/*
    * Copyright (C) 2007, Robin Rosenberg <robin.rosenberg@dewire.com>
    * 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.treewalk.filter;
  
  import java.util.Collection;
  
  import org.eclipse.jgit.errors.StopWalkException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.treewalk.TreeWalk;
  import org.eclipse.jgit.treewalk.filter.ByteArraySet.Hasher;
  import org.eclipse.jgit.util.RawParseUtils;
  
  /**
   * Includes tree entries only if they match one or more configured paths.
   * <p>
   * Operates like {@link org.eclipse.jgit.treewalk.filter.PathFilter} but causes
   * the walk to abort as soon as the tree can no longer match any of the paths
   * within the group. This may bypass the boolean logic of a higher level AND or
   * OR group, but does improve performance for the common case of examining one
   * or more modified paths.
   * <p>
   * This filter is effectively an OR group around paths, with the early abort
   * feature described above.
   */
  public class PathFilterGroup {
  	/**
  	 * Create a collection of path filters from Java strings.
  	 * <p>
  	 * Path strings are relative to the root of the repository. If the user's
  	 * input should be assumed relative to a subdirectory of the repository the
  	 * caller must prepend the subdirectory's path prior to creating the filter.
  	 * <p>
  	 * Path strings use '/' to delimit directories on all platforms.
  	 * <p>
  	 * Paths may appear in any order within the collection. Sorting may be done
  	 * internally when the group is constructed if doing so will improve path
  	 * matching performance.
  	 *
  	 * @param paths
  	 *            the paths to test against. Must have at least one entry.
  	 * @return a new filter for the list of paths supplied.
  	 */
  	public static TreeFilter createFromStrings(Collection<String> paths) {
  		if (paths.isEmpty())
  			throw new IllegalArgumentException(
  					JGitText.get().atLeastOnePathIsRequired);
  		final PathFilterfilter/PathFilter.html#PathFilter">PathFilter[] p = new PathFilter[paths.size()];
  		int i = 0;
  		for (String s : paths)
  			p[i++] = PathFilter.create(s);
  		return create(p);
  	}
  
  	/**
  	 * Create a collection of path filters from Java strings.
  	 * <p>
  	 * Path strings are relative to the root of the repository. If the user's
  	 * input should be assumed relative to a subdirectory of the repository the
  	 * caller must prepend the subdirectory's path prior to creating the filter.
  	 * <p>
  	 * Path strings use '/' to delimit directories on all platforms.
  	 * <p>
  	 * Paths may appear in any order. Sorting may be done internally when the
  	 * group is constructed if doing so will improve path matching performance.
  	 *
  	 * @param paths
  	 *            the paths to test against. Must have at least one entry.
  	 * @return a new filter for the paths supplied.
  	 */
  	public static TreeFilter createFromStrings(String... paths) {
  		if (paths.length == 0)
  			throw new IllegalArgumentException(
  					JGitText.get().atLeastOnePathIsRequired);
  		final int length = paths.length;
  		final PathFilterfilter/PathFilter.html#PathFilter">PathFilter[] p = new PathFilter[length];
  		for (int i = 0; i < length; i++)
  			p[i] = PathFilter.create(paths[i]);
  		return create(p);
  	}
  
  	/**
  	 * Create a collection of path filters.
  	 * <p>
  	 * Paths may appear in any order within the collection. Sorting may be done
  	 * internally when the group is constructed if doing so will improve path
  	 * matching performance.
  	 *
  	 * @param paths
  	 *            the paths to test against. Must have at least one entry.
  	 * @return a new filter for the list of paths supplied.
 	 */
 	public static TreeFilter create(Collection<PathFilter> paths) {
 		if (paths.isEmpty())
 			throw new IllegalArgumentException(
 					JGitText.get().atLeastOnePathIsRequired);
 		final PathFilterfilter/PathFilter.html#PathFilter">PathFilter[] p = new PathFilter[paths.size()];
 		paths.toArray(p);
 		return create(p);
 	}
 
 	private static TreeFilter create(PathFilter[] p) {
 		if (p.length == 1)
 			return new Single(p[0]);
 		return new Group(p);
 	}
 
 	static class Single extends TreeFilter {
 		private final PathFilter path;
 
 		private final byte[] raw;
 
 		private Single(PathFilter p) {
 			path = p;
 			raw = path.pathRaw;
 		}
 
 		@Override
 		public boolean include(TreeWalk walker) {
 			final int cmp = walker.isPathPrefix(raw, raw.length);
 			if (cmp > 0)
 				throw StopWalkException.INSTANCE;
 			return cmp == 0;
 		}
 
