/*
    * Copyright (C) 2014, Andrey Loskutov <loskutov@gmx.de> 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.ignore.internal;
  
  import static org.eclipse.jgit.ignore.internal.Strings.checkWildCards;
  import static org.eclipse.jgit.ignore.internal.Strings.count;
  import static org.eclipse.jgit.ignore.internal.Strings.getPathSeparator;
  import static org.eclipse.jgit.ignore.internal.Strings.isWildCard;
  import static org.eclipse.jgit.ignore.internal.Strings.split;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.eclipse.jgit.errors.InvalidPatternException;
  import org.eclipse.jgit.ignore.IMatcher;
  import org.eclipse.jgit.ignore.internal.Strings.PatternState;
  
  /**
   * Matcher built by patterns consists of multiple path segments.
   * <p>
   * This class is immutable and thread safe.
   */
  public class PathMatcher extends AbstractMatcher {
  
  	private static final WildMatcherher.html#WildMatcher">WildMatcher WILD_NO_DIRECTORY = new WildMatcher(false);
  
  	private static final WildMatcherr.html#WildMatcher">WildMatcher WILD_ONLY_DIRECTORY = new WildMatcher(
  			true);
  
  	private final List<IMatcher> matchers;
  
  	private final char slash;
  
  	private final boolean beginning;
  
  	private PathMatcher(String pattern, Character pathSeparator,
  			boolean dirOnly)
  			throws InvalidPatternException {
  		super(pattern, dirOnly);
  		slash = getPathSeparator(pathSeparator);
  		beginning = pattern.indexOf(slash) == 0;
  		if (isSimplePathWithSegments(pattern))
  			matchers = null;
  		else
  			matchers = createMatchers(split(pattern, slash), pathSeparator,
  					dirOnly);
  	}
  
  	private boolean isSimplePathWithSegments(String path) {
  		return !isWildCard(path) && path.indexOf('\\') < 0
  				&& count(path, slash, true) > 0;
  	}
  
  	private static List<IMatcher> createMatchers(List<String> segments,
  			Character pathSeparator, boolean dirOnly)
  			throws InvalidPatternException {
  		List<IMatcher> matchers = new ArrayList<>(segments.size());
  		for (int i = 0; i < segments.size(); i++) {
  			String segment = segments.get(i);
  			IMatcher matcher = createNameMatcher0(segment, pathSeparator,
  					dirOnly, i == segments.size() - 1);
  			if (i > 0) {
  				final IMatcher last = matchers.get(matchers.size() - 1);
  				if (isWild(matcher) && isWild(last))
  					// collapse wildmatchers **/** is same as **, but preserve
  					// dirOnly flag (i.e. always use the last wildmatcher)
  					matchers.remove(matchers.size() - 1);
  			}
  
  			matchers.add(matcher);
  		}
  		return matchers;
  	}
  
  	/**
  	 * Create path matcher
  	 *
  	 * @param pattern
  	 *            a pattern
  	 * @param pathSeparator
  	 *            if this parameter isn't null then this character will not
  	 *            match at wildcards(* and ? are wildcards).
  	 * @param dirOnly
  	 *            a boolean.
  	 * @return never null
  	 * @throws org.eclipse.jgit.errors.InvalidPatternException
  	 */
  	public static IMatcher createPathMatcher(String pattern,
  			Character pathSeparator, boolean dirOnly)
  			throws InvalidPatternException {
  		pattern = trim(pattern);
  		char slash = Strings.getPathSeparator(pathSeparator);
 		// ignore possible leading and trailing slash
 		int slashIdx = pattern.indexOf(slash, 1);
 		if (slashIdx > 0 && slashIdx < pattern.length() - 1)
 			return new PathMatcher(pattern, pathSeparator, dirOnly);
 		return createNameMatcher0(pattern, pathSeparator, dirOnly, true);
 	}
 
 	/**
 	 * Trim trailing spaces, unless they are escaped with backslash, see
 	 * https://www.kernel.org/pub/software/scm/git/docs/gitignore.html
 	 *
 	 * @param pattern
 	 *            non null
 	 * @return trimmed pattern
 	 */
 	private static String trim(String pattern) {
 		while (pattern.length() > 0
 				&& pattern.charAt(pattern.length() - 1) == ' ') {
 			if (pattern.length() > 1
 					&& pattern.charAt(pattern.length() - 2) == '\\') {
 				// last space was escaped by backslash: remove backslash and
 				// keep space
 				pattern = pattern.substring(0, pattern.length() - 2) + " "; //$NON-NLS-1$
 				return pattern;
 			}
 			pattern = pattern.substring(0, pattern.length() - 1);
 		}
 		return pattern;
 	}
 
 	private static IMatcher createNameMatcher0(String segment,
 			Character pathSeparator, boolean dirOnly, boolean lastSegment)
 			throws InvalidPatternException {
 		// check if we see /** or ** segments => double star pattern
 		if (WildMatcher.WILDMATCH.equals(segment)
 				|| WildMatcher.WILDMATCH2.equals(segment))
 			return dirOnly && lastSegment ? WILD_ONLY_DIRECTORY
 					: WILD_NO_DIRECTORY;
 
