/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     QNX Software System
 *     Markus Schorn (Wind River Systems)
 *******************************************************************************/
package org.eclipse.cdt.internal.ui.util;

import java.util.Vector;

public class StringMatcher {
	protected String fPattern;
	protected int fLength; // pattern length
	protected boolean fIgnoreWildCards;
	protected boolean fIgnoreCase;
	protected boolean fHasLeadingStar;
	protected boolean fHasTrailingStar;
	protected String fSegments[]; //the given pattern is split into * separated segments

	/* boundary value beyond which we don't need to search in the text */
	protected int fBound= 0;

	protected static final char fSingleWildCard= '\u0000';

	public static class Position {
		int start; //inclusive
		int end; //exclusive
		public Position(int start, int end) {
			this.start= start;
			this.end= end;
		}
		public int getStart() {
			return start;
		}
		public int getEnd() {
			return end;
		}
	}

	/**
	 * Find the first occurrence of the pattern between <code>start</code)(inclusive) 
	 * and <code>end</code>(exclusive).  
	 * @param text the String object to search in 
	 * @param start the starting index of the search range, inclusive
	 * @param end the ending index of the search range, exclusive
	 * @return an <code>StringMatcher.Position</code> object that keeps the starting 
	 * (inclusive) and ending positions (exclusive) of the first occurrence of the 
	 * pattern in the specified range of the text; return null if not found or subtext
	 * is empty (start==end). A pair of zeros is returned if pattern is empty string
	 * Note that for pattern like "*abc*" with leading and trailing stars, position of "abc"
	 * is returned. For a pattern like"*??*" in text "abcdf", (1,3) is returned
	 */

	public StringMatcher.Position find(String text, int start, int end) {
		if (fPattern == null || text == null)
			throw new IllegalArgumentException();

		int tlen= text.length();
		if (start < 0)
			start= 0;
		if (end > tlen)
			end= tlen;
		if (end < 0 || start >= end)
			return null;
		if (fLength == 0)
			return new Position(start, start);
		if (fIgnoreWildCards) {
			int x= posIn(text, start, end);
			if (x < 0)
				return null;
			return new Position(x, x + fLength);
		}

		int segCount= fSegments.length;
		if (segCount == 0) //pattern contains only '*'(s)
			return new Position(start, end);

		int curPos= start;
		int matchStart= -1;
		for (int i= 0; i < segCount && curPos < end; ++i) {
			String current= fSegments[i];
			int nextMatch= regExpPosIn(text, curPos, end, current);
			if (nextMatch < 0)
				return null;
			if (i == 0)
				matchStart= nextMatch;
			curPos= nextMatch + current.length();
		}
		return new Position(matchStart, curPos);
	}
	/**
	 * StringMatcher constructor takes in a String object that is a simple 
	 * pattern which may contain  *  for 0 and many characters and
	 *  ?  for exactly one character. Also takes as parameter a boolean object
	 * specifying if case should be ignored
	 * @deprecated Use StringMatcher(pattern, ignoreCase, ignoreWildCards).
	 */
	@Deprecated
	public StringMatcher(String aPattern, boolean ignoreCase) {
		this(aPattern, ignoreCase, false);
	}
	/**
	 * StringMatcher constructor takes in a String object that is a simple 
	 * pattern which may contain  *  for 0 and many characters and
	 *  ?  for exactly one character.  
	 *
	 * Literal '*' and '?' characters must be escaped in the pattern 
	 * e.g., "\*" means literal "*", etc.
	 *
	 * Escaping any other character (including the escape character itself), 
	 * just results in that character in the pattern.
	 * e.g., "\a" means "a" and "\\" means "\"
	 *
	 * If invoking the StringMatcher with string literals in Java, don't forget
	 * escape characters are represented by "\\".
	 *
	 * @param aPattern the pattern to match text against
	 * @param ignoreCase if true, case is ignored
	 * @param ignoreWildCards if true, wild cards and their escape sequences are ignored
	 * 		  (everything is taken literally).
	 */
	public StringMatcher(String aPattern, boolean ignoreCase, boolean ignoreWildCards) {
		fIgnoreCase= ignoreCase;
		fIgnoreWildCards= ignoreWildCards;
		fLength= aPattern.length();

		/* convert case */
		if (fIgnoreCase) {
			char[] chars= aPattern.toCharArray();
			for (int i = 0; i < chars.length; i++) {
				chars[i]= Character.toUpperCase(chars[i]);
			}
			fPattern= new String(chars);
		} else {
			fPattern= aPattern;
		}

		if (fIgnoreWildCards) {
			parseNoWildCards();
		} else {
			parseWildCards();
		}
	}
	/**
	 * Given the starting (inclusive) and the ending (exclusive) poisitions in the   
	 * <code>text</code>, determine if the given substring matches with aPattern  
	 * @return true if the specified portion of the text matches the pattern
	 * @param text  a String object that contains the substring to match 
	 * @param start marks the starting position (inclusive) of the substring
	 * @param end marks the ending index (exclusive) of the substring 
	 */
	public boolean match(String text, int start, int end) {
		if (null == fPattern || null == text)
			throw new IllegalArgumentException();

		if (start > end)
			return false;

		if (fIgnoreWildCards)
			return fPattern.regionMatches(fIgnoreCase, 0, text, start, fLength);
		int segCount= fSegments.length;
		if (segCount == 0) //pattern contains only '*'(s) or empty pattern
			return true;
		if (start == end)
			return fLength == 0;
		if (fLength == 0)
			return start == end;

		int tlen= text.length();
		if (start < 0)
			start= 0;
		if (end > tlen)
			end= tlen;

		int tCurPos= start;
		int bound= end - fBound;
		if (bound < 0)
			return false;
		int i= 0;
		String current= fSegments[i];
		int segLength= current.length();

