block(s.shift - BLOCK_SHIFT);
 				s = (Block) s.contents[i];
 			}
 
 			final Object[] dst = s.contents;
 			while (size <= highMark && index < BLOCK_SIZE) {
 				c = walker.next();
 				if (c == null) {
 					walker = null;
 					return;
 				}
 				enter(size++, (E) c);
 				dst[index++] = c;
 			}
 		}
 	}
 
 	/**
 	 * Ensures all commits until the given commit are loaded. The revision
 	 * walker specified by {@link #source(RevWalk)} is pumped until the
 	 * specified commit is loaded. Callers can test the final size of the list
 	 * by {@link #size()} to determine if the high water mark specified was met.
 	 * <p>
 	 *
 	 * @param commitToLoad
 	 *            commit the caller wants this list to contain when the fill
 	 *            operation is complete.
 	 * @param highMark
 	 *            maximum number of commits the caller wants this list to
 	 *            contain when the fill operation is complete. If highMark is 0
 	 *            the walk is pumped until the specified commit or the end of
 	 *            the walk is reached.
 	 * @throws java.io.IOException
 	 *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
 	 * @throws org.eclipse.jgit.errors.IncorrectObjectTypeException
 	 *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
 	 * @throws org.eclipse.jgit.errors.MissingObjectException
 	 *             see {@link org.eclipse.jgit.revwalk.RevWalk#next()}
 	 */
 	@SuppressWarnings("unchecked")
 	public void fillTo(RevCommit commitToLoad, int highMark)
 			throws MissingObjectException, IncorrectObjectTypeException,
 			IOException {
 		if (walker == null || commitToLoad == null
 				|| (highMark > 0 && size > highMark))
 			return;
 
 		RevCommit c = walker.next();
 		if (c == null) {
 			walker = null;
 			return;
 		}
 		enter(size, (E) c);
 		add((E) c);
 
 		while ((highMark == 0 || size <= highMark) && !c.equals(commitToLoad)) {
 			int index = size;
 			Block s = contents;
 			while (index >> s.shift >= BLOCK_SIZE) {
 				s = new Block(s.shift + BLOCK_SHIFT);
 				s.contents[0] = contents;
 				contents = s;
 			}
 			while (s.shift > 0) {
 				final int i = index >> s.shift;
 				index -= i << s.shift;
 				if (s.contents[i] == null)
 					s.contents[i] = new Block(s.shift - BLOCK_SHIFT);
 				s = (Block) s.contents[i];
 			}
 
 			final Object[] dst = s.contents;
 			while ((highMark == 0 || size <= highMark) && index < BLOCK_SIZE
 					&& !c.equals(commitToLoad)) {
 				c = walker.next();
 				if (c == null) {
 					walker = null;
 					return;
 				}
 				enter(size++, (E) c);
 				dst[index++] = c;
 			}
 		}
 	}
 
 	/**
 	 * Optional callback invoked when commits enter the list by fillTo.
 	 * <p>
 	 * This method is only called during {@link #fillTo(int)}.
 	 *
 	 * @param index
 	 *            the list position this object will appear at.
 	 * @param e
 	 *            the object being added (or set) into the list.
 	 */
 	protected void enter(int index, E e) {
 		// Do nothing by default.
 	}
 }