 		PatternState state = checkWildCards(segment);
 		switch (state) {
 		case LEADING_ASTERISK_ONLY:
 			return new LeadingAsteriskMatcher(segment, pathSeparator, dirOnly);
 		case TRAILING_ASTERISK_ONLY:
 			return new TrailingAsteriskMatcher(segment, pathSeparator, dirOnly);
 		case COMPLEX:
 			return new WildCardMatcher(segment, pathSeparator, dirOnly);
 		default:
 			return new NameMatcher(segment, pathSeparator, dirOnly, true);
 		}
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public boolean matches(String path, boolean assumeDirectory,
 			boolean pathMatch) {
 		if (matchers == null) {
 			return simpleMatch(path, assumeDirectory, pathMatch);
 		}
 		return iterate(path, 0, path.length(), assumeDirectory, pathMatch);
 	}
 
 	/*
 	 * Stupid but fast string comparison: the case where we don't have to match
 	 * wildcards or single segments (mean: this is multi-segment path which must
 	 * be at the beginning of the another string)
 	 */
 	private boolean simpleMatch(String path, boolean assumeDirectory,
 			boolean pathMatch) {
 		boolean hasSlash = path.indexOf(slash) == 0;
 		if (beginning && !hasSlash) {
 			path = slash + path;
 		}
 		if (!beginning && hasSlash) {
 			path = path.substring(1);
 		}
 		if (path.equals(pattern)) {
 			// Exact match: must meet directory expectations
 			return !dirOnly || assumeDirectory;
 		}
 		/*
 		 * Add slashes for startsWith check. This avoids matching e.g.
 		 * "/src/new" to /src/newfile" but allows "/src/new" to match
 		 * "/src/new/newfile", as is the git standard
 		 */
 		String prefix = pattern + slash;
 		if (pathMatch) {
 			return path.equals(prefix) && (!dirOnly || assumeDirectory);
 		}
 		if (path.startsWith(prefix)) {
 			return true;
 		}
 		return false;
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public boolean matches(String segment, int startIncl, int endExcl) {
 		throw new UnsupportedOperationException(
 				"Path matcher works only on entire paths"); //$NON-NLS-1$
 	}
 
 	private boolean iterate(final String path, final int startIncl,
 			final int endExcl, boolean assumeDirectory, boolean pathMatch) {
 		int matcher = 0;
 		int right = startIncl;
 		boolean match = false;
 		int lastWildmatch = -1;
 		// ** matches may get extended if a later match fails. When that
 		// happens, we must extend the ** by exactly one segment.
 		// wildmatchBacktrackPos records the end of the segment after a **
 		// match, so that we can reset correctly.
 		int wildmatchBacktrackPos = -1;
 		while (true) {
 			int left = right;
 			right = path.indexOf(slash, right);
 			if (right == -1) {
 				if (left < endExcl) {
 					match = matches(matcher, path, left, endExcl,
 							assumeDirectory, pathMatch);
 				} else {
 					// a/** should not match a/ or a
 					match = match && !isWild(matchers.get(matcher));
 				}
 				if (match) {
 					if (matcher < matchers.size() - 1
 							&& isWild(matchers.get(matcher))) {
 						// ** can match *nothing*: a/**/b match also a/b
 						matcher++;
 						match = matches(matcher, path, left, endExcl,
 								assumeDirectory, pathMatch);
 					} else if (dirOnly && !assumeDirectory) {
 						// Directory expectations not met
 						return false;
 					}
 				}
 				return match && matcher + 1 == matchers.size();
 			}
 			if (wildmatchBacktrackPos < 0) {
 				wildmatchBacktrackPos = right;
 			}
 			if (right - left > 0) {
 				match = matches(matcher, path, left, right, assumeDirectory,
 						pathMatch);
 			} else {
 				// path starts with slash???
 				right++;
 				continue;
 			}
 			if (match) {
 				boolean wasWild = isWild(matchers.get(matcher));
 				if (wasWild) {
 					lastWildmatch = matcher;
 					wildmatchBacktrackPos = -1;
 					// ** can match *nothing*: a/**/b match also a/b
 					right = left - 1;
 				}
 				matcher++;
 				if (matcher == matchers.size()) {
 					// We had a prefix match here.
 					if (!pathMatch) {
 						return true;
 					}
 					if (right == endExcl - 1) {
 						// Extra slash at the end: actually a full match.
 						// Must meet directory expectations
 						return !dirOnly || assumeDirectory;
 					}
 					// Prefix matches only if pattern ended with /**
 					if (wasWild) {
 						return true;
 					}
 					if (lastWildmatch >= 0) {
 						// Consider pattern **/x and input x/x.
 						// We've matched the prefix x/ so far: we
 						// must try to extend the **!
 						matcher = lastWildmatch + 1;
 						right = wildmatchBacktrackPos;
 						wildmatchBacktrackPos = -1;
 					} else {
 						return false;
 					}
 				}
 			} else if (lastWildmatch != -1) {
 				matcher = lastWildmatch + 1;
 				right = wildmatchBacktrackPos;
 				wildmatchBacktrackPos = -1;
 			} else {
 				return false;
 			}
 			right++;
 		}
 	}
 
 	private boolean matches(int matcherIdx, String path, int startIncl,
 			int endExcl, boolean assumeDirectory, boolean pathMatch) {
 		IMatcher matcher = matchers.get(matcherIdx);
 
 		final boolean matches = matcher.matches(path, startIncl, endExcl);
 		if (!matches || !pathMatch || matcherIdx < matchers.size() - 1
 				|| !(matcher instanceof AbstractMatcher)) {
 			return matches;
 		}
 
 		return assumeDirectory || !((AbstractMatcher) matcher).dirOnly;
 	}
 
 	private static boolean isWild(IMatcher matcher) {
 		return matcher == WILD_NO_DIRECTORY || matcher == WILD_ONLY_DIRECTORY;
 	}
 }