		/* process first segment */
		if (!fHasLeadingStar) {
			if (!regExpRegionMatches(text, start, current, 0, segLength)) {
				return false;
			}
			++i;
			tCurPos= tCurPos + segLength;
		}

		/* process middle segments */
		for (; i < segCount && tCurPos <= bound; ++i) {
			current= fSegments[i];
			int currentMatch;
			int k= current.indexOf(fSingleWildCard);
			if (k < 0) {
				currentMatch= textPosIn(text, tCurPos, end, current);
				if (currentMatch < 0)
					return false;
			} else {
				currentMatch= regExpPosIn(text, tCurPos, end, current);
				if (currentMatch < 0)
					return false;
			}
			tCurPos= currentMatch + current.length();
		}

		/* process final segment */
		if (!fHasTrailingStar && tCurPos != end) {
			int clen= current.length();
			return regExpRegionMatches(text, end - clen, current, 0, clen);
		}
		return i == segCount;
	}
	/**
	 * match the given <code>text</code> with the pattern 
	 * @return true if matched eitherwise false
	 * @param text a String object 
	 */
	public boolean match(String text) {
		return match(text, 0, text.length());
	}
	/**
	 * This method parses the given pattern into segments seperated by wildcard '*' characters.
	 * Since wildcards are not being used in this case, the pattern consists of a single segment.
	 */
	private void parseNoWildCards() {
		fSegments= new String[1];
		fSegments[0]= fPattern;
		fBound= fLength;
	}
	/**
	 *  This method parses the given pattern into segments seperated by wildcard '*' characters.
	 */
	private void parseWildCards() {
		if (fPattern.startsWith("*")) //$NON-NLS-1$
			fHasLeadingStar= true;
		if (fPattern.endsWith("*")) { //$NON-NLS-1$
			/* make sure it's not an escaped wildcard */
			if (fLength > 1 && fPattern.charAt(fLength - 2) != '\\') {
				fHasTrailingStar= true;
			}
		}

		Vector<String> temp= new Vector<String>();

		int pos= 0;
		StringBuffer buf= new StringBuffer();
		while (pos < fLength) {
			char c= fPattern.charAt(pos++);
			switch (c) {
				case '\\' :
					if (pos >= fLength) {
						buf.append(c);
					} else {
						char next= fPattern.charAt(pos++);
						/* if it's an escape sequence */
						if (next == '*' || next == '?' || next == '\\') {
							buf.append(next);
						} else {
							/* not an escape sequence, just insert literally */
							buf.append(c);
							buf.append(next);
						}
					}
					break;
				case '*' :
					if (buf.length() > 0) {
						/* new segment */
						temp.addElement(buf.toString());
						fBound += buf.length();
						buf.setLength(0);
					}
					break;
				case '?' :
					/* append special character representing single match wildcard */
					buf.append(fSingleWildCard);
					break;
				default :
					buf.append(c);
			}
		}

		/* add last buffer to segment list */
		if (buf.length() > 0) {
			temp.addElement(buf.toString());
			fBound += buf.length();
		}

		fSegments= new String[temp.size()];
		temp.copyInto(fSegments);
	}
	/** 
	 * @param text a string which contains no wildcard
	 * @param start the starting index in the text for search, inclusive
	 * @param end the stopping point of search, exclusive
	 * @return the starting index in the text of the pattern , or -1 if not found 
	 */
	protected int posIn(String text, int start, int end) { //no wild card in pattern
		int max= end - fLength;

		if (!fIgnoreCase) {
			int i= text.indexOf(fPattern, start);
			if (i == -1 || i > max)
				return -1;
			return i;
		}

		for (int i= start; i <= max; ++i) {
			if (text.regionMatches(true, i, fPattern, 0, fLength))
				return i;
		}

		return -1;
	}
	/** 
	 * @param text a simple regular expression that may only contain '?'(s)
	 * @param start the starting index in the text for search, inclusive
	 * @param end the stopping point of search, exclusive
	 * @param p a simple regular expression that may contains '?'
	 * @return the starting index in the text of the pattern , or -1 if not found 
	 */
	protected int regExpPosIn(String text, int start, int end, String p) {
		int plen= p.length();

		int max= end - plen;
		for (int i= start; i <= max; ++i) {
			if (regExpRegionMatches(text, i, p, 0, plen))
				return i;
		}
		return -1;
	}

	protected boolean regExpRegionMatches(String text, int tStart, String p, int pStart, int plen) {
		while (plen-- > 0) {
			char tchar= text.charAt(tStart++);
			char pchar= p.charAt(pStart++);

			/* process wild cards */
			if (!fIgnoreWildCards) {
				/* skip single wild cards */
				if (pchar == fSingleWildCard) {
					continue;
				}
			}
			if (pchar == tchar)
				continue;
			if (fIgnoreCase) {
				char tc= Character.toUpperCase(tchar);
				if (tc == pchar)
					continue;
			}
			return false;
		}
		return true;
	}
	/** 
	 * @param text the string to match
	 * @param start the starting index in the text for search, inclusive
	 * @param end the stopping point of search, exclusive
	 * @param p a string that has no wildcard
	 * @return the starting index in the text of the pattern , or -1 if not found 
	 */
	protected int textPosIn(String text, int start, int end, String p) {

		int plen= p.length();
		int max= end - plen;

		if (!fIgnoreCase) {
			int i= text.indexOf(p, start);
			if (i == -1 || i > max)
				return -1;
			return i;
		}

		for (int i= 0; i <= max; ++i) {
			if (text.regionMatches(true, i, p, 0, plen))
				return i;
		}

		return -1;
	}
}