 		@Override
 		public boolean shouldBeRecursive() {
 			return path.shouldBeRecursive();
 		}
 
 		@Override
 		public TreeFilter clone() {
 			return this;
 		}
 
 		@Override
 		public String toString() {
 			return "FAST_" + path.toString(); //$NON-NLS-1$
 		}
 	}
 
 	static class Group extends TreeFilter {
 
 		private ByteArraySet fullpaths;
 
 		private ByteArraySet prefixes;
 
 		private byte[] max;
 
 		private Group(PathFilter[] pathFilters) {
 			fullpaths = new ByteArraySet(pathFilters.length);
 			prefixes = new ByteArraySet(pathFilters.length / 5);
 			// 5 is an empirically derived ratio of #paths/#prefixes from:
 			// egit/jgit: 8
 			// git: 5
 			// linux kernel: 13
 			// eclipse.platform.ui: 7
 			max = pathFilters[0].pathRaw;
 			Hasher hasher = new Hasher(null, 0);
 			for (PathFilter pf : pathFilters) {
 				hasher.init(pf.pathRaw, pf.pathRaw.length);
 				while (hasher.hasNext()) {
 					int hash = hasher.nextHash();
 					if (hasher.hasNext())
 						prefixes.addIfAbsent(pf.pathRaw, hasher.length(), hash);
 				}
 				fullpaths.addIfAbsent(pf.pathRaw, pf.pathRaw.length,
 						hasher.getHash());
 				if (compare(max, pf.pathRaw) < 0)
 					max = pf.pathRaw;
 			}
 			// Adjust max for the git sort order. A path we compare
 			// with may end with a slash at any position (but the
 			// first, but we ignore that here since it's not relevant).
 			// Such paths must be included in the processing
 			// before we can give up and throw a StopWalkException.
 			byte[] newMax = new byte[max.length + 1];
 			for (int i = 0; i < max.length; ++i)
 				if ((max[i] & 0xFF) < '/')
 					newMax[i] = '/';
 				else
 					newMax[i] = max[i];
 			newMax[newMax.length - 1] = '/';
 			max = newMax;
 		}
 
 		private static int compare(byte[] a, byte[] b) {
 			int i = 0;
 			while (i < a.length && i < b.length) {
 				int ba = a[i] & 0xFF;
 				int bb = b[i] & 0xFF;
 				int cmp = ba - bb;
 				if (cmp != 0)
 					return cmp;
 				++i;
 			}
 			return a.length - b.length;
 		}
 
 		@Override
 		public boolean include(TreeWalk walker) {
 
 			byte[] rp = walker.getRawPath();
 			Hasher hasher = new Hasher(rp, walker.getPathLength());
 			while (hasher.hasNext()) {
 				int hash = hasher.nextHash();
 				if (fullpaths.contains(rp, hasher.length(), hash))
 					return true;
 				if (!hasher.hasNext() && walker.isSubtree()
 						&& prefixes.contains(rp, hasher.length(), hash))
 					return true;
 			}
 
 			final int cmp = walker.isPathPrefix(max, max.length);
 			if (cmp > 0)
 				throw StopWalkException.INSTANCE;
 
 			return false;
 		}
 
 		@Override
 		public boolean shouldBeRecursive() {
 			return !prefixes.isEmpty();
 		}
 
 		@Override
 		public TreeFilter clone() {
 			return this;
 		}
 
 		@Override
 		public String toString() {
 			final StringBuilder r = new StringBuilder();
 			r.append("FAST("); //$NON-NLS-1$
 			boolean first = true;
 			for (byte[] p : fullpaths.toArray()) {
 				if (!first) {
 					r.append(" OR "); //$NON-NLS-1$
 				}
 				r.append(RawParseUtils.decode(p));
 				first = false;
 			}
 			r.append(")"); //$NON-NLS-1$
 			return r.toString();
 		}
 	}
 
